A History of GM EV1 Battery
Chemistries

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Gen1 = Delco (PbA) > Gen2 = Panasonic (PbA) > Gen3 = Ovonic (NiMH)

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Here are a few pictures of all three battery chemistry modules
for size comparison.

The EV1 was originally fitted with a Delco manufactured PbA (Lead Acid)
(53Ah) battery that yielded 16.4 kWh and 40 to 60 miles of range in the 1994 - 1996
period, and was the first OEM module in the original EV1 production vehicles.
The second generation of EV1 battery was an advanced PbA
(lead-acid) (55Ah) module from Panasonic, model 1260U,
which yielded 18.7 kWh and 60 to 80 miles of range.  The third and final EV1
module had NiMH chemistries (85Ah), was manufactured by the Ovonic Energy
Conversion Devices organization, and yielded 26.4 kWh and 80 to
120 miles of range in the EV1's original configuration.

We are interested in retrofitting several different battery options for our 
EV1s from PbA (Lead-Acid) to NiMH (Nickel Medal Hydride) to (LiON) Lithium and
even old-timers like NiFe (Nickel Iron).  Each different chemistry offers
different attributes, from ease of availability (PbA) to increased life span (NiMH) to
longer range/density (LiON) to, maybe the most interesting, (NiFe)
for outright lifespan.  One of the several tricks is the
physical footprint of the original OEM modules is not currently
manufactured in the US, and tricking the EV1's BPCM into recognising
voltages and resistances is important to continuing to 
use OEM charging profiles, i.e.: keeping the vehicles in an OEM
survivor environment.