42v prius cells

[cdnsolarpriusbus108]

have a bunch of gen2 / gen3 prius cells, they are nimh, top out at about 8.5 volt so 5 in series would be perfect 42 v for ebike motor controller applications... wondering about a bms? dont think i would ever find one so im thinking may even just using a lithium one? whatever will work anyone have any suggestions? more experimental than long term... also a single cell is like 6x1.5v to make it up in the single pack... anything im overlooking or any comments thank you

 

[Korishan]

Lithium based BMS won't work. NiMH has a completely different charge and behavior characteristics than Li-Ion.

What motor controller you plan on using? 42V seems a bit low for most standard voltages

 

[floydR]

42V should work with 36V Ebike motor controllers, not sure how well. many work from 32V-45V. 3 x 12V lead acid battteries 10.5V-15V a battery.
Later floyd

 

[Redpacket]

Like already said, the cell voltage & charging requirements are very different to lithium type cells.
NiMH has a nominal voltage of approx 1.2V, & they are fully charged at approx 1.5V.
Using a lithium type charger (full = 4.2V) would be a bad idea, charger might not start (think NiMH cell = too low) + definitely would over charge.
Some NiMH fast chargers use voltage rise rate to end charging, ie when full, the voltage spikes up.
Also when NiMH's are full, if charging isn't stopped, they start to heat which has to be monitored.
NiMH's are also more "lossy" ie the round trip charge > discharge energy efficiency isn't as good as lithium types.
See info here:

Nickel Metal Hydride Battery Safety Notes

Nickel Metal Hydride 3.0 Nickel Metal Hydride (NiMH) 3.1 NiMH Principles of Operation The principles in which NiMH cells operate are based on their ability to absorb, release, and transport (move) hydrogen between the electrodes within the cell. The following sections will discuss the...

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