crystalyte 35a 36-72v controller keeps popping fuse

I made the mistake of lightly feathering the throttle at standstill when testing the controller at 72 volts (it was working great before at 72v) and the battery fuse totally melted in a serious fashion. I wired in a new 40 amp fuse but now as soon as I turn the controller on the fuse blows .I took the controller apart and there was no funny smells or burned FETS or areas I could see. Any easy ideas? or ways to test the controller? Thanks.

Check your fets

i'm 99% sure it is the fets .. i had the exact same problem when i had my 4710mosfets

-steveo

Sounds ugly. Don't try connecting it anymore, you might blow more parts.

See page 4 of this thread (When things go boom): http://endless-sphere.com/forums/viewtopic.php?f=2&t=764&st=0&sk=t&sd=a&start=45

OK , I'm wondering if this will be worth upgrading the FETS. I beleive they may be blown- per Fechers guide - I only have 1 ohm of resistance from pos lead to green and blue and no continuity(signal) at all from pos to yellow. Same holds true for negative side. I took it apart and tested the individual FETS. I checked resistance thru the outer legs of each- first 4 fets= no signal, #5= 1 ohm, #6=21ohms, last 6 = 1 ohm. Before I go ahead and order and attempt to replace I wanted to check with the experts to see if its most likely the fets - or could it be another blown part as well? Thanks for the help.

Definitely FETs. Definitely.

All of those FETs that are reading <7kOhms stuck closed or are blown. Either way, they must be replaced, since they are causing shoot-through shorts and blowing your fuses. The good news is, of course, that the fuses have been doing their job.

The first four that are open - that is, showing no connection between the phase (yellow) and either battery pole, are likely intact and would not need replacing.

What FETs does the controller currently have? Chances are that they're IRF4710s or IRFB4310s, in which case you might as well upgrade all of the FETs to IRFB4110s. You have to replace 2/3 of them anyway, and the 4110s will be a big improvement.

Yes they are 4710's- thanks for the reassurance. I've started pulling out the old fets. Looks like this is going to be a tedious job. I'll do a little at a time - mabye I'll be done by the end of summer :lol:

Hi

Yes 100% fets, for a long time on here I have been advising folks not to run more than 60V on Pumas (BMC) motors without upgrading the fets in the controllers, I blew 2 x controllers on a BMC at 72V, its also worth checking those little insulating tubes, follow fechters guide, on my Bullet proof controller i fitted 150V fets, i also used fet insulating pads and tab washers for all of the fets, I have run this controller on a Puma at 72V for over a year now and it has not put a foot wrong!!

Follow Fechters thread when you do the re-build, watch out for those pesky gate resistors as well as they blow, use your DVM and check all of them, you can sometimes blow the gate driver, change all low and high side transistors, they are so cheap its not worth taking the risk, don't bother with phase fuses, they are not quick enough to catch a blown fet, just use them on the main battery supply.

Its funny as all my blow ups were like yours, relatively low load but high rpms, I blew one just by lifting the wheel off the ground and showing someone how quick it span up! crazy.

Good luck with fixing the controller, I have fixed lots of them so give us a shout if you struggle, you can buy those surface mtd resistors in strips really cheap as well, if your eyes aren't that good you can piggy back them over the blown ones, my technique for holding them in place is using some blue tac, roll it out in to a long thin tiny sausage then stick the resistor to the end of it, you can then using the other hand simply dab the iron on to it, works really well.

Knoxie

Konxie, where did you buy the fet washers I have to replace all the fets in my comtroller and i am 6 washer and screws short as my controller only came with 6 fets.

$3.00 including postage and i can send you a set of 12 nylon shoulder washers. some people call these the "upgrade washers" as they are a single piece instead of the separate plastic tube on the screw and fibre washer under the head.

the majority of the $3.00 is for the postage and the padded envelope.

rick

rkosiorek said:

$3.00 including postage and i can send you a set of 12 nylon shoulder washers. some people call these the "upgrade washers" as they are a single piece instead of the separate plastic tube on the screw and fibre washer under the head.

the majority of the $3.00 is for the postage and the padded envelope.

rick

Click to expand...

check your PM
thanks

Right, there's 12 gate resistors. If they read 0, that might not be bad. When they read over 10, they're bad.

You might need to remove the FETs first, then measure them.

The IR2101's are the gate driver chips. Let's hope they are not blown.

Ok I've ordered some of those IRFB4110s from china, yea I'm cheap- but what the heck if it works it works. Still in the process of de soldering. Will keep updating....