[octagondd]

Well, I think I am going to take the plunge. Hopefully, if it looks good, I will be purchasing a 1986 Honda CRX HF tomorrow. A bit scary, but I have been thinking about this for at least a year if not longer. I have virtually no mechanical or elctrical engineering experience, but have a friend who may help me out a bit. I will definitely contact other CRX converters for any info I can get as well as post any questions I may have here. Here is what I am planning for the moment.

1986 Honda CRX HF (1725 lbs)
144-160VDC system
30 mile round trip commute on Los Angeles Freeways (70mph)
Impulse 9 motor (If it will fit in a Rex) Brushless motor?
Zilla 1KLV controller (maybe new Netgain controller?? Anyone tried one yet?)
(40) 100AH LiFePo4 battery pack (Not sure on AH yet-charge at work?)
Clutchless?
BMS?
Charger?
Budget - Hope to keep it under 12K. Less if I can charge at work

I am open to any and all suggestions. As you can see my plans are pretty much wide open at this point. The biggest deal for me now is deciding if its worth it to get a large battery pack and charge once a day or a smaller pack and charge twice a day. Do I really need a battery pack to last for 12, 16, 20 years?

Anyways, I am excited to be starting this journey and look forward to discussing as much as I can with everyone here.

Dave

[octagondd]

Quick question. Why are TS LFP Batteries listed as 4.25V instead of 3.6 like SE Batts? Do they all still function at 3.2V or do the TS Batts function at a higher voltage?

[madderscience]

The CRX is a great conversion candidate. Very light and aero. The 90-91 SI model
was my first pick for a conversion chassis but I couldn't find a cheap enough one that wasn't a total wreck.

100AH at 120-ish volts (12KwH or so) of litium will easily give you 30 miles at 70mph while weighing only a few hundred pounds.

If you slow it down a bit, 50+ miles is a distinct possibility on that pack. With good tires and alignment and some simple body mods (air dam, etc) you should be below 200wh/mile battery-to-wheels at 55mph.

a 9" motor should fit in the car, but if it doesn't, you will still get good performance with an 8" with a lightweight car and a lightweight battery. The netgain "transwarp" is a 9" motor designed to fit where an ADC 8" does so that is a possibility if length is a problem on a normal 9".

Again with the light weight (since you are avoiding nearly a 1000 lbs of lead) even a pretty modest controller like a curtis will give you plenty of oomph. Logisystems, zilla, soliton all have 1000 amp controllers in your voltage range, but with the 100AH lithiums you will want to limit battery current with such a high power controller.

FWIW with my MR2 full of 1200lbs of lead, I basically never exceed 300A accelerating. that is 3C on a 100AH battery; 3C is a safe maximum discharge rate on most of the chinese lithiums out there, though they are getting better. So a car like you are proposing which would weigh probably 800 to 1000lbs less than mine would be able to do quite a bit on "only" 300 battery amps.

The voltage difference between SE and TS and any of the other ones has to do with the slightly different chemistries of the batteries. Build the pack using the nominal voltage rating of the batteries you select and make sure to get the regulators/shunts that are correct for your battery chemistry.

Keep the clutch. That is good policy with a DC conversion that isn't using a monster controller and high amp batteries. You can always convert to clutchless later, but for first timers its good to keep. (but if you go to an AC motor with higher RPM ratings, you could probably lose it)

Manzanita micro makes high end (and pricey) regulators and chargers that work with thunder sky batteries. The battery manufacturers all offer regulation/charging solutions as well and lots of other BMSes in various stages of development or production are out there.

Good luck.

[octagondd]

Thanks for the great reply madderscience. I have been thinking I might be able to use a Kelly or Curtis, but wasn't sure. Since seeing your post I looked at the EV calculator on evconvert.com and looked at what battery and motor amps I would need. I have a 3% grade for 2 miles on my commute. It says 270 motor amps and 206 battery amps at 70mph. Would I need a controller that has a continuous rating of 300amps?

[electromet]

"The netgain "transwarp" is a 9" motor designed to fit where an ADC 8" does so that is a possibility if length is a problem on a normal 9"."


Just a little correction: The TranswarP is a regular 9" with a GM Turbo 400 tailshaft attached. The Impulse 9 is a shorter version of the WarP9.

[madderscience]

Doh!!!!!!!!!!!