rectifier, the temp rise

hi everyone, iv seen 4 burnt rectifiers and all where way over rated. there are my thoughts from experience and testing. there are many sites selling the Chinese 90-100amp rectifiers { there not a bad unit just over rated } for a price but, I tested one 90amp at a controlled  { using a shunt on the dc side } 60amp draw and it burnt in 10 seconds and was in flames before I was able to disconnect the load. I was given one to test the same way { the fella up the road heard from a friend that watched the test } and the results were no different, 10 seconds to flames. testing one more I controlled the dc draw 10amp at a time until the unit was 40 deg c . I was drawing only 50 amps at the 40 deg c and as time spent at 50amp lengthened the temp continued to rise, I stopped the test at a recorded 69 deg c , this was 15 minute test. between 50-60amp seems to be the point where it gos from overkill to failure. WOW in no time this thing could burn the house down. after cooling I lowered the amp draw to a steady 35 amp draw, although better the temp still reached 50 deg c but stayed there for 30 min test. I felt that this was still to close to burning the house down because my test controlled the voltage and amperage, the wind system would not. I lowered the amp draw at the 30 minute mark while still continuing the test and the temp dropped to42 deg at 23 amp. I felt that this is just short of being liveable , I would like to see 40 deg or less but this would mean lowering the amp even more. from my tests I would say these are a constant 20amp useable rectifier . for these reasons there is none in my system, to risky. I purchased four 200amp unit and they tested at 85amp constant at 39 deg. none of my gen,s will produce that much power without failure so I feel safe at this rating. I paid 44$ each and was less than the common wind and solar sites where charging for the Chinese ones. when it comes to rectifiers I would feel safe to say to only use at 1/4 of its rating for a long and happy life. the Chinese ones would prove ok for the smaller system that produce 20amp or so in a stormy condition. also my rectifiers are outside with the disconnects . and a temp controlled cooling fan for the summer, they never seem to run in the cooler months. all rectifiers should be mounted on a heat sink at minimum, but should have a temp controlled fan I think, when they start to heat up the heat will rise vary quickly on these rectifiers. like all other part of the system, they must match the intended purpose properly to live long and safely . I hope this will help rectify any concerns . thanks for reading.