# Need 72v sepex 400a controller



## major (Apr 4, 2008)

amesmich said:


> I am currently makign an electric go kart and plan to use a 72v led acid pack. I have a sep ex motor off a forklift. My problem is I cant seem to find a cheap 72v sep ex motor controller. I think I will only need a 400 amp controller.................Any help would be appreciated...... Or maybe I should go with a 60v system... Will I still have enough torque to smoke the wheels with 60v?


Hi ames,

Well, you have a motor capable of moving an 8000# forklift at 7 mph or a 2000# car at 50 mph, so I think you could smoke the tires at 12 volts with the right ratio and current 

And if you don't want to spend the money for an appropriate controller, it might be wise to get going at a much lower voltage. Or maybe find a 36 or 48 volt SepEx controller from a golf cart on the used market. Or figure out how to make you own controller. You can find much discussion on SepEx on this site and likely elsewhere on the web.

Most of the SepEx controllers require programming to match the motor and application. This takes a special handheld device or PC pack which can cost as much as the controller itself. Not sure about the Kelly. It may interface to a PC without a dongle. Then on top of that, you have to know how to set the field map.

An EV cart is a great way to learn EV stuff and have some fun. Don't kill yourself in the process.

major


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## Guest (Apr 22, 2010)

The Kelly is programmable and you can adjust the field settings and you can also run much lower voltages with it. Kelly is about the best you can get right now for that motor. It will prove to be a decent controller. Fully upgradable to higher voltages up to 72 volts for your needs. I agree that 72 volts is quite high but maybe someday you can learn to control that power. I'd keep what you have but derate it to a safe setting. You also get regen too if you buy the regen SepEx controller like I have. 

Pete 

Be safe and have fun. Post the photos of the first drive. Be careful. It is lots of power to handle.

PS. Nice Looking cart


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## albano (Jan 12, 2009)

Hi, ames.

Nice cart you built. What is the motor spec, lenght, diameter, kw.... What batteries are you going to use?


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## amesmich (Nov 17, 2009)

Wow, Thanks for all the feedback from all. I really appreciate it. 

The motor is a 36 volt Schaeff Model no 7600088 MVX4003 Class H

The size is 15" X 8" I dont know any other spec on it because I bought it used on ebay. I only know it was from a Schaeff forkl lift. 

I plan on using a bank of led acid batteries. I toyed with buying or making a LI PO pack with A1233's but decided gainst it because of cost. 



I was goign to run 6 batteries for a 72 volt system but now I am thinking of droping that to a 60 volts system. That will save me some money on the controller and one less battery. 


This place is great.


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## major (Apr 4, 2008)

amesmich said:


> I was goign to run 6 batteries for a 72 volt system but now I am thinking of droping that to a 60 volts system. That will save me some money on the controller and one less battery.


Why do you think a 60 volt controller would be less costly than a 72V? If you could even find such a thing. And 60V system makes for an oddball charger.


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## amesmich (Nov 17, 2009)

By shopping around I can use an Alltrax DCX controller rated 48v Nominal but 60v max. Kelly also makes similar products. I realized 72v nominal controllers are less common.

The least expensive 72v Sepex controller I found was $699 and it was 600 amps. I could not find a smaller controller for 72 volts. 

I can buy an Alltrax DCX controller rated for 60v max and 400 amps for $319. As far as the charger. I agree. I thought about making one since I am using lead acid batteries.


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## major (Apr 4, 2008)

amesmich said:


> By shopping around I can use an Alltrax DCX controller rated 48v Nominal but 60v max. Kelly also makes similar products. I realized 72v nominal controllers are less common.
> 
> The least expensive 72v Sepex controller I found was $699 and it was 600 amps. I could not find a smaller controller for 72 volts.
> 
> I can buy an Alltrax DCX controller rated for 60v max and 400 amps for $319. As far as the charger. I agree. I thought about making one since I am using lead acid batteries.


You had better clarify nominal vs max voltage. 60 volt nominal systems are uncommon, like using five 12 volt batteries. The 48 volt controllers may have a max voltage rating of 60 to contend with fully charged 48 volt battery systems which could be 54 or 55 volts. It may not be able to handle a 60 volt nominal system where fully charged battery may be 68 volts.


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## amesmich (Nov 17, 2009)

major said:


> 48 volt battery systems which could be 54 or 55 volts. It may not be able to handle a 60 volt nominal system where fully charged battery may be 68 volts.


Your right I will have to rthink this. I really wanted more than a 48v system but its looks most feasibel.


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## albano (Jan 12, 2009)

Hi ames,

It great to see another go kart with a great motor. You can see as i'm busy building an drag race go kart and my thread is also here on DIY at http://www.diyelectriccar.com/forums/showthread.php/drag-racing-go-kart-41436.html Yes it is true that we should start with lower volts then increase the volts as we start to feel comfortable and enjoying the speed. It is not that easy to go that fast in the begening, cause you will feel the speed much faster when you are only a inch from the ground. It took me more than 15 run to feel the speed of only 175km/h on a friend of mine kart. He has a Yamaha R6 motor on that kart and believe me I didn't even had it full throttle and that is really scary.


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## amesmich (Nov 17, 2009)

WOW 175kph..... I dont want to even get close to that. I am looking for a top speed of @ 60mph. I dont even want to go that fast I just want the capability. I am looking for quick acceleration and tire smoking torque. 

Thansk for sharing your pics. Good lcuk with it.


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## Guest (Apr 25, 2010)

> I am looking for quick acceleration and tire smoking torque.


More like neck breaking acceleration and axle snapping torque. Be careful. With that kind of torque and such small axles you can snap those axles right in two. I have to be careful in the VW. Can't imagine the torque applied to yours. Enjoy and be sure to get us video. Even if you crash or bust parts and have it on tape? We all like video footage. 


Pete


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## frodus (Apr 12, 2008)

GE Makes a sepex controller, 72V 400A for the Zapi.


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## amesmich (Nov 17, 2009)

I found a kelly 400 amp online. Thanks. Imust have missed it the first time.


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## albano (Jan 12, 2009)

amesmich said:


> I found a kelly 400 amp online. Thanks. Imust have missed it the first time.


Try and post some photos of your cart here please.


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## amesmich (Nov 17, 2009)

Heres Some 

http://amesweb.net/photos/main.php?g2_itemId=26099


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## albano (Jan 12, 2009)

amesmich said:


> Heres Some http://amesweb.net/photos/main.php?g2_itemId=26099


Cool, nice build. Where are you planning to fit the batteries. Is that pinion solid with the armuter or can it be remove. What gear ratio do you have at the moment.


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## amesmich (Nov 17, 2009)

I have not spent any time trying to remove the pinion so I dont know. It was not directly in my way so I left it. Perhaps in the future I will look into removing it if I can. 

The batteries will go along the side. I will weld up a tray and bracket system to keep them in place. 


The ratio as it satnds now it a 1:1.


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## major (Apr 4, 2008)

amesmich said:


> The ratio as it satnds now it a 1:1.


Hey ames,

I'd rethink your ratio selection. For starters, I'd put the smallest sprocket on the motor shaft and the largest sprocket on the axel which will possibly fit. Do some calculations and figure the mph vs motor RPM ratio. Now, what is the cart speed at 3000 motor RPM?

And the flip side is that speed reduction ratio is a torque increase ratio. You said you want wheel smokin' performance. That takes torque on the wheels 

major


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## albano (Jan 12, 2009)

major said:


> Hey ames,
> 
> I'd rethink your ratio selection. For starters, I'd put the smallest sprocket on the motor shaft and the largest sprocket on the axel which will possibly fit. Do some calculations and figure the mph vs motor RPM ratio. Now, what is the cart speed at 3000 motor RPM?
> 
> ...



I have to agree on this one. You should at least start with 2.3:1 that will give you a nice burnout and save your battery and motor. That will give you 30 teeth rear and 13 teeth front. If you want higher top end then increase the front sprocket to 17 or 19.


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## frodus (Apr 12, 2008)

get a 600A kelly if you want to get 400A out of it. Everything I've read on them says they really exagerate their specs.


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## amesmich (Nov 17, 2009)

albano said:


> I have to agree on this one. You should at least start with 2.3:1 that will give you a nice burnout and save your battery and motor. That will give you 30 teeth rear and 13 teeth front. If you want higher top end then increase the front sprocket to 17 or 19.


 
I agree as well but I could not find the motor RPM anywhere online. So I figured I would start with 1:1 and change it from there. From the coments of others I should have more than enough power to run the 1:1. 

At 3000 RPM, if the motor will turn that fast the top speed would be 93 mph. I dont need that much speed. I have sprockets ready to go so I can change them once I get it running.


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## albano (Jan 12, 2009)

amesmich said:


> I agree as well but I could not find the motor RPM anywhere online. So I figured I would start with 1:1 and change it from there. From the coments of others I should have more than enough power to run the 1:1.
> 
> At 3000 RPM, if the motor will turn that fast the top speed would be 93 mph. I dont need that much speed. I have sprockets ready to go so I can change them once I get it running.



Ames,

I think we should move this thread to "All EV Conversions and Builds" and maybe there will be more member giving us some advise. "A thread about karts"


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## amesmich (Nov 17, 2009)

albano said:


> Ames,
> 
> I think we should move this thread to "All EV Conversions and Builds" and maybe there will be more member giving us some advise. "A thread about karts"


Thats cool


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