diy solar

diy solar

10 year old solar needs battery bank upgrade

CJmy72

CJmy72

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Dec 14, 2020
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I have (2) magnum ms4448pae with an outback flex 80 with 18 panel solar array im needing to upgrade my battery bank (currently 2 banks of 8 - full river agm dc400-6) i dont have issue with building out batteries from raw cell but i wonder if the warranty exchange is worth the cost comparison when buying like an sok or battleborn - would appreciate suggestions for ideal long term set up
 
IMHO, buy 5-10% more than you need, test them along with the others, charge them to 50% and store them in a mild environment. Check voltage once a year.

800Ah * 48V = 38.4kWh

3X 16S 280Ah batteries will get you 43kWh.

Since your usable will be dramatically higher than your old bank, 2X would be an upgrade with 23kWh usable vs. 19.2 of your Fullrivers.

18S is about $2K delivered (2 spare per 16S battery) + BMS.

You'll be saving massive amounts of money, doing a lot of work yourself, learning stuff and being your own warranty department with near zero down time if something goes wrong.
 
snoobler said:
IMHO, buy 5-10% more than you need, test them along with the others, charge them to 50% and store them in a mild environment. Check voltage once a year.

800Ah * 48V = 38.4kWh

3X 16S 280Ah batteries will get you 43kWh.

Since your usable will be dramatically higher than your old bank, 2X would be an upgrade with 23kWh usable vs. 19.2 of your Fullrivers.

18S is about $2K delivered (2 spare per 16S battery) + BMS.

You'll be saving massive amounts of money, doing a lot of work yourself, learning stuff and being your own warranty department with near zero down time if something goes wrong
Click to expand...
 
Overkillsolar just introduced 16S 100A units.

At 8800W peak, 48V, that's 183A, so 2X of those batteries in parallel, each with their own BMS, should cover it if you have them well balanced for loads. 3X batteries would be better, and you could stop yelling at people for leaving the lights on... :)
 
snoobler said:
Overkillsolar just introduced 16S 100A units.

At 8800W peak, 48V, that's 183A, so 2X of those batteries in parallel, each with their own BMS, should cover it if you have them well balanced for loads. 3X batteries would be better, and you could stop yelling at people for leaving the lights on... :)
Click to expand...
Will the overkill 16s 100A BMS work with the 16s 280ah cells? Or is that only for the 100ah. Thats the wall ive hit each time i start looking for a good 48v bms
 
100A is the current the BMS can pass. It doesn't matter if you put it on a 1Ah or a 10,000Ah battery.
 
I get the impression that they are rated properly. Given that the vast majority of running will likely not occur at peak, I wouldn't expect it to be an issue.

@OverkillSolar would know.
 
Fan of ECPC, but you'd need at least 4 of those to match your old capacity, and each is limited to 100A discharge.

But if you're looking at near turnkey, you get almost 4X the capacity vs. something like Battleborn for the $/kWh.
 
If your previous battery lasted 10 years, what is the appeal of Lithium over another AGM, or perhaps FLA forklift battery?
Lead-acid may last as long as lithium with your usage, and cost less.
 
If he DIYs, it's almost a wash. Buying his existing bank new would probably run about $5K,

$4K for 2 48V 280Ah Lithiums with 4 spare cells is less and has about 15% more capacity.
 
Hedges said:
If your previous battery lasted 10 years, what is the appeal of Lithium over another AGM, or perhaps FLA forklift battery?
Lead-acid may last as long as lithium with your usage, and cost less.
Click to expand...
Have a bad bank (all 8 or bloated) that is only about 5 years old - i have approx $4800 in this bank and it is much heavier and takes up much more room. And i havent really gotten much out of them in the last year so to me not even close in cost comparison
 
OK, but just get a good BMS and make sure charge/discharge are controlled properly.
Plenty of pictures of bloated lithium LiFePO4 cells on the forum.
 
Hedges said:
OK, but just get a good BMS and make sure charge/discharge are controlled properly.
Plenty of pictures of bloated lithium LiFePO4 cells on the forum.
Click to expand...
Thats where i keep coming to, not real sure about good bms for my size system and why i keep going back to like the sok or even the electriccarparts prebuilt stuff and then you still have to figure out a reputable or or least shady place to get the 280ah raw cells
 
The least shady places are well established, and the vast majority of experiences are positive. Ordering a few spare cells essentially guarantees a favorable outcome.

3X 280Ah 48V DIY batteries each with an overkillsolar BMS will more than meet your needs.
 
MisterSandals said:
Are the Overkill BMSs rated properly or by what factor is it recommended you oversize your Overkill?

Are folks running both charge and discharge currents thru their BMSs ?
Click to expand...
The 100a rating is at 100% duty cycle. I have tested every model at multiples of the rated current. Heat buildup is the limiting factor.

It's a common port, so simultaneous charging and discharging would be averaged out in the external bus bars, and the BMS/battery would see the sum of the current in the system. For equal charge and discharge current, the battery would see zero amps.
 
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