LFP for boats staying mostly in the slip

[jimp1234]

I recently upgraded my house bank to LFP with the intention of retiring and doing some cruising. Because of the pandemic I've changed plans and will continue to work until next year. So for the next year the boat will be used on the weekends and remain in slip the rest of the week on shore power. Typical daysailer schedule. My question is concerning the batteries being left on shore power and fully charged most of the time. In the slip the draw should be low so was wondering if there was any benefit to leaving it off shore power periodically (one week on, one week off for instance) just to let the batteries discharge a bit. Or just let them stay fully charged most of the time and don't worry about.


Thanx

[Reefmagnet]

LFP batteries are happiest at about 50% charge and shouldn't be held at more than 90% continuously for long periods if maximum working life is to be achieved. You probably wont kill them if you keep them at full charge, but it wont do them any favours.



If you're daysailing, you can probably get away with partially charged batteries. If you have a suitable charging system, and the inclination to do so, the easiest way to keep the charge down is to re-program the maximum charge voltage. 13.2V is about the 50%-70% charge value.

[Flod]

I always try to have the batteries at 40-60% at the dock and never leave the shore power on. I then try to cycle them even if I have access to shore power. I mean the spec says they can do like 4000 cycles and I maybe spend 50 nights a year in the boat. If I where you I would not leave them on shore power all week

[Nicholson58]

Originally Posted by Reefmagnet

LFP batteries are happiest at about 50% charge and shouldn't be held at more than 90% continuously for long periods if maximum working life is to be achieved. You probably wont kill them if you keep them at full charge, but it wont do them any favours.



If you're daysailing, you can probably get away with partially charged batteries. If you have a suitable charging system, and the inclination to do so, the easiest way to keep the charge down is to re-program the maximum charge voltage. 13.2V is about the 50%-70% charge value.

All true BUT, make sure float is zero. Lithium batteries can be destroyed by float. It should not be part of any charging device.