large road legal electric go kart build. need help!

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Re: large road legal electric go kart build. need help!

Postby nuxland » Mon Apr 10, 2017 3:08 am

falshami wrote:are you saying that with the VEC500 48v model, we can actually run as high as 60v safely and run the 10kw motor also at 60v? what kind of power did you squeeze out of that?

Here is my controller inside fets
VEC500.jpg

Here is one of the last races I was using this combo
https://youtu.be/v_uUkrmJ_1c
Battery amps were lower than with 48V battery (mybe VEC500 lowered it somehow because I had the same parameters when using 16S lifepo4)
So I only gained more rpm, but power was before also around 13kw.
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Re: large road legal electric go kart build. need help!

Postby falshami » Tue Apr 18, 2017 3:05 am

im confused how you keep pulling 13kw, what is your programming? i struggle to get 7kw out of my motor, i think that maybe 60v or in that realm may be more helpful? i just dont know what to do with my 48v charger, i wonder if i can reprogram it as well?

i have put a 5:1 ratio and it seems that my buggy now only does 22mph again, from 45 mph when i had it at 2:1 but it had no torque... im at a bit of a loss... am i just not getting enough power to spin up?
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Re: large road legal electric go kart build. need help!

Postby Hillhater » Tue Apr 18, 2017 4:10 am

What motor rpm are you getting ?
Did you check the ratio in the axle diff ?
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Re: large road legal electric go kart build. need help!

Postby nuxland » Tue Apr 18, 2017 6:14 am

falshami wrote:im confused how you keep pulling 13kw, what is your programming? i struggle to get 7kw out of my motor, i think that maybe 60v or in that realm may be more helpful? i just dont know what to do with my 48v charger, i wonder if i can reprogram it as well?

I bought me a new charger when upgraded from 16s to 20s. But you do not need 60V to get 13kw out of that controller.
Here is one of my conf from 2015-06-10
Controller_Settings_20150610.jpg

falshami wrote:i have put a 5:1 ratio and it seems that my buggy now only does 22mph again, from 45 mph when i had it at 2:1 but it had no torque... im at a bit of a loss... am i just not getting enough power to spin up?

Here is another video I found in my harddrive, when I tested 16s vs 20s. As you can see I got about 300 more rpm in the straight end and as battery amps were the same I got also more kw-s in to the controller. All that was saved by cycle analyst analogger and rpm were calculated from the speed that was measured from the rear shaft by cycle analyst. I had 300A shunt between minus battey wire and from there I got battery amps.
https://youtu.be/_HKTkKx89e8
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Re: large road legal electric go kart build. need help!

Postby falshami » Wed Apr 19, 2017 5:18 am

ok so first off, can our controller take a cycle analyser? i dont see a connector for it, also any idea why our controller has two of the same plugs on it? . your settings look amazing, i have mine currently set at 75 starting phase amps. that may be a bit of the problem. next your forward loop is set WAY higher than mine which may be another issue, my shunt is reading a peak of maybe 130a from the battery. i had a feeling my motor controller settings were wrong and tomorrow i now get to go find out since i do beleive this setup should be able to get me to at least 45mph. and that is hunky dorry for regular traffic. also what charging system are you using ?


thank you so much for posting !! this may be my fix we will see tomorrow
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Re: large road legal electric go kart build. need help!

Postby galderdi » Wed Apr 19, 2017 6:21 am

The cycle analyst is an independent device. It has it's own shunts etc. No need to connect to your controller.
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Re: large road legal electric go kart build. need help!

Postby falshami » Wed Apr 19, 2017 11:14 pm

how does it measure rpm then?


sp update, the new settings were awesome they relally helped the buggy get scooting, i had to leave the throttle type as hyperbola which really slows the start up but prevented it from tearing my transmission to bits. it was crazy torquey on linear. i tried with 4:1 and i got 24mph... then 3:1 and got to 31.2 mph at 46 volts... so at least were moving up now. unloaded the motor spun up to 4200rpm which confuses me as well, since i beleive unloaded it should spin at 6000 rpm, and loaded at up to 4500 rpm? so according to the calculator i have if i maxed at 31 mph that means my motor underload only did 1300 rpm? so what am i missing here?
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Re: large road legal electric go kart build. need help!

Postby falshami » Thu Apr 20, 2017 7:17 pm

also as a further update, my shunt has read that it wont exceed 130 amps from the battery which again has me lost... is a 96v setup what i need? what will i gain from this?
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Re: large road legal electric go kart build. need help!

Postby nuxland » Fri Apr 21, 2017 1:36 am

falshami wrote:also as a further update, my shunt has read that it wont exceed 130 amps from the battery which again has me lost... is a 96v setup what i need? what will i gain from this?
One thing I can think of, if your bms/battery is not restricting the current and you have set more thatn 130A battery current in the controller.
Have you measured what voltage your acceleration pedal will input to controller? And have you configured your controller according to these throttle voltages?
With that VEC500 controller, its torque driven and when wheels off ground even half or less throttle will give you max rpm. But when wheels down and half throttle it will give you only half torque and therefor also less top speed.
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Re: large road legal electric go kart build. need help!

Postby falshami » Sat Apr 22, 2017 12:06 am

Ok so further update today, got her up to 42 mph , using a 17 tooth on my motor and a 31 tooth on the axle, it seems that nothing in between gets me to where i need to be, this time it pulled about 216 amps, so it really needed a heavy load or else it wont use the amps it can push out, i guess i need to try maybe a 13 or 14 tooth and see if that helps get me a happy medium? im guessing with a 10kw motor it wont do more than 45 mph, does that seem reasonable? and without ehavy loads it will never use the full power at its disposal due to torque vectoring... when i did 5:1 i got literally 24mph. with great acceleration. when i do 3:1 i can touch 36 mph with decent acceleration, when i did nearly 2:1 i got poor accleration but got up to roughly 41mph... im at a tad of a loss. your thoughts folks? also learned that the person who told me that my wire could handle 10kw was full of crap :) BIG explosion and now rewiring for larger gauge wire haha! missing an eye brow and eye lashes but all is good !
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