My MEGA battery bank build

[silviasol]

Building a mega battery bank to use to charge my scooter when I am not near a power plug and also for my 100w led when I need light
7series 20ah total using older lipo cells that still hold good charge just sag terribly over 2c.
Just need add the balance wires for the bms/pcm. Any comments or advice?

 

[dnmun]

put them under compression so there is a uniform force across the entire surface holding the electrodes forcefully against each other.

it turns out that back in the 1930's when the gel type SLA batteries, called VRLA batteries were developed, it was discovered that the life cycles of the batteries was extended by stacking the electrodes horizontally like pancakes.

imo this helped prevent the electrodes from being forced away from the gel electrolyte when charging as the gas is formed at the electrode/electrolyte interface. i am of the opinion this is equally important for lithium ion storage cells.

so find some way to compress those pouches while they still have some life left in them. all of these pouch packs should be under compression and the shrink wrap does nothing but damage the ends of the pouches.

 

[silviasol]

My plan was to wrap the batteries in cling wrap and add dow great stuff foam spray inside the box then close it but I really want to keep an eye on the cells since one of them had corroded and the side of the pouch was open after it sat over the winter. But the box is a very tight fit, I can just add a few buisness cards on top and it will press against the cells, probably the first thing I will try.

One thing that I don't understand is the amps the converter will charge at when the pack goes lower. If the pack is at full voltage and the converter is charging the pack at say nominal voltage as the battery bank cells get lower does the voltage still stay at the initial voltage/amps I set it at? Or does the voltage stay the same going out of the converter but the total amps lowers as the cells lower?

 

[dnmun]

what happens if you have a short and it sets the foam on fire? cyanide released by burning isocyanurate foam can be toxic.

 

[silviasol]

All the wiring is secure, no way to cross connections. The converter is 10amp max so I don't think there will be a problem since I ran these cells up to 4c before and 10amp is only .5c. I keep all my lipo stuff in a room with smoke detector, probably find a small grill to keep this box in when I don't use it.

 

[liveforphysics]

Handle pouch cells as though they gain defects from from human handling. They do.

 

[silviasol]

This seems to work well with some silicone tube, this cushion foam stuff and some paper towels. I can shake the box and the cells don't budge.

 

[silviasol]

Just did some tests. I can run my controller with a brushless motor and it will put about 8 amps at 40volts into the motor. I plan on using it to charge while riding like having an extended pack or will keep charging when I stop riding.