Monday, June 28, 2010

In the name of science part II

If you recall from the last testing I put two Kelley controllers up against my Curtis 1231C. We did some repeated 0-30mph tests and compared times while monitoring the motor side amp output. The Curtis accelerated my car in second gear to 30mph in 7-8 seconds (nothing official just eye-balling a standard watch).

I've been in touch with a great guy who works at Curtis. This weekend I had the opportunity to test a modified Curtis 1231C. Unfortunately I only had a 500 amp shunt so we weren't able to test the motor side amps. I did see my battery amps peaking somewhere around 650-700 though as the controller reached Vmax. This controller reduced my 0-30 to 5 seconds. I will add the shunt later and get the real output from it soon.

He also has an even higher end modified 1231C, but we were having some issues with it. It should be 200 amps more or so. It would be nice to see a 3 second 0-30 :)

Unfortunately I can't give out any of the secret sauce that is being used to upgrade/modify these controllers since I didn't obtain the information myself and don't want to get anybody in trouble.

We should be doing some more tests with the 2nd upgraded controller later and I'll be sure to have the shunt ready for some numbers. I realize most people won't be able to make these modifications, but it should give you a good idea of expected acceleration for a given amount of continuous amps.

Tuesday, June 22, 2010


Things are still looking good on the daily commute. The car itself broke 100k miles a couple weeks ago and I'm now at 15k EV miles!

The increase in temperature has made a little improvement to the increasing voltage sag. I think the bottom line is I'm pushing these cells harder than I should for longevity. I believe my commute to work is using >80% capacity and this is taking a toll on capacity. Some mornings I have cell that is very close to fully discharged. I don't know how many miles I have left before at least one cell can't make it and possibly gets ruined to get me here.

I keep going in circles, but I'm leaning towards not selling it now. I'm thinking of making some modifications though now that I see how reliable the conversion itself is. Nothing official yet but here are some ideas I'm toying around with.

Motor controller: The Curtis 1231C has been reliable but I want to get the acceleration back in this car. I'm leaning towards the Soliton1 again for a few reasons.
  • It will increase my motor side amps from 500 to 1000.
  • It's much larger and has great cooling with the option of water cooling if needed. In the hot summer days on my long commute doing 70mph the Curtis is kicking down the amps sometimes.
  • It has many features that will make protecting the batteries, and motor a breeze. I'd like to add some features, but reduce complexity of the build and I think this will be a good step in that direction.
  • I'll have the ability to run a pack voltage that is much higher than the voltage applied to the motor. This allows you to run more smaller batteries allowing you to still get the capacity you want, but make it easier to fit them. It also will remove volt sag during hard acceleration. The pack itself will sag, but if your pack voltage is high enough the motor will receive a steady voltage increasing performance even on those cold days.

Trunk mod:
I think I'll end up cutting out the current trunk and expanding it. There is a LOT of room that is not being utilized under there. This will allow me to add more batteries and even move some of the front batteries to the back giving me room to finally mount that AC that I've been missing.

Currently I'll just add some more cells (I'd like to add another 15 or so) so I can get as much from the existing cells. This should ease up on them and extend there life some on my commute. This will give me not only more capacity but the ability to crank up the motor voltage a bit also to increase high end performance along side of the low end performance I'll gain from the controller change.

I'd like to get the car to a point where I don't have to look at anything and worry about what's going on. I want to simplify this side of things most of all. I want to be able to get in the car, look at my "fuel" gauge and know if I'm good to go. If there are any issues, then be able to connect something and diagnose the problem. I'm looking into some options for a low cost over haul here. The biggest problem with adding more and more cells is the complexity of protecting them.

As always, anything I do I'll document and share with you.