Originally Posted by Danny/SMC
John Bull: So far what we found out is that the IB3800s require a different motor setup than the GP cells. Next time your at the track measure the temp of your motors after the run and you should see a higher temperature with the IBs. You can either use a higher turn or drop the timing on the same motor when using IBs.
With stock motors, I've found that reducing the amp draw by either of the following two ways kept the voltage high and the motor temps low. I was able to gear up a tooth for more top speed without losing punch in the corners.
1. Use a 1.5mm drill bit with a slow speed drill and light pressure to drill a hole directly in the center of both brushes. You have to be carefull to put the hole directly in the center and not allow the bit to touch and scratch any other part of the brush surface. If you use too much pressure or speed, the brush may break apart as well. Go to stiffer springs on the positive and negative as well. I prefer to use the Reedy 769's when available. They are the same compound as the 767's, but have a hole pre-drilled perfectly.
2. Another modification you can use by itself, or in conjunction with drilling, is use a file to shave .25mm of the sharp edges off both lips of the brush surface.
I used both of these successfully this past race weekend. Taking out the first (very short lap time) and second (let the pole setter pass me) lap times, my average lap time in the first half (13 of 15) was 10.444. Taking out the 24th (made a mistake) lap, my average lap time in the second half was 10.433.
If you split it into thirds and take away the first four laps of peak voltage and the 24th lap for the mistake, here are the average lap times:
Laps 5-12: 10.423
Laps 13-20: 10.324
Laps 21-29: 10.518 (10.472 if you also take away the 25th lap)
Keep in mind that the mistake on the 24th lap carried over into the 25th lap as I had to slow up and let the race leader lap me. It cost me about 4 tenths in the 25th lap. The fastest lap was a 10.174 on lap 17 and the last lap time was 10.320.
I stored the IB3800 pack after discharging it to .9v/cell earlier in the week after testing and then trayed it overnight Friday on an Integy zero tray. I took it straight off the tray and used the step charge info below before each run. After the qualifiers, I only had time to discharge it with a 30A light tree and let it cool to below 85F on a fan before step charging again. I didn't use the tray on race day at all.
8A until 3050mAh
.2A until 3080mAh
6.5A until 3500mAh and waited until 5 to 10 minutes before the next run
7A until peak of 15mV/pack
The pack came off the charger around 140F(60C) each time with only a hint of venting seconds before the peak and no other problems noticeable.