Lithium Short Term Storage Best Practices

manyman297

So I keep hearing conflicting messages about lifepo4 batteries and how they should be stored in between camping trips. Some say to discharge to 80% and disconnect any charging (solar, shore). Others just leave solar or shore on and leave it up to the charge controller or converter to manage it. 

What are those here with lithium doing? I’d love to try and baby these for as long as possible.

Bayliss

@manyman297, I have a 100 Ah Battle Born LiFePO4.  Per Battle Born's advice, when I complete a trip, I charge my battery to 100% (14.2V-14.6V), and leave it connected at that voltage for about 20 minutes to "balance" the battery cells.  I then remove it from my trailer for storage at my house (in a cool, dry location), because our temps range from very hot, to very cold, depending on the time of year.  I do not keep the battery connected to a trickle charger/maintainer, because Battle Born says it is not necessary.  The battery can drop down to 75%-80% SOC if stored for six months (per Battle Born), but they say to just top it off before its next use.

Depending on who manufactured your battery, my best advice would be to check their specific website, or contact them by phone, to obtain their specific recommendation(s.)  I believe the differences in opinion that you and I read on how to maintain a lithium battery is because the various manufacturers provide different instructions.  Apparently, one size does not fill all.

Another cause of confusion regarding charging/maintaining batteries is that those posting information on the web are, likely inadvertently, mixing apples with oranges (i.e., LiFePO4 vs AGM vs Wet Cell.)

pthomas745

My AmpereTime (the company that changed their name to LiTime) went into the battery box in the tub. I keep it charged (parked in my back yard) with my solar controller.  It has been in the trailer for three years, and I've never even opened the battery box.

manyman297

Removing ours between trips would be impractical as we have the 400 (batteries are under the bed). We also have LiTime batteries so maybe it’s ok to leave it fully charged. I’ll check with them to verify.

Horigan

We keep ours charged and connected to the solar charger during the entire camping season.  In the winter we'll discharge to ~50% and disconnect the chargers.  Being a 400, we leave them in the trailer in the PNW winter.

LiFe batteries are capable of thousands of 100% complete discharge/charge cycles, and many more with the partial discharge cycles we all normally encounter.  Loosing a few percent of that performance due to leaving them fully charged all season isn't a concern for us. 

SLJ

Mine has two 100ah and is stored in an unheated garage. I just charge them up to 100% and switch them off for the winter. I keep them charged in case I need the camper. Camper stays on shore power (not charging the batteries). The battery monitor shows they drop about 1-2% over the Winter if not used at all. When Spring comes I flip the smart charger back on and put them back to 100% and go. I've done that for two winters now with no problems.

manyman297

We live in Utah where temps can get down to single digits in January. I’m assuming I’d be smart to pull them out of the trailer and into the house?

Maxcamp

@manyman297, we've stored our Battleborns fully charged on-board three winters now as low as -12F.   It is critical to isolate all connections including solar charge fuses to ensure no damaging Cold Charging below 32F or so.  Each battery terminal is isolated by a switchable in-line breaker which is very handy for occasional Balance Charging, troubleshooting, and battery capacity measurements "At-Rest."  

manyman297

@Maxcamp8 That’s great…wow -12. Theoretically as long as I turn off charging on the controller I should be fine right?

Maxcamp

Pulling the solar fuse (or maybe using the victron app?) should suffice, however in a fit of overcaution I make sure to isolate the battery terminals from eachother as well to prevent drawndown by a rogue cell.  They're just too darned expensive. 
I've experienced battery failures in different battery chemistries over the years, from mining lights to construction lights to ebikes.  LiFePo seem so much less temperamental.
Bear Lake and Wasatch Range surely get colder?

manyman297

Anything I can do to not have to remove them in winter would be great. I have the LiTime batteries and their specs say to not store them in weather colder than 14 degrees. I’m in Salt Lake and the trailer is stored at our home. Coldest I’ve seen it get here is 2 degrees maybe…pretty rare. Most of the winters were maybe in the teens. I’d still like to exercise some caution though.

pthomas745

As far as lithium batteries and charging: many batteries these days have "low temp charging protection".  A circuit on the battery (inside the battery case, near the BMS) that will prevent any charging when the temps get low enough to trigger the circuit.  And, it is not the air temperature that is the issue: a lithium battery can't be charged below "freezing"....but that means the battery cells themselves have to be below freezing. 

manyman297

My cheapskate tendencies made me opt for the batteries without low-temp charge protection. I felt I’d be mindful of the temps and could shut off charging.