Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Paul & Sabrina's cheap DIY 144v motor controller

XmodAlloy · 10-11-2011, 10:03 PM

Hey everybody!
Man, this stuff is getting mighty exciting! 1000 Amps of home-brew power, I'm diggin' it Paul!
Anyway, I had a minor concerning incident today, I was revving the massive motor in my Geo a bit and decided to see what kind of RPM I could get out of it with 8 drive batteries, all went well and nothing is blown up yet, but when it got to a certain fairly high RPM the volt meter began to flutter badly into the 150 volt range with only 96 volts of nominal power. the meter is analog so it's nt some bug that a digital one might have with high frequency input. I suspect it's the back EMF from the motor surpassing 200 volts and jumping the on-board diodes of the MOSFETs, does that sound at least possible? I already have replaced the main blocking diodes with 600 volt ones after the 200 volt ones decided to become silicon popcorn.
Obviously I should restrain myself from revving the motor that high again but I am now very curious about what can be causing this voltage spiking back into my batteries.
The motor in my car is a mysterious 12 inch monstrosity which refuses to pull more than 250 amps and is quite happy to spew back all the voltage I can get rid of when running.
It's overkill I know, but I was rather naive when I bought it and everything else is built around it now, otherwise I would swap it out for something a little smaller. Who would have guessed there is such a thing as too big? Lol...
-Donovan Gibson.
P.S. I really don't mean to bug you any more Paul, it's just I can't help it! I'm cursed with oddities in my car's system!

10-11-2011, 10:03 PM	#5128 (permalink)
XmodAlloy EcoModding Lurker Join Date: Jun 2011 Location: Missouri, USA Posts: 20 Thanks: 0 Thanked 1 Time in 1 Post	Hey everybody! Man, this stuff is getting mighty exciting! 1000 Amps of home-brew power, I'm diggin' it Paul! Anyway, I had a minor concerning incident today, I was revving the massive motor in my Geo a bit and decided to see what kind of RPM I could get out of it with 8 drive batteries, all went well and nothing is blown up yet, but when it got to a certain fairly high RPM the volt meter began to flutter badly into the 150 volt range with only 96 volts of nominal power. the meter is analog so it's nt some bug that a digital one might have with high frequency input. I suspect it's the back EMF from the motor surpassing 200 volts and jumping the on-board diodes of the MOSFETs, does that sound at least possible? I already have replaced the main blocking diodes with 600 volt ones after the 200 volt ones decided to become silicon popcorn. Obviously I should restrain myself from revving the motor that high again but I am now very curious about what can be causing this voltage spiking back into my batteries. The motor in my car is a mysterious 12 inch monstrosity which refuses to pull more than 250 amps and is quite happy to spew back all the voltage I can get rid of when running. It's overkill I know, but I was rather naive when I bought it and everything else is built around it now, otherwise I would swap it out for something a little smaller. Who would have guessed there is such a thing as too big? Lol... -Donovan Gibson. P.S. I really don't mean to bug you any more Paul, it's just I can't help it! I'm cursed with oddities in my car's system! Last edited by XmodAlloy; 10-13-2011 at 08:59 PM..