tips for modding KT 9-fet controller for higher volts ?

I would like to up the voltage capability a bit on my 9 Fet KT controller. I see the 3 big caps that are 63 volts. Two of them are across the voltage input line, and the other I'm not certain what it is doing. I got some 100 volt caps of similar size but lower uf . I'm hoping that is not an issue, but if it is I can run more caps external to the case, right ?
There are some small caps that are 50 volts, I don't know if they need changing too.
Now to the Fets. Since this is a 9 fet unit, it is lopsided in that they put more but 'cheaper' fets on one side. If it was balanced it would be a 6 fet controller or a 12 fet controller. I don't know why they did a 9 fet. Maybe marketing reasons. So I will replace the 68 V 110 A fets in there with more of the 85V 150 A fets also in there, maybe making it a 6 fet controller as I see no reason for one side being different that the other. Does my plan seem OK ? I only want to run maybe 60 volts. I was running 52 before. Side note : I feed it from a dc dc boost converter, so I can dial in what voltage I desire. Yes , the DC DC is a bit wacky, but I got a good supply of 10S packs a while back, and it's my way of getting some more speed out of what I have, and I don't want to go to 72 volts. Would the 85 volts fets ( K150E09NE ) be ok at 60 volts, assuming voltage spikes and noise ? The controller is 500 watt and never got above slightly warm even on steep hills. I may shunt it to 600 watts.

if it's not getting warm then by definition it can't be wasting much energy as heat. and if you're only using 60V with caps rated to 63V that is still within their rating, no point in changing them out!

Up voltage for speed, as said your limited on the capacitors inside the controller.

If you want more power to get up hills or whatever, then add more material to the shunts but you wont be able to know exactly how much extra power you have until you measure the phase or battery amps or go by feel. Is your battery able to handle some more power becaue your controller will then be asking for more amps from the battery.

Otherwise you need to buy a new controller and for KT display you need a specific controller for KT display.

Probably not what you want to hear but your controller should do fine on a 16s battery pack the caps at 63v aren't likely to melt down over 4 volts( if you are not comfortable trying this jus set your dc to dc converter right to 62/3v you will be fine)and I know it sounds irresponsible but soldering the shunts then add copper wire to long run on the back of the fets for increased heat dissipation and add solder to all the parts that looks a little thin for increased current flow. Im no expert but I can be very irresponsible though If you wish I could disconnect it to take pictures for you if that helps? and if you need your mind putting to rest the day after tomorrow ( as tomorrow holds a 10 mile ride to gfs place) i could collect my battery packs from my mates n run the 16s packs to try this for you?. I have a similar controller I was doing experiments to but is back in temporary services. Once its retired again I plan to finish my experiments then see jus how much voltage it'll take. Rather than spending money on replacement components look on ebay for around 40 dollars you can get a really good 1500w 40a 36/48v controller that is very good happily takes a 16s 67v I know because I bought 1 and had running from my 60v pack plus the components inside are already rated in the 80v region I know because the 1st thing I did was open it........ and yes being as irresponsible as I am took a screwdriver to my yula 3000w controller which I got for Christmas.

On a serious note as all modifications should be done in a safe and controlled manner as possible and learn as much as you can before you do! though you should seriously consider 40 dollars for a new controller as you could get up to 2000w for your money which would likely have 100v rated components and also have 3 speed switch for economy and going jus that little bit faster and all round much better to modify..... good luck in what you choose

Sorry my experiments controller has similar rated components though is not a kt. And I never thought about weather you have a display or not personally I dont ride with one and as mark said kt displays only work with kt controllers. Still have a good look at the controllers available you might be surprised by what you find

Thanks for the reply. Do you have an online shop link for that $40 controller you said is pretty good ? Maybe on the e - bay ? ( not sure it's allowed to link to shopping sites from here )
I feel I should swap out the 68 volt fets, as the inductor can make nasty voltage spikes and that is too close for comfort. 85 volts fets safer, for my goal of 60 volts at least.

How about the LM317T that drops the battery voltage down to 15 volts for the lower voltage circuits in the KT controller. Depending on the vendor, its input limit is 60V. More reason for buying a higher voltage controller.

View attachment S06S_schematic.pdf

Hey marka no problem I dont know how to link ebay stuff but I took 2 screen shot for you. Once you found those you will get similar options I always tend to watch things from the shops on ebay as they often relist new items once they sell. Please dont let buying a new controller stop you from modding that 1 as you can always take what you learned and do it to the new one at a later date experiments can be quite fun and an important part of learning have fun and good luck

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So far have have reduced the fet count to 6, all 85 volt 150 amp ones. Runs fine at 53 volts. The issue with the LM317T regulator is a concern. I'll have to look into that, maybe dropping the voltage before it somehow, or substituting a different regulator. Isn't there also an over volt concern with the lcd3 display unit ? Anyhow, I still don't get why this was a 9 fet controller in the first place. Marketing so they can say '9 fet ' ? A way to use cheaper fets for the doubled up ones ? I won't push the volts more until I get the spare 350 controller I ordered for $15 . Good to limp home with.