Hello, I am troubleshooting my cordless drill battery charger that stoped charging. I narrowed the problem down to a component that sits between the battery positive lead charging connector and the internal circuits of the charger. I attached a photo of the component.
The text on the component are “AUPO. AO - 3A, Q2. 89 degree C, 250 V - Jet “

Prior to this component I can measure 24V DC, no voltage past this component.

I would be grateful if someone can ID this, and tell me what it does, where I can find a replacement or if I can eliminate it.

Thank you in Evan e for your support.

 

Manufacturer:
http://www.aupo.com.hk/Product/index/334.html


This one is close but I believe the A2 in the part number lets it heat up a little more then the A0. All i saw from a quick glance at google for simular part number.
https://www.amazon.com/Aupo-Thermal-Fuse-Cutoff-A2-3A-F/dp/B0124KOOQO
I'll update posts of I see one closer for you later on.

What it is:
https://en.wikipedia.org/wiki/Thermal_cutoff

 

3 Amp fuse made by AUPO company out of Hong Kong. If fuse blew, look for other issues.
Lol, you beat me to it.

 

Thank you for the quick reply.
It is soldered on, right where the battery is inserted, the way is is soldered looks poor and the leads could be shorted could that have caused to blow?

 

it probably did its job and died in the process.

Actually the A2 replacement I posted may not be a good idea, Its rated for 115C and yours is for 84C. maybe someone who knows more then me can answer if its ok or how safe it is to step up the rating like that. May be better to just buy another brand/type that is rated at 84C 250V 3A

 

Manufacturer:
http://www.aupo.com.hk/Product/index/334.html


This one is close but I believe the A2 in the part number lets it heat up a little more then the A0. All i saw from a quick glance at google for simular part number.
https://www.amazon.com/Aupo-Thermal-Fuse-Cutoff-A2-3A-F/dp/B0124KOOQO
I'll update posts

It seems weird to have a cut off fuse in that location which renders the entire charger useless. I thought they would use a thermal switch that resets itself when the battery is removed. I am not an expert in this however.

 

I am not a 100% sure, but I believe the 84 degrees does play a part in the way this fuse works. I believe if memory serves correct, it is a type of thermal fuse and will start to melt at that temperature. Someone else may know for sure but I believe that is how this one operates. It is not unusual for them to be located in this area in this or any other charger. If the leads of the fuse shorted, there would be no problem other than the fact that you would have no fuse protection. I believe it either overheated or too much current went through it. Perhaps you can bypass it temporarily with another 3A fuse while you troubleshoot the unit. Put an ammeter in series with it or use an inductive ammeter and see how much current is going through it. If this is mains voltage which I suspect it is, disregard and send it to someone who is well equipped for the job. It's simply not worth it.

 

Hello,

Using the link from @narkeleptk I foun this page with the excact part:
http://www.aupo.com.hk/Product/productInfo/867.html

Bertus

 

Hello,

Using the link from @narkeleptk I foun this page with the excact part:
http://www.aupo.com.hk/Product/productInfo/867.html

Bertus

Thank you Bertus.

 

I am not a 100% sure, but I believe the 84 degrees does play a part in the way this fuse works. I believe if memory serves correct, it is a type of thermal fuse and will start to melt at that temperature. Someone else may know for sure but I believe that is how this one operates. It is not unusual for them to be located in this area in this or any other charger. If the leads of the fuse shorted, there would be no problem other than the fact that you would have no fuse protection. I believe it either overheated or too much current went through it. Perhaps you can bypass it temporarily with another 3A fuse while you troubleshoot the unit. Put an ammeter in series with it or use an inductive ammeter and see how much current is going through it. If this is mains voltage which I suspect it is, disregard and send it to someone who is well equipped for the job. It's simply not worth it.

Thank you Bwilliams. The temporary fuse idea is a good one for troubleshooting purposes.

 

Temporary fuse is a decent idea (in my opinion) but I'd probably use a lightbulb in place of the fuse. If there's a problem the lightbulb will light up. It also acts to limit current in the event of a short.

Yes, it's a fusible link. They are specifically designed to fail when an over-temp condition exists, caused by any number of factors including over-current. One thing I learned quickly with fusible links is they don't like to be soldered in place. Usually soldering them makes them fail. Been there - done that. ONCE! If you DO solder one in - be sure to use a damned good heatsink to prevent the heat from reaching the fusible element. Solder quick and not with an overly hot iron. Best practice is to crimp connect it.

 

I was just typing about the DBT method when I seen your post @Tonyr1084 but then I pulled back because I think we are working with mains voltage and not sure how comfortable OP is with that.

 

Temporary fuse is a decent idea (in my opinion) but I'd probably use a lightbulb in place of the fuse. If there's a problem the lightbulb will light up. It also acts to limit current in the event of a short.

Yes, it's a fusible link. They are specifically designed to fail when an over-temp condition exists, caused by any number of factors including over-current. One thing I learned quickly with fusible links is they don't like to be soldered in place. Usually soldering them makes them fail. Been there - done that. ONCE! If you DO solder one in - be sure to use a damned good heatsink to prevent the heat from reaching the fusible element. Solder quick and not with an overly hot iron. Best practice is to crimp connect it.

Thank you Tonyr1084. Appreciate the insights.

 

I was just typing about the DBT method when I seen your post @Tonyr1084 but then I pulled back because I think we are working with mains voltage and not sure how comfortable OP is with that.

Bwilliams60, the cutoff is located at the output of the charger on the DC side immediately at the contact point of the positive lead on the battery it is charging.

 

Okay sorry, then go with DBT method and hunt down the short.

 

It's probably close to the battery to sense an over temp condition with the battery. I'd also recommend checking the batteries you charge for any faults there. Could be the fusible link did its job because of a bad battery pack.