Battery problem?

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Originally Posted by Tins

OK, this is very much a "newbie" question. Does the controller/charger ( any, not just yours ) display the actual battery voltage, ie the potential difference between +ve and -ve posts, or does it display what the chip in the battery says it is?

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From one newbie to another - :spudnikwhat:

Hopefully someone will enlighten us. [biggrin]

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Originally Posted by drivesafe

Hi Dale and sorry, I missed replying to your question.

I don't take to much notice of the "settled" voltage of any battery after they have been charged, regardless of what is used to charge them.

All batteries once fully charged properly, will have a surface voltage.

While lead acid batteries usually loose this surface charge a few hours after being charged, I have noticed that lithium batteries can hold a surface charge for many days.

In both cases, with either lead acid batteries and lithium batteries, applying a small load, will very quickly remove the surface charge and you will get a more accurate settlement voltage reading.

This is also why I have always recommended people ignore "OPEN CIRCUT" type voltage reading and make sure you have at least a small load applied to the battery for a short period of time before taking a voltage reading with any lead acid battery, while that load is still applied.

Back to the lithium voltage readings. I have two 100Ah lithium batteries, of the same brand and age and while one was last charged ( but not used ) 3 month ago, the other was charged and then removed from in my VW Tiguan two weeks ago, and both are sitting at 13.34, with no load applied.

Later on today, I will apply a small load to each of them and see what voltage they have then.

BTW, I find BM2 Bluetooth battery monitors have very accurate voltage readings.

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Tim, I took you at your word and applied a 'small' (11w) load from a 12V fluoro light I had in the shed from my pre-LED days and let it run for a 'short' half an hour. The only other option is a portable Blue Tongue compressor as everything else is locked in the camper trailer under a cover to stop water ingress during a monsoonal Wet Season...

At commencement the reading was 13.65 & after the half hour was up it was 13.44.

22 hours later it is reading 13.43V.

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Originally Posted by Narangga

Tim, I took you at your word and applied a 'small' (11w) load from a 12V fluoro light I had in the shed from my pre-LED days and let it run for a 'short' half an hour. The only other option is a portable Blue Tongue compressor as everything else is locked in the camper trailer under a cover to stop water ingress during a monsoonal Wet Season...

At commencement the reading was 13.65 & after the half hour was up it was 13.44.

22 hours later it is reading 12.43V.

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Hi Dale, what is your battery’s Ah capacity?

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22 hours later it is reading 12.43V.

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You must have a considerable drain on the battery.
One thing forgotten is modern radios have an always live wire to the station memory, but this doesn't take much at all. But it will flatten a battery over a few weeks.
However you have a drain somewhere. if you have fuses take them all out, then replace them one by one until you see the voltage drop, or alternatively take out the fuses and put an amp meter across the fuse contacts.
That is why I have a master switch which isolates the battery from everything including the watt, amp, voltmeter which takes a little bit of power to run it.
Regards PhilipA

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Originally Posted by Narangga

From one newbie to another - :spudnikwhat:

Hopefully someone will enlighten us. [biggrin]

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Nope, the grown ups are ignoring us. Again.

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Originally Posted by drivesafe

Hi Dale, what is your battery’s Ah capacity?

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2 x 50Ah

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Originally Posted by PhilipA

You must have a considerable drain on the battery.
One thing forgotten is modern radios have an always live wire to the station memory, but this doesn't take much at all. But it will flatten a battery over a few weeks.
However you have a drain somewhere. if you have fuses take them all out, then replace them one by one until you see the voltage drop, or alternatively take out the fuses and put an amp meter across the fuse contacts.
That is why I have a master switch which isolates the battery from everything including the watt, amp, voltmeter which takes a little bit of power to run it.
Regards PhilipA

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After using the light for 30 mins the voltage read 13.44.

22 hours after the 13.44 reading the voltage read 13.43.

The batteries are in the camper trailer and there is no load on them as everything is switched off. There is no radio in the camper trailer.

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Originally Posted by Tins

Nope, the grown ups are ignoring us. Again.

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Well ignoring you anyway...[bigrolf]

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Originally Posted by Narangga

After using the light for 30 mins the voltage read 13.44.

22 hours after the 13.44 reading the voltage read 13.43.

The batteries are in the camper trailer and there is no load on them as everything is switched off. There is no radio in the camper trailer.

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I think you have a typo in reply #112 ????

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Originally Posted by Narangga

Well ignoring you anyway...[bigrolf]

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You forgot the voices in my head.