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Lead Acid puzzle

Started by Tabby August 26, 2020
Cart with 2x 12v 33Ah progolf AGM lead acids. 1.5 years after fitting new batteries the available range is down to below 10%. I'm not clear what's gone wrong.

The charger in use has been a cheap chinese one with 2x13.7v=27.4v output. Single stage charging only. It has always been promptly charged after use, and never run below 50% charge.

I checked the battery voltages after charge, they were 13.6 & 13.8v. Charged each battery independantly to 15.2v, which took maybe half an hour or so. No range improvement.

When apparently flat the batteries read, offload, 12.3v & 12.8v. I expected to see lower.

What's going on here? 


NT
On 2020/08/26 5:30 p.m., Tabby wrote:
> Cart with 2x 12v 33Ah progolf AGM lead acids. 1.5 years after fitting new batteries the available range is down to below 10%. I'm not clear what's gone wrong. > > The charger in use has been a cheap chinese one with 2x13.7v=27.4v output. Single stage charging only. It has always been promptly charged after use, and never run below 50% charge. > > I checked the battery voltages after charge, they were 13.6 & 13.8v. Charged each battery independantly to 15.2v, which took maybe half an hour or so. No range improvement. > > When apparently flat the batteries read, offload, 12.3v & 12.8v. I expected to see lower. > > What's going on here? > > > NT >
http://batteryuniversity.com John :-#)#
On Thursday, 27 August 2020 01:39:18 UTC+1, John Robertson  wrote:
> On 2020/08/26 5:30 p.m., Tabby wrote:
> > Cart with 2x 12v 33Ah progolf AGM lead acids. 1.5 years after fitting new batteries the available range is down to below 10%. I'm not clear what's gone wrong. > > > > The charger in use has been a cheap chinese one with 2x13.7v=27.4v output. Single stage charging only. It has always been promptly charged after use, and never run below 50% charge. > > > > I checked the battery voltages after charge, they were 13.6 & 13.8v. Charged each battery independantly to 15.2v, which took maybe half an hour or so. No range improvement. > > > > When apparently flat the batteries read, offload, 12.3v & 12.8v. I expected to see lower. > > > > What's going on here? > > > > > > NT > > > > http://batteryuniversity.com > > John :-#)#
I didn't find much on premature failure there. I did here: https://www.ecmweb.com/content/article/20887522/why-batteries-fail-prematurely The only issue I'm seeing there is uncontrolled temperatures which may have resulted in the battery drying out. Charging to 15.2v has if anything worsened them, which lines up with that. I'll try adding acid & water. Thanks I'm guessing they managed about 200 cycles of maybe 15-20% discharge average. NT
On Thursday, 27 August 2020 02:21:08 UTC+1, Tabby  wrote:
> On Thursday, 27 August 2020 01:39:18 UTC+1, John Robertson wrote: > > On 2020/08/26 5:30 p.m., Tabby wrote: > > > > Cart with 2x 12v 33Ah progolf AGM lead acids. 1.5 years after fitting new batteries the available range is down to below 10%. I'm not clear what's gone wrong. > > > > > > The charger in use has been a cheap chinese one with 2x13.7v=27.4v output. Single stage charging only. It has always been promptly charged after use, and never run below 50% charge. > > > > > > I checked the battery voltages after charge, they were 13.6 & 13.8v. Charged each battery independantly to 15.2v, which took maybe half an hour or so. No range improvement. > > > > > > When apparently flat the batteries read, offload, 12.3v & 12.8v. I expected to see lower. > > > > > > What's going on here? > > > > > > > > > NT > > > > > > > http://batteryuniversity.com > > > > John :-#)# > > I didn't find much on premature failure there. I did here: > https://www.ecmweb.com/content/article/20887522/why-batteries-fail-prematurely > > The only issue I'm seeing there is uncontrolled temperatures which may have resulted in the battery drying out. Charging to 15.2v has if anything worsened them, which lines up with that. I'll try adding acid & water. Thanks > > I'm guessing they managed about 200 cycles of maybe 15-20% discharge average. > > > NT
PS I read somewhere that connecting a welder for a few seconds can break off sulphation. NT
On 2020/08/26 6:21 p.m., Tabby wrote:
> On Thursday, 27 August 2020 01:39:18 UTC+1, John Robertson wrote: >> On 2020/08/26 5:30 p.m., Tabby wrote: > >>> Cart with 2x 12v 33Ah progolf AGM lead acids. 1.5 years after fitting new batteries the available range is down to below 10%. I'm not clear what's gone wrong. >>> >>> The charger in use has been a cheap chinese one with 2x13.7v=27.4v output. Single stage charging only. It has always been promptly charged after use, and never run below 50% charge. >>> >>> I checked the battery voltages after charge, they were 13.6 & 13.8v. Charged each battery independantly to 15.2v, which took maybe half an hour or so. No range improvement. >>> >>> When apparently flat the batteries read, offload, 12.3v & 12.8v. I expected to see lower. >>> >>> What's going on here? >>> >>> >>> NT >>> >> >> http://batteryuniversity.com >> >> John :-#)# > > I didn't find much on premature failure there. I did here: > https://www.ecmweb.com/content/article/20887522/why-batteries-fail-prematurely > > The only issue I'm seeing there is uncontrolled temperatures which may have resulted in the battery drying out. Charging to 15.2v has if anything worsened them, which lines up with that. I'll try adding acid & water. Thanks > > I'm guessing they managed about 200 cycles of maybe 15-20% discharge average. > > > NT >
Battery University goes into the recommended charging voltages for batteries - your voltages are too high for lead-acid - and their business is battery chargers so it seems to make sense to follow their advice. John :-#(#
On Wednesday, August 26, 2020 at 5:30:47 PM UTC-7, Tabby wrote:
> Cart with 2x 12v 33Ah progolf AGM lead acids. 1.5 years after fitting new batteries the available range is down to below 10%. I'm not clear what's gone wrong. > > The charger in use has been a cheap chinese one with 2x13.7v=27.4v output. Single stage charging only. It has always been promptly charged after use, and never run below 50% charge. > > I checked the battery voltages after charge, they were 13.6 & 13.8v. Charged each battery independantly to 15.2v, which took maybe half an hour or so. No range improvement. > > When apparently flat the batteries read, offload, 12.3v & 12.8v. I expected to see lower. > > What's going on here? > > > NT
You have a bad cell in one of the batteries, which may be reversed polarity. The charger is over-charging the other cells to bring it up to voltage.
Tabby wrote:
> Cart with 2x 12v 33Ah progolf AGM lead acids. 1.5 years after fitting new batteries the available range is down to below 10%. I'm not clear what's gone wrong. > > The charger in use has been a cheap chinese one with 2x13.7v=27.4v output. Single stage charging only. It has always been promptly charged after use, and never run below 50% charge. > > I checked the battery voltages after charge, they were 13.6 & 13.8v. Charged each battery independantly to 15.2v, which took maybe half an hour or so. No range improvement. > > When apparently flat the batteries read, offload, 12.3v & 12.8v. I expected to see lower. > > What's going on here? > > > NT >
Test a 12V battery, (13.8V appx no load) under 100 amp load and monitor during test. If full charge and good battery, the voltage will not be below 10V for ten seconds. Thanks.
On 27/08/2020 11:21 am, Tabby wrote:
> On Thursday, 27 August 2020 01:39:18 UTC+1, John Robertson wrote: >> On 2020/08/26 5:30 p.m., Tabby wrote: > >>> Cart with 2x 12v 33Ah progolf AGM lead acids. 1.5 years after fitting new batteries the available range is down to below 10%. I'm not clear what's gone wrong. >>> >>> The charger in use has been a cheap chinese one with 2x13.7v=27.4v output. Single stage charging only. It has always been promptly charged after use, and never run below 50% charge. >>> >>> I checked the battery voltages after charge, they were 13.6 & 13.8v. Charged each battery independantly to 15.2v, which took maybe half an hour or so. No range improvement. >>> >>> When apparently flat the batteries read, offload, 12.3v & 12.8v. I expected to see lower. >>> >>> What's going on here? >>> >>> >>> NT >>> >> >> http://batteryuniversity.com >> >> John :-#)# > > I didn't find much on premature failure there. I did here: > https://www.ecmweb.com/content/article/20887522/why-batteries-fail-prematurely > > The only issue I'm seeing there is uncontrolled temperatures which may have resulted in the battery drying out. Charging to 15.2v has if anything worsened them, which lines up with that. I'll try adding acid & water. Thanks > > I'm guessing they managed about 200 cycles of maybe 15-20% discharge average. > > > NT >
200 cycles and a not great battery charger? It sounds like the batteries are just plain worn out. No mystery at all. New batteries and a better charger next time.
On a sunny day (Thu, 27 Aug 2020 16:26:57 +1000) it happened david eather
<eathDELETEer@tpg.com.au> wrote in <UmI1H.928252$Cq6.877074@fx44.am4>:

>200 cycles and a not great battery charger? It sounds like the batteries >are just plain worn out. No mystery at all. New batteries and a better >charger next time.
And if you have enough money why not replace with lifepo4 and a charger for that?
On 27/08/2020 01:30, Tabby wrote:
> Cart with 2x 12v 33Ah progolf AGM lead acids. 1.5 years after fitting new batteries the available range is down to below 10%. I'm not clear what's gone wrong. > > The charger in use has been a cheap chinese one with 2x13.7v=27.4v output. Single stage charging only. It has always been promptly charged after use, and never run below 50% charge. > > I checked the battery voltages after charge, they were 13.6 & 13.8v. Charged each battery independantly to 15.2v, which took maybe half an hour or so. No range improvement. > > When apparently flat the batteries read, offload, 12.3v & 12.8v. I expected to see lower. > > What's going on here?
Battery abuse. The cheap charger has knackered both of your batteries. Recharging lead acid cells for maximum longevity requires some form of thermal compensation of the voltage per cell during charging. eg https://batteryuniversity.com/learn/article/charging_at_high_and_low_temperatures Too much over voltage and they gas. Incorrect treatment on top up and they sulphate or corrode internally either way you do damage to them. The weakest cell in a chain fails first and the others then wreck it. -- Regards, Martin Brown