Question about lithium batteries and storage

[radarcontact]

Looked thru previous posts but couldn't find a clear answer on this...

When storing your lithium battery FWC in the garage between camping adventures, SHOULD you ever plug it into shore power and walk away? Since the camper AC to DC converter will float charge, I'm thinking it's not a good idea, nor necessary because of the slow discharge rates of Li batteries, but there's lots of conflicting info out there on this topic.

I'm basically talking about spring/summer/fall usage and storage. In winter I would take measures to ensure the battery didn't get too cold (I live in Wyoming), and check charge every two months/charge with battery charger if needed.

 

[TacomaAustin]

My preference would be to replace the stock Iota AC to DC converter which is for a lead acid with an updated converter/charger that has the correct profile for lithium. Also, there are other considerations such as the 10 AWG wiring FWC uses from the truck battery to the house battery and whether to install a DC to DC charger for charging while driving.

From the one of many threads on the Electrical, Charging, Solar, Charging and Generator forum - https://www.wanderthewest.com/forum/topic/22201-battery-novice-needs-help/?p=258037

 

[radarcontact]

Tacoma, thanks for the link, missed it somehow. Rando has been very helpful in the past when I've had questions regarding electrical stuff. I'm onboard with the wiring revisions and DC-DC charger.

I'll probably limit my shore power charging.

 

[Charlie]

I think one of the confusing aspects of this topic is the self-discharge rate of a lithium battery vs. base load. For sure, a completely unconnected lithium battery has a very low self-discharge rate, and can sit on a shelf for a very very long time before it gets to a significantly low state-of-charge.

However, it’s typical for a camper to have some very low draw devices, which will still add up to a significant load. For instance, my camper has a base load of about 300 mA. Half of this is from the CO/propane detector, and the rest is from lighted USB outlets and the circuit breakers LED indicator lights. That amounts to ~6 Ah/day, which will clearly draw down a 100 Ah battery in a few weeks. Similar to the dome light in your car when you you leave the door open for a few weeks.

FWC has the “silver switch” which lets you disconnect the battery from all loads, if you remember to use it. I replaced the Iota IQ4 charger (AGM) with a Victron IP22 (lithium) charger, just so that I could plug it in for the winter and just forget about it.

 

[rubberlegs]

I've read that lithium batteries like to be at about 50% while in storage. So one idea is to attempt to use it to about that level, plus or minus quite a bit (35%-65%?), then disconnect the battery and forget about it all winter. I'm not sure if that's ok in very cold temperatures though.

 

[PaulT]

I've read that lithium batteries like to be at about 50% while in storage. So one idea is to attempt to use it to about that level, plus or minus quite a bit (35%-65%?), then disconnect the battery and forget about it all winter. I'm not sure if that's ok in very cold temperatures though.

Contact the engineering/technical department of the company that made your battery and ask them. They have a vested interest in you having good information as to the care & feeding of their batteries and are certainly the best source of info. Send an email with the list of questions you need answered.

Paul

 

[m5040]

Contact the engineering/technical department of the company that made your battery and ask them. They have a vested interest in you having good information as to the care & feeding of their batteries and are certainly the best source of info. Send an email with the list of questions you need answered.

Paul

It would be nice to let us know what they advised.

 

[BlueSky]

Every LifePo4 battery I looked at was required to be stored at less than 100% charge. The instructions that came with mine (off-brand Amazon) said store at 80% and do not charge when temps are below freezing (so I don't leave it on trickle charge of any kind). I have always disconnected batteries from the fuse panel to eliminate phantom draw down during long term storage.

 

[radarcontact]

I think one of the confusing aspects of this topic is the self-discharge rate of a lithium battery vs. base load. For sure, a completely unconnected lithium battery has a very low self-discharge rate, and can sit on a shelf for a very very long time before it gets to a significantly low state-of-charge.

However, it’s typical for a camper to have some very low draw devices, which will still add up to a significant load. For instance, my camper has a base load of about 300 mA. Half of this is from the CO/propane detector, and the rest is from lighted USB outlets and the circuit breakers LED indicator lights. That amounts to ~6 Ah/day, which will clearly draw down a 100 Ah battery in a few weeks. Similar to the dome light in your car when you you leave the door open for a few weeks.

FWC has the “silver switch” which lets you disconnect the battery from all loads, if you remember to use it. I replaced the Iota IQ4 charger (AGM) with a Victron IP22 (lithium) charger, just so that I could plug it in for the winter and just forget about it.

I would use the silver switch and do what you do if I had the IP22....but living in Wyoming, where my garage gets down below zero regularly, negates winter garage charging. I'll probably move the battery into the house during winter months.

Because I don't have a lithium friendly AC to DC converter, I'll most likely just plug it in to AC for a day or so if needed during the warmer months, as Rando suggested, then unplug it and use the camper cutoff switch (silver knob) to disconnect camper loads from the battery when it's sitting idle.

 

[radarcontact]

I've read that lithium batteries like to be at about 50% while in storage. So one idea is to attempt to use it to about that level, plus or minus quite a bit (35%-65%?), then disconnect the battery and forget about it all winter. I'm not sure if that's ok in very cold temperatures though.

My take on this is similar to yours, except I've read that the batteries like to be anywhere between 50%-100%....the percentages seem to be all over the map, and there's no clear-cut rule to follow on set level before you disconnect and leave it idle. I'm not sure if it makes much of a difference...main thing is to not allow the battery to drain to 0%, then you can't recharge it. Leaving Li batteries idle without charging, in cold weather, from my understanding, is OK, but there's evidence that it shortens the overall life span of the battery...so putting it in an environment that's above freezing is supposedly helpful during winter storage.

 

[Charlie]

That's right, charging a lithium up from a non-lithium charger for short periods of time will work just fine. As you said, the guidance for SOC during storage is all over the map, and seems like it is focused on preserving the lifespan of the battery. They never seem to say how much the lifespan gets diminished, but I bet it is not much. My lithium is kept topped off at 100% continuously by the solar. I don't worry about it.

 

[Wallowa]

Everyone has a "best method"...here is what BB CEO says about storing, using and charging LiFePo4 BB...I have their 100aH battery and follow this advice....


"Dennis [BB] says in this interview that if you charge a BB to a full 14.4V then disconnect and let it sit the voltage will drop to 13.3V and stay there for months. Watch at 16:36 time on this video.

"

Phil

 

[veryactivelife]

Everyone has a "best method"...here is what BB CEO says about storing, using and charging LiFePo4 BB...I have their 100aH battery and follow this advice....


"Dennis [BB] says in this interview that if you charge a BB to a full 14.4V then disconnect and let it sit the voltage will drop to 13.3V and stay there for months. Watch at 16:36 time on this video.

"

Phil

The storage recommendations provided by manufacturers and other experts does seem to be all over the place. I believe the common denominator is do not store the battery at 100%, so do not leave it on a charger.

As for charging with shore power using an IOTA, the IOTA charges at 13.6v which is the resting voltage for LiFePO4 batteries. So no chance of harming the battery, you just will have a slow charge. But like other chargers, don’t leave it on for storage.

Dean

 

[Wallowa]

Another point to remember is that cold is not the enemy of LiFeP04 battery but heat is......

 

[rubberlegs]

There's no doubt that lithium batteries are far different than AGM batteries. Our 2006 Prius has Nickel metal hydride batteries, and the system keeps the batteries charged 40-60% the vast majority of the time.

I've also heard lithium batteries, for longest life, should be used from 20%-80%. I've been using 40%-80% on my iPhone, which lasted 7 years. Other things went wrong with that phone, but the battery was still decent. Anyway, 20-80% is a total of 60%... AGM is 50-100% which is a total of 50%... so it seems lithium is only 60/50 or 20% more energy stored (ideally) than AGM. However, lithium can handle a lot more discharges, and we only use our camper maybe 50 days per year, not 365 like our phone! So with 1000 charge cycle life, that a lot of years.

I may have a lot of these numbers wrong... take it all with a grain of saltpeter.

 

[Wallowa]

Remember with LiFeP04 you can use 100% and not damage battery; below 50% on AGM and it can reduce the life-span...

Another grain of SP....