Heat, storage, charge level, lifetime

[IGBT]

I know this has been discussed previously, and I did dig around a fair bit, but I have some questions about our particular use case.

We have installed one bank of four Li-time group 24 with bluetooth batteries in our sailboat v-berth in a 4s, 48 volt configuration for propulsion. We installed these about three weeks ago and have been through one discharge/charge cycle. They are currently at 13.37v or thereabouts (each) and showing 99%. I have the second set that I just got shipped charged up to 100%, all four showing 13.46V +/- 10mV and ready to be installed for the second bank.

Ok, now the question. The daytime temperatures in our area are getting up to 97F to 100F. The batteries in the v-berth are not in direct sun but I would imagine they are getting near that temp for several hours each day. The nighttime temps are around 68F.

Am I killing the batteries having them at 99% SoC while being stored in those temperatures for a few hours a day? How much if so? I will be extremely happy if I get 500 charge/discharge cycles before they drop to 90% as that should be enough to complete the 6000 mile Great Loop over the next 2 years. Is this realistic while treating the batteries such, or should I be pulling them out of the boat and storing them at 70F in the house. This is quite the pain to do since we are wanting to test the boat in various ways this summer. Alternatively, would discharging them to 50% make a huge difference in storage? Am I being too anal here and 99F for a few hours each day is just nothing to worry?

 

[Horsefly]

Am I killing the batteries having them at 99% SoC while being stored in those temperatures for a few hours a day?

Probably. The heat accelerates the otherwise inevitable calendar aging of LiFePO4 batteries. But if it can't be avoided, it can't be avoided. If they really are being stored, you would be much better off if you could discharging them to around 50% SoC while they are not being cycled. Storing at 99% SoC also accelerates the aging of these batteries.

enough to complete the 6000 mile Great Loop over the next 2 years

Your profile says you are in Seattle, but you are going to transit the Great Loop?! Is this a different Great Loop, or are you going to also have to transit through the Panama Canal to get to the east coast?

 

[IGBT]

Probably. The heat accelerates the otherwise inevitable calendar aging of LiFePO4 batteries. But if it can't be avoided, it can't be avoided. If they really are being stored, you would be much better off if you could discharging them to around 50% SoC while they are not being cycled. Storing at 99% SoC also accelerates the aging of these batteries.


Your profile says you are in Seattle, but you are going to transit the Great Loop?! Is this a different Great Loop, or are you going to also have to transit through the Panama Canal to get to the east coast?

It is a lil boat 10.24kwh of LFP, 6kw electric motor (80+nm range at 3.7kts with no solar, plan on 600 watts solar)

That'd be a hoot going through the Panama Canal, but I think we will take I-90