Lithium Ion NanoPhosphate Battery by A123 Systems
Track test
Air temp 90 F track temp 125 F.
I
got the new Li nPO4 (5 cell equivalent) battery today, and it it fit nicely in the TC5 battery tray. I made a few small modifications for ease of removal and replacement. I sanded slightly the top plate which is highlighted red in the center picture below. This allowed the Battery strap to go on and off with no interference. I extended my end supports with a small threaded tube and second 4-40 long set screw. My battery supports are shortened for Lipos. A stock car may get away with just a longer set screw. The first picture shows an almost complete setup for the batterry. I would add two tape straps to the battery around the top strap and battery to hold the battery better side to side or make some kind of support to keep it off the belts.
I made 2-10 minute runs with the battery. I tried 16, 17, and18 tooth pinions. The battery had good punch and speed in the infield. It was a little sluggish on the straight. It was fastest with the 87/17 or 10.23 overall. Motor temp after 10 minutes was only 155 F. Battery temp was 137, Speed control 134. I would say that this system with the Novak 3.5 R motor passed the heat test with flying colors.
I ran a LiPo (2S1P, 6 cell equivalent) on the last run. I got more top speed and more punch in the infield. The track had cooled to 105 by this time so motor temps were also good. Interestingly the motor still liked the 17 tooth pinion the best. This is my late model 3.5 which is not as fast as an earlier model that I have in the pan car.
The car is at 52 oz with no ballast, body on. Side to side weights are good with the right edge of the battery even with the right edge of the chassis. I have my batt slightly left (1/8 inch) in the photo giving a 2 ounce excess on the left side.
The battery came specified at 4600 mA-h. Nice. I'll test this. The outer tape label was pretty sloppy underneath. They need a shrink label. Charge time was fast. The battery weighs 11.4 ounces.
Discharge Data
4535 mA-h average over two discharge cycles.
6.10 V average at 20 A on the second cycle.
6.33 Volts average for the first 94 seconds.
6.11 V at 300 seconds.
Charge from a full discharge took 40 minutes (7 amps average)
charge after an 8 minute run took 20 minutes.
Temperature after a full discharge only 94F!! this is very good.
John