Leaving LifePO battery for 3 months

[mrybas]

Hi,
I’m leaving my boat at the dock, unattended for 3 months.
Everything is off except for the bilge pumps (never run).
Only charging source is solar.
Should I set the bulk, absorption, and float settings on the solar charge controller to a lower voltage so the batteries are not at 100% for 3 months?

[markcouz]

I suggest setting all bulk/absorb/float to 3.3 to 3.4v per cell (13.2 to 13.6v for a 12v pack).

My 12v LiFePO4 batteries have been happily sitting at 13.5v since August last year with only 4x 10 day visits over that time with no ill effects (solar only).

[smac999]

if you are worried you could disconnect them and tempory install say a group 31 battery. to charge from solar and run the bilge if needed.

[vtomanov]

Get a www.boat-bitals.com monitoring device - my LiFePo4 batteries has been with no problems every winter for 6m on the hard - engine with no charging house with solars only

[Ragha]

My LiFePo4 batteries are left 3+ months unattended with 220V charging (Mastervolt) connected as the boat is in the water with basic heating throughout the winter in northern Norway. I have not disconnected the batteries. Have not noticed any decrease in performance.

[zstine]

• Storing a LiPo battery near 100% capacity results in the formation of a restrictive layer of deposits in the battery’s anode
• Allowing a battery to go into deep discharge – or the state where it goes below 3.0 V – can happen whether during use or long-term storage. When this happens, there is a huge risk of the anode material starting to dissolve into the electrolyte solution
• Assuming that you are using typical LiPo batteries that hold a full charge of 4.2 V per cell, then you should be targeting a storage voltage between 3.6 V to 3.8 V, corresponding to roughly 85% to 90% of the battery’s full capacity. This is necessary if you will be storing your LiPo batteries for longer than 3 days without using them.

from 3dinsider.com

[tanglewood]

Will the temp range be OK where the boat is stored?

[mrybas]

Originally Posted by tanglewood

Will the temp range be OK where the boat is stored?

Should be fine. Charleston,SC

[seandepagnier]

If stored at 100% charge you can lose 5% capacity after 3 months at 25C

At 40% you lose 1% capacity after 3 months.


Colder is better



It's best you discharge to 13.1 volts and disconnect the battery from everything.


People claiming their battery is just fine at 13.5 volts maybe just lost a few more percent capacity which is difficult to notice but not what you want.

[markcouz]

All batteries degrade over time, that is a fact of life.

The batteries are there to do a job, if a disaster happens you need your bilge pumps to work overnight while waiting for the sun to rise.

At 13.5V you will be at around 90% capacity and very little plating degradation will occur, even better if you are on solar which is cycling rather than shore power with no rest from charging.

At 13.2 (3.3v/cell) you will be at 40% which is preferable, but you must be sure that you have sufficient capacity to deal with disaster should it happen.

In my case I prefer the safety margin over the very marginal benefit.

In the end the choice is yours.

[rgleason]

Sometimes we hit 0F or -10F for a day or so, but they would be inside the boat and more protected. Should a heat blanket be added for these events?