Best way to parallel these prebuilt 4S 42Ah li-ion packs or otherwise make them useful

[atomicthumbs]

I work at an e-waste recycler and have acquired several dozen of these Batteryspace 611wh 4S lithium packs (a slightly different version, CU-JAS466, without the SMbus wiring present). They're very lightly used.

I'd like to use these as-is to supply both AC and DC power. My two problems are:

• they're 4S packs, and almost nothing except a Victron inverter or wide-range buck-boost converter will take that voltage
• they max out at 10A each and I want to run more than 10A of equipment

I'd prefer to save money and use one of the 2000w 12v inverters I do have, a Renogy pure sine and a Xantrex ProWatt SW. My DC-powered radio equipment takes ~12v nominal, and tops out at 15-16v; I will need 25-30a of that, ideally without involving a switching regulator for RFI reasons.

The boards on the packs are these, I believe.

The way I see it, these are my options:

• Find or build ~7-8A (for derating) 12v buck converters for each battery, with a current share bus to split the load properly; this would result in a fully modular system and seems like the ideal... if anyone makes prebuilt equipment for this. Learning PCB design for the first time for something that can burn down my house or a forest if I screw up seems ill-advised
• Parallel the batteries directly (with diodes? I'm uncertain of proper procedure for paralleling batteries with a BMS already installed, and I haven't yet put them on a battery analyzer to figure out how closely matched they are) and use a stepdown regulator for 12v
• Series the batteries directly - the specs for the PCM I found in a battery I opened up doesn't indicate anything about this, but the MOSFETs are HY4008s rated for 80v
• Peel the boards off the packs, analyze the batteries, and turn them into 8s or 12s packs (not certain this would be any more useful)
• Bite the bullet, dismantle the packs, and build bigger packs in another configuration with the INR18650MJ1 cells
• Partially bite the bullet, and partially dismantle the packs into 12P strings, then build several bigger batteries out of those
• Give up, sell the packs, and buy LiFePo4

Has anyone here done anything similar? Any tips? What would you do with these things if you got 'em for 20 cents a pound?

 

[Rednecktek]

I'm guessing they're not very large individually so you could maybe find a box that fits a few inside, put a bus bar inside, then wire the internal bus bar to exterior ports. Basically make some "4p" or "6p" 12v batteries so you're not having to string dozens of small batteties together on lication.

From there you can grab any 12v inverter and have a stack of "160ah" batteries.

EDIT: I don't see a BMS on those batteries, you're going to want one of those. Adding in the cost of a dozen small BMS's makes it worth it to break them apart and re-assemble as larger capacity packs.