Thermal fuse question

I have a Schumacher model se-1010 6/12v 10a automotive battery charger with a blown thermal fuse. I managed to pull it out of the transformer and it looks like a common 10a type thermal fuse. Only problem is it is covered with shellac and I cannot read the temperature rating of it. The shellac will not come off without scraping it. Any suggestions as to what temperature it might be? The transformer and everything else is good and the charger works perfectly when the fuse is bypassed however I do not want to permanently bypass it and create a potential fire hazard.

Ken1 said:

I have a Schumacher model se-1010 6/12v 10a automotive battery charger with a blown thermal fuse. I managed to pull it out of the transformer and it looks like a common 10a type thermal fuse. Only problem is it is covered with shellac and I cannot read the temperature rating of it. The shellac will not come off without scraping it. Any suggestions as to what temperature it might be? The transformer and everything else is good and the charger works perfectly when the fuse is bypassed however I do not want to permanently bypass it and create a potential fire hazard.

Click to expand...

It's good not to burn up. I have no idea whether this is of any help, but I like to learn new things as a rationale for avoiding other kinds of work...

Is the "thermal fuse" you mentioned listed as a circuit breaker here?

I watched this video where he replaced a thermal fuse (different model than yours) and I just wanted to say that I would have tossed anything that looked like that - not saying yours does, and not saying it should have been tossed, just saying that I would...but then again, I don't own a [edit: automobile] battery charger.

I have replaced a lot of thermal fuses working in a repair capacity. They fail far more often than they should under a normal wear and tear environment. I would not stress too much about matching the exact temperature of the one that went bad. Standard ones of 145 degrees C would work fine. But anything else you have in that range will be acceptable. As long as it will fail if the transformer catches fire....

I applaud your diligence in finding the failure and your desire to repair it.

JimW

This is what the defective fuse looks like.

Looks right. They are only a few dollars on line. If you are going to make a hobby of repairing these types of failures, you can buy a selection of all common values for not too much. Remember that if you plan to solder it in place, use a large heat sink between the solder joint and the thermal fuse (or else you will install a newly failed fuse).

The Repair Cafe where I do repairs will replace from 2 to 5 of these at each repair event. They are a common failure in appliances these days. We try to match the exact temperature when we can, but often put in an over temperature one when we can't determine the intended value. They are installed to prevent catastrophic fires, so any temperature that is less than the ignition point of the device accomplishes the job.

JimW