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oceanwolfe avatar image
oceanwolfe asked

Best tactic for setting Multiplus charging of LiFePO4 battery when boat is "stored" at dock.

From previous threads, I've seen how I can set my Multiplus Compact's charging for CC/CV charging of my LiFePO4 drop-in batteries. That approach (setting Max Amp to the batteries charging specs, setting equalization to the shortest time, then setting the float voltage to the level at which you wish the charging to kick back in again.

As a side note, it seems strange that selecting the lithium battery mode in the charger doesn't seem to change the menus to offer the types of charging parameters one uses for lithium batteries.

My understanding is that for long storage periods (say a month or more) it is best to leave the lithium batteries at about half charge. Can I accomplish this by setting the Multiplus with bulk charging voltage of that of a half-charged battery, minimum equalization time, and a float voltage that is also the half-charge voltage? Will the charger then keep the battery in that mid-charge range?


Is there a better approach to this?

Basically, our boat tends to be either used for long cruises with the energy system heavily used, or sitting at dock for long periods of time. Not much "day sailing" activity. Since this would seem a fairly common situation, it would be nice to be able to easily switch back and forth between "use" and "store".

Any ideas for a good way to address this are much appreciated.

battery chargingLithium Battery
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2 Answers
Trina avatar image
Trina answered ·

I think u might still be think of lifepo4 like they are somehow similar to any kind of lead or gel based battery. Charge'm up and leave them unless you are going to be gone a YEAR but that still won't hurt your batteries.

You should have a strong charging system onboard and turn it on while getting the boat ready to go. If you are going offshore then your solar can be the "trickle" charger while u start your cruise.

LifePo4 can handle serious neglect absolutely opposite FLA AGM and gels. So wonderful.

on a boat your charger only needs bulk and bulk modes and maybe a brief float for a few minutes. I'd skip float completely and let the BMS deal with it and put in a SmartSolar MPPT with a 50w ams set it for Lithium.


Super easy!


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oceanwolfe avatar image oceanwolfe commented ·

Trina, every lithium battery for which I've read the specs recommends long-term storage at a partial charge. Apparently, the battery capacity will be reduced otherwise. I, too, like the simplicity of lithium batteries, but they cost enough (and mine spend enough time not being used) that I want to maximize their capacity/life.

If I understand correctly, most don't have a problem with being kept fully charged if they are being used (that is, have occasional loads applied). It is just if they are sitting without activity where the problem occurs.

If I sound a little vague here, it's because I am. Don't quite understand all the details of why a partial charge is best for storage. As you may have noticed, however, if you get a new lithium battery, they always arrive at half charge.

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cleaver avatar image
cleaver answered ·

I just drained mine down to 60% and disconnected them entirely, but I have an RV and keep them nice and warm through winter. If just leaving for a month then drain them down to 60% and shut off all charging (warm climate). Above 0 deg celsius.


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