Lithium battery down to 11.3v

[Pablo19]

I posted a thread recently about a small discharge. Turning the power off completely has resulted in the solar now keeping the charge nicely topped up. the control panel can drain more than you realise although like others have said, lithium should last longer than that unless there is a substantial drain from somewhere.

 

[MichaelT]

Hopefully it is switched off when ignition is off.

No it draws quite a bit.

Does your battery have a BMS you can connect to you can then see any draw.

 

[TheBig1]

I think the main issue is a new lithium battery should not fully discharge in four weeks with no load. One of the main advantages is slow rate of discharge. Another is ability to work down to as much as 90% discharge.
Solar panels kept my previous van fully charged in winter storage.
In 25 years of motorhoming and 5 vans, I’ve never experienced anything as bad as this with a leisure battery.
I cannot find anywhere to change charging profile.
Just to add to my worries I’m due to set off for Spain on Monday.

Highly likely you will need a newer solar charger with lithium option. Doesn't need to be eyewatering expensive, but the best you can fit on your budget is money well spent. Personally prefer Victron, as I can monitor what the charger is receiving and putting out via my phone

 

[Dolmen]

Went for 20 mile drive.

View attachment 841130 View attachment 841131

Is the engine still running? Looking at your panel batteries look to be around 50% full yet showing vehicle 12.8 which is around 100% and leisure 12.9 which is around 20% for lithium. In your OP you said battery down to 11.5 and 11.1 assume this was the lithium as van would probably not start at 11.1. Assume you are not having problems with cab battery, can that be eliminated from concerns?

 

[Lenny HB]

Get yourself a DC clamp meter so you can see what is going on, long term it's best to fit a Victron Shunt either a Smart Shunt or a BMV712.

Amazon product ASIN B00O1Q2HOQ

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[jeddy]

Is the engine still running? Looking at your panel batteries look to be around 50% full yet showing vehicle 12.8 which is around 100% and leisure 12.9 which is around 20% for lithium. In your OP you said battery down to 11.5 and 11.1 assume this was the lithium as van would probably not start at 11.1. Assume you are not having problems with cab battery, can that be eliminated from concerns?

 

[jeddy]

No problem with engine battery. Photo of panel taken after drive. Have shut down EC700 to ensure no draw on leisure battery. Will check in the morning. If battery has significantly discharged again will then contact dealer.
However, I have noticed batteries are not included on their warranty. They installed it as new 4 weeks ago. One would hope it is covered.

 

[Dolmen]

No problem with engine battery. Photo of panel taken after drive. Have shut down EC700 to ensure no draw on leisure battery. Will check in the morning. If battery has significantly discharged again will then contact dealer.
However, I have noticed batteries are not included on their warranty. They installed it as new 4 weeks ago. One would hope it is covered.

One last question, is it a newish van with a smart alternator? The only reason I ask is that when my lithium leisure was fitted it discharged rather than charged, the smart alternator was effectively letting it do its job, the installer obtained a diagram from Sargent showing how to fit a relay to modify the actions of the split charge system, worked perfectly from then on.

 

[jeddy]

The van is 2020.

 

[Peavy]

If you get a complete diagram of what you have in your system (charger, B2B if any, etc...) and how it is connected, someone here will be able to help.
The dealer should help with this

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[jeddy]

If you get a complete diagram of what you have in your system (charger, B2B if any, etc...) and how it is connected, someone here will be able to help.
The dealer should help with this

This came in the pack

 

[olley]

This came in the pack

View attachment 841203

That has a lithium setting, I have one in the RV.

 

[Guigsy]

In the winter, my battery discharged in 2 weeks on the factory fit lead acid battery in my 2020 registered van. 175w of solar is virtually useless over the winter as most of the day the van ends up in the shade when the sun is low. I've replaced the factory lead acid with a 280Ah lithium battery. Which means it'll last many weeks before its dead. I've not yet put a B2B in there, so running the engine will only put about 18A in, so which is about 6% per hour... so not a practical method to recharge it. I'll upgrade it at some point, but probably only to 30A. During the winter, there's no way around it, I have to plug it into the mains for a couple of days once every few weeks.

As a backup though, the lithium's BMS should prevent it from being discharged to the point that there's significant damage.

 

[Kannon Fodda]

Lots of things to be considered here.

Fully charged a 12V rated lithium (LifePo4) leisure battery will have a voltage at around 13.6V. They rest much higher than a fully charged lead-acid type which would only be around 12.6-12.7V. None of the OP's comments and screenshots of the panel imply that the lithium has been anywhere near close to a full charge. Indeed lithium has a fairly flat voltage profile so only once below say 90% will the output voltage start to drop sharply. If resting lithium is below 13.0V consider it to be flat.

Due to the flat volt profile, voltage based metering on lithium is not suitable for assessing the lithium battery charge state. The control panel in the Autosleeper is of little use. Either use a bluetooth type app to interrogate the battery's BMS, or get a smartshunt fitted.

The Sargent 700 does seem to have a lithium suitability, but has that profile been correctly set by the installer? As a maximum it can output 25A, but that is with no other loads on it. A fridge or even a radio running will reduce that charging ability. and assumes the vehicle alternator is working fully without too much other load off the engine systems. At the maximum, you would need to be driving some 4 hours to fully recharge a 100Ah lithium battery.

Your posts imply you have a Sterling B2B fitted. This should charge better than the Sargent, but even a 60A rated charger will need over 2 hours driving from completely flattened, assuming you get the maximum rating (on my van the alternator seems to max out around 45A through the Sterling).

Solar at this time of year in the UK will be lucky to simply maintain a battery against discharge from alarm systems or other background parasitic losses. It is unlikely to be able recharge. Radios such as Pioneer are notorious for having heavy loads even when apparently switched off since they only go into a standby type mode, and those will take a lot from a battery. On my vehicle the radio is wired to work off the leisure battery, not the engine battery.

The Sargent 700 seems to have links between the engine (cab) and leisure battery so it can monitor both, do some sort of split charging from the solar and other clever stuff. But this may not be working correctly if lithium has been fitted especially if you have a Sterling B2B fitted. The B2B may be duplicating some of the leisure battery charging if it was not wired correctly to properly bypass the Sargent, with the Sargent circuits from the cab being isolated. It may now be that the Sargent is incorrectly reporting the cab or leisure battery if those are somehow crosswired. On my Autotrail, which originally had the ability to select either leisure or cab battery on it's panel, now I have a B2B with some other circuits amended, the panel is confused reporting the leisure battery on both the leisure and cab settings and no longer reports the cab. Are you certain, looking at the panel that you are correctly seeing the cab and leisure batteries?

 

[Ditcha]

13.0V consider it to be flat.

13v on a lithium certainly ain't flat I would say 10.6v is about flat.

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[Gromett]

I wouldn't be charging my lithium to 4.4v per cell max 3.65v

I never said anything about 4.4v?

 

[Ditcha]

I never said anything about 4.4v?

Your attachment does

 

[Gromett]

Your attachment does

View attachment 841283

I see your confusion/point. I wasn't providing this as an example of the charging voltage but of the flat nature of the voltage discharge curve. See the title.
The cell in the graph is a high energy one not an LiFePO4 cell.

Common cells do indeed require such a high charge although usually stepped back to 4.2V to extend the lifespan.
For example.

Molicel P28A 18650 Battery

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[Ditcha]

I see your confusion/point. I wasn't providing this as an example of the charging voltage but of the flat nature of the voltage discharge curve. See the title.
The cell in the graph is a high energy one not an LiFePO4 cell.

Common cells do indeed require such a high charge although usually stepped back to 4.2V to extend the lifespan.
For example.

Molicel P28A 18650 Battery

Upgrade your electronics with our high-performance Molicel P28A 18650 batteries. As an authorised UK distributor, we offer genuine cells direct from the factory. Enjoy long-lasting power, rapid charging, and next-day delivery. Perfect for power tools, video doorbells, and more.

www.fogstar.co.uk

Apologies I thought you were a little confused with the different battery chemistries as I thought we were talking LiFepo4.

 

[Pausim]

The van is 2020.

Your posts imply you have a Sterling B2B fitted.

A 2020 van may have a smart alternator and if so the B2B needs to be D+ activated and I think Stirling ones are sometimes wired to voltage activation not D+.

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[Gromett]

Apologies I thought you were a little confused with the different battery chemistries as I thought we were talking LiFepo4.

I should have looked specifically for an LiFePO4 profile in hindsight. I just took the clearest image from google image search to show the flat nature of the discharge curve to demonstrate why you can put it on charge for a few minutes and have a voltage that looks fully charged but is in fact not.

 

[Ingwe]

This is a chart given to us in relation to our Eco Tree batteries.

EcoTree Lithium - Approximate Capacity
This is a chart to help work out the approximate capacity remaining from the voltage reading.

LVD or Low Voltage Disconnect is a safety feature to prevent complete discharge as this would damage your battery. When your battery reaches 10.5 volts the internal battery management system will switch it off. When your battery is in low voltage disconnect mode it will appear to be completely dead but it is fine and just 'sleeping'.
It is important to charge the battery as soon as possible if it enters low voltage disconnect.
Most chargers will be able to wake the battery up i.e. Solar, Mains or engine charge. If your charging system cannot wake the battery up you just need to briefly connect an alternative 12v volt source to wake the battery up then immediately charge the battery before it goes back to sleep.

 

[Raul]

I see your confusion/point. I wasn't providing this as an example of the charging voltage but of the flat nature of the voltage discharge curve. See the title.
The cell in the graph is a high energy one not an LiFePO4 cell.

Common cells do indeed require such a high charge although usually stepped back to 4.2V to extend the lifespan.
For example.

Molicel P28A 18650 Battery

Upgrade your electronics with our high-performance Molicel P28A 18650 batteries. As an authorised UK distributor, we offer genuine cells direct from the factory. Enjoy long-lasting power, rapid charging, and next-day delivery. Perfect for power tools, video doorbells, and more.

www.fogstar.co.uk

Thats a wrong graph for lifepo4. Definitely wrong voltages to, at 12v you still got about 10% left with lifepo4 on discharge curve.

 

[Raul]

This is a chart given to us in relation to our Eco Tree batteries.


View attachment 841329
EcoTree Lithium - Approximate Capacity
This is a chart to help work out the approximate capacity remaining from the voltage reading.

LVD or Low Voltage Disconnect is a safety feature to prevent complete discharge as this would damage your battery. When your battery reaches 10.5 volts the internal battery management system will switch it off. When your battery is in low voltage disconnect mode it will appear to be completely dead but it is fine and just 'sleeping'.
It is important to charge the battery as soon as possible if it enters low voltage disconnect.
Most chargers will be able to wake the battery up i.e. Solar, Mains or engine charge. If your charging system cannot wake the battery up you just need to briefly connect an alternative 12v volt source to wake the battery up then immediately charge the battery before it goes back to sleep.

Close but not definite. Voltages differ if they are at rest, charge, or discharge curve.
But i agree as a rough estimate its pretty close.

 

[pappajohn]

90% discharge would be below 11v
50% discharge would be around 12v.
Sorry. Was thinking lead acid not lithium.

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[Ingwe]

Close but not definite. Voltages differ if they are at rest, charge, or discharge curve.
But i agree as a rough estimate its pretty close.

The chart does say “Approximate” . But always reassuring (for me) to get Raul ‘s confirmation!

 

[Gromett]

Thats a wrong graph for lifepo4. Definitely wrong voltages to, at 12v you still got about 10% left with lifepo4 on discharge curve.

I already conceded that point. But I was just looking to show how flat the discharge curve was.

I should have looked specifically for an LiFePO4 profile in hindsight. I just took the clearest image from google image search to show the flat nature of the discharge curve to demonstrate why you can put it on charge for a few minutes and have a voltage that looks fully charged but is in fact not.

 

[Raul]

I already conceded that point. But I was just looking to show how flat the discharge curve was.

I know now, sorry Gromett, I was typing when you was posting.
But, a small observation, all other li ion, do not drop in voltage much after charge, you have to remove some serious energy for the voltage to come down, lifepo4 on the other hand, from 3.55-3.6v charged, at rest will come down to 3.35-3.4v (depending on temperature), without any discharge. Hence that graph can not illustrate lifepo4 characteristics. Lifepo4, it is much flater curve, compared with any li ion.

 

[Gromett]

I know now, sorry Gromett, I was typing when you was posting.
But, a small observation, all other li ion, do not drop in voltage much after charge, you have to remove some serious energy for the voltage to come down, lifepo4 on the other hand, from 3.55-3.6v charged, at rest will come down to 3.35-3.4v (depending on temperature), without any discharge. Hence that graph can not illustrate lifepo4 characteristics. Lifepo4, it is much flater curve, compared with any li ion.

Which makes my point about the flatness of lithium cells discharge cycle even more valid. My original point was the OP went from 11.5v to 12.4v by running the engine. My point being that this rise would have just taken him so far up the knee of the charge cycle and effectively put next to nothing in the battery.

I am really regretting posting that image now as the technicalities and details are taking away from the actual meaning I was trying to demonstrate.

 

[Raul]

Which makes my point about the flatness of lithium cells discharge cycle even more valid. My original point was the OP went from 11.5v to 12.4v by running the engine. My point being that this rise would have just taken him so far up the knee of the charge cycle and effectively put next to nothing in the battery.

I am really regretting posting that image now as the technicalities and details are taking away from the actual meaning I was trying to demonstrate.

Please, Don’t worry about it, I understand what you meant. We can agree that the battery is very low discharged, probably close, or on to bms protection. I’m sure the OP needs more help than we can offer, there is something in his system not right. Without hands on diagnostic and measurements, we can shoot at guesses and may miss something that we can’ see.

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