Occasional Mobile Solar ? Best Battery Life Questions

[datac]

Hello, We see plenty of RV and Mobile Solar Install reports of how to size one and how to set it up for proper charging, and how to "long term store" a Lithium Battery.

But I have not really seen answers on achieving the longest battery life when something like a Van or RV is not used every single day.

So, here is my situation. I have a cargo trailer with a successful Ampere Time 200Ah+ battery, EPEver 40A Mppt controller and (4) 100 watt Rich Solar Panels. While I would love to be living in and out of it all the time, I am not. In fact, it can sit for a month or even a few months doing nothing. Yet, with the solar system, We know it is always discharging with small loads that are unnecessarily left on and recharging when the sun shines.

I'd think these "unnecessary loads" could easily run for a month or more without making much of a dent in a charged battery.

How much does this constant daily discharge/re-charge event count up regarding battery life cycles ? Could a battery last longer if I would pull the solar panel fuses and just check that I do not discharge the battery too much before turning the panels back on ?

Thanks !

 

[frater secessus]

If it were me I'd config the controller setpoints to 13.0v or something when the RV isn't in use. It would sit somewhere in the middle, state of charge wise.

If there really are no loads the SoC will not change and the charger will not charge the next day. Li self-discharge is something crazy low like 1%/month at human-comfortable temps.

Could a battery last longer if I would pull the solar panel fuses and just check that I do not discharge the battery too much before turning the panels back on ?

The problem is knowing for sure here are no loads. Technomadia smoked an early $5000 bank because they thought there were no loads when (IIRC) the internal active balancers had LEDs on them. Also consider any battery warming circuits during cold weather.

 

[Camper]

I try to keep my Ampere Time LIthiums about 80% when I'm not using them.

 

[Tom_M]

The safest approach would be to discharge the battery to at least the 75% state of charge and disconnect the battery.

 

[datac]

Thanks for the replies. I guess I will find a way to monitor and drop the battery to that 75-80% charge level after use, then just pull the ability to charge or draw until next use.