diy solar

diy solar

3.2 Volt 50AH Lithium batteries for $50 on ebay. Would these be a good choice to build an RV solar system battery bank?

With shipping, that's $268 for one 12V 50Ah battery, less than 1/2 the price of a ready-to-go 12V 50Ah battery. You just have to build it up.
 
Was thinking that when connected they would be 12 volt 200AH,......but I am new to all this,....just learning and I do appear to have a brain block for the series/parallel math.
 
If you wired them in series, 3.2V each x 4 cells = 12.8VDC. Since they are in series, the amps stay the same, so whether it's one cell or 10, it's still 50Ah.

If you wired 4 of them in parallel, then you'd have a 3.2VDC battery at 200Ah. To get 12.8VDC at 200Ah, you need 16 cells, 4 each in series to make 12.8VDC, then parallel it with 3 more of the same to get 12.8VDC at 200Ah.
 
I bought these batteries from this seller, 8 of them in series, 24V at 50Ah, 1,280 Watts total potential for $459.36 USD. I'm very happy with them after almost 2 months now. I've been using them most everyday since.

I got them mainly as a test bed to learn from and explore options towards a larger system. Great for testing and small capacity usage as I didn't make a huge investment if I were to damage them through experimentation.

NOTE: I had to make my own battery buss bars and I bought an active BMS and other associated accessories (ie. battery protect, meters, fuses, breakers, cabling, tools, connectors, etc...), about another $250 or so.

For RV usage, I would think going with larger Ah batteries would be preferred. 4 batteries, 12V at 50Ah is about 640 Watts per cycle. And don't forget to consider efficiency/ conversion losses (~15% or so) if you're using an inverter to power AC devices.
 
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I would recommend this as a better value (Free shipping and buss bars) Its also the same company Lionenergy."Here" ( I have a pac from them ) They have GREAT customer service. At 400.00 for 8 cells.
 
grizzzman said:
I would recommend this as a better value (Free shipping and buss bars) Its also the same company Lionenergy."Here" ( I have a pac from them ) They have GREAT customer service. At 400.00 for 8 cells.
Click to expand...
Interesting... That's what I received. 8 cells with the interlocking harness to group them together. I like the way they keep them together. Guess the difference is I paid for shipping.

Also, I received those connector brackets. My listing didn't show them. Had no idea what they were for. Interesting way of connecting 8 cells, 4S2P (12V@100Ah). I didn't use them as I was going 24V and needing an 8S BMS wiring harness instead. Plus, they're not copper.
 
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I just purchased 24 of these from the same ebay listing. My thought process was to make 4 cell packs, and then parallel 6 of them together with each pack having BMS for a total of 12v 300ah. But I just read that you shouldn't parallel more than 2 packs together. Is there any way around this? Even with BMS on each pack? I am just trying to get to 300ah for my sprinter van camper. Any way to have 3 separate 4s2p and have them all still charge and discharge in the same system somehow without subjecting myself to the potential risks in having a 4s6p system?
I appreciate the feedback!
 
Busbars could be an alternative. They can reduce the strain on the outer batteries in a parallel string.

I build a battery box with 6V 215Ah FLA golf cart batteries about a year and a half ago, 24V 537Ah configuration (4S5P, 20 batteries, 50% DOD). Still going strong using low-medium C-rate.

Diagram below is for 4S6P with solid Copper busbars (1.5" W x 72" L x 1/4" Thick).

Could try something similar with 6 12V batteries each with a BMS. Or, possibly have 3 12V batteries with paralleled cells (4S2P) each with a BMS all connected to the busbars. Sort of a nested Parallel within a Parallel configuration.

Battery Box3_7.jpg
 
Anyone had any luck looking up the QR code on these cells? I purchased 64 of them from lion energy for a 16s-4p bank, and would like to optimize the parallel capacities to minimize the burden on the chargers bms.
 
Does anyone have a line on serial bus bars for these same 50Ah from Lion? switching from a 4p4s 12V with home made 1/4" thick copper bar to a 48V for my next project.
 
Yeah, I agree but I'm too … specific... when it comes to building things. it would take me calendar months to cut and finish 96 BBs
 
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