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
Chevy Bolt EV joins the family
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 )

The PTC thermistors

The PTC thermistors
Protecting against a short like a self resetting fuse

Several years ago I did some experiments to figure out what the red thingies on the battery packs were, and what they are for.
I hit one with a heat gun, and saw the resistance shoot up from ~ 160 ohms to over 600 with a quick blast. I explained my findings on Insight central, but someone else tried the test in an oven, and was not able to duplicate what I found.
I finally found myself with a loose Insight side terminal plate in my hand, and decided to put my original theory to a different type of test.
I set up my lab supply with 30V, and the current adjustment was set to the 1 A maximum for the supply, so no power supply current limiting would be involved.
I clipped two probes to the thermistor leads, and used one of the banana jacks as an on off switch. On first application of the voltage, the current pulsed up to just about the expected 185mA, but rapidly over only a few seconds the current dropped to only 25mA and the thermistor was at 250 degrees F. I held it for a minute, and the thermistor stayed at the 250 f.
If the battery tap cable was crushed and all wires shorted, all that would happen would be for the battery end plate to get warm. Nice safety. Swap crushed cable, and the battery pack is good to go.
A self resetting fuse.