diy solar

diy solar

Big battery Issue

2.4kwh 8s5p 100ah....no documentation of course
Maybe this guy can help you:
https://diysolarforum.com/threads/bigbattery.19545/

Looks like the same battery maybe. At this point I am just guessing, so probably not much help. I honestly think you are ok with the battery shutting off at 24.8v. Like I said there is not much power below that voltage anyway. So all we need to figure out is why is the battery getting to 24.8v in the first place? If you are charging to 27.7v you should be netting at least 2kwh of power before the battery shuts off. I get the feeling you are not charging from solar (or not much), so the battery just keeps draining. I would think it would last longer than a night though. Maybe shut the inverter off if you are not there, or at least set the power conservation mode on. Are you going there sometime soon? I would love to see how much power the solar panels have generated into the LV2424.


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To give you an idea, my setup has been up since 3/6 and has generated 128kwh as of Sunday, and I think I turned the inverter off the first couple of weeks. I am burning over 1.5kw a day just powering the inverter, a 5wh porch light (dusk to dawn), a old laptop (in sleep mode), and a Ryobi 18v battery charger. I probably get 5 hours of sun, but my panels are facing South East (more East sadly). If I only had 400w I would probably kill the batteries eventually. Fortunately I am over paneled, so the batteries are usually fully charged by 10am and I haven't had a single issue. I know you already have some panels, but if you can get used 250w panels and panel the crap out of your cabin.
 
Can you turn the inverter off and just keep the MPPT running on those? If not, get a separate charge controller (Epever 100V / 20A, Victron 75/15 (wire the panels in 2s2p) or similar) and turn the MPP solar unit off when it's not in use, the standby current is substantial and you simply don't have enough power generation to keep up.
 
Bigbattery let me know I could open case to reset BMS. (Didn't want to void warranty of course). I unplugged the BMS and the battery came back on at 24.8 volts. This is the dilemma that MPP will only go up to 24.0 V for low voltage cutoff and battery bms turns off at 24.8 V. I usually leave the inverter off but I wanted to see if it would last through the week for a security system that was only pulling 20watts. I will just keep the invertor off and have battery power when I am there. I at least now know that if battery is "off"/bms-tripped that I can open up and unplug BMS. Bigbattery says battery can go down to 22.0 V but evidently not this one. I ordered more panels but I will always have to deal with this with this battery.
 
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