# Curtis controller voltage upgrade



## TheSGC (Nov 15, 2007)

I really don't know if its even possible to upgrade the controller by just replacing the MOSFETS. I haven't seen the guts to it, but if the controller logic board is powered by the 24-36 volt input, then most likely it is not possible to upgrade the voltage in the controller without redesgining the whole thing. They are usually programmed for a certain voltage range, and it will either fry when outside that range, or shutdown due to overvoltage.

Although if you could post some pictures or the guts, or even schematics that would give me at least a better idea.


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## ngrimm (Oct 19, 2007)

Here is what I was looking at from Cafe Electric. It is for the 120 volt model but I think it will be pretty similar to mine since the amps are the same. I notice they use a 15 volt regulator for the logics so maybe the input voltage wouldn't matter for that part.  Notice in the upper rh corner they are showing only one of the 35 Mosfets and associated components. The mosfets cost $2-$3 each from Digikey but I don't know about the other parts. http://cafeelectric.com/curtis/curtis.php


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## TheSGC (Nov 15, 2007)

That Curtis design uses the AUX 12 volt battery for the power source for the logic board. The LM317 can only handle 38 Volts input maximum. I did find that 35 MOSFETs is a lot, and there are plenty out there that are different specs, but can give you 120 volts and 400 amps using way less than 35. For instance, this: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=497-5321-5-ND You would need only 4 of them, and they are $13 a piece.

For instance, I am completing an 84 Volt controller with 264 AMPs and it uses 8 MOSFETs, each MOSFET being 100 volts 33 AMPS. I planned on using 20 MOSFETS, but then realized that 660 AMPS would destroy my motor in matter of seconds, so it wasn't worth it.


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## ngrimm (Oct 19, 2007)

You made some good points. My thinking is that I already have the 24-36volt Curtis but also there are tons of them out there sometimes free for the taking. Would'nt it be pretty easy to drop the voltage to the LM 317 regulator with a zener diode or even a higher voltage regulator? I realize that is a lot of Mosfets but it would just be a matter of swapping them out without having to modify the board I think. I'm pretty sure the 220 uf caps would need to be upgraded but what do you think about some of the diodes? I really appreciate any and all input. Thankyou. Norm


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## TheSGC (Nov 15, 2007)

Do you happen the know the model number of the diodes in there already? They would probably need to be changed. I don't know about the capacitors though. I really don't know how to size up capacitors in a controller, nor have I found any equation to even give me an idea on capacitors vs amps. I would love to get my hands on some old dead (or even working!) golf cart controllers just to play with them and figure out ways to do things like voltage upgrades. Do you know of any places or anyone chucking old controllers?


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## ngrimm (Oct 19, 2007)

The 1204x appears to use 12 IRFZ48 Mosfets which are N channel 60 volt 50 amps each or 600 total. A Curtis 1221's 35 mosfets that total to 735 amps which is also rated at 400 amps. I found some 200 volt 61 amp mosfets in the TO220 style at Digikey.The part number is FDP61N20-ND for $2.20 ea. You mentioned the capacitor size but since I don't plan to increase amps, only volts, I would only need to worry about the voltage ratings as far as know. The free wheeling diodes are the same part number for both units. Norm


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## theboy16 (Feb 28, 2008)

have we thought of ripping out all the mosfets and replacing with one, large, IGBT? would that be easier?

- i'm liking the curtis on steroids idea, especially since small 24V controllers are out there in abundance. what are the disadvantages to this though? do we lose out on features?

Steph


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## epyon (Mar 20, 2008)

I just got a 1209B 5501 an still have the 1205 101 . is there any body out there that modifies these alot like upping volts , amps , puting in a automatic pre-charge , lights for funtions and or meters . 130 volts an 700 amps would be nice , butt 72 volts an 520 amps will be O.K .


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## Ziggythewiz (May 16, 2010)

If you want to build a new controller I think you're better off starting to build a new controller. Do an Open ReVolt and design in everything you want.


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## dragonsgate (May 19, 2012)

Ngrimm or anyone else interested I have eleven of these never used. I had to by a dozen when I replaced one in my Curtis 1231c-8601 controller. I will sell them for $15 for the bunch as is. That will pay for shipping and a soda. They have been hanging in my studio for 5? years. I will never use them. Measurements are 1 5/8 overall length by 5/8 wide by3/16 inches thick. Made in Korea. They have IXYS 1X50N20 SKO452 KO453AC etched on them. I found Curtis very secretive about their stuff and parts near impossible to find. At least that was that way it seemed some years ago.


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