madin88 wrote: ↑
Apr 14, 2018 1:53 am
stasergey wrote: ↑
Apr 13, 2018 2:06 pm
Can I swap all the 100V HY045N10 fets for AOT2500?
You have the 24s <100V BMS, right? so it would be really stupid to swap them out for AOT2500 which have more than twice the resistance.
The HY's are not bad. Almost as good as the widley used IRF4110 in terms of Rds on
How do I check if the fets are broken?
It is simple you just need to set a multimeter to continuity test mode (where it beeps) and measure between B- and P- (the row beteween the two groups of FETs) and between P- and C-. If it beeps, than one or more FET's of this group have a short and are dead. To find the brokden one, you would need to desolder all and measure them individual.
Make sure the BMS is not attached to the battery.
If you realistically want the BMS to support 150 volts, then yes, 100 volt mosfets are not the right answer. BUT, will they likely ever see more than 100 volts? No not really. On C- 100 volt mosfets are OK...ish. Assuming getting down to 2.5 volts per cell at 32S which is probably the largest voltage difference the mosfets are ever likely to see. That's 80 volts. At fully charged at 4.1 volts per cell, that's 131.5 volts or a difference of 51.5 volts. This is what those 100 volt 45N10 mosfets are likely to ever see so it's probably OK for them to not be 150 volt parts. The 45N10 does have half the RDS of the AOT2500 and similar current capabilities. Of course you are leg limited to 75 amps so 150 amps or 164 amps is irrelevant. However, I'd still power the EV at P- and use C- only for charging.
Chinese made BMS...extremely high chance that these are Chinese mosfets...AKA NOT as good as the legit part. I have some IRF4110's that I bought from Digikey and some that came from a Chinese seller. I can tell you they are NOT the same grade of part. Lots of mosfets are similar enough in specs that if you get a small sample, you would NOT know 2 parts were different. They could fit within the specs for any number of similar parts. Then it comes down to laser etching whatever part number you want on the package. AKA a 34n10 can be an irf4110 can be an 85n10 and so on. Good mosfets from legit sources cost more for good reasons.
You can see this quite literally in LED's. Get a real CREE XML and one from a Chinese seller. Power both at the exact same factory spec'd voltage (3 volts I think). I bet the CREE part will be brighter, run cooler and draw less current than the Chinese part. Turn the voltage up gradually on each LED until they burn out. The Chinese LED will take maybe an extra .2 or .3 volts while the CREE will take 1-2 volts more. You do get what you pay for! I did this test not so long ago on a Chinese XHP70 and a real CREE XHP70. They are 6 volt LED's. Power them up and the CREE is blindingly bright and the light is yellowish (on the BIN i bought). The Chinese LED was still bright, but probably 70-80% as bright, drew more current, ran hotter and was very bluish (6700K or so). I then added .2 volts, that got both LEDs a good bit brighter, but the Chinese LED within a 20 seconds was getting hotter. I then bumped to 6.4 volts. The Chinese LED was rapidly having serious issues and a minute later was at maybe 50% brightness (burned out). The CREE on the other hand suffered no loss of brightness many hours later despite being ran at 7 volts continuous. THat's legit parts vs Chinese parts for you!
China is great for cheap stuff, but it also means you may not be getting legit parts either. They have no copy right laws there and anybody can make and sell fakes with no consequences to them...buyer beware! Depending on the factory mosfets for the maximum current they supposedly can handle is possible, but can you keep them there for very long? I'm not entirely sure you can.