Thursday, September 23, 2010

Something Stupid

Just when everything is going well...

I've been making slow progress zeroing in on getting the charger set to bring the batteries up to the optimal charge point before it turns off. It's tough because the charger uses a little screw potentiometer to adjust it up and down. It's exceedingly difficult to get it right where you want it. Plus I've found that if you change the current you're pushing to the pack, the high voltage point at which the charger believes it's done changes.

When I have the charger turned up all the way so that it's pushing 28 amps, it would cut off at 164.5 volts. But if I ramp the current down to 10 amps, it trips off at 165.8 volts. It would be so much nicer if the charger had a digital interface for setting the cut off voltage. I realize that would add to the cost of the charger, but I have to tell you, I'd pay for it.

This morning I was charging the car at 10 amps The charger hit it's limit threshold at 164.7, which is about where I want it. I started taking measurements on the cells to monitor how they were doing. There are a couple that come up to 3.6 volts faster than the others. While measuring one of the cells I slipped and touched the probe to the chassis while it was on the positive terminal for that cell. Well, there was a loud pop, and a nice bright flash. When I looked down, the point on the end of my probe had been melted to a nice rounded blob, the terminal had a big black spot around it, and the charger had flipped off.

I checked everything and couldn't find any obvious problems to any of the systems. I tried to turn the charger back on, but there was no power to the charger; the breaker for the outlet had popped too. I reset it and tried to turn the charger on again. Loud pop, but no flash anywhere, and the charger tripped it's breaker and the breaker on the house tripped too. *Sigh*

So it would seem that through clumsiness or carelessness, I've damaged my charger. I've sent an email off to Rich Rudman at Manzanita Micro to get his advice. But I'm pretty sure that the chargers coming out of the car soon and making a trip to Washington. Man I hate it when I do stupid stuff. And just as the weather is really getting beautiful for top down driving! *Sigh*


I heard back from Rich at Manzanita. Apparently I've blown the input AC rectifier. So, I'll be taking the charger out of the car ASAP and sending it back to them for repair.

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