I'm thinking about experimented with DIY DC fast charging. Imagine a situation with no BMS, limited (like six) charge cycles, and the only requirements are quick charging and quick discharging. Used automotive quality 32kw battery pack. Think 25kw use and immediately 15-30kw DC fast charging after use. Battery cooling done during charging.
Here are some of the challenges I've found:
Transforming 3 phase power into DC in a 15kw+ format at a desirable voltage (200-500vdc)
Managing the saturation charge above 4.0v/cell for lithium (nonlinear current)
I guess my real question is: can the core 3.2-4.0vdc charge be done in a relatively crude manner so long as voltage and amperage are supplied until the cells reach 4.0vdc? Then move them to a smarter charger to correctly provide current along the ideal curve for the saturation to 4.2vdc?
Here are some of the challenges I've found:
Transforming 3 phase power into DC in a 15kw+ format at a desirable voltage (200-500vdc)
Managing the saturation charge above 4.0v/cell for lithium (nonlinear current)
I guess my real question is: can the core 3.2-4.0vdc charge be done in a relatively crude manner so long as voltage and amperage are supplied until the cells reach 4.0vdc? Then move them to a smarter charger to correctly provide current along the ideal curve for the saturation to 4.2vdc?