Lithium-ion and solar panel life cycles?

[jaycocreek]

With a lithium-ion battery is it better to run it down or keep solar plugged in?

I have an Engel compressor refer/freezer that draws 36-37 watts when it runs..I also have a portable 100 watt solar panel that puts out on average about 65 watts..It has been as high as 81 watts if I take the time to aim it right..

My question is,when I hooked it up,it quickly charged the battery to 100% with the Engel running and then it showed 0% input from the panel for a while then back to 64-65 watts input then 0%..

Is this method better or worse for battery cycles/longevity than running the battery down then charging it?

Completely new to solar and trying the portable solar for now...So I am a solar dummy of sorts for the time being..LOL

[red31]

I let the BMS and CC do their thing.

[pianotuna]

noteven wrote:
Suggest you call your battery manufacturer for advice on correct charging with low current.

My research has discovered Li-FO4 batteries can discharge and charge at high rates, are happy to sit partially charged, and are good for 3000-4000 cycles to 20-30% when operated and stored properly. It makes them particularly suited for generator and vehicle alternator charging with the right equipment.

SiO2 is also happy to not be charged. Storage time is 2 years. They require NO special equipment to charge and do not require cell balancing devices. Maximum discharge rate is 9 C. 1/3 the price of Lifepo4

[CA_Traveler]

100W solar might keep the battery charged with no other loads. Do a energy audit and determine your usage and then what's needed. A battery monitor will be even better. You're asking about a very expensive battery that has different charging needs than flooded.

Maybe experiment with flooded first before spending the big bucks.

[Lwiddis]

I wish Don would buy those batteries so we could have a real world report. I’m hoping for great results.

[pianotuna]

Hi,

For greatest longevity Li doesn't like to be charged above 90% of full, nor discharged below 40%, especially for storage.

The deeper the discharge the fewer total cycles. Attempt to not go below 20%.

All the recommendations I find are charge to 90% before storage. Refresh the charge from time to time.

Do not store below -4 f (-20 c).

I'm going SiO2 instead. They can survive being discharged to stone bone dead 620 times. Of course, that is not recommended. They appear to be better than LI in every category except for weight. The SiO2 are similar weight to lead acid. They can be used and charged at -40.

This solar series in plain English may help: https://freecampsites.net/adding-solar/

[2oldman]

Li batteries don't really care what SOC they're in.

[noteven]

Suggest you call your battery manufacturer for advice on correct charging with low current.

My research has discovered Li-FO4 batteries can discharge and charge at high rates, are happy to sit partially charged, and are good for 3000-4000 cycles to 20-30% when operated and stored properly. It makes them particularly suited for generator and vehicle alternator charging with the right equipment.