Is this the result of buying a cheap timer Chinese relay off Alliexpress?
Yes and no. The relay did say it was rated for 25(16)A, and I was putting 41A through it, so that was my fault for the solder melting off the terminal and relay connections. I would say the cap blew up because the bridge rectifier failed and put AC on the DC bus.
I had previous repaired this relay with copper wire and solder as I had a constant load of 24.5A and it had burnt the PCB and melted the tracks. The solder that had previously been evenly distributed over the area has now pooled towards the bottom of the relay following the copper.
I had another relay which I purchased at the same time as the last one. I added extra conductor material so it shouldn’t melt under a 25A load I’ll just have to not put a 41A load on this one.