View Full Version : FET "brownout"?

2006.02.06, 06:39 PM
Do fets have a temporary state of functionality somewhere between working and fried?

I have a Firelap 2.0 running an X-Speed motor with a seven tooth pinion. Seems like a totally safe setup, but every now and then after a little continuous driving, the car will just slow to a stop. I have lights in the car, and I can see them slowly dim and go off as well. It's weird because it's not like the power just cuts out.

The steering still functions throughout, and the motor will come back online in about 5-8 seconds, and it seems like the further I am into a set of batteries, the more frequently it happens. It just kind of feels like something is getting too hot and needs a little rest, then it's fine again. Is this possible, or is the symtom of something else?

2006.02.07, 01:18 AM
i had the same problem once. in my case the battery tabs were getting red hot, and pulling away from the batts, as they cooled off they slowly expanded back to full contact with the batts, and the power came back, as you described above

2006.02.07, 04:36 AM
Interesting, another thing to check is if you may have a "dead" cell.

2006.02.07, 02:17 PM
Interesting, another thing to check is if you may have a "dead" cell.

noob question: how would I do that? I use Rayovac IC-3s. I have a small multimeter. Just charge them and check output?

2006.02.07, 07:10 PM
I think it may be a bad battery or a battery not getting charged up as much as the others. From what you describe in the first post, sounds like one of the cells may not be working, and it is slowing the others down.