Headway Cells & Zombie Misc. Info

Mike, sorry but 10Ah Headways are not 15C (it’s closer to 8-10C) and 8Ah Headways are not 30C capable.

I’m building a 880 cell pack for my BMW

Mate, I was in on some of the 8 ah testing and personally watched them effortlessly and repeatably dish out 240 amps for 15 seconds without the cells going below 2+ volts – that is indeed, 30C. I also help abuse them to the tune of 540 amp for pulses of around 3-4 seconds and they still were not yet down to 1/2 their voltage…that’s a 67C discharge!

On another note – preparations for the assembly of the 29.6V, 2.4 kiloamp, 64 ahr (C2) LiPol modules (2P X 8 S) has been going on the past couple of weeks, with this weekend slated for the actual loading of the cells into the modules. We’ve had to come up with creative ways of assembly to keep adjacent opposite polarity cells tabs from touching each other as they are passed through then bent over the slots in the Lexan top piece and clamped into place on their respective conductor/clamp pads. Rated at 1200 amps for 10 seconds each and 2400 amps with each paralleled pair, these cells make one sweat a bit when being handled!

Interesting info on these Kokam cells…at 3.7V nominal, fully charged just after charger shut-down, they fall from 4.17V to 4.15V, then stay there…three weeks later with imperceptible self discharge, the cells are all still at 4.15V! The Zombie’s 12 module race pack is 355V nominal but will sit at 398V fully charged, and with the surface charge pulled down, at around 375V ready to rock.

For longer street driving range, the 13th module will be added to make a 385V nominal pack that sits at 432V fully charged, and at a more Zilla friendly 406V with the surface charge pulled down. At C2 discharges this will be a 24.6 kWh pack. The 2650 lb. Zombie with the heavy 360V lead acid pack – 14 X 6 wheels with 215/6014 drag radials in back and 13 X 5.5 inch rims with 185/55/13 tires in front, had typically required about 25-30 amps to cruise on the freeway at 60-65 mph, so I think 120-125 miles per charge is possible, perhaps a bit less when we get the wider wheels and larger footprint tires in back. With the 12 module pack, the wider tires (225/50/15) on 15 X 8 wheels in back, but with narrower tires and wheels up front (15 X 4.5 with 165/50/15 rubber) and about 400 lbs. less weight than before, a solid 100 miles range no matter how we drive the car, should be a realistic figure… not bad considering the projected 0-60 of 2.5 seconds and high 10 second ET capability!

The new tire & wheel combo allows us to finally install our killer Wilwood disc brakes, as the large racing set wouldn’t clear the 14 inch wheels. The 15 X 8 American Racing Torque Thrust D wheels change all this, as do the newly released 225/50/15 G Force Drag radials (same diameter as the out-going 215/60/14s). Up front, we are redoing things as well, dramatically increasing the rotor size and switching to the same 5 on 4.5 bolt pattern that’s been in back. Even though the front wheel size is going up from 13 to 15 inches (stock 1200s came with 12 X 4 wheels), American Racing offers the Torque Thrust D in a drag racer’s narrow 4.5 inch width, so rolling resistance up front will go down (185 section width on 5.5 in rims down to 165 section width on 4.5 in rims, but tire diameter essentially stays the same – 21.8 original 12 inch tires vs 21.5 low profile 15 inch tires). The 165 footprint is more in keeping with the stock 155 footprint of the original 155/80/12 tires that the Datsun 1200 came with.

See Ya…John Wayland

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