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Old 05-11-2019, 06:50 AM
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Originally Posted by itsid View Post
yeah.. I was afraid to ask myself tbh..
I feel like the hackerspace guys did their best to measure and test..
and found a dead brick controller..
And now voided is in search for a properly sized dual motor replacement
which I'm afraid will be a unicorn hunt

IDK I soo hope I'm wrong and he just forgot to let us know once the kart was running
(excitement overwhelmed eating, drinking, sleeping on the driver seat ever since)

curious minds need to know

To continue the discussion (& maybe some inspiration for Voided) what would or how would he figure/look for a "properly sized dual motor replacement" controller?
...the Ohm method, like you showed me (a long time ago)?

For example, would a Kelly KDZ 72550 controller, like I have on ElMoto be a possibility?
...it's for (up to) 72V systems & can produce ~550A (max) (~$330.00)

I notice that they now have a KDZ-E line of controllers that go up to 800A (72V 800A ~$450.00)

Could (1) of these power his (2) motors
......or would he need (2) of 'em?
Old 05-11-2019, 07:37 AM
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that's the problem, two controllers do not make up for a twin motor controller very well

If the originals are independend (differentially powered)
you need to do that yourrself externally (manipulated throttle signal to each controller)
FN was kinda famous for having mastered this electronic and code mess
and since the gokart was 'testvehicle' for that kinda innovation I'm afraid that's what voided is dealing with
Which you would have to scratch code and build yourself,
frankly I'd have a few ideas for that but the testing for those ideas alone would take months.
I'd be scared in a kart that powerfull with a messed up throttle signal going chaotic.

If those are just powering the same fixed axle, you would still need to laod balance the motors externally (again manipulate the throttle signal) but in a much lesser complicated fashion,
still needs to be tested to a degree in order to keep the motors alive, have failsave modes and all that ...
And likely you have a lesser agile kart in the end.

I almost bet I could get that controller to work if I had it here.
The PCB looks still good, a few hairline cracks in the coating is all I can see from here..
I also bet that 90%+ of the partsa re in working condition.
The ONLY part that is certainly not fixable (or replaceable) is the FNR microchip,
they had them made to their specs for all I know and burned custom code in house,
they're not available to the public anywhere.
And even if you find one, you can't tell if it's the same code burnt in or not.
SO that is the one thing that can render the original controller dead.

There are a few golf carts with a twin motor controller for all I know,
so there are options available.
If any is viable.. IDK *shrugs*

but frankly, it's the controller that makes this kart unique and maybe even historically relevant to some degree.
Since that carries all the innovation Frazer Nash was wanting to test and improve upon.

IDK what power the motors draw so I can't tell what size controller
would be able to power them reliably.
but I guess the 550 Amp version should be plenty.
I doubt they draw much more than 240 Amps each tbh.
the controller carries 20 MosFets.. assuming ten per motor and no reverse..
and assuming 20-25 Amps per mosfet makes 200-250 amps per motor

just a guess, but you rarely see Mosfets with more than 20Amps used in a constant power
config (the pcb would quickly heat up to desolder itself)
very large cooling fins on the controller case...
*shrugs* maybe 40 amp MosFets? *headscratch*

Anyways.. voided doesn't need to guess,
a look on the mosfets will tell what model they are,
and with model and count he knows what the controller was able to provide
and he just could match to that and it should be good

Jokes about german sausage are the wurst.
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Old 05-14-2019, 08:09 PM
voided voided is offline
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Unfortunately the hacker space guys wouldn’t touch it . Most looked at it and scratched heads or smoke came out of their ears..

I’ve called and emailed dozens of people locally, and have found no one to be able to help..
Old 05-15-2019, 04:27 AM
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... shirt

as I said, I bet I could get it to work as long as the microcontroller itself isn't the cause!

If you are willing to, I can try and talk you through the process of finding and replacing
defective parts.
But you would need some tools in order to test and repair.

I hope 70'ish bucks for tools should do
Or say 20'ish bucks for testers that hopefully find the part
and 50'ish bucks for a cheap soldering station, a desolder pump and some consumables.

Oncce we found a part you can then ask the hackerspace guys or a friend to replace a few specific components on the board if you're uncomfortable soldering on the PCB.

Whaddya think? shall we give it a try?


PS shipping will most likely be a real PITA since I'm halfway across the planet,
otherwise I'd say just pack it in a well padded box and send it over
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Old 05-15-2019, 12:20 PM
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If you weren’t across the pond I’d send it over.. right now it’s on the back burner as i try and get my power racing series kart together and running for the race in September..
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