SegwayChat - View Single Post - My NiMH -> LiPo battery rebuild for i167. Success!

Ground Loop · 01-09-2011, 01:32 AM

Another update -- I had to build TWO conversion packs in order to ride. (Alas, I have not a single viable NiMH pack to ride with.)

So far, so good! These cheap 3S battery packs are not a perfect fit to Segway riding -- there are complications.

First, the overall loaded voltage of 9S LiPo is slightly lower than what the Segway wants for NiMH. So right off the bat, with charged batteries, the Segway goes to 3 bars (half) charge indicator. After a couple miles, it's down to 2 bars.

The good news is that this seems to bother it not at all -- it stays on 2 bars for a long time. Without more detailed voltage monitoring, I'm not going to find the limit, but it's good enough to call the Segway serviceable once again.

The 2200mAh 20C packs are probably borderline for hillclimbing or demanding rides. I rode full-speed up some moderate hills, and the packs got just a little warm to the touch -- still below body temperature. I wouldn't try sustained extreme climbs in hot weather, since I effectively have no temperature monitoring on these, and no airflow.

Charging turns out to be easier than I thought.. I just bus all six of the packs in PARALLEL for charging, since they're all discharged the same amount. I bus all the balance taps as well. No problem. The charger treats it as a 3S 13.2 Amp-hour pack, charges at 25 Amps and has them fully done in 20 minutes, balanced.

I removed one of the circuit boards from a junk battery pack, and it's far more complicated than I thought. I was hoping to adjust its notion of "charged" to match the min/max of LiPo, but forget it.

01-09-2011, 01:32 AM	#14
Ground Loop Member Join Date: Dec 2003 Location: San Diego, California, USA. Posts: 517	Another update -- I had to build TWO conversion packs in order to ride. (Alas, I have not a single viable NiMH pack to ride with.) So far, so good! These cheap 3S battery packs are not a perfect fit to Segway riding -- there are complications. First, the overall loaded voltage of 9S LiPo is slightly lower than what the Segway wants for NiMH. So right off the bat, with charged batteries, the Segway goes to 3 bars (half) charge indicator. After a couple miles, it's down to 2 bars. The good news is that this seems to bother it not at all -- it stays on 2 bars for a long time. Without more detailed voltage monitoring, I'm not going to find the limit, but it's good enough to call the Segway serviceable once again. The 2200mAh 20C packs are probably borderline for hillclimbing or demanding rides. I rode full-speed up some moderate hills, and the packs got just a little warm to the touch -- still below body temperature. I wouldn't try sustained extreme climbs in hot weather, since I effectively have no temperature monitoring on these, and no airflow. Charging turns out to be easier than I thought.. I just bus all six of the packs in PARALLEL for charging, since they're all discharged the same amount. I bus all the balance taps as well. No problem. The charger treats it as a 3S 13.2 Amp-hour pack, charges at 25 Amps and has them fully done in 20 minutes, balanced. I removed one of the circuit boards from a junk battery pack, and it's far more complicated than I thought. I was hoping to adjust its notion of "charged" to match the min/max of LiPo, but forget it.