Volkswagen 44.4v 25ah battery module dismantling.

[Edguy83]

I recently picked up two 1kwh 25ah VW battery modules that I though I might use to power a lawn tractor conversion or a portable power station build. I am a novice when it comes to electronics so would appreciate any advice. Would a 48v inverter work OK with the lower voltage of the modules? Would it be practical to dismantle the module and arrange the cells in a 7s set up for 24v?

 

[Risky Rob]

36V inverters often have a upper limit of 45V DC input. What is the voltage of these modules when they're fully charged?

 

[Edguy83]

36V inverters often have a upper limit of 45V DC input. What is the voltage of these modules when they're fully charged?

I believe they are 50v fully charged

 

[Risky Rob]

These modules don't seem to fit conventional inverter parameters. I've read that some modules have welded bus bars, and can be difficult to disassemble.

 

[Edguy83]

36V inverters often have a upper limit of 45V DC input. What is the voltage of these modules when they're fully charged?

Maybe dismantling these modules and putting the cells into a more user friendly format of 7s to make a nominal voltage of 25.9v is the way forward then. If I dismantle the 2 modules that would give me 24 calls that I could use 21 of them to make 3 24v 7s.

 

[Risky Rob]

Maybe dismantling these modules and putting the cells into a more user friendly format of 7s to make a nominal voltage of 25.9v is the way forward then. If I dismantle the 2 modules that would give me 24 calls that I could use 21 of them to make 3 24v 7s.

That's what I would try. You will need a new BMS as well.

 

[Edguy83]

That's what I would try. You will need a new BMS as well.

Well here is an update! I successfully split the module into a 24v section, I will do the same to the other module and try and join them together in series. I think if I use some metal straps to tie the 2 or 3 sections together and keep them in the original metal frame this should stop any cells swelling. I guess then I'll need a separate 7s bms for each 24v section?

 

[Risky Rob]

Well here is an update! I successfully split the module into a 24v section, I will do the same to the other module and try and join them together in series. I think if I use some metal straps to tie the 2 or 3 sections together and keep them in the original metal frame this should stop any cells swelling. I guess then I'll need a separate 7s bms for each 24v section?

If you are going to run motors, you want a bms that will discharge high amps. I used 2 gauge copper wire to put my two 12V batteries in series. Each battery has it's own bms, and the bms's are designed to work in series. I can output 100A at 24V.

 

[Dacflyer]

Well here is an update! I successfully split the module into a 24v section, I will do the same to the other module and try and join them together in series. I think if I use some metal straps to tie the 2 or 3 sections together and keep them in the original metal frame this should stop any cells swelling. I guess then I'll need a separate 7s bms for each 24v section?

What VW are those batteries out of ? I recently got some from a 2013 Jetta.. Got em cheap.. but only rated for 5A and 1110Wh. I plan to reconfig for either 24 or 48v use.
How did you get your cells separated ? looks neat.