In order to ensure proper BPCM programming the EV1 utilized technology resistors to identify the appropriate battery chemistry. This was a method of ensuring that software calibrations matched the physical traction pack as EV1 development progressed.
The rarest of the EV1 technology resistors is the gen1 Delco Valve Regulated Lead-Acid (PbA) resistor as pictured here. Delco modules were only used in the gen1 97 EV1s and were replaced by the Panasonic 1260U modules in the latter months of 1997.
The EV1s technology resistors are located inside the traction pack immediately next to the BPCM (Battery Pack Control Module).
The original gen1 Delco Valve Regulated Lead-Acid modules were assigned a 70K ohm resistor; the gen2 Panasonic Advanced Lead-Acid 1260U modules used a 133K ohm resistor, and; the gen3 Ovonic Nickel Metal Hydride (NiMH) modules used a 97.6K ohm resistor as pictured here.
Rumor has it that GM had developed calibrations for the Panasonic EV-95 Nickel Metal Hydride Modules, as used in the 1996 and later Toyota Rav4-EV, Honda EVPlus, and Ford Ranger EV, but no such modules or programing made it to the EV1 fleet. An EV-95 traction pack could have bumped the 1997 EV1s range north of 150 miles per charge but would have required re-engineering of the thermal design of the EV1s traction pack.