One of mine has gone flat, and won't charge with the supplied charger.
Turns out not to be too difficult to strip; four concealed screws, a
clipped-together case that needs to be forced quite firmly, and WD40
applied to the sticky foam that holds the battery pack into the case.

As I think TNP guessed in a previous discussion, these contain three
cells in series for the main "jump start" supply. There's also a
switched mode power supply that provides the various higher voltages
required for laptops, as well as the supplies to the "torch" and the
"emergency flashing red" LEDs. No *obvious* sign of why it won't charge.

It turns out that the batteries can be charged directly through the big
"battery clips", and it is currently sitting on my desk being fed from a
small (half amp max) lab power supply. It was taking 300 mA but has now
dropped to about 150 for some reason. Supply is giving about 10.5 volts.
For obvious reasons I am being gentle with the batteries, not using a
car battery charger for example! But as they are about 125 x 45 mm and
the stack is 20 mm thick I can't believe that half an amp will bother them.

It looks rather like one of these

https://www.amazon.co.uk/Starter-dis...n+jump+starter

although mine claims 18000 mA-h and 600 amp peak, but only has one USB
socket.

On Thu, 28 Sep 2017 18:54:06 +0100, newshound
wrote:

One of mine has gone flat, and won't charge with the supplied charger.
Turns out not to be too difficult to strip; four concealed screws, a
clipped-together case that needs to be forced quite firmly, and WD40
applied to the sticky foam that holds the battery pack into the case.

As I think TNP guessed in a previous discussion, these contain three
cells in series for the main "jump start" supply. There's also a
switched mode power supply that provides the various higher voltages
required for laptops, as well as the supplies to the "torch" and the
"emergency flashing red" LEDs. No *obvious* sign of why it won't charge.

It turns out that the batteries can be charged directly through the big
"battery clips", and it is currently sitting on my desk being fed from a
small (half amp max) lab power supply. It was taking 300 mA but has now
dropped to about 150 for some reason. Supply is giving about 10.5 volts.
For obvious reasons I am being gentle with the batteries, not using a
car battery charger for example! But as they are about 125 x 45 mm and
the stack is 20 mm thick I can't believe that half an amp will bother them.

It looks rather like one of these

https://www.amazon.co.uk/Starter-dis...n+jump+starter

although mine claims 18000 mA-h and 600 amp peak, but only has one USB
socket.

I beleive that it can be dangerous to attempt to recharge a Lithium
Ion cell if the cell voltage has fallen below a threashold value. It
may be that the charging circuit has detected an under volt condition
and refused to charge the cell because of that.

On Thu, 28 Sep 2017 18:54:06 +0100, newshound wrote:

One of mine has gone flat, and won't charge with the supplied charger.
Turns out not to be too difficult to strip; four concealed screws, a
clipped-together case that needs to be forced quite firmly, and WD40
applied to the sticky foam that holds the battery pack into the case.

Mine needs to be switched on with it's on/off switch before it will
charge.

It turns out that the batteries can be charged directly through the big
"battery clips", and it is currently sitting on my desk being fed from a
small (half amp max) lab power supply. It was taking 300 mA but has now
dropped to about 150 for some reason. Supply is giving about 10.5 volts.
For obvious reasons I am being gentle with the batteries, not using a
car battery charger for example! But as they are about 125 x 45 mm and
the stack is 20 mm thick I can't believe that half an amp will bother them.

They are lithium, if you don't charge them correctly they have a
tendancy to explode and if you overcharge them they will burst into
flames.

--
Faster, cheaper, quieter than HS2
and built in 5 years;
UKUltraspeed http://www.500kmh.com/

In article ,
newshound writes:
One of mine has gone flat, and won't charge with the supplied charger.
Turns out not to be too difficult to strip; four concealed screws, a
clipped-together case that needs to be forced quite firmly, and WD40
applied to the sticky foam that holds the battery pack into the case.

As I think TNP guessed in a previous discussion, these contain three
cells in series for the main "jump start" supply. There's also a
switched mode power supply that provides the various higher voltages
required for laptops, as well as the supplies to the "torch" and the
"emergency flashing red" LEDs. No *obvious* sign of why it won't charge.

It turns out that the batteries can be charged directly through the big
"battery clips", and it is currently sitting on my desk being fed from a
small (half amp max) lab power supply. It was taking 300 mA but has now
dropped to about 150 for some reason. Supply is giving about 10.5 volts.
For obvious reasons I am being gentle with the batteries, not using a
car battery charger for example! But as they are about 125 x 45 mm and
the stack is 20 mm thick I can't believe that half an amp will bother them.

You need to check the voltage on each cell.
If one cell has died, you may be over charging the others, which
risks turning them into a giant firework.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

(Andrew Gabriel) Wrote in message:
In article ,
newshound writes:
One of mine has gone flat, and won't charge with the supplied charger.
Turns out not to be too difficult to strip; four concealed screws, a
clipped-together case that needs to be forced quite firmly, and WD40
applied to the sticky foam that holds the battery pack into the case.

As I think TNP guessed in a previous discussion, these contain three
cells in series for the main "jump start" supply. There's also a
switched mode power supply that provides the various higher voltages
required for laptops, as well as the supplies to the "torch" and the
"emergency flashing red" LEDs. No *obvious* sign of why it won't charge.

It turns out that the batteries can be charged directly through the big
"battery clips", and it is currently sitting on my desk being fed from a
small (half amp max) lab power supply. It was taking 300 mA but has now
dropped to about 150 for some reason. Supply is giving about 10.5 volts.
For obvious reasons I am being gentle with the batteries, not using a
car battery charger for example! But as they are about 125 x 45 mm and
the stack is 20 mm thick I can't believe that half an amp will bother them.

You need to check the voltage on each cell.
If one cell has died, you may be over charging the others, which
risks turning them into a giant firework.


Prophetic words?
--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

On 28/09/2017 20:10, Andrew Gabriel wrote:
In article ,
newshound writes:
One of mine has gone flat, and won't charge with the supplied charger.
Turns out not to be too difficult to strip; four concealed screws, a
clipped-together case that needs to be forced quite firmly, and WD40
applied to the sticky foam that holds the battery pack into the case.

As I think TNP guessed in a previous discussion, these contain three
cells in series for the main "jump start" supply. There's also a
switched mode power supply that provides the various higher voltages
required for laptops, as well as the supplies to the "torch" and the
"emergency flashing red" LEDs. No *obvious* sign of why it won't charge.

It turns out that the batteries can be charged directly through the big
"battery clips", and it is currently sitting on my desk being fed from a
small (half amp max) lab power supply. It was taking 300 mA but has now
dropped to about 150 for some reason. Supply is giving about 10.5 volts.
For obvious reasons I am being gentle with the batteries, not using a
car battery charger for example! But as they are about 125 x 45 mm and
the stack is 20 mm thick I can't believe that half an amp will bother them.

You need to check the voltage on each cell.
If one cell has died, you may be over charging the others, which
risks turning them into a giant firework.

Noted, thanks! I wasn't planning to leave them unattended while
experimenting.

With it stripped, I have access to each battery terminal. Wikipedia
suggests that the safe maximum cell voltage is 4.2V, is that correct?

After a little bit of charging, the cells are currently showing 3.72,
3.73, and 3.71 volts. There's a little "floating" circuit board which,
to judge by the layout and wire colours, takes the charging current as
input, and has charging wires going to each end of the stack with sensor
wires to the intermediate junctions. This must be the "safety" circuit,
tomorrow I will check whether that has gone open circuit.

I can live without the other features of the unit, if the safety circuit
looks OK I might just rewire it direct to the charging socket, and dump
the control board which does all the other stuff. (I don't normally use
it for jump starting, I use it to power CCTV).

newshound Wrote in message:
One of mine has gone flat, and won't charge with the supplied charger.
Turns out not to be too difficult to strip; four concealed screws, a
clipped-together case that needs to be forced quite firmly, and WD40
applied to the sticky foam that holds the battery pack into the case.

As I think TNP guessed in a previous discussion, these contain three
cells in series for the main "jump start" supply. There's also a
switched mode power supply that provides the various higher voltages
required for laptops, as well as the supplies to the "torch" and the
"emergency flashing red" LEDs. No *obvious* sign of why it won't charge.

It turns out that the batteries can be charged directly through the big
"battery clips", and it is currently sitting on my desk being fed from a
small (half amp max) lab power supply. It was taking 300 mA but has now
dropped to about 150 for some reason. Supply is giving about 10.5 volts.
For obvious reasons I am being gentle with the batteries, not using a
car battery charger for example! But as they are about 125 x 45 mm and
the stack is 20 mm thick I can't believe that half an amp will bother them.

It looks rather like one of these

https://www.amazon.co.uk/Starter-dis...n+jump+starter

although mine claims 18000 mA-h and 600 amp peak, but only has one USB
socket.


As you don't use most of its features why not a cheaper one?
--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

On 28/09/2017 21:38, jim wrote:
newshound Wrote in message:
One of mine has gone flat, and won't charge with the supplied charger.
Turns out not to be too difficult to strip; four concealed screws, a
clipped-together case that needs to be forced quite firmly, and WD40
applied to the sticky foam that holds the battery pack into the case.

As I think TNP guessed in a previous discussion, these contain three
cells in series for the main "jump start" supply. There's also a
switched mode power supply that provides the various higher voltages
required for laptops, as well as the supplies to the "torch" and the
"emergency flashing red" LEDs. No *obvious* sign of why it won't charge.

It turns out that the batteries can be charged directly through the big
"battery clips", and it is currently sitting on my desk being fed from a
small (half amp max) lab power supply. It was taking 300 mA but has now
dropped to about 150 for some reason. Supply is giving about 10.5 volts.
For obvious reasons I am being gentle with the batteries, not using a
car battery charger for example! But as they are about 125 x 45 mm and
the stack is 20 mm thick I can't believe that half an amp will bother them.

It looks rather like one of these

https://www.amazon.co.uk/Starter-dis...n+jump+starter

although mine claims 18000 mA-h and 600 amp peak, but only has one USB
socket.


As you don't use most of its features why not a cheaper one?

Such as? In any case, I already have this, if I can fix it.

On 28/09/2017 21:38, jim wrote:
newshound Wrote in message:
One of mine has gone flat, and won't charge with the supplied charger.
Turns out not to be too difficult to strip; four concealed screws, a
clipped-together case that needs to be forced quite firmly, and WD40
applied to the sticky foam that holds the battery pack into the case.

As I think TNP guessed in a previous discussion, these contain three
cells in series for the main "jump start" supply. There's also a
switched mode power supply that provides the various higher voltages
required for laptops, as well as the supplies to the "torch" and the
"emergency flashing red" LEDs. No *obvious* sign of why it won't charge.

It turns out that the batteries can be charged directly through the big
"battery clips", and it is currently sitting on my desk being fed from a
small (half amp max) lab power supply. It was taking 300 mA but has now
dropped to about 150 for some reason. Supply is giving about 10.5 volts.
For obvious reasons I am being gentle with the batteries, not using a
car battery charger for example! But as they are about 125 x 45 mm and
the stack is 20 mm thick I can't believe that half an amp will bother them.

It looks rather like one of these

https://www.amazon.co.uk/Starter-dis...n+jump+starter

although mine claims 18000 mA-h and 600 amp peak, but only has one USB
socket.


As you don't use most of its features why not a cheaper one?


Like a car battery?

On 28-Sep-17 9:28 PM, newshound wrote:
On 28/09/2017 20:10, Andrew Gabriel wrote:
In article ,
Â*Â*Â*Â*newshound writes:
One of mine has gone flat, and won't charge with the supplied charger.
Turns out not to be too difficult to strip; four concealed screws, a
clipped-together case that needs to be forced quite firmly, and WD40
applied to the sticky foam that holds the battery pack into the case.

As I think TNP guessed in a previous discussion, these contain three
cells in series for the main "jump start" supply. There's also a
switched mode power supply that provides the various higher voltages
required for laptops, as well as the supplies to the "torch" and the
"emergency flashing red" LEDs. No *obvious* sign of why it won't charge.

It turns out that the batteries can be charged directly through the big
"battery clips", and it is currently sitting on my desk being fed from a
small (half amp max) lab power supply. It was taking 300 mA but has now
dropped to about 150 for some reason. Supply is giving about 10.5 volts.
For obvious reasons I am being gentle with the batteries, not using a
car battery charger for example! But as they are about 125 x 45 mm and
the stack is 20 mm thick I can't believe that half an amp will bother
them.

You need to check the voltage on each cell.
If one cell has died, you may be over charging the others, which
risks turning them into a giant firework.

Noted, thanks! I wasn't planning to leave them unattended while
experimenting.

With it stripped, I have access to each battery terminal. Wikipedia
suggests that the safe maximum cell voltage is 4.2V, is that correct?

After a little bit of charging, the cells are currently showing 3.72,
3.73, and 3.71 volts. There's a little "floating" circuit board which,
to judge by the layout and wire colours, takes the charging current as
input, and has charging wires going to each end of the stack with sensor
wires to the intermediate junctions. This must be the "safety" circuit,
tomorrow I will check whether that has gone open circuit.

I can live without the other features of the unit, if the safety circuit
looks OK I might just rewire it direct to the charging socket, and dump
the control board which does all the other stuff. (I don't normally use
it for jump starting, I use it to power CCTV).

I had a blinding CREE LED 1800Lm bike lamp with 2s2p battery pack. I
swear it was as bright as a Cibie motorcycle halogen headlamp (the sort
with a concave lens). Then after about a year and maybe 100 uses the
battery pack stopped working, it was the PCM module. I bought a 2nd
battery but it's blown the PCM in that up as well. It seems something
has happened in the CREE LED lamp so it now draws too much current. So
now I have a somewhat less blinding replacement 1200Lm LED lamp.

On Thu, 28 Sep 2017 21:28:37 +0100, newshound
wrote:

snip

With it stripped, I have access to each battery terminal. Wikipedia
suggests that the safe maximum cell voltage is 4.2V, is that correct?

I believe it is (for Li-Po) but could be considered as an absolute
maximum (like a speed limit). If you charge to a lower and discharge
to a higher-than maximum voltage(s) you can both minimise the risk to
(and from) ... and increase the life (cycles) of such batteries.

After a little bit of charging, the cells are currently showing 3.72,
3.73, and 3.71 volts.

Standard procedure to see if you are likely to be at a risk from
potentially faulty / neglected cells is to charge them all to a safe
voltage (say 4vpc), leave them for a week and see how much they have
(self) discharged by. If it's not a lot and equal across all the cells
then the chances they are ok.

There's a little "floating" circuit board which,
to judge by the layout and wire colours, takes the charging current as
input, and has charging wires going to each end of the stack with sensor
wires to the intermediate junctions. This must be the "safety" circuit,

They are generally referred to as the / a 'Battery Management System'.
They both monitor the charge and 'hold back any cells getting close to
the maximum voltage to ensure they don't become overcharged whilst
also both disconnecting the load once any cell has reached the 'low'
voltage threshold and might (also as mentioned elsewhere) 'protect'
the battery from being charged at all, once it goes below a very low
voltage threshold (for the reasons stated above [1]).

tomorrow I will check whether that has gone open circuit.

I'm not sure how you will do that without a variable PSU plus your DMM
etc?

I can live without the other features of the unit, if the safety circuit
looks OK I might just rewire it direct to the charging socket, and dump
the control board which does all the other stuff. (I don't normally use
it for jump starting, I use it to power CCTV).

Many people (mostly RC / aero moddlers) go without the BMS becuse:

It would have to manage very high currents.
It would add weight.
They use a low voltage alarm that (ideally) monitors each cell.
They use a sophisticated charger with a 'balance lead' / function for
bench charging.

Also as mentioned elsewhere, be areful with them as they can go off
like a firework (check Youtube for 'Li-po fires' and see howm may
'fire protection' charging bags and boxes you can get for Lithium
batteries and what levels many manufacturers of commercoial / domestic
packs go to to minise the risks (non resettable fuses to prevent
re-charging over discharged batteries and mutiple temperature sensors
etc).

Cheers, T i m

[1] I believe the risks from internal self destruction are because
large sharp crystals can grow under certain circumstances and punture
the internal insulators (or somesuch).

On Thu, 28 Sep 2017 21:28:37 +0100, newshound wrote:

After a little bit of charging, the cells are currently showing 3.72,
3.73, and 3.71 volts. There's a little "floating" circuit board which,
to judge by the layout and wire colours, takes the charging current as
input, and has charging wires going to each end of the stack with sensor
wires to the intermediate junctions. This must be the "safety" circuit,
tomorrow I will check whether that has gone open circuit.

It's probably the charger, one for each cell. They manage each cell
separately so that none can get reverse polarised. Didn't you see the
burning Sony laptops on the news a couple of years ago? You would be
much safer simply replacing it. Keeping an eye on it won't really help
because the first thing you notice will be it roaring into flames!

--
Faster, cheaper, quieter than HS2
and built in 5 years;
UKUltraspeed http://www.500kmh.com/

Depends on the construction. Often if one has already go an internal short
then its almost impossible to blow it up as it will not charge enough.
However depends on how they are charged, ie, I seem to recall the cells are
monitored completely seperately to stop overchaarging ones fully charged if
one is shorted internally.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"rp" wrote in message
ohit.me.uk...
On Thu, 28 Sep 2017 18:54:06 +0100, newshound wrote:

One of mine has gone flat, and won't charge with the supplied charger.
Turns out not to be too difficult to strip; four concealed screws, a
clipped-together case that needs to be forced quite firmly, and WD40
applied to the sticky foam that holds the battery pack into the case.

Mine needs to be switched on with it's on/off switch before it will
charge.

It turns out that the batteries can be charged directly through the big
"battery clips", and it is currently sitting on my desk being fed from a
small (half amp max) lab power supply. It was taking 300 mA but has now
dropped to about 150 for some reason. Supply is giving about 10.5 volts.
For obvious reasons I am being gentle with the batteries, not using a
car battery charger for example! But as they are about 125 x 45 mm and
the stack is 20 mm thick I can't believe that half an amp will bother
them.

They are lithium, if you don't charge them correctly they have a
tendancy to explode and if you overcharge them they will burst into
flames.

--
Faster, cheaper, quieter than HS2
and built in 5 years;
UKUltraspeed http://www.500kmh.com/

On 29-Sep-17 6:11 AM, rp wrote:
On Thu, 28 Sep 2017 21:28:37 +0100, newshound wrote:

After a little bit of charging, the cells are currently showing 3.72,
3.73, and 3.71 volts. There's a little "floating" circuit board which,
to judge by the layout and wire colours, takes the charging current as
input, and has charging wires going to each end of the stack with sensor
wires to the intermediate junctions. This must be the "safety" circuit,
tomorrow I will check whether that has gone open circuit.

It's probably the charger, one for each cell. They manage each cell
separately so that none can get reverse polarised. Didn't you see the
burning Sony laptops on the news a couple of years ago? You would be
much safer simply replacing it. Keeping an eye on it won't really help
because the first thing you notice will be it roaring into flames!


2 series 2 parallel PCM only has 3 connections to batteries. Ground, mid
and full voltage. Only the series battery voltage is monitored and
controls charging. The individual cells of a parallel pair isn't controlled.

http://www.ebay.com/itm/2S2P-18650-7...-/220642512136

On Fri, 29 Sep 2017 06:11:40 +0100 (BST), "rp"
wrote:

snip

It's probably the charger, one for each cell. They manage each cell
separately so that none can get reverse polarised.

I'd say they manage each cell to stop it way before anything like
being reverse polarised, eg, even going below 3Vpc for example.

Cheers, T i m

On 28/09/2017 23:38, MrCheerful wrote:
On 28/09/2017 21:38, jim wrote:
newshound Wrote in message:
One of mine has gone flat, and won't charge with the supplied charger.
Turns out not to be too difficult to strip; four concealed screws, a
clipped-together case that needs to be forced quite firmly, and WD40
applied to the sticky foam that holds the battery pack into the case.

As I think TNP guessed in a previous discussion, these contain three
cells in series for the main "jump start" supply. There's also a
switched mode power supply that provides the various higher voltages
required for laptops, as well as the supplies to the "torch" and the
"emergency flashing red" LEDs. No *obvious* sign of why it won't charge.

It turns out that the batteries can be charged directly through the big
"battery clips", and it is currently sitting on my desk being fed from a
small (half amp max) lab power supply. It was taking 300 mA but has now
dropped to about 150 for some reason. Supply is giving about 10.5 volts.
For obvious reasons I am being gentle with the batteries, not using a
car battery charger for example! But as they are about 125 x 45 mm and
the stack is 20 mm thick I can't believe that half an amp will bother
them.

It looks rather like one of these

https://www.amazon.co.uk/Starter-dis...n+jump+starter


although mine claims 18000 mA-h and 600 amp peak, but only has one USB
socket.


As you don't use most of its features why not a cheaper one?


Like a car battery?

Partly the capacity/weight relationship. I could use a motorcycle or
stairlift type battery, but one nice thing about this is that it slips
into the DIN-slot sized storage pocket. I've used lead acid gel
batteries for other things (like horse clippers) but same argument
applies, it's worth paying a bit more for a lighter high capacity
battery (as long as it lasts a reasonable time).

On 29/09/2017 01:17, T i m wrote:
On Thu, 28 Sep 2017 21:28:37 +0100, newshound
wrote:

snip

With it stripped, I have access to each battery terminal. Wikipedia
suggests that the safe maximum cell voltage is 4.2V, is that correct?

I believe it is (for Li-Po) but could be considered as an absolute
maximum (like a speed limit). If you charge to a lower and discharge
to a higher-than maximum voltage(s) you can both minimise the risk to
(and from) ... and increase the life (cycles) of such batteries.

After a little bit of charging, the cells are currently showing 3.72,
3.73, and 3.71 volts.

Standard procedure to see if you are likely to be at a risk from
potentially faulty / neglected cells is to charge them all to a safe
voltage (say 4vpc), leave them for a week and see how much they have
(self) discharged by. If it's not a lot and equal across all the cells
then the chances they are ok.

Thanks, very helpful tip. I've got enough DVMs lying around to be able
to build a charge/discharge setup measuring the voltage of each cell.
Might even get some of these

http://www.ebay.co.uk/itm/New-Mini-D...19.m1438.l2649


There's a little "floating" circuit board which,
to judge by the layout and wire colours, takes the charging current as
input, and has charging wires going to each end of the stack with sensor
wires to the intermediate junctions. This must be the "safety" circuit,

They are generally referred to as the / a 'Battery Management System'.
They both monitor the charge and 'hold back any cells getting close to
the maximum voltage to ensure they don't become overcharged whilst
also both disconnecting the load once any cell has reached the 'low'
voltage threshold and might (also as mentioned elsewhere) 'protect'
the battery from being charged at all, once it goes below a very low
voltage threshold (for the reasons stated above [1]).

tomorrow I will check whether that has gone open circuit.

I'm not sure how you will do that without a variable PSU plus your DMM
etc?

That's exactly how I'll do it.


I can live without the other features of the unit, if the safety circuit
looks OK I might just rewire it direct to the charging socket, and dump
the control board which does all the other stuff. (I don't normally use
it for jump starting, I use it to power CCTV).

Many people (mostly RC / aero moddlers) go without the BMS becuse:

It would have to manage very high currents.
It would add weight.
They use a low voltage alarm that (ideally) monitors each cell.
They use a sophisticated charger with a 'balance lead' / function for
bench charging.

Also as mentioned elsewhere, be areful with them as they can go off
like a firework (check Youtube for 'Li-po fires' and see howm may
'fire protection' charging bags and boxes you can get for Lithium
batteries and what levels many manufacturers of commercoial / domestic
packs go to to minise the risks (non resettable fuses to prevent
re-charging over discharged batteries and mutiple temperature sensors
etc).

Oh I will, I am fairly used to being around dangerous stuff. High
voltages or currents, various nasty chemicals. Radioactive sources. Not
so much experience with pyrotechnics, but in truth for an uncontained
laptop battery the risk is temperature and smoke, as long as it is away
from people and anything else inflammable.


Cheers, T i m

[1] I believe the risks from internal self destruction are because
large sharp crystals can grow under certain circumstances and punture
the internal insulators (or somesuch).


If it does look like it is recoverable, I will give it a few cycles in a
safe environment, and relegate it to jump starting duty.

On 28/09/2017 18:54, newshound wrote:

No *obvious* sign of why it won't charge.

A reasonable guess is that the anti self immolation protection has been
activated by the cells being flat for too long.

It turns out that the batteries can be charged directly through the big
"battery clips", and it is currently sitting on my desk being fed from a
small (half amp max) lab power supply. It was taking 300 mA but has now
dropped to about 150 for some reason. Supply is giving about 10.5 volts.
For obvious reasons I am being gentle with the batteries, not using a
car battery charger for example! But as they are about 125 x 45 mm and
the stack is 20 mm thick I can't believe that half an amp will bother them.

If you are going to do that I'd suggest putting it on a firebrick and
outdoors well away from anything combustible. Even the humble eCigs go
quite spectacularly well when they have had enough abuse. The lilac
flames are quite amusing but metal fires can be hard to put out.

--
Regards,
Martin Brown

On Fri, 29 Sep 2017 11:08:50 +0100, newshound
wrote:

On 28/09/2017 23:38, MrCheerful wrote:

snip

Like a car battery?

Partly the capacity/weight relationship. I could use a motorcycle or
stairlift type battery, but one nice thing about this is that it slips
into the DIN-slot sized storage pocket. I've used lead acid gel
batteries for other things (like horse clippers) but same argument
applies, it's worth paying a bit more for a lighter high capacity
battery (as long as it lasts a reasonable time).

Agreed ... and I was just there re portable power for an electric
outboard on my folding dinghy.

I actually bought 6 x 18,000mAh Li-Po packs with the idea of using
them in 2 groups of three in parallel but after looking closer at what
their usage for that role required, I sent them back and went back to
Lead Acid ... because ...

Li-Po Pros:
They were very light.
They had a more useable capacity (~80% V ~50%)
They were actually cheaper per kwh than a quality cyclic LA gel
battery (especially if you include their greater DOD).

Li-Po Cons:
Because our usage was potentially very intermittent / unpredictable
and certainly wasn't going to be using them daily or in the winter,
they would need putting into 'storage mode' and with a total capacity
of nearly 90Ah, that would take a pretty big charger (discharger in
this case) or monitored LVD / load etc.

So that lead on to needing a big (and expensive) charger (~50A!) to
bring the batteries up from storage to full charge when we decided at
the last moment that we wanted to go outboarding.

If we ended up not outboarding after all they would need discharging
again to storage charge.

Then it was where would we store / charge them when you aren't
supposed to leave them unsupervised when being charged and they should
be stored / transported in a fireproof container (many buildings and
vehicles have been burnt out because of Li-Po fires).

I bought a fire-safe container that would physically take 3 of these
18Ah packs, only to find that it was only rated to take 10Ah's worth
of Li-Po (not 54Ah). ;-(

Lead Acid (gel) Pros:
They could be charged gently overnight on a fairly std charger and
left at 100% charge status ready for use.
They were very unlikely to ever catch fire, especially spontaneously
(especially so being sealed VR / gel etc).
The outboard was 'designed' for 12V (not 11.1V nominal)
No requirement for special storage or transport.
They wouldn't become unstable if the got wet.
There was no need for any additional balance / monitoring circuitry
for safe usage.
They were readily available.
Whilst the weight was an issue whist being transported to the water,
it wasn't an issue in use (it would have been if you had to carry them
regularly etc).

Lead Acid (gel) Cons:
Lower depth of discharge than Li-Po
Heavier than Li-Po

I'm still 'playing' with (ex laptop battery) 18650 Li-Ion cells but
more for the S&G's than with the thought of using them on the outboard
for the same cautions re Li-Po mentioned above.

Cheers, T i m

On Fri, 29 Sep 2017 11:28:19 +0100, newshound
wrote:

snip

Standard procedure to see if you are likely to be at a risk from
potentially faulty / neglected cells is to charge them all to a safe
voltage (say 4vpc), leave them for a week and see how much they have
(self) discharged by. If it's not a lot and equal across all the cells
then the chances they are ok.

Thanks, very helpful tip. I've got enough DVMs lying around to be able
to build a charge/discharge setup measuring the voltage of each cell.

;-)

Might even get some of these

http://www.ebay.co.uk/itm/New-Mini-D...19.m1438.l2649


They would indeed give you the voltage across each parallel group but
the 'Li-Po boys' use little modules that scroll though all the cells
and give the total voltage and have an audible low voltage alarm (for
less). ;-)

http://www.ebay.co.uk/itm/1S-8S-Lipo...AOSw~e5ZTRh 5

There's a little "floating" circuit board which,
to judge by the layout and wire colours, takes the charging current as
input, and has charging wires going to each end of the stack with sensor
wires to the intermediate junctions. This must be the "safety" circuit,

They are generally referred to as the / a 'Battery Management System'.
They both monitor the charge and 'hold back any cells getting close to
the maximum voltage to ensure they don't become overcharged whilst
also both disconnecting the load once any cell has reached the 'low'
voltage threshold and might (also as mentioned elsewhere) 'protect'
the battery from being charged at all, once it goes below a very low
voltage threshold (for the reasons stated above [1]).

tomorrow I will check whether that has gone open circuit.

I'm not sure how you will do that without a variable PSU plus your DMM
etc?

That's exactly how I'll do it.

But you really have to be there all the time it's going on ...

http://www.ebay.co.uk/itm/1S-8S-Lipo...AOSw~e5ZTRh 5

However, I'd go for one where you can set the maximum charge voltage
to below the 4.2V threshold, suffer the slight capacity loss and enjoy
the greater cycle life. ;-)


snip

Also as mentioned elsewhere, be areful with them as they can go off
like a firework (check Youtube for 'Li-po fires' and see howm may
'fire protection' charging bags and boxes you can get for Lithium
batteries and what levels many manufacturers of commercoial / domestic
packs go to to minise the risks (non resettable fuses to prevent
re-charging over discharged batteries and mutiple temperature sensors
etc).

Oh I will, I am fairly used to being around dangerous stuff.

Ok. ;-)

High
voltages or currents, various nasty chemicals. Radioactive sources.

But not things that can spontaneously combust then?

https://www.youtube.com/watch?v=fF9fhlr9S5s

Not
so much experience with pyrotechnics, but in truth for an uncontained
laptop battery the risk is temperature and smoke, as long as it is away
from people and anything else inflammable.

Gdgd.

[1] I believe the risks from internal self destruction are because
large sharp crystals can grow under certain circumstances and punture
the internal insulators (or somesuch).


If it does look like it is recoverable, I will give it a few cycles in a
safe environment, and relegate it to jump starting duty.

And store it in a concrete bunker. ;-)

Cheers, T i m

On Fri, 29 Sep 2017 11:34:47 +0100, Martin Brown
wrote:

On 28/09/2017 18:54, newshound wrote:

No *obvious* sign of why it won't charge.

A reasonable guess is that the anti self immolation protection has been
activated by the cells being flat for too long.

It turns out that the batteries can be charged directly through the big
"battery clips", and it is currently sitting on my desk being fed from a
small (half amp max) lab power supply. It was taking 300 mA but has now
dropped to about 150 for some reason. Supply is giving about 10.5 volts.
For obvious reasons I am being gentle with the batteries, not using a
car battery charger for example! But as they are about 125 x 45 mm and
the stack is 20 mm thick I can't believe that half an amp will bother them.

If you are going to do that I'd suggest putting it on a firebrick and
outdoors well away from anything combustible. Even the humble eCigs go
quite spectacularly well when they have had enough abuse. The lilac
flames are quite amusing but metal fires can be hard to put out.

A Li-Ion generates it's own oxygen under those circumstances so can
burn in space! ;-(

Cheers, T i m

T i m wrote:
On Fri, 29 Sep 2017 11:34:47 +0100, Martin Brown
wrote:

On 28/09/2017 18:54, newshound wrote:

No *obvious* sign of why it won't charge.

A reasonable guess is that the anti self immolation protection has been
activated by the cells being flat for too long.

It turns out that the batteries can be charged directly through the big
"battery clips", and it is currently sitting on my desk being fed from a
small (half amp max) lab power supply. It was taking 300 mA but has now
dropped to about 150 for some reason. Supply is giving about 10.5 volts.
For obvious reasons I am being gentle with the batteries, not using a
car battery charger for example! But as they are about 125 x 45 mm and
the stack is 20 mm thick I can't believe that half an amp will bother them.

If you are going to do that I'd suggest putting it on a firebrick and
outdoors well away from anything combustible. Even the humble eCigs go
quite spectacularly well when they have had enough abuse. The lilac
flames are quite amusing but metal fires can be hard to put out.

A Li-Ion generates it's own oxygen under those circumstances so can
burn in space! ;-(

Cheers, T i m


Did Boeing give up on LI for dreamliners?

On 29/09/2017 12:20, T i m wrote:
On Fri, 29 Sep 2017 11:28:19 +0100, newshound
wrote:

snip

Standard procedure to see if you are likely to be at a risk from
potentially faulty / neglected cells is to charge them all to a safe
voltage (say 4vpc), leave them for a week and see how much they have
(self) discharged by. If it's not a lot and equal across all the cells
then the chances they are ok.

Thanks, very helpful tip. I've got enough DVMs lying around to be able
to build a charge/discharge setup measuring the voltage of each cell.

;-)

Might even get some of these

http://www.ebay.co.uk/itm/New-Mini-D...19.m1438.l2649


They would indeed give you the voltage across each parallel group but
the 'Li-Po boys' use little modules that scroll though all the cells
and give the total voltage and have an audible low voltage alarm (for
less). ;-)

http://www.ebay.co.uk/itm/1S-8S-Lipo...AOSw~e5ZTRh 5

Wow that is neat!

However, I'd go for one where you can set the maximum charge voltage
to below the 4.2V threshold, suffer the slight capacity loss and enjoy
the greater cycle life. ;-)

Good thinking. But I *think* the regulating unit is still working, I'll
test it and see what voltage it controls to. Out-doors, and using the
vermiculite blocks that I use for brazing. More convenient than fire-brick!


But not things that can spontaneously combust then?

https://www.youtube.com/watch?v=fF9fhlr9S5s

Scary. I would *definitely* have been going for the extinguisher rather
than trying to "stamp it out" in that case, far too much chance of it
melting its way into the sole of the trainers! I have seen video of
irradiated uranium metal igniting during cutting operations, inside a
shielded facility. (Easily put out by covering with plastic bags
containing dry powder, for those interested).


And store it in a concrete bunker. ;-)

Note to self: should have got a couple of those dry powder extinguishers
when they were on offer in Lidl. I currently only have a CFC one in my
workshop.

On Fri, 29 Sep 2017 14:44:08 +0100, newshound
wrote:

snip

However, I'd go for one where you can set the maximum charge voltage
to below the 4.2V threshold, suffer the slight capacity loss and enjoy
the greater cycle life. ;-)

Good thinking. But I *think* the regulating unit is still working, I'll
test it and see what voltage it controls to. Out-doors, and using the
vermiculite blocks that I use for brazing. More convenient than fire-brick!

LOL ... good idea. ;-)


But not things that can spontaneously combust then?

https://www.youtube.com/watch?v=fF9fhlr9S5s

Scary. I would *definitely* have been going for the extinguisher rather
than trying to "stamp it out" in that case, far too much chance of it
melting its way into the sole of the trainers!

That must have been some tasty sarni the guy sitting on the left was
eating as if you watch it / him again he doesn't let go of it amidst
all the chaos. ;-)

have seen video of
irradiated uranium metal igniting during cutting operations, inside a
shielded facility. (Easily put out by covering with plastic bags
containing dry powder, for those interested).

That sounds pretty frightening all the same.


And store it in a concrete bunker. ;-)

Note to self: should have got a couple of those dry powder extinguishers
when they were on offer in Lidl. I currently only have a CFC one in my
workshop.

;-)

Cheers, T i m

In article ,
Huge writes:
On 2017-09-29, Capitol wrote:

[28 lines snipped]


Did Boeing give up on LI for dreamliners?

No. But they did redesign them.

Think I heard they are now inside a welded stainless steel
case.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]