1997 EV1 Traction Battery t-pack
Thermal Modifications

Upgrade / Retofit to '99 EV1 t-pack Thermal Fan System


The '97 & '99 model year EV1s had very few differences; however, one
varience was the battery t-pack thermal cooling design.

The '97's air cooling system operated with a rear mounted fan
feeding ambient air into the rear PS (passanger side) corner of the t-pack,
exiting the t-pack via vent holes in both the 1) rear DS (driver's side)
corner, and, 2) the top-front of the t-pack. This design only
provided ambient air cooling to the t-pack regardless of the outside
temperature. If it was too cold outside, then the fans would simply not
operate, if too warm, the fans would push air at their maximum
rate to attempt to cool the t-pack. This was a poorly thought-out design
at best and the '97 EV1's regularly suffered battery pack
overheating further stressing the already marginal battery
modules to failure.

The '99 EV1's design made a number of improvements, but
did not go far enough to control the heating and cooling of the t-pack.
This system reversed the airflow from preserization to suction,
pulled air out of the rear center of the t-pack, and drew air
into the t-pack from the 1) rear DS corner, 2) rear PS
corner, and, 3) top-front of the t-pack. Along with that ambient air,
the EV1's cabin A/C & Heat pump was vented into the t-pack to
provide mechanical cooling and heating, although only from the front
of the t-pack. This was certainly an improvement, but was more of a
bandaid then a true redesgin of the overall system.

To improve the collections survivor EV1, and maintain the highest
possible degree of originality, we have chosen to add
the '99's suction system to the mix, but have left the A/C & Heat pump
in its original '97 configuration. Below are a few pictures
of the airflow modifications we have made to enhance the t-pack's


---> Additional pictures below <---