Managing a Lithium battery

[Chuns]

I have read that lithium batteries don't like to be kept on a float charge, continually topped up. Does anyone know how that reconciles with the systems we seem to have, that is charging while driving, charging as soon as connected to the mains, meanwhile being charged by our solar panels?

Is damage being done under this regime? I don't mind a shortened (battery) life if it is shortened by, say, 5%, but a significantly bigger amount would concern me.

Meanwhile, I love the absence of concern about electricity availability (I no longer turn off the lights that my wife leaves on), and the weight saving.

 

[Ingwe]

I have read that lithium batteries don't like to be kept on a float charge, continually topped up. Does anyone know how that reconciles with the systems we seem to have, that is charging while driving, charging as soon as connected to the mains, meanwhile being charged by our solar panels?

Is damage being done under this regime? I don't mind a shortened (battery) life if it is shortened by, say, 5%, but a significantly bigger amount would concern me.

Meanwhile, I love the absence of concern about electricity availability (I no longer turn off the lights that my wife leaves on), and the weight saving.

Am interested in the answer too. Am soon to have 2 lithium batteries fitted along with the usual necessaries like B2B charger, better solar control etc but am unsure of the very questions raised. Currently, when not in use, our van is stored in a garage 5 miles from home. We have a battery master fitted and keep the van on hook up, but with a timer connected limiting the daily charge. This way our cab battery also stays charged. But wonder how the regimen will change when we have the lithium batteries.

 

[funflair]

We have lithium fitted, as driving is not a huge amount of the total battery life I don't think the B2B is a big issue, we very rarely plug into EHU as the point of lithium for us is to be free from that requirement and when the van is not in use it is inside so I run the batteries down to 80% and then isolate them, if it was stored outside our solar can be set to different profiles so we would just charge to a lower voltage so lower % state of charge.

So really it depends on what you already have fitted and how you use/store your van/batteries.

 

[Ingwe]

funflair-can you please elaborate how you isolate the batteries?

 

[funflair]

funflair-can you please elaborate how you isolate the batteries?

We just have a big isolator switch that is connected to a low voltage protection device or you just turn it manually, you could argue that it is an extra layer of security as the door won't even open when it is all tripped, doing this the solar is still connected though and a Battery master is connected to keep the starter battery good.

^{_{Subscribers  do not see these advertisements}}

 

[autorouter]

I have read that lithium batteries don't like to be kept on a float charge, continually topped up. Does anyone know how that reconciles with the systems we seem to have, that is charging while driving, charging as soon as connected to the mains, meanwhile being charged by our solar panels?

Is damage being done under this regime? I don't mind a shortened (battery) life if it is shortened by, say, 5%, but a significantly bigger amount would concern me.

If you have chargers with a lithium profile, they will stop charging when the battery is sufficiently full, and won't 'float charge' it.

If you have dropped a lithium battery into an existing lead-acid charger setup, then the chargers will eventually go to 'float charge'. However it's not a proper float charge, which has the voltage set to just feed in a small current to compensate for self-discharge of a lead-acid battery. The float charge voltage level is not high enough to continually feed in a current, so the battery will settle down at the float voltage, which will keep it at just less than 100% charged.

If the chargers are not 3-stage intelligent chargers like that, then it's possible that the battery will be overcharged and its lif will be affected.

 

[Chuns]

Thank you for that comprehensive, clear and complete explanation. I am reassured, as my solar charger has a lithium setting, and I have had my Nordelettronica control box modified, (by the excellent Apuljack business).

Oh, the power of this forum!

 

[Ingwe]

@autoroute—so if I‘ve fully understood you, if my charger has a lithium profile, when my van is stored inside so solar doesn't operate and I keep the van on hook—up, the charger will ensure the lithium batteries do not overcharge and my battery master will keep the cab battery charged? Sorry to be thick; I’m just concerned with what to do when the van’s in storage.

 

[autorouter]

Lead-acid based batteries (flooded, gel, agm) should be kept at 100% charge while in storage, or they will gradually deteriorate with sulphation. This idea is so engrained it's hard to get away from. A lithium battery is best stored well below 100%, around the 50% mark is good. They don't suffer deterioration like lead-acids. Keeping them at 100% if anything is detrimental. Lithiums can last for decades if kept within their 10% to 90% levels.

I'm surprised that charger manufacturers don't have a 'storage' setting for lithium batteries. Maybe it's more difficult than I think it is. And it could be misunderstood in that after storage the battery wouldn't be 'charged and ready' like we expect lead-acids to be.

Anyway, rant over. If the charger has a lithium profile it should cut off when it's fully charged. I presume it monitors the voltage so of it falls too low, it will start the charge cycle again, so from that point of view it should be OK. The thing with batteries stored in a MH is there is still some drain from the connected circuits. Isolated on a bench an lithium battery will stay charged for months.

 

[Tombola]

As per what autorouter said.

But I also fitted a switch between the solar and batteries and also my b2b and batteries and if concerned I just flick em off..
Also helps if you need to do something on the solar or battery circuit to isolate them.

^{_{Subscribers  do not see these advertisements}}

 

[the1andonly]

My understanding of the lithium game
The lithium profile on the various chargers (b2b and solar) (ehu not used) look after the battery in normal use.
To winterize reduce SOC to 80% and issolate at battery negative, leaving votronics controllers to charge the SB.
i have just acquired a bmv712, i believe this can be set up to turn on and off relays at given SOC. NOW I need to get some large relays and have a play with the software. Anybody done this allready? Can it be programmed from bluetooth, pherhaps i should read the manual.