New consulting relationship with GreenTecAuto begins
What actually goes wrong with the batteries????
A look at todays Hybrid and EV battery packs
Battery packs exposed
2006 and up civic packs
Lead acid battery failure examined
Testing the sticks at the cell level
MaxIMA stick full discharge
Bumblebee battery replacements for the stock subpacks
Inside the cells
Seprating the cells for reuse
How it is wired
PTC strips exposed
The PTC thermistors
Battery current sensor
Inside the 100A semiconductor battery pack fuse
Did it again for the last time
A bad Prius subpack explored and fixed????
Rebalancing the Insight battery?
Insight battery
Insight Battery switching/current monitoring
The battery controller
Prius battery pack
State Of Charge (SOC) determination with NIMH batteries
Battery pack monitoring
What happens to a Prius subpack when you overcharge it?
Keeping Warm In New England
Plugging into the SUN
Making a small solar concentrator
Building MIMA and the plug in adapters
Converting a telephone truck to electric
DIY dual pulse Capacitor Discharge Spotwelder
Getting in shape while making electricity
Replacing gasoline with solar electric lawn equipment
What is Genesis One?
How to stop the aging process DIY
MIMA Install Day 2005 a Big Success!
Building a hybrid car grid charger
Tapping into the Wind
Expanding MIMA with the Distribution board ( users projects )

A bad Prius subpack explored and fixed????

A bad Prius subpack explored and fixed????
blasting a prius subpack

Carolyn Coquillette from Luscious Garage in San Fransisco,
( http://www.lusciousgarage.com/ )was kind enough to send me a first gen Prius battery pack. The pack was bad and the codes indicated two bad subpacks.
Carolyn attended one of the Hybrid classes that I was involved with, and is a highly qualified hybrid auto technician.If you live in the bay area, and have a hybrid, you should consider Luscious Garage for all of your service.
I have not had the opportunity until now to examine a Prius subpack that was actually bad, so I immediately labeled the subpacks, and removed them from the enclosure. A quick voltage test showed two subpacks that were a full 1.2V or more lower than the rest, and one that was about .7V lower.
I put the two bad subpacks on a charger to see if the subpacks would recover, but shortly after the charge seemed to be complete, the subpack dropped back to the same condition, indicating that the subpack likely had a shorted cell.
I used my milling machine to expose the cell to cell connections, and indeed, one cell was at 0 volts while the rest were fully charged.
One must be very careful playing with charged NIMH batteries in a milling machine.
My end mill managed to hit the plates of one of the good cells, and the current lit up the shorted area cherry red.
In my RC modeling days, when a NICAD cell would short, it usually was a symptom of a plate to plate short caused by a nickel whisker.The trick we used to do was to blast away the short by discharging a big capacitor into the cell. Sure enough, I took the shorted cell, and blasted it with 250V from a 6100uf cap, and the cell was able to be charged. Next I took the other subpack with the same problem, and blasted the whole subpack with the same capacitor.
While I do not expect the blasted subpack to be equal to a good subpack, it was nice to see that the initial response was to fix the shorted cell. If ever there were an imbalance condition, this is it. one cell started at zero charge while the rest were fully charged. I will give the subpack some time to equilibrate, and then compare it under load with a good subpack in a series configuration.
While blowing out some plastic chips from the machined subpack, some of the potassium hydroxide electrolyte sprayed past my glasses into my left eye. It burned a bit, and I immediately flushed my eye with a lot of water, and my eye is fine. Batterys are dangerous in many ways.