A long time ago I bought a flexible solar panel (the type you stick on
boats or strap to the boom).
Just to play with.
It is a Uni-Solar 5W(!) panel.

I soon found that you have to have something to stop the panel drawing
current when the sun doesn't shine.
Back in the box for a bit (where a bit is of undefined length).

I'm now thinking of playing with it again and am looking for a simple
controller.

There are loads of apparently different brands on Amazon for around £10
upwards.

https://www.amazon.co.uk/solar-panel...?k=solar+panel
+controller

A remarkable number seem to have the LCD screen, USB ports, buttons etc.
all in identical places which suggests that they may all be one product
(or at least underlying board).

https://www.amazon.com/solar-panel-controller/s?k=solar+panel+controller

seems to show this more markedly.

Does anyone have any experience of these, perhaps enough to make a
recommendation?

Still only playing.

Cheers



Dave R

--
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On 27 Jun 2020 11:41:06 GMT, David wrote:

snip

Does anyone have any experience of these, perhaps enough to make a
recommendation?


Sort of.

Daughter had an electric fence around a rabbit hutch, powered by a 12V
17Ah sealed battery. On every night and if the area wasn't attended (=
my Mum was away g) and the battery would last (safely) over a week.

I added a 5W solar panel and one of the LCD / USB controllers you
mentioned and the battery would then last nearer 3 weeks.

The reason it wasn't more was mainly down to the fact the panel wasn't
anywhere near optimally mounted, in fact it would only be exposed to
any real sunlight for a couple of hours each day.

The real reason for adding the controller was it allowed the electric
fence to run automatically only dusk to dawn and protected the battery
from over discharge.

The 'problem' with any of these controllers and smaller panels is the
parasitic energy they draw to run themselves.

I could have re-orientated the panel, got a bigger panel or put
another panel at the other end of the building (to catch the sun later
in the day) but it was easier to just swap the battery for it's
partner and on an Optimate 2 charge / maintainer.

So, unless you know the overall balance of the system (worst case
energy in V typical energy out) is 'suitable' for your needs and so if
a controller is 'worth it', you may be better off with just an
anti-discharge protection diode.

Whilst a controller is a must to protect a battery from overcharge, if
the panel can deliver more current (and voltage) than the battery
should get once fully charged, the use of one with smaller panels
(where the ability of the panel is offset by the self discharge of the
controller) only really works to protect the battery from over
discharge, ironically, partially caused by the controller itself.

Cheers, T i m

On 27 Jun 2020 11:41:06 GMT, David wrote:

A remarkable number seem to have the LCD screen, USB ports, buttons etc.

Stikes me as a good way to use all the 5W (in bright direct sunlight)
output of the panel, giving no nett benefit...

all in identical places which suggests that they may all be one product
(or at least underlying board).

Wouldn't be surprised, lots of gadgets are based on the same
underlying chipset if not board.

Still only playing.

The "controller" in my small solar panel is nothing more than a
series schotty diode and a self flashing blue LED. When the LED is on
the battery doesn't get charged unless the panel is well illuminated.
Schotty diode as they have less forward volt drop than silicon.

--
Cheers
Dave.

On Saturday, 27 June 2020 12:41:09 UTC+1, David WE Roberts (Google) wrote:
A long time ago I bought a flexible solar panel (the type you stick on
boats or strap to the boom).
Just to play with.
It is a Uni-Solar 5W(!) panel.

I soon found that you have to have something to stop the panel drawing
current when the sun doesn't shine.
Back in the box for a bit (where a bit is of undefined length).

I'm now thinking of playing with it again and am looking for a simple
controller.

There are loads of apparently different brands on Amazon for around £10
upwards.

https://www.amazon.co.uk/solar-panel...?k=solar+panel
+controller

A remarkable number seem to have the LCD screen, USB ports, buttons etc.
all in identical places which suggests that they may all be one product
(or at least underlying board).

https://www.amazon.com/solar-panel-controller/s?k=solar+panel+controller

seems to show this more markedly.

Does anyone have any experience of these, perhaps enough to make a
recommendation?

Still only playing.

Cheers



Dave R

Assuming you're charging a lead acid battery and it's not SLA, 5w is not enough to need a controller. A diode stops any discharge.


NT

On 27/06/2020 12:41:06, David wrote:
A long time ago I bought a flexible solar panel (the type you stick on
boats or strap to the boom).
Just to play with.
It is a Uni-Solar 5W(!) panel.

That won't supply enough power for the controller's backlight.

Simple diode would be best.

On Sat, 27 Jun 2020 07:22:11 -0700 (PDT), wrote:
true

Assuming you're charging a lead acid battery and it's not SLA, 5w is not enough to need a controller. A diode stops any discharge.

True, but it doesn't prevent any overdischarge of the battery?

The trick is to find a LVD solution that doesn't draw any significant
current itself, or find one where the LVD draws far less than any
potential load.

A latching relay / circuit might be such and could be used to
disconnect itself and the load when the LV threshold was detected.

Cheers, T i m

On 27/06/2020 12:41, David wrote:
A long time ago I bought a flexible solar panel (the type you stick on
boats or strap to the boom).
Just to play with.
It is a Uni-Solar 5W(!) panel.

I soon found that you have to have something to stop the panel drawing
current when the sun doesn't shine.

A diode?


--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On Saturday, 27 June 2020 16:05:50 UTC+1, T i m wrote:
On Sat, 27 Jun 2020 07:22:11 -0700 (PDT), tabbypurr wrote:

true

Assuming you're charging a lead acid battery and it's not SLA, 5w is not enough to need a controller. A diode stops any discharge.

True, but it doesn't prevent any overdischarge of the battery?

yees

The trick is to find a LVD solution that doesn't draw any significant
current itself, or find one where the LVD draws far less than any
potential load.

A latching relay / circuit might be such and could be used to
disconnect itself and the load when the LV threshold was detected.

Cheers, T i m

I don't recall the op requesting a discharge protecting relay. If he wants one, I would not regard it as a trick in any way, just some basic electronics. A bistable relay can eliminate most of the current draw. Drive it with a low current opamp, 2 transistors or fets & 2 big caps and Robert's your relative.


NT

On Sat, 27 Jun 2020 10:58:18 -0700 (PDT), wrote:

On Saturday, 27 June 2020 16:05:50 UTC+1, T i m wrote:
On Sat, 27 Jun 2020 07:22:11 -0700 (PDT), tabbypurr wrote:

true

Assuming you're charging a lead acid battery and it's not SLA, 5w is not enough to need a controller. A diode stops any discharge.

True, but it doesn't prevent any overdischarge of the battery?

yees

So not provided by a simple diode.

The trick is to find a LVD solution that doesn't draw any significant
current itself, or find one where the LVD draws far less than any
potential load.

A latching relay / circuit might be such and could be used to
disconnect itself and the load when the LV threshold was detected.


I don't recall the op requesting a discharge protecting relay.

He didn't specifically request a lot of things but did request general
advice.

If he wants one, I would not regard it as a trick in any way, just some basic electronics.

'Basic electronics' that provides the LVD function whilst not
consuming any power itself?

A bistable relay can eliminate most of the current draw.

I know, I suggested it.

Drive it with a low current opamp, 2 transistors or fets & 2 big caps and Robert's your relative.

Schematic? ;-)

The point was, whilst a simple series diode can negate any self
discharge by the panel (and should be built into most panels in any
case), a big hole many fall into is wrecking a perfectly good /
expensive battery by over discharging it. So, it might be considered
'better' to have a less efficient system that protects the battery
than a more efficient one without.

The OP was looking for feedback from people who had experience of the
items he referenced, and I have ... and one of the 'virtues' is that
they typically protect the battery from over discharge.

Cheers, T i m

wrote:
On Saturday, 27 June 2020 16:05:50 UTC+1, T i m wrote:
On Sat, 27 Jun 2020 07:22:11 -0700 (PDT), tabbypurr wrote:

true

Assuming you're charging a lead acid battery and it's not SLA, 5w is not enough to need a controller. A diode stops any discharge.

True, but it doesn't prevent any overdischarge of the battery?

yees

The trick is to find a LVD solution that doesn't draw any significant
current itself, or find one where the LVD draws far less than any
potential load.

A latching relay / circuit might be such and could be used to
disconnect itself and the load when the LV threshold was detected.

Cheers, T i m

I don't recall the op requesting a discharge protecting relay. If he wants one, I would not regard it as a trick in any way, just some basic electronics. A bistable relay can eliminate most of the current draw. Drive it with a low current opamp, 2 transistors or fets & 2 big caps and Robert's your relative.


NT

https://www.briandorey.com/post/low-...-using-max8212

https://datasheets.maximintegrated.c...11-MAX8212.pdf

The leakage current isn't zero, but it's a relatively simple circuit.

The version here is non-recovering, and you press a reset button
after a battery-rundown event. Not very convenient.

https://www.maximintegrated.com/en/d...tes/9/926.html

Paul

On 27/06/2020 22:08, Paul wrote:

https://www.briandorey.com/post/low-...-using-max8212

https://datasheets.maximintegrated.c...11-MAX8212.pdf

The leakage current isn't zero, but it's a relatively simple circuit.

I wonder if it oscillates around the cut off point. 0.3V hysteresis
seems too low.
Battery under load gets to 12.4V and the circuit cuts off the output.
Battery no longer under load and recovers to 12.7V and circuit restores
output.
Battery now under load at 12.4V and ..........

Any circuit that requires a heat sink in such a small enclosed die cast
box is going to run at elevated temperatures. I personally would have
chosen a capacitor temperature rated at 105C




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mailto : news {at} admac {dot} myzen {dot} co {dot} uk

alan_m wrote:
On 27/06/2020 22:08, Paul wrote:

https://www.briandorey.com/post/low-...-using-max8212

https://datasheets.maximintegrated.c...11-MAX8212.pdf

The leakage current isn't zero, but it's a relatively simple circuit.

I wonder if it oscillates around the cut off point. 0.3V hysteresis
seems too low.
Battery under load gets to 12.4V and the circuit cuts off the output.
Battery no longer under load and recovers to 12.7V and circuit restores
output.
Battery now under load at 12.4V and ..........

Any circuit that requires a heat sink in such a small enclosed die cast
box is going to run at elevated temperatures. I personally would have
chosen a capacitor temperature rated at 105C

That would depend on the channel resistance and the load current.
As to what extent it would heat up.

I thought the voltage trip values a bit silly, but using the datasheet,
you can likely adjust it.

A tight hysteresis loop like that, might be intended for cases
where the solar panel cannot provide an infinite amount of power,
the "application" requires motor power at fairly closely
spaced intervals, and so the time to charge is being reduced
a bit. So the thing runs in "spurts".

If you set the hysteresis for the entire battery charging range,
it might take a number of hours for the battery to refill, and
maybe the barrel full of water overflows or something.

I suppose there's a value statement involved here, about what
the output resistance of a battery is. If the battery is elderly,
you might well run into cases where that circuit oscillates.
If the battery is "solid", then it'll be unflappable at low load.

My car battery went from 12.8V to 9V with a 150A load on it.
But I couldn't tell you whether that's a "healthy" battery or not.
4V for 150A. At 25A, that would be 4/6V or 0.66V, which would
run afoul of the tight hysteresis. So maybe a 10A load would be OK.
Even if the circuit had a fuse, we'd have some idea what he
had in mind :-) But there's no fuse. Short the output and
see what that MOSFET can take ???

Paul

On Sat, 27 Jun 2020 23:20:29 +0100, alan_m
wrote:

snip


Any circuit that requires a heat sink in such a small enclosed die cast
box is going to run at elevated temperatures.

And that's enough to suggest to me that it might not be the best
solution, if you are looking to conserve energy?

Cheers, T i m

On Sat, 27 Jun 2020 17:08:27 -0400, Paul
wrote:

snip

https://www.briandorey.com/post/low-...-using-max8212

https://datasheets.maximintegrated.c...11-MAX8212.pdf

The leakage current isn't zero, but it's a relatively simple circuit.

The version here is non-recovering, and you press a reset button
after a battery-rundown event. Not very convenient.

https://www.maximintegrated.com/en/d...tes/9/926.html

The chances are there is something like that built into the charge
controllers you referenced (there certainly was in the one with two
USB outlets as that's the one we used for a couple of years).

I went to turn the electric fence off and found it was already off.
Then I checked to battery voltage (LCD display) and realised why (it
had gone into LVD mode and it hadn't been sunny enough, long enough to
re-trigger it again).

When I was looking for a suitable charge controller (again, really for
the LDV function) I was looking for something 'lightweight' that might
have a correspondingly low parasitic load but couldn't find anything.

The thing is, if the charge to total load capability it's sufficient
to stop the battery flattening in the first place, not having it auto
reset may still be 'better' than destroying a battery?

I have re-cycled too many 'brand new, used a couple of times'
batteries from motorcycles and other roles from lack of maintenance to
know I'd rather avoid that over anything else.

Cheers, T i m

T i m wrote:
On Sat, 27 Jun 2020 23:20:29 +0100, alan_m
wrote:

snip

Any circuit that requires a heat sink in such a small enclosed die cast
box is going to run at elevated temperatures.

And that's enough to suggest to me that it might not be the best
solution, if you are looking to conserve energy?

Cheers, T i m

If you draw high amperage through the switch, you're
not exactly conserving energy.

It's a linear solution.

It operates in its saturated mode (full on), and the losses
are a function of the channel resistance (I^2*R).

https://www.mouser.ca/datasheet/2/38...f55-956481.pdf

Rds-on = 0.018 ohms

At 10 amps, loss = 1.8W, while the load receives 12V*10A = 120W.

In normal situations, the junction capacitance might be a
problem for allowing such a device to switch repetitively
at a high frequency.

In this case, response time isn't particularly a problem.

Paul

On Saturday, 27 June 2020 20:16:24 UTC+1, T i m wrote:
On Sat, 27 Jun 2020 10:58:18 -0700 (PDT), tabbypurr wrote:
On Saturday, 27 June 2020 16:05:50 UTC+1, T i m wrote:
On Sat, 27 Jun 2020 07:22:11 -0700 (PDT), tabbypurr wrote:

true

Assuming you're charging a lead acid battery and it's not SLA, 5w is not enough to need a controller. A diode stops any discharge.

True, but it doesn't prevent any overdischarge of the battery?

yees

So not provided by a simple diode.

ICBA to explain the obvious


The trick is to find a LVD solution that doesn't draw any significant
current itself, or find one where the LVD draws far less than any
potential load.

A latching relay / circuit might be such and could be used to
disconnect itself and the load when the LV threshold was detected.


I don't recall the op requesting a discharge protecting relay.

He didn't specifically request a lot of things but did request general
advice.

If he wants one, I would not regard it as a trick in any way, just some basic electronics.

'Basic electronics' that provides the LVD function whilst not
consuming any power itself?

If you manage to invent electronics tht uses no power I'm sure the world will be curious. Do you have any other silly requests?

A bistable relay can eliminate most of the current draw.

I know, I suggested it.

Drive it with a low current opamp, 2 transistors or fets & 2 big caps and Robert's your relative.

Schematic? ;-)

feel free.

The point was, whilst a simple series diode can negate any self
discharge by the panel (and should be built into most panels in any
case),

There are sound reasons why they aren't. If you run panels in series you don't benefit from multiple V drops. There are also ways to prevent discharge that don't drop a volt or so under load.

a big hole many fall into is wrecking a perfectly good /
expensive battery by over discharging it.

Yes. And some are more careful. And in some situations it's better to run it low on infrequent occasion than cut off early etc.


So, it might be considered
'better' to have a less efficient system that protects the battery
than a more efficient one without.

The OP was looking for feedback from people who had experience of the
items he referenced, and I have ... and one of the 'virtues' is that
they typically protect the battery from over discharge.

Cheers, T i m

It's hard to know what the op wants without enough detail.


NT

On Sun, 28 Jun 2020 12:38:16 -0400, Paul
wrote:

T i m wrote:
On Sat, 27 Jun 2020 23:20:29 +0100, alan_m
wrote:

snip

Any circuit that requires a heat sink in such a small enclosed die cast
box is going to run at elevated temperatures.

And that's enough to suggest to me that it might not be the best
solution, if you are looking to conserve energy?

snip

If you draw high amperage through the switch, you're
not exactly conserving energy.

Well, if that's what you want to do I'm not sure the fact that 'the
switch happens to waste energy (because it's not 100% efficient) is
the issue is it? The issue here was nor wasting *unnecessary* energy
that *isn't* part of the desired load (even if the load itself is
inefficient etc)?

It's a linear solution.

It operates in its saturated mode (full on), and the losses
are a function of the channel resistance (I^2*R).

https://www.mouser.ca/datasheet/2/38...f55-956481.pdf

Rds-on = 0.018 ohms

At 10 amps, loss = 1.8W, while the load receives 12V*10A = 120W.

Then in the absence of a better alternative, that's part of the deal.

In normal situations, the junction capacitance might be a
problem for allowing such a device to switch repetitively
at a high frequency.

In this case, response time isn't particularly a problem.

Quite?

So, the issue is back to ... can you afford to keep replacing
over-discharged (with best case reduced recycle count, worst case
completely ruined (sulphated, if LA) batteries or are you willing to
sacrifice some capacity for their protection? Yes / No.

The alternative would be to do things like:

Cycle the battery manually with a mains charged one every 'n' interval
(where n was fairly constant pre the addition of the controller /
solar panel) V n + x, where x is the time gained as a function of
adding the solar panel?

Monitor the battery voltage manually and remove it before it went
below a safe threshold.

Monitor the battery remotely and remove it (or the load, add the
charger etc) before it became over-discharged.

Ensure the worst case load V charge never goes negative.

Ensure the capacity of the battery is large enough to maintain the
load between instances of sufficient charge (if the load isn't
constant etc).

Cheers, T i m

On Sun, 28 Jun 2020 10:11:50 -0700 (PDT), wrote:

On Saturday, 27 June 2020 20:16:24 UTC+1, T i m wrote:
On Sat, 27 Jun 2020 10:58:18 -0700 (PDT), tabbypurr wrote:
On Saturday, 27 June 2020 16:05:50 UTC+1, T i m wrote:
On Sat, 27 Jun 2020 07:22:11 -0700 (PDT), tabbypurr wrote:

true

Assuming you're charging a lead acid battery and it's not SLA, 5w is not enough to need a controller. A diode stops any discharge.

True, but it doesn't prevent any overdischarge of the battery?

yees

So not provided by a simple diode.

ICBA to explain the obvious

Yeah, right. ;-)


The trick is to find a LVD solution that doesn't draw any significant
current itself, or find one where the LVD draws far less than any
potential load.

A latching relay / circuit might be such and could be used to
disconnect itself and the load when the LV threshold was detected.


I don't recall the op requesting a discharge protecting relay.

He didn't specifically request a lot of things but did request general
advice.

If he wants one, I would not regard it as a trick in any way, just some basic electronics.

'Basic electronics' that provides the LVD function whilst not
consuming any power itself?

If you manage to invent electronics tht uses no power I'm sure the world will be curious.

I wasn't trying to, I was suggesting such didn't exist.

Do you have any other silly requests?

Do you have any other stupid statements (before you dig the hole
deeper and then hiding etc).

A bistable relay can eliminate most of the current draw.

I know, I suggested it.

Drive it with a low current opamp, 2 transistors or fets & 2 big caps and Robert's your relative.

Schematic? ;-)

feel free.

No, you were the one suggesting it was fixable with some 'basic
electronics'? You tell me what they are (before you confirmed such
didn't exist etc).

The point was, whilst a simple series diode can negate any self
discharge by the panel (and should be built into most panels in any
case),

There are sound reasons why they aren't.

I know. I was talking of the sort of panel sold to maintain a 12V
battery.

If you run panels in series you don't benefit from multiple V drops.

Agreed.

There are also ways to prevent discharge that don't drop a volt or so under load.

There are?

a big hole many fall into is wrecking a perfectly good /
expensive battery by over discharging it.

Yes. And some are more careful.

Of course? Duh!

And in some situations it's better to run it low on infrequent occasion than cut off early etc.

Of course ... other than for the lifespan of the battery (with LA
specifically). I'm not sure the OP is thinking on running some life
support kit off this solar panel. ;-)


So, it might be considered
'better' to have a less efficient system that protects the battery
than a more efficient one without.

The OP was looking for feedback from people who had experience of the
items he referenced, and I have ... and one of the 'virtues' is that
they typically protect the battery from over discharge.


It's hard to know what the op wants without enough detail.

Indeed. ;-)

Cheers, T i m

T i m wrote:
On Sun, 28 Jun 2020 12:38:16 -0400, Paul
wrote:

It operates in its saturated mode (full on), and the losses
are a function of the channel resistance (I^2*R).

https://www.mouser.ca/datasheet/2/38...f55-956481.pdf

Rds-on = 0.018 ohms

At 10 amps, loss = 1.8W, while the load receives 12V*10A = 120W.

Then in the absence of a better alternative, that's part of the deal.

If you were obsessed, you could put ten MOSFETs in parallel :-)

And perhaps use a series resistor from the 8212, to limit the
peak current into the gates.

Paul

On Sunday, 28 June 2020 18:49:50 UTC+1, T i m wrote:
On Sun, 28 Jun 2020 10:11:50 -0700 (PDT), tabbypurr wrote:
On Saturday, 27 June 2020 20:16:24 UTC+1, T i m wrote:
On Sat, 27 Jun 2020 10:58:18 -0700 (PDT), tabbypurr wrote:
On Saturday, 27 June 2020 16:05:50 UTC+1, T i m wrote:
On Sat, 27 Jun 2020 07:22:11 -0700 (PDT), tabbypurr wrote:

true

Assuming you're charging a lead acid battery and it's not SLA, 5w is not enough to need a controller. A diode stops any discharge.

True, but it doesn't prevent any overdischarge of the battery?

yees

So not provided by a simple diode.

ICBA to explain the obvious

Yeah, right. ;-)

I refuse to believe you can't figure it out for yourself. And if you can't, life's too short for discussions that stupid. Sorry.

The trick is to find a LVD solution that doesn't draw any significant
current itself, or find one where the LVD draws far less than any
potential load.

A latching relay / circuit might be such and could be used to
disconnect itself and the load when the LV threshold was detected.


I don't recall the op requesting a discharge protecting relay.

He didn't specifically request a lot of things but did request general
advice.

If he wants one, I would not regard it as a trick in any way, just some basic electronics.

'Basic electronics' that provides the LVD function whilst not
consuming any power itself?

If you manage to invent electronics tht uses no power I'm sure the world will be curious.

I wasn't trying to, I was suggesting such didn't exist.

Do you have any other silly requests?

Do you have any other stupid statements (before you dig the hole
deeper and then hiding etc).

I merely pointed out your sudden invention of a new unrealistic imagined requirement was silly. It is.


A bistable relay can eliminate most of the current draw.

I know, I suggested it.

Drive it with a low current opamp, 2 transistors or fets & 2 big caps and Robert's your relative.

Schematic? ;-)

feel free.

No, you were the one suggesting it was fixable with some 'basic
electronics'? You tell me what they are (before you confirmed such
didn't exist etc).

I've given enough info for anyone competent at electronics to go do it. If you want to me give a tutorial for folk that aren't, too bad.


The point was, whilst a simple series diode can negate any self
discharge by the panel (and should be built into most panels in any
case),

There are sound reasons why they aren't.

I know. I was talking of the sort of panel sold to maintain a 12V
battery.

If you run panels in series you don't benefit from multiple V drops.

Agreed.

There are also ways to prevent discharge that don't drop a volt or so under load.

There are?

yes, like FET rectification, or even more basic using a schottky. If you don't know this stuff why are you arguing about electronics?

a big hole many fall into is wrecking a perfectly good /
expensive battery by over discharging it.

Yes. And some are more careful.

Of course? Duh!

And in some situations it's better to run it low on infrequent occasion than cut off early etc.

Of course ... other than for the lifespan of the battery (with LA
specifically). I'm not sure the OP is thinking on running some life
support kit off this solar panel. ;-)

I would seriously hope no-one designing or using life support equipment would be running it off a battery that they let go flat.


So, it might be considered
'better' to have a less efficient system that protects the battery
than a more efficient one without.

The OP was looking for feedback from people who had experience of the
items he referenced, and I have ... and one of the 'virtues' is that
they typically protect the battery from over discharge.


It's hard to know what the op wants without enough detail.

Indeed. ;-)

Cheers, T i m

NT

On Sunday, 28 June 2020 19:13:47 UTC+1, Paul wrote:
T i m wrote:
On Sun, 28 Jun 2020 12:38:16 -0400, Paul
wrote:

It operates in its saturated mode (full on), and the losses
are a function of the channel resistance (I^2*R).

https://www.mouser.ca/datasheet/2/38...f55-956481.pdf

Rds-on = 0.018 ohms

At 10 amps, loss = 1.8W, while the load receives 12V*10A = 120W.

Then in the absence of a better alternative, that's part of the deal.

If you were obsessed, you could put ten MOSFETs in parallel :-)

And perhaps use a series resistor from the 8212, to limit the
peak current into the gates.

Paul

5w at 12v is 0.42A, not 10A. If a FET dissipates 1.8W doing that then you chose the wrong fet.


NT

wrote:
On Sunday, 28 June 2020 19:13:47 UTC+1, Paul wrote:
T i m wrote:
On Sun, 28 Jun 2020 12:38:16 -0400, Paul
wrote:
It operates in its saturated mode (full on), and the losses
are a function of the channel resistance (I^2*R).

https://www.mouser.ca/datasheet/2/38...f55-956481.pdf

Rds-on = 0.018 ohms

At 10 amps, loss = 1.8W, while the load receives 12V*10A = 120W.
Then in the absence of a better alternative, that's part of the deal.
If you were obsessed, you could put ten MOSFETs in parallel :-)

And perhaps use a series resistor from the 8212, to limit the
peak current into the gates.

Paul

5w at 12v is 0.42A, not 10A. If a FET dissipates 1.8W doing that then you chose the wrong fet.


NT

I picked 10A because I don't know what the actual load is.
It was an illustration, using a number picked from the
air for the illustration.

When the designer tested his creation with the light bulb,
that was for test purposes, and wasn't likely to be the
actual load.

Obviously if the load is insignificant, the series element
dissipation is likely to be insignificant as well.

In the illustration, wasting 1.8W compared to 120W isn't too bad.
I have worse linear stuff running in the house right now,
stuff that isn't even close to being that good.

Paul

On Monday, 29 June 2020 02:56:36 UTC+1, Paul wrote:
tabbypurr wrote:
On Sunday, 28 June 2020 19:13:47 UTC+1, Paul wrote:
T i m wrote:
On Sun, 28 Jun 2020 12:38:16 -0400, Paul
wrote:
It operates in its saturated mode (full on), and the losses
are a function of the channel resistance (I^2*R).

https://www.mouser.ca/datasheet/2/38...f55-956481.pdf

Rds-on = 0.018 ohms

At 10 amps, loss = 1.8W, while the load receives 12V*10A = 120W.
Then in the absence of a better alternative, that's part of the deal.
If you were obsessed, you could put ten MOSFETs in parallel :-)

And perhaps use a series resistor from the 8212, to limit the
peak current into the gates.

Paul

5w at 12v is 0.42A, not 10A. If a FET dissipates 1.8W doing that then you chose the wrong fet.


NT

I picked 10A because I don't know what the actual load is.
It was an illustration, using a number picked from the
air for the illustration.

When the designer tested his creation with the light bulb,
that was for test purposes, and wasn't likely to be the
actual load.

Obviously if the load is insignificant, the series element
dissipation is likely to be insignificant as well.

In the illustration, wasting 1.8W compared to 120W isn't too bad.
I have worse linear stuff running in the house right now,
stuff that isn't even close to being that good.

Paul

thing is you can pick whatever series dissipation you want. Naturally the lower it is the more you pay for your fets. But high current very low Rdson fets are readily available now.


NT

On Sun, 28 Jun 2020 16:05:11 -0700 (PDT), wrote:

snip

Assuming you're charging a lead acid battery and it's not SLA, 5w is not enough to need a controller. A diode stops any discharge.

True, but it doesn't prevent any overdischarge of the battery?

yees

So not provided by a simple diode.

ICBA to explain the obvious

Yeah, right. ;-)

I refuse to believe you can't figure it out for yourself.

Of course you do, because you have no idea what I actually know about
this subject because you don't have the means. Stop digging! ;-(

And if you can't, life's too short for discussions that stupid. Sorry.

No need to be sorry. You were the one suggesting a solution could be
found with some 'basic electronics' and I was wondering why you
weren't rich?

snip

No, you were the one suggesting it was fixable with some 'basic
electronics'? You tell me what they are (before you confirmed such
didn't exist etc).

I've given enough info for anyone competent at electronics to go do it.

You think you can mention some components and that forms a solution do
you? How does your imagined solution compare with the internals of the
devices the OP was referencing OOI?

If you want to me give a tutorial for folk that aren't, too bad.

Like you could! ;-)


snip

There are also ways to prevent discharge that don't drop a volt or so under load.

There are?

yes, like FET rectification, or even more basic using a schottky.

Yes, we know that ...

If you don't know this stuff why are you arguing about electronics?

I know it, you don't realise I know it and try to suggest simple
solutions without realising all the real world issues. eg, You 'simple
diode' won't prevent the battery being ruined by being over discharged
and that could be an expensive experiment.

At least a Charge controller will prevent that, even if it's not as
good from a parasitic load POV.

snip

Of course ... other than for the lifespan of the battery (with LA
specifically). I'm not sure the OP is thinking on running some life
support kit off this solar panel. ;-)

I would seriously hope no-one designing or using life support equipment would be running it off a battery that they let go flat.

No, really ... that's what you hope is it ... ;-)


Now, as per the OP's request, what personal experience do you have of
the charge controllers he was asking about and what models have you
used for say, at least 1 year?

Cheers, T i m

On Sun, 28 Jun 2020 14:13:42 -0400, Paul
wrote:

T i m wrote:
On Sun, 28 Jun 2020 12:38:16 -0400, Paul
wrote:

It operates in its saturated mode (full on), and the losses
are a function of the channel resistance (I^2*R).

https://www.mouser.ca/datasheet/2/38...f55-956481.pdf

Rds-on = 0.018 ohms

At 10 amps, loss = 1.8W, while the load receives 12V*10A = 120W.

Then in the absence of a better alternative, that's part of the deal.

If you were obsessed, you could put ten MOSFETs in parallel :-)

;-)

And perhaps use a series resistor from the 8212, to limit the
peak current into the gates.

A 12V 5W (~.5)A should provide enough wetting current to keep some
relay contacts happy and a latching relay might be a 'simpler'
solution to at least protect the battery from over discharge than
anything then needs actively driving.

It could re designed to re-energise the load with a suitably large
hysteresis, if 'battery care' is important.

I know the controller I have had on the panels in the Workshop for the
last 10 years has a very low parasitic load but not insignificant, if
running a battery that matches the rating of the panel and especially
during the winter months.

The battery feeds some low power flouros (sorta emergency /
convenience lighting) and I have left them on by mistake several
times. 'Luckily', the charge controller has a LVD built in but it
still take a log time to get the battery anything like charged again
to be able to support the lights for any time.

Cheers, T i m

On Sun, 28 Jun 2020 21:56:33 -0400, Paul
wrote:

wrote:
On Sunday, 28 June 2020 19:13:47 UTC+1, Paul wrote:
T i m wrote:
On Sun, 28 Jun 2020 12:38:16 -0400, Paul
wrote:
It operates in its saturated mode (full on), and the losses
are a function of the channel resistance (I^2*R).

https://www.mouser.ca/datasheet/2/38...f55-956481.pdf

Rds-on = 0.018 ohms

At 10 amps, loss = 1.8W, while the load receives 12V*10A = 120W.
Then in the absence of a better alternative, that's part of the deal.
If you were obsessed, you could put ten MOSFETs in parallel :-)

And perhaps use a series resistor from the 8212, to limit the
peak current into the gates.

Paul

5w at 12v is 0.42A, not 10A. If a FET dissipates 1.8W doing that then you chose the wrong fet.


NT

I picked 10A because I don't know what the actual load is.
It was an illustration, using a number picked from the
air for the illustration.

Don't worry, our NT is very literal. ;-)

When the designer tested his creation with the light bulb,
that was for test purposes, and wasn't likely to be the
actual load.

;-)

Obviously if the load is insignificant, the series element
dissipation is likely to be insignificant as well.

Yup.

In the illustration, wasting 1.8W compared to 120W isn't too bad.
I have worse linear stuff running in the house right now,
stuff that isn't even close to being that good.

So, now we have ascertained that we will *have* to waste (valuable /
solar generated) energy to prevent damage to the battery from
over-discharge, the issue is how to do that.

Are the commercial charge controller solutions as 'good' when it comes
to any parasitic load then we might be able to come up with ourselves?

If we had something that could sleep for say 5 mins (depending on the
size of the load to the battery capacity (so rate of discharge), and
given no solar charge) and only wake long enough to check the battery
voltage and either toggle the output off or not before sleeping, as
long as the total energy consumed during that cycle was less than the
average of something more linear, then we may have a solution. ;-)

ESP32 / Deep sleep (10uA?)

https://lastminuteengineers.com/esp3...r-consumption/

Cheers, T i m

On Monday, 29 June 2020 12:49:00 UTC+1, T i m wrote:
On Sun, 28 Jun 2020 16:05:11 -0700 (PDT), tabbypurr wrote:

Assuming you're charging a lead acid battery and it's not SLA, 5w is not enough to need a controller. A diode stops any discharge.

True, but it doesn't prevent any overdischarge of the battery?

yees

So not provided by a simple diode.

ICBA to explain the obvious

Yeah, right. ;-)

I refuse to believe you can't figure it out for yourself.

Of course you do, because you have no idea what I actually know about
this subject because you don't have the means. Stop digging! ;-(

what you might know about it is not my concern, and does not change the fact that a person competent in electonics can design something from my brief comment. If you can't I couldn't care less, and I'm not interested in your trolling nonsense. If you knew your stuff you would not be resorting to childishness.


And if you can't, life's too short for discussions that stupid. Sorry.

No need to be sorry. You were the one suggesting a solution could be
found with some 'basic electronics' and I was wondering why you
weren't rich?

I'm not seeing a connection between the 2, and you know jack about my finances.


No, you were the one suggesting it was fixable with some 'basic
electronics'? You tell me what they are (before you confirmed such
didn't exist etc).

I've given enough info for anyone competent at electronics to go do it.

You think you can mention some components and that forms a solution do
you?

I can and did. It is a solution for people that can do the rest. That ought to be obvious. For others, I've no interest in spending however long designing something for them for free. If you object to that go ahead & do it. Otherwise you're a pointless whiner.


How does your imagined solution compare with the internals of the
devices the OP was referencing OOI?

If you want to me give a tutorial for folk that aren't, too bad.

Like you could! ;-)

It's pretty basic stuff. I've already given the outline. And I've written a enough EE teaching material before now.

You seem to have this wacko obsession with the idea that others must be pretending to be something they're not. Clue: I could not give one flying whatsit what you think. You talk so much rubbish that I mostly don't read your posts. What on earth does anyone gain by seeking approval for something they're not? The only sane answer is nothing. Only fools fail to realise that. If you disagree with that I don't care.


There are also ways to prevent discharge that don't drop a volt or so under load.

There are?

yes, like FET rectification, or even more basic using a schottky.

Yes, we know that ...

If you don't know this stuff why are you arguing about electronics?

I know it, you don't realise I know it

given the questions you ask it's not convincing. Who knows.

and try to suggest simple
solutions without realising all the real world issues. eg, You 'simple
diode' won't prevent the battery being ruined by being over discharged
and that could be an expensive experiment.

You've said that over & over. It's stating the bleeding obvious. The diode was never intended to be a low voltage cutoff, as you perfectly well know. It's all that's used in many cases. I don't care what you think about that, it just is.


At least a Charge controller will prevent that, even if it's not as
good from a parasitic load POV.

'not as good' is one way to put it. What is the I_q of your proposed solution? What is the cost? Is it justified to get 5w peak some of the time? We don't even know the op's app or setup yet you seem very keen on your guess as to best solution! If I look at my current uses of lead acids, it would be the best solution for precisely none of them. Your confidence in your guessed opinion is unrealistic.


Of course ... other than for the lifespan of the battery (with LA
specifically). I'm not sure the OP is thinking on running some life
support kit off this solar panel. ;-)

I would seriously hope no-one designing or using life support equipment would be running it off a battery that they let go flat.

No, really ... that's what you hope is it ... ;-)

you're departing from sanity at this point


Now, as per the OP's request, what personal experience do you have of
the charge controllers he was asking about and what models have you
used for say, at least 1 year?

Cheers, T i m

I've worked a fair bit with lead acids, but very little with solar pv. PV has enough issues to make it not a satisfactory solution in most cases. But that really does not address your issue with circuit choices, so is of limited relevance.


NT

On Monday, 29 June 2020 13:16:22 UTC+1, T i m wrote:
On Sun, 28 Jun 2020 21:56:33 -0400, Paul
wrote:
tabbypurr wrote:
On Sunday, 28 June 2020 19:13:47 UTC+1, Paul wrote:
T i m wrote:
On Sun, 28 Jun 2020 12:38:16 -0400, Paul
wrote:
It operates in its saturated mode (full on), and the losses
are a function of the channel resistance (I^2*R).

https://www.mouser.ca/datasheet/2/38...f55-956481.pdf

Rds-on = 0.018 ohms

At 10 amps, loss = 1.8W, while the load receives 12V*10A = 120W.
Then in the absence of a better alternative, that's part of the deal.
If you were obsessed, you could put ten MOSFETs in parallel :-)

And perhaps use a series resistor from the 8212, to limit the
peak current into the gates.

Paul

5w at 12v is 0.42A, not 10A. If a FET dissipates 1.8W doing that then you chose the wrong fet.


NT

I picked 10A because I don't know what the actual load is.
It was an illustration, using a number picked from the
air for the illustration.

Don't worry, our NT is very literal. ;-)

When the designer tested his creation with the light bulb,
that was for test purposes, and wasn't likely to be the
actual load.

;-)

Obviously if the load is insignificant, the series element
dissipation is likely to be insignificant as well.

Yup.

In the illustration, wasting 1.8W compared to 120W isn't too bad.
I have worse linear stuff running in the house right now,
stuff that isn't even close to being that good.

So, now we have ascertained that we will *have* to waste (valuable /
solar generated) energy to prevent damage to the battery from
over-discharge, the issue is how to do that.

you have come nowhere remotely near establishing that. You are not a good engineer.


Are the commercial charge controller solutions as 'good' when it comes
to any parasitic load then we might be able to come up with ourselves?

If we had something that could sleep for say 5 mins (depending on the
size of the load to the battery capacity (so rate of discharge), and
given no solar charge) and only wake long enough to check the battery
voltage and either toggle the output off or not before sleeping, as
long as the total energy consumed during that cycle was less than the
average of something more linear, then we may have a solution. ;-)

ESP32 / Deep sleep (10uA?)

https://lastminuteengineers.com/esp3...r-consumption/

Cheers, T i m

So are you actually proposing using an ESP32 to cut the battery off at low voltage?

"At the heart of the ESP32 chip is a Dual-Core 32-bit microprocessor along with 448 KB of ROM, 520 KB of SRAM and 4MB of Flash memory.

It also contains WiFi module, Bluetooth Module, Cryptographic Accelerator (a co-processor designed specifically to perform cryptographic operations), the RTC module, and lot of peripherals."

If so, you're lost in space.


NT

On Mon, 29 Jun 2020 05:54:04 -0700 (PDT), wrote:

snip crazy ranting

I've worked a fair bit with lead acids,

Same here (ignoring the PEV I've had for 30 years that uses them).
JOOI, I can probably lay my hands on 20+ lead acid batteries within 10
paces from here.

but very little with solar pv.

I guessed.

PV has enough issues to make it not a satisfactory solution in most cases.

Agreed. But not the question raised here.

But that really does not address your issue with circuit choices, so is of limited relevance.

My 'circuit choices' (and by that your mean potentially the OP's, as
he was asking about charge controllers and people who had *experience*
of them) ... included full consideration of the OP's overall question,
so it's *totally* relevant.

So, again, if *your* basic electronics suggestion can beat the
parasitic drain of any of the charge controllers you are familiar with
and are commercially available, I'm sure the OP (and electronics
industry) would be interested to hear about them?

And why wouldn't you be happy to show the world how clever you were?

Cheers, T i m

On Mon, 29 Jun 2020 05:59:22 -0700 (PDT), wrote:

snip

So, now we have ascertained that we will *have* to waste (valuable /
solar generated) energy to prevent damage to the battery from
over-discharge, the issue is how to do that.

you have come nowhere remotely near establishing that.

It's a fact mate. I'd stop digging if I were you.

You are not a good engineer.

I'm not 'an engineer', I'm an electronics / datacoms service tech (by
training).


Are the commercial charge controller solutions as 'good' when it comes
to any parasitic load then we might be able to come up with ourselves?

If we had something that could sleep for say 5 mins (depending on the
size of the load to the battery capacity (so rate of discharge), and
given no solar charge) and only wake long enough to check the battery
voltage and either toggle the output off or not before sleeping, as
long as the total energy consumed during that cycle was less than the
average of something more linear, then we may have a solution. ;-)

ESP32 / Deep sleep (10uA?)

https://lastminuteengineers.com/esp3...r-consumption/

Cheers, T i m

So are you actually proposing using an ESP32 to cut the battery off at low voltage?

Nope, I'm considering the use of one to manage a latching relay to do
that (and potentially many other things that could be handy in such
circumstances).

"At the heart of the ESP32 chip is a Dual-Core 32-bit microprocessor along with 448 KB of ROM, 520 KB of SRAM and 4MB of Flash memory.

It also contains WiFi module, Bluetooth Module, Cryptographic Accelerator (a co-processor designed specifically to perform cryptographic operations), the RTC module, and lot of peripherals."

Very good, at least you can copy and paste. Now, do you actually
*have* an ESP32 there OOI and if so, what have you used it for so far?

If so, you're lost in space.

And you are still so literal / difficult / stubborn that you are
missing the bigger picture.

How many uA would your proposed 'basic electronics' LVD solution draw?
I mean, even if you don't want to show the schematic here (to help
others) you could give us the value?

Answer that or STFU.

Cheers, T i m

On Monday, 29 June 2020 14:41:49 UTC+1, T i m wrote:
On Mon, 29 Jun 2020 05:54:04 -0700 (PDT), tabbypurr wrote:


But that really does not address your issue with circuit choices, so is of limited relevance.

My 'circuit choices' (and by that your mean potentially the OP's, as
he was asking about charge controllers and people who had *experience*
of them)

no, it's your choices I take issue with


... included full consideration of the OP's overall question,
so it's *totally* relevant.

not to the question of preventing discharge into the PV panel. You specifically objected to a diode not doing other things which were not requested, and which you clearly have no clue whether are wanted or needed.


So, again, if *your* basic electronics suggestion can beat the
parasitic drain of any of the charge controllers you are familiar with
and are commercially available, I'm sure the OP (and electronics
industry) would be interested to hear about them?

If the op has been reading this thread they've already heard it.

And why wouldn't you be happy to show the world how clever you were?

Cheers, T i m

With all due respect
1. A suggestion of a simple circuit has nothing to do with my level of cleverness
2. I've already made clear that I don't intend to spend a bunch of time for nothing
3. you're simply wasting time


NT

On Monday, 29 June 2020 14:49:20 UTC+1, T i m wrote:
On Mon, 29 Jun 2020 05:59:22 -0700 (PDT), tabbypurr wrote:

So, now we have ascertained that we will *have* to waste (valuable /
solar generated) energy to prevent damage to the battery from
over-discharge, the issue is how to do that.

you have come nowhere remotely near establishing that.

It's a fact mate. I'd stop digging if I were you.

It's nowhere remotely close to a fact. I've already explained why.


You are not a good engineer.

I'm not 'an engineer', I'm an electronics / datacoms service tech (by
training).

OK this explains some. I AM a qualified EE. And I would seriously hope I've come a very long way from the kind of 101 stuff we had to do for that degree.


Are the commercial charge controller solutions as 'good' when it comes
to any parasitic load then we might be able to come up with ourselves?

If we had something that could sleep for say 5 mins (depending on the
size of the load to the battery capacity (so rate of discharge), and
given no solar charge) and only wake long enough to check the battery
voltage and either toggle the output off or not before sleeping, as
long as the total energy consumed during that cycle was less than the
average of something more linear, then we may have a solution. ;-)

ESP32 / Deep sleep (10uA?)

https://lastminuteengineers.com/esp3...r-consumption/

Cheers, T i m

So are you actually proposing using an ESP32 to cut the battery off at low voltage?

Nope, I'm considering the use of one to manage a latching relay to do
that (and potentially many other things that could be handy in such
circumstances).

so yes, you do want to use an ESP32 with the specs of yesterday's desktop computer to control a voltage threshold! That's just insanity.


"At the heart of the ESP32 chip is a Dual-Core 32-bit microprocessor along with 448 KB of ROM, 520 KB of SRAM and 4MB of Flash memory.

It also contains WiFi module, Bluetooth Module, Cryptographic Accelerator (a co-processor designed specifically to perform cryptographic operations), the RTC module, and lot of peripherals."

Very good, at least you can copy and paste.

And can see this is wildly far from what is appropriate or even relevant to use for a LV cutoff.


Now, do you actually
*have* an ESP32 there OOI and if so, what have you used it for so far?

no, and that fact is of zero relevance. Don't pretend it is.


If so, you're lost in space.

And you are still so literal / difficult / stubborn that you are
missing the bigger picture.

How many uA would your proposed 'basic electronics' LVD solution draw?
I mean, even if you don't want to show the schematic here (to help
others) you could give us the value?

Answer that or STFU.

Cheers, T i m

Lol. OK so you think parasitic draw or I_q is the bigger picture. What I_q what I proposed uses depends on the comparator (or opamp) used. Take your pick. I would however point out that whether a cutout circuit uses 1uA, 10uA or 100uA is utterly irrelevant in this situation.


NT