Following the suggestion here that the charging voltage for Circuit C
was too high
("C: 14.6V, +0.01A")
I checked with an accurate meter. The voltage was 13.86V. That accords
with the very low residual charge rate. As I suspected, the van's
voltmeter is reading a bit high.

Bill

williamwright pretended :
Following the suggestion here that the charging voltage for Circuit C was too
high
("C: 14.6V, +0.01A")
I checked with an accurate meter. The voltage was 13.86V. That accords with
the very low residual charge rate. As I suspected, the van's voltmeter is
reading a bit high.

Bill

My caravans limited range analogue voltmeter is in the panel, by the
door - some way from the battery. It's reasonably accurate for an
analogue, but the daft part is that they have shared it's supply with
everything else - it measures across the main feed. Absolutely anything
you turn on, will cause voltage drop and the reading to decline
drastically. The only way to get a true reading, is with the main
isolator on, the rest of the isolators off and use a torch in the dark
to read it.

In article ,
williamwright wrote:
Following the suggestion here that the charging voltage for Circuit C
was too high
("C: 14.6V, +0.01A")
I checked with an accurate meter. The voltage was 13.86V. That accords
with the very low residual charge rate. As I suspected, the van's
voltmeter is reading a bit high.

That's still high for a float charge. Should be more like 13v.

--
*I brake for no apparent reason.

Dave Plowman London SW
To e-mail, change noise into sound.

On 28/04/2021 11:04, Dave Plowman (News) wrote:
In article ,
williamwright wrote:
Following the suggestion here that the charging voltage for Circuit C
was too high
("C: 14.6V, +0.01A")
I checked with an accurate meter. The voltage was 13.86V. That accords
with the very low residual charge rate. As I suspected, the van's
voltmeter is reading a bit high.

That's still high for a float charge. Should be more like 13v.

But the charge rate is 0.01A

Bill

On 28/04/2021 18:11, williamwright wrote:
On 28/04/2021 11:04, Dave Plowman (News) wrote:
In article ,
Â*Â*Â* williamwright wrote:
Following the suggestion here that the charging voltage for Circuit C
was too high
("C: 14.6V, +0.01A")
I checked with an accurate meter. The voltage was 13.86V. That accords
with the very low residual charge rate. As I suspected, the van's
voltmeter is reading a bit high.

That's still high for a float charge. Should be more like 13v.

But the charge rate is 0.01A

That suggests the battery is fully charged and the current is there to
offset the self-discharge current.

In article ,
williamwright wrote:
On 28/04/2021 11:04, Dave Plowman (News) wrote:
In article ,
williamwright wrote:
Following the suggestion here that the charging voltage for Circuit C
was too high
("C: 14.6V, +0.01A")
I checked with an accurate meter. The voltage was 13.86V. That accords
with the very low residual charge rate. As I suspected, the van's
voltmeter is reading a bit high.

That's still high for a float charge. Should be more like 13v.

But the charge rate is 0.01A

Assuming the ammeter is as good as the voltmeter? ;-)

--
*Speak softly and carry a cellular phone *

Dave Plowman London SW
To e-mail, change noise into sound.

On 28/04/2021 11:04, Dave Plowman (News) wrote:
In article ,
williamwright wrote:
Following the suggestion here that the charging voltage for Circuit C
was too high
("C: 14.6V, +0.01A")
I checked with an accurate meter. The voltage was 13.86V. That accords
with the very low residual charge rate. As I suspected, the van's
voltmeter is reading a bit high.

That's still high for a float charge. Should be more like 13v.

13.8v is a nominal fully charged lead acid battery. I have one or two
PSUs kicking around that output that voltage for powering kits that is
designed for lead acid accumulators from the mains.

It probably is a bit on the high side for a float charge. A silicon
diode in series and a 1k resistor in parallel might help.

--
Regards,
Martin Brown

In article ,
Martin Brown wrote:
On 28/04/2021 11:04, Dave Plowman (News) wrote:
In article ,
williamwright wrote:
Following the suggestion here that the charging voltage for Circuit C
was too high
("C: 14.6V, +0.01A")
I checked with an accurate meter. The voltage was 13.86V. That accords
with the very low residual charge rate. As I suspected, the van's
voltmeter is reading a bit high.

That's still high for a float charge. Should be more like 13v.

13.8v is a nominal fully charged lead acid battery. I have one or two
PSUs kicking around that output that voltage for powering kits that is
designed for lead acid accumulators from the mains.

13.8v is the standard for a car, engine running. So tends to be the output
of a PS designed to be used with things like a car radio, etc. A fully
charged battery, left to settle, is under 13v.

It probably is a bit on the high side for a float charge. A silicon
diode in series and a 1k resistor in parallel might help.

--
*Many people quit looking for work when they find a job *

Dave Plowman London SW
To e-mail, change noise into sound.

On 01/05/2021 11:59, Dave Plowman (News) wrote:
In article ,
Martin Brown wrote:
On 28/04/2021 11:04, Dave Plowman (News) wrote:
In article ,
williamwright wrote:
Following the suggestion here that the charging voltage for Circuit C
was too high
("C: 14.6V, +0.01A")
I checked with an accurate meter. The voltage was 13.86V. That accords
with the very low residual charge rate. As I suspected, the van's
voltmeter is reading a bit high.

That's still high for a float charge. Should be more like 13v.

13.8v is a nominal fully charged lead acid battery. I have one or two
PSUs kicking around that output that voltage for powering kits that is
designed for lead acid accumulators from the mains.

13.8v is the standard for a car, engine running. So tends to be the output
of a PS designed to be used with things like a car radio, etc. A fully
charged battery, left to settle, is under 13v.

It probably is a bit on the high side for a float charge. A silicon
diode in series and a 1k resistor in parallel might help.

For most people, car engines don't run for much of the time. They do
need to top up the starter drain reliably, it's not really a float
charge regime.

In article ,
newshound wrote:
For most people, car engines don't run for much of the time. They do
need to top up the starter drain reliably, it's not really a float
charge regime.

Quite. A car is unlikely to run continuously for more than a few hours.
Given the driver will want a comfort break of some sort, or indeed fuel.

A float charger could be running for weeks on end.

--
*Change is inevitable, except from a vending machine.

Dave Plowman London SW
To e-mail, change noise into sound.

On Sun, 02 May 2021 15:38:28 +0100, Dave Plowman (News) wrote:

In article ,
newshound wrote:
For most people, car engines don't run for much of the time. They do
need to top up the starter drain reliably, it's not really a float
charge regime.

Quite. A car is unlikely to run continuously for more than a few hours.
Given the driver will want a comfort break of some sort, or indeed fuel.

A float charger could be running for weeks on end.

How about months on end? As I mentioned in a previous post, car
batteries are no substitute for the SLAs specified for UPSes. I learnt
this the hard way a few years back when the first set (luckily only a 60
quid investment on a set of four 36AH NOS SLIs bought from my local car
parts/breaker supplier) failed after just 6 or 7 months of being kept at
a float charge voltage of 13.8v.

Rather stupidly, I chanced yet another 60 quid's worth with pretty much
the same result before the lesson was finally learnt. :-(

I had Ass U Med that the much gentler operating conditions in UPS
service would extend the service life of SLI class batteries. Oh, just
how wrong can one be? Well, in this case, VERY wrong!

To use an anthropomorphic analogy, SLI lead acid batteries could best be
described as having a masochistic character. They positively thrive under
the sadomasochistic regime of automotive use where they're not only
subjected to a few hundred amps of abuse from the starter motor load but
also suffer the various acceleration forces throughout a typical journey
which they crave in order to keep the electrolyte nicely stirred up to
keep electrolyte stratification at bay, all of which is absent in UPS
service.

It turns out that my UPS was killing them with an excess of 'kindness'.
Who'd have guessed? Well, more to the point, who'd have guessed that car
batteries had been SO optimised for SLI service as to make them so
incredibly unsuited to the gentler routine of UPS service? Well, I don't
have to guess any more - I now _KNOW_ (and it has only cost me a mere 120
quid for that knowledge).

I did briefly toy with the idea of using yet a third set of SLIs but on
a reduced to 13.5v float charge setting but, considering the other need
to avoid stratification of the electrolyte, decided against running this
experiment.

I've since come to realise that LFP batteries are a far better fit for
this task than the SLA battery technology in current universal use with
UPSes. However, I'm still considering the best way to make such a long
term investment in something that'll outlast not only the UPS itself but
also my remaining lifetime.

--
Johnny B Good