RV 24V System
Suntrekker Registered Users Posts: 139 ✭✭
edited August 2022 in Off Grid Solar & Battery Systems #1
640W 24V LiFePO4 280AH
I jumped from the build thread (https://forum.solar-electric.com/discussion/356634/life-cell-internal-resistance#latest) and will post off grid system details, performance and experiences.
Thnx Bill/Forum members for the support!
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I’m dry camping in national forest, northern Arizona. Off grid system has power to spare, running all appliances including AC (no generator). I’m a happy camper! : )
And 24V battery is clicking on all cells (credit the active cell balancer), it floats under 27V (90%+ SoC).
The only issue was a 60A fuse meltdown between the SCC and battery. …my fault, I installed an audio fuse.
MRBF holders and fuses are relatively small form factor--If space is an issue:
Also, I don't remember your actual battery charging current (maximum/continuous)--I like to always suggest that battery charging circuits (wiring/breakers/fuses) be rated for 1.25x (1/0.80 or 1/80%) of charging current. For example, if you are really charging at 60 amps, suggest:
When charging batteries--A well discharged battery can usually accept maximum/rated charger current (i.e., 60 amp charger) for "hours" (600 AH bank @ 10% rate of charge = 60 amps)... And a 50% discharged bank can take that current for upwards of 5 hours continuous rated current flow. A fuse/breaker (and wiring) running at 100% of rated current (or for example 60 amp fuse * 0.80 NEC derating = 48 amps suggested max continuous current flow) is going to run hot and possibly trip after hours of rated current flow.
You could also replace the fuse with a breaker (with manual trip) and have the OCP and "switch" function too (turn off for service, winter storage, etc.).
Yeah I installed another fuse and happy to report all’s good.
Off grid hardware:
REC 320NP mono 320W panel (2)
Tamarack tilt kit
Outback FM60 SCC
Aims 3K pure sine wave inverter
Aims remote LCD display
DC converter 60A
LiFePO4 24V 280AH battery bank
Active cell balancer
Cole Hersee solenoid 24V 200A
PowerMon smart battery monitor
Perko main disconnect switch 250A
Assorted breakers, fuses
Love Off Grid - away from the hubbub.
BTW, nice set up. TY for the beautiful pictures.
Be aware that I had that exact active balancer and something went haywire on it while I was testing. One side (around 50% of the capacitors) got too hot to touch, and the board was draining one of my cells pretty quickly. That cell would have been destroyed had I not checked on the system when I did. Since then I only plug in the active balancer when the cells look out of balance, which I can see on my BMS Bluetooth app. I unplug it again a few hours later after it's done its job.
Thnx Horsefly for mentioning the active balancer, I’ll keep it in mind. Battery performance is monitored by phone (Bluetooth). All looks good!
And I’ll post more pics of my surroundings, BLM land and Prescott National Forest.
…phone/internet service is spotty but I’m not complaining
Cold nights (20°) have prevented solar charging until the battery warms up. I didn’t foresee camping in low temps (or take the necessary precautions). …charging has been reduced to 4 hours/day.