1997 EV1 Traction Battery t-pack

EV1 Panasonic EV-95 NiMH - Retrofit


With the EV1's original battery modules now obsolete and unobtainable,
and the BPCM programing hard-coded to those modules,
operating an EV1 on original OEM programing is a difficult task
to say the least. The programming has to 'see' 26 modules, with appropriate
voltages and resistances. Fortunately, these older EV1 era traction
packs did not include overly complex BMSs, but were instead
rather basic when it came to programing. Therefore, to keep the EV1s
running on original programming the challenge is to mirror the original
battery modules. The next level difficulty is the original OEM
battery footprints, quite unusual, and rarely used in other applications.
Space is an issue. To get around all these challenges, we have utalized
another older battery module, the Panasonic EV-95, a very well manufactured
module originating from the same era. The EV-95s, although no longer
manufactured, remain in-service in a number of Rav4-EVs of the era, including
vehicles in the Beata collection.

Pictured below is a EV1 traction pack fitted with EV-95s for the purposes of
continuing to operate on the EV1's original programing, with its original
Magne-Charge paddle charging systems, and continuing to be able to monitor
those systems via the original Tech2 OBD scan tool.

Another challenge in this sequence is module cooling. Where the original
modules, the Delco PbA, the Panasonic 1260u PbA, and the Ovonic
NiMH, were all designed for exterior cooling, the EV-95 is
primarily cooled with air flow betw
een the module's 10 cells, and
from that perspective requires greater care and monitoring
to insure proper temperatures are not exceed.

An interesting piece of EV1 history is displayed in the last picture
below. Check-out this battery pack's serial number.