Lithium battery - low voltage shutdown

[gerry mcg]

I went out to my van today to do something - and i was surprised the van power was off at the main distribution panel - and theTruma CP was also off. Strange…. As we leave it on, and i was in the van a few days ago and all was working.
I turned on the Control panel and Lights / fridge etc came on -

Anyway - i went back out this afternoon and the power was off again and the Victron BMV700 low battery alarm was sounding.
and showing a low voltage at 11.47v, but then cycling to 13.5v

This is the first time I've had an issue. what can be going on? Nothing is on that could ne causing the battery drain?

im wondering if there is a problem with a cell in hte the lithium battery? (KS-Energy 205Ah under seat)

looking at the 78 day BMV plot, you can see the time when the B2B is running , and when solar is on,
we used the van a couple w/e ago, and that is when something funny has happened - there appears to be massive current drain dropping the voltage to <11.2v

in the 2hr27 min plot, one can see the voltage fluctuating from 11.2v to 13.5v in very short frequency.

It feels to me like a short in a lithium battery cell?
thoughts?

 

[autorouter]

I think the first thing to establish is whether it's the battery terminal voltage that is varying as the graph shows, or whether it is a bad connection somewhere that is causing a voltage drop somewhere. Can you get a multimeter on the actual battery terminals when the system is showing a voltage drop down to 11.5V or so? If the multimeter also says it's 11.5V then you do indeed have a battery problem. Does the KS app show the individual cell voltages. Or if not, the difference between the highest and lowest cell?

 

[gerry mcg]

It's not possible to get a multimeter easily onto the terminals as it involves removing the drivers seat.
That said, the victron Smartbatterysense is directly onto the battery terminals and is providing the voltage information and I've no reason to doubt it.

The KS Energy app doesn't show the individual cell voltages, but the Onboard KS-ENERGY BT BMS appears to match the Victron SBS Readings.

What is odd is the short phase cycling from 11.2v to 13.65v tho.
Can't fathom the reason / explanation behind that except that perhaps the 4th cell is shorting in / out?

I think an email to KS-Energy is required for their thoughts

 

[autorouter]

What is odd is the short phase cycling from 11.2v to 13.65v tho.
Can't fathom the reason / explanation behind that except that perhaps the 4th cell is shorting in / out?

If one cell was shorting, surely it would reduce from 13.65V to 3/4 of that, which is 10.2V.

 

[gerry mcg]

If one cell was shorting, surely it would reduce from 13.65V to 3/4 of that, which is 10.2V.

Yes, I’d done that maths too. Not sure what is going on

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[lorger]

I’ve no idea what’s wrong, if you think it’s a cell can you not look at individual cells on the is app. Know nothing about electrical stuff so might be nonsense again

 

[Grianan]

Yours wasn’t one that was affected by recent recall Gerry? I’d be calling them on Monday …

 

[gerry mcg]

Yours wasn’t one that was affected by recent recall Gerry? I’d be calling them on Monday …

No, it wasn’t a recall affected one to the best of my knowledge - my one has the terminals on the top, whereas the recall had the terminals on the side iirc - different model

 

[bubble63]

Even if it’s not the recall one it’s still the recall company, would it be wise to take that into account

 

[monzer]

That tab there should give you individual cell voltages.

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[gerry mcg]

Cell voltages were pretty uniform and showed a combined voltage of 11.2v
. It has been on mains charging for last 7hrs at 15A and is now at 70% charge

 

[AshFencing]

Even if it’s not the recall one it’s still the recall company, would it be wise to take that into account

Agreed
It was my very first thought, and then I still considered it a wise course of action all the same due to it being from the same company/manufacturer.
If KS Energy are at all flippant I’d go elsewhere to have the batteries checked.

 

[gerry mcg]

After a full charge overnight at 15A with the dedicated victron IP22 lithium charger, all seems to be normal, with the battery having taken a full charge of 165A and the onboard BMS And the BMV 700 Showing full SOC.
The compressor fridge had been running, and the solar usually keeps up with the drain, but the weather over the last few weeks has not been great, so I it is possible it was unable to keep up with the fridge current drain.

What is odd was the rapid cycling from low 11.2v to apparently normal 13.6v on the SBS trace.
I'll monitor for now

 

[ambulancekidd]

Not sure if this'll help, but try watching this video that I put on. It might explain what your up against.

Whats inside a lithium battery & can it be repaired if it gets too low. Watch & see

I watch a couple of guys on You-Tube & today they were doing a job on a car which has a lithium battery which had become flattened & switched itself off, so it refused to charge up. It dawned on me that this might be of interest to forum members as many have switched over to lithium. Sorry the...

www.motorhomefun.co.uk

 

[gerry mcg]

As a follow up to this, i contacted KS-Energy with screenshots of the voltage plots from the SBS.
they were a bit surprised the onboard BMS had kicked in at 11.2v - their recommendation if the BMS got out of sync was to discharge all the way to 10.2V, then do a full recharge to recalibrate the BMS.
I got the impression is it should have discharged to below 15% SOC / 30Ah remaining before the BMS shut it down.

so is there any reason my battery appears to have shut down to 11.2v?
Perhaps some setup in my Victron BMV 700 that would cause it to shut down / disconnect the lithium battery.

it seemed my BMV SOC deviated from the BMS SOC - perhaps resetting the BMV SOC to 100% when the actual BMS SOC was declining - this might be because the Solar Voltage absorptio voltage is set at 14.4v and the charged voltage is slow 14.4v? Should i change the BMV settings?

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[AdrianChen]

Unless you have a relay setup to disconnect the battery I don't think your BMV can do this (i've seen it done on some systems using a latching relay, but controlled by the batteries BMS).

On my SmartShunt I have the charge efficiency factor set to 99%, tail current to 2.3% and Peukert set to 1.05 on my lithium system (But I guess KS have recommended settings for these), and the "Battery SOC on reset" is set to "Keep SOC", which I suppose is the equivalent to "Battery starts synchronised" set to off? Its the last item that I think will make the biggest difference....

 

[two]

This may not help, but have you considered things outside the battery?
I assume that the battery is an upgrade, so wonder if any other changes took place at the same time?
it could be that the cause has come from one of those other changes...

 

[nabsim]

After a full charge overnight at 15A with the dedicated victron IP22 lithium charger, all seems to be normal, with the battery having taken a full charge of 165A and the onboard BMS And the BMV 700 Showing full SOC.
The compressor fridge had been running, and the solar usually keeps up with the drain, but the weather over the last few weeks has not been great, so I it is possible it was unable to keep up with the fridge current drain.

What is odd was the rapid cycling from low 11.2v to apparently normal 13.6v on the SBS trace.
I'll monitor for now

View attachment 820413 View attachment 820414 View attachment 820415

Do you by chance have a Victron mppt? If so look at the history page, it will show lowest battery voltages for last 30 days. If it did go down gradually due to poor harvesting that may identify it