I have a Harbor Freight Cen-Tech Battery charger SKU 60653. I was attempting to charge my riding mower battery when it fried. I inspected the insides and found that the thermal fuse was melted and a relay had burned out.

I replaced the relay with the same Songle Relay SRU-06VDC-SL-C type. The thermal fuse was different. I used a 50A Auto Automatic Reset Stud Type Circuit Breaker for the thermal fuse.

When I plugged it in and attached it to my mower battery it lite up and seemed to be in a cycle of charging. I had it set to 2 amps. I assumed by the noise it was making, buzzing followed by silence. Only thing was the analog meter wasn't moving, it was stuck at 100%. After a few cycles it popped and started smoking. The SRU-06VDC-SL-C relay went out in the same spot the original did. There is a metal leg? in between 2 others and this continues to blow out. I resoldered a 3rd one and it blew the same spot.

Can anyone suggest what I should be test/measuring and why the relay keeps going out? I'm not giving up on the charger just yet.

I didn't test any of the diodes. Not sure how yet.

Thanks.