Thursday, December 17, 2009

Inertia Switch

This switch will shut-off the keyed switch power to the main contactor in the event of a collision. It is odd to plan for events that you hope will never happen.

Tuesday, December 15, 2009

EV Dashboard is Open Source

I've setup EV Dashboard as an Open Source project on Codeplex. There are still a couple of open issues I'll have to fix but the beta version is available to download. The Paktrakr implementation is working and a placeholder for the Elithion BMS and Xantrex Link-10 have been created.

Tuesday, December 8, 2009

New controller & single cell charger

Kelly Controls sent a new KDH15600B, which is 11" long compared to the 7" KDH14401A. It fits into the same spot as the smaller model with only one new cable needed. Notice the paktrakr resting there. I'm waiting for an extension cable to run from the last remote in the trunk. Then I'll strap the remotes and display in a permanent location.

Single Cell Charger
After the initial charge to the TS cells and they rested the voltages were all between 3.32V and 3.36, which is pretty good. I bought a single cell LiFePo4 6A charger to manually balance the cells in the interim before I can find an inexpensive and adequate BMS. The single charger has a 3.8V cut-off and each cell charged for 1-2 hours then after rest the cells are all at 3.50V. The weather was a little colder the past few days, -5F and the garage was cold too and each cell appeared to dip a little to 3.48V. I expect when they warm up they might come back to 3.5V.

According to the ThunderSky charging curve 3.8V is 75% charged and the remaining part of the charge curve is at 4.2V with a tapering current for about 30-90 minutes. So, I'm not sure that shunt style BMS that limits part of the current to 3.8V is appropriate unless it can "release" all the cells once they are balanced to finish the charging cycle.

Monday, December 7, 2009

EEStor and Zenn

A recent Zenn press release has EEStor listed as the technology behind Zennergy. At the Zennergy site, EESU (Electrical Energy Storage Unit) is an Ultracapacitor storage device with about a third the weight of Li-ion, no over discharge degradation and 1/10th the charge time ("minutes").