Leisure battery losing charge

[M+M+M]

Hi everyone, I’ve had a good look through existing threads and can’t find anything (yet) to resolve my issue.
We have a fairly new Autosleeper Symbol Plus and we had the dealer fit a 120ah lithium battery to replace the stock 68ah lithium supplied. This has been fine for our needs, even managed a weekend off grid last summer, but we’ve had some problems with a low battery alert while it’s in storage the last few weeks. We had it outside the house over Christmas and it went back into storage fully charged. Just 10 days later the battery alert triggered. Thought it might be the very cold weather so brought it home to charge up. (Learned a bit about cold batteries and charging, of course I didn’t buy a heated one). Back into storage and here we are, 3 weeks later and the alert has triggered again. It’s been really mild most of that time so maybe the cold was a red herring. Also it should get a trickle of solar.
Obviously we switch everything off and winterise it but am getting a bit worried about this, anybody got any suggestions or do we need to put up with this and recharge regularly?

 

[ChrisL]

Is it possible that your stereo is wired into the leisure battery? Some stereos can still draw current whilst turned off. Perhaps the first thing to do would be to buy a DC clamp meter and find out if anything is draining the battery with everything turned off. The Uni-T UT210 ones are reliable and accurate at reasonable cost.

 

[peterc10]

Are you sure the alert is for the habitation battery and not the engine battery?

 

[Just smiffy]

What lithium battery is it..? Some BMS shut down if too cold or get below a certain voltage…

 

[Spriddler]

Deleted. Irrelevant.

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[starquake]

Some BMS won't accept a solar charge (or any charge) below 0 celicus.

 

[jwells]

Your Sargent tracker system will have a slow drain, AS didn't do a good job of their initial LiPo charging and engine batteries don't keep their charge for long. Make sure that you have all the Sargent settings for isolation/charging correctly set when everything is isolated to leave the van.
Is there actually any topping up going from the hab to engine battery?

 

[autorouter]

Is it possible that your stereo is wired into the leisure battery? Some stereos can still draw current whilst turned off. Perhaps the first thing to do would be to buy a DC clamp meter and find out if anything is draining the battery with everything turned off. The Uni-T UT210 ones are reliable and accurate at reasonable cost.

Be careful choosing a DC clamp meter. I use a Uni-T UT210E. There are five models, A, B, C, D and E. The A, B and C models are AC only, they won't measure DC current, which is what your battery sends out. Only the D and E models measure DC. That's why they are a bit more expensive, they can measure both AC and DC current (amps).

The D model can measure high DC currents, but the E model can measure low and medium DC currents. The E model is better for finding small drain currents, which is the OP's problem.

 

[autorouter]

How much solar do you have? Do the panels get any sun in the storage site? It shouldn't take much to keep batteries topped up in storage. A 100W panel, even if flat on the roof, not tilted, should be plenty. Maybe the solar isn't getting through to the batteries. Do you have a meter that can measure the voltage at the battery terminals?

 

[LithiumConvert]

Are you sure the alert is for the habitation battery and not the engine battery?

The lithium battery should not self discharge, whereas the lead-acid starter battery will.

Do you have a Vanbitz battery master (orr similar) fitted?
If so, the battery master will drain the lithium battery to keep the starter battery topped up.

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[The Artilleryman]

Is it just a case of the BMS shutting down as there is no charge/discharge over a given period of time ?
Ours does that and the control panel flashes "low voltage" and beeps. It's a pain to get it back on as battery is fully charged and starting the engine so it charges doesn't have much effect, it needs a reasonable load to wake it up but as the MH has been winterised - it's too much faff to fill the heating system and then run it to wake up the hab battery - it will be left till the end of this month, when it gets taken in to have self levelling and fill the water system.

 

[M+M+M]

Is it possible that your stereo is wired into the leisure battery? Some stereos can still draw current whilst turned off. Perhaps the first thing to do would be to buy a DC clamp meter and find out if anything is draining the battery with everything turned off. The Uni-T UT210 ones are reliable and accurate at reasonable cost.

Thanks for the tip

 

[M+M+M]

The lithium battery should not self discharge, whereas the lead-acid starter battery will.

Do you have a Vanbitz battery master (orr similar) fitted?
If so, the battery master will drain the lithium battery to keep the starter battery topped up.

Ah now that might be happening. We get some detail of battery voltage over time from the remote monitoring and the vehicle battery has little peaks at regular intervals. Could that be the root cause?

 

[M+M+M]

Are you sure the alert is for the habitation battery and not the engine battery?

Yes definitely leisure battery.

 

[M+M+M]

Ah now that might be happening. We get some detail of battery voltage over time from the remote monitoring and the vehicle battery has little peaks at regular intervals. Could that be the root cause?

Or could that be a bit of solar going in?

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[M+M+M]

Is it just a case of the BMS shutting down as there is no charge/discharge over a given period of time ?
Ours does that and the control panel flashes "low voltage" and beeps. It's a pain to get it back on as battery is fully charged and starting the engine so it charges doesn't have much effect, it needs a reasonable load to wake it up but as the MH has been winterised - it's too much faff to fill the heating system and then run it to wake up the hab battery - it will be left till the end of this month, when it gets taken in to have self levelling and fill the water system.

It’s definitely discharged, voltage is down to 11.9v

 

[M+M+M]

Some BMS won't accept a solar charge (or any charge) below 0 celicus.

Yes and we experienced this when I brought it home to hookup last time. Ended up putting the heating on to bring everything up a bit. Wish I’d known and would have purchased a heated battery.

 

[M+M+M]

How much solar do you have? Do the panels get any sun in the storage site? It shouldn't take much to keep batteries topped up in storage. A 100W panel, even if flat on the roof, not tilted, should be plenty. Maybe the solar isn't getting through to the batteries. Do you have a meter that can measure the voltage at the battery terminals?

80W and the storage yard is very open so if there’s any sun it will get some. Don’t have a meter but others have suggested what I should maybe purchase.

 

[LithiumConvert]

Ah now that might be happening. We get some detail of battery voltage over time from the remote monitoring and the vehicle battery has little peaks at regular intervals. Could that be the root cause?

Certainly worth investigating further. Those peaks have to be coming from somewhere and the battery master is certainly an option.

Also the software in the solar regulator on our new van crashes from time to time, thus not delivering any charge.
I do not know why and I am not ready yet to publicise the make, but if you tell me the make (and model) of your solar regulator we can compare notes.

 

[autorouter]

Yes and we experienced this when I brought it home to hookup last time. Ended up putting the heating on to bring everything up a bit. Wish I’d known and would have purchased a heated battery.

I don't think a heated battery (or a heating pad under the battery) would be much use in your situation in storage. The solar would probably not be able to heat the battery up to charging temperature, it would take quite a lot of power, and probably not much daylight left by the time it was warm enough to charge. It's better for hookup situations, where the charger can send its output to the heater until it's warm enough, then fill up the battery straightaway. Is there any way you could get a hookup at the storage site, say once a fortnight or so for a few hours?

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[RogerIvy]

I’d recommend fitting a Smartshunt if you don’t have one.
Lithium BMS’s are pretty bad at measuring current draws of less than 1A accurately. They are quite often out by 60% or so. At higher currents they are better.
The reason I mention this is because it will help you debug a “parasitic draw”.