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Talk:Motor controller

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Curtis-Killer DC controller

My essential spec/feature list for a Curtis"-Killer" DC controller is:

  • 600 adjustable battery amps
  • handles at least the range of 96-144V; 156V is almost essential, and up to ~200V would be even better
  • precharge/contactor control
  • basic fault detection (open/short throttle, high pedal lockout)
  • rev limiter (and a tach drive output sure would be nice)
  • integrated heatsink (water-cooled is preferable
  • priced on par with 1231C + appropriate heatsink.
  • contactor failure detection
  • controller failure detection & auto contactor dropout

I got a kit from KTA using a 1231C-7701 for my 120v system.

Did they tell you up front that this controller will cause your EV's drive motor to make an irritating non-varying squeal when you take off or cruise with a light throttle? Did they tell you that this controller has no safety features? Did they tell you it has no automatic precharge, and that if you don't design your own, it could blow up when the line contactor engages and send your EV off at full throttle? Did they tell you it cannot be adjusted for a battery input current limit to protect your battery pack investment? My guess is no to all the above.

If it's not too late, you could save a bundle by purchasing a used Curtis 1221B controller. It's a bit less powerful at 400 amps, but it's silent and you could get one for maybe $300 if anyone has one available. The money saved would allow you to build a precharge circuit and pocket at least $500 cash, too. Better still, a used Raptor 600 could be found for maybe $800, is silent, properly cooled, has dip switch programming, and 900 amps motor loop current.

Consider the used / surplus market where I can get a complete GE EV-1 fully functional with pot box and contactors for $100 or less. Or an EV-100 or even EV-200. All used, all cheap, all still very functional. Why would I buy a Curtis?

Two main reasons: we're all typically wanting more range from our Evs, and a modern high-frequency controller like (even) the Curtis will give you nearly 2x the range from the same battery pack; and, we're all typically wanting more life from our batteries, and the low-frequency EV-1 type controllers will kill your pack faster than the higher frequency alternatives.

The only EV-1 worth considering for an on-road EV is the 84-144V model; how common are these on the used market?

As far as controller rebuilding and modifications, why not buy some GE EV-1's as I have done and try to boost the voltage / current. It may be possible to take it up to 144 V (maybe) and current (double up the SCR) and some other stuff.

144V is certainly possible, since the EV-1 used in the Jet Industries Electrica 007 cars is rated for 84-144V. I've been told that reliability may suffer if pushed right to 144V, but certainly they hold up fine at 120V.

The current thing has been done also. Its been years since I've seen a post from Dale Glubrecht on the list, but as I recall he described having but together a monster EV-1 using the high current panel from a lower voltage model and the control card from a higher voltage model. The comment that sticks in my mind is that he didn't hear a growling noise from his motor; he could hear his *batteries* complain from the high current pulses they were being subjected to!

When you get to more than 600 batt amps, you are really killing the pack.

Floodeds don't like the high current, but AGMs such as Optimas, Orbitals, and Hawkers don't mind it at all.

The key here is that with controllers such as the Zilla, DCP, etc. vs the Curtis, you can adjust the maximum battery amps to a limit appropriate for your batteries, *without* restricting the low speed motor current. With a Curtis, if you turn down the current to protect the batteries, then the motor current is similarly reduced and acceleration suffers.

Is this one of those comments again, where one has to have read everything that came before and know that you might be talking about wet cell type batteries (and just didn't specify this), or do you really think that currents this low will harm powerful AGMs like Optimas, Hawkers, and Orbitals? Those of us using AGMs of higher quality know that the opposite is true, in that the high performance type AGMs actually give their best service life routinely dishing out BIG currents. 600 amps from the better AGMs is nothing. The Optimas in Blue Meanie lasted 6.5 years, and pretty close to each time it was taken out for a run, 1000 amps were sucked from them multiple times. Sure, under all out racing where you might suck 1000 amps from small 24.5 lb. batteries for 12 continuous seconds, it is stressful and sometimes fatal for the batteries, but for normal fun street driving 1000 amps for 5-6 seconds from larger 40+ lb. AGMs is kid's stuff....besides, you're already well above the speed limit in that amount of time and will be off throttle and back to sub 100 amp levels.

Posted by unknown -- 21 October 2006