Re: [electricboats] Storage of LiFe PO4 Battery for 6 Months

The devil is in the details.

Got an online link to the specs for these batteries to share?

From your simple description, it sounds as if these are LiFePO4 "boxes" with embedded battery cell management electronics.  As such, you likely cannot disable these "managers" from sucking power for months.  Some such embedded electronics will fully deplete its own LiFePO4 battery within 2 years, or even within months.  I have seen this---we had some 30 LiFePO4 12v boxes (7ah only) that had sat "new in box" in storage and every single one of them (at $120 a pop) was dead and unrecoverable due to the onboard cell manangement electronics killing them.

 

IFF you are able to disable such electronics while you are gone for months, then separate all your batteries and disable the BMS.  Likely you have no access to do so.  And so, you need the specs.  Now, probably a "box" with 100ah capacity would not lose much capacity at all in 6mos or even 2 years…nothing like a 7ah capacity situation.

And so, you can probably just charge these up 50 to 80% or so and leave them for months.

Charging to 100% may be okay, but sitting for months at this level may cut down on the life of the batteries.

Leaving these on a "trickle" or connected to any other charge setup shouldn't be necessary unless the specs suggest that it is wise to do so.  I'd guess that most of these box lithium batteries allow steady "trickle" overcharge currents since they are designed to bypass when the box voltage gets above something like 16v.

 

Good luck.

 

-MT

 

From: electricboats@groups.io [mailto:electricboats@groups.io] On Behalf Of Draggett@live.com
Sent: Wednesday, March 30, 2022 1:11 PM
To: electricboats@groups.io
Subject: [electricboats] Storage of LiFe PO4 Battery for 6 Months

 

I have recently purchased a bank of 8 LiFePO4 12v 100ah batteries for my sailboat. However progress on the refit is taking longer than I anticipated. I will be heading back to Canada from Florida shortly and would like to give the batteries the best chance at a long life. I'll be returning in 6 months and was wondering if anyone has any advice on how best to store thhe batteries to ensure longevity. They will be fully charged before I leave and will be kept in an air conditioned space at 78F for a Florida summer.

Should I leave them disconnected for the six months?
Should I connect them together in parallel and leave them.
Should I connect them in parallel and leave them on a 12v trickle charger?
Should I connect them into the configuration in which I'll be using them (48v) and leave them?
Should I connect them as above and leave them on a 48v charger?
Other storage strategy.

Any advice deeply appreciated.