Hello All,

I have a 2 meter glider with an electric propulsion system:
35A brushless ESC with BEC
2000kv brushless motor
8x4 direct drive folding prop

2100 mah, 7.4 volt li poly battery

Everything was working great until yesterday. I bought a second battery pack, I couldn't get the same 2100 mah so I got a 1200 mah 7.4 volt pack. It charged fine. I set up the brake just like on the bigger pack. When I went to launch, the motor would go to about half power and quit. The esc would go into BEC mode and not recover.

After that, it started doing the same thing intermittently on the big pack.

What gives? Am I exceeding the max current?

Thanks in advance for any help on this.

Mitch

Mitch,
It's a safe assumption that you are drawing WAY to much current from that pack. no 1200Mah pack can deliver what a 2000Mah pack can deliver.
If you don't have a watt meter, now's the time to invest in one.
You did not mention the "C" rating of the battery pack, if it's a good C15 rated pack, drawing anywhere around 15A will beat up the pack in short order.
Good luck,
Pete

I'm not sure what's happening with the original larger pack but it's a pretty safe bet from your description that you tried to draw far too much off the new pack. Your symptoms are a classic example of trying to suck out too much too fast.

I'm going to suggest that your original pack was on the edge and has suffered a reduced lifespan as a result. BUt without knowing more about the setup it's hard to say. But a safe bet is that Pete is right about the fact that it's time to invest in one of the fancy watt/current/ meters. It'll be $50 well spent by the sounds of it.

Thanks, I guess I should have read the fine print. I will follow your advice, and set my radio (digital) to limit the max throttle to a value that keeps the current to a reasonable level. I guess I'll have to have two model settings, one for the larger pack and one for the 1200, but that's no big deal.

RCU to the rescue once again!