Looking for a buggy project - Page 20 - RC-Monster Forums

BrianG · 07:37 PM

Did a little more running this afternoon using the new battery. Ran until the Quark cutoff (3.0/cell), which worried me a little. Usually, when the LVC kicks in, I can stop for a sec or two, and then run it back to me (I'm lazy). Not this time. I thought I popped my ESC. Turns out everything was fine, just the battery was done. Didn't notice much loss of power before the LVC point.

And since the LVC was at 3.0v/cell, the Turnigy pack was a bit warmer than I would like (didn't get a measurement, but I would estimate ~115*F-120*F), but not nearly as hot as the MA pack I was using.

Took an Eagletree graph and got repeated spikes near 150A. Average current draw was ~12A. Max burst was 168A. Some burst sample points (and all were taken at least 1/3 into the run):

3.4v/cell @ 168A (33.6C)
3.67v/cell @ 150A (30C)
3.78v/cell @ 100A (20C)

Not too shabby. Cell resistance calculates to somewhere between 0.001 and 0.003 ohms per cell (higher as current increased, and the further into the run I went).

emaxxnitro · 09.16.2009, 07:46 PM

yeah i have some Turnigys they are great cells

BrianG · 09.19.2009, 01:35 AM

Just an update on the Turnigy pack. I used it twice and noticed cell #4 is always lower than the rest and takes FOREVER to balance out. Even if I charge that cell individually to even it out faster (charging through the balance connector via custom harness at ~500mA), the voltage falls quicker than the rest. So look like there is a bad cell. That sucks, but there is some good news.

I got this pack from my LHS (they started carrying all kinds of Turnigy stuff recently), but they have a ~75% markup. Yeah, that's high, but I figured I would support my LHS. And I'm glad I did. Once I explained my situation (the guys there know that I know what I'm doing), they replaced the bad pack on the spot. So really, what did I lose? If I had gotten the pack from HC, I would be faced with a huge waiting period, not to mention the extra shipping charges to and from there. Either that or just remove the bad cell to make a 3s pack and buy another 4s.

This got me thinking: I wonder how many people would be willing to pay a few extra bucks if they could get these locally (or even through RCM)? A little peace of mind and less waiting is always nice. The price would be higher, but still lower than most (if not all) other brands.