Lipo Cell Drop Off

[Ellis]

They won't supply double the discharge unless they're wired such that their capacity is doubled. The C rating for each cell is the same, series or parallel. For them to be capable of 176a in series the C rating of each cell must double, and that can't happen.

You only get a higher discharge if you up the capacity, i.e., wire in parallel. But in series you aren't changing capacity, so the discharge is the same. You'd get a 12s pack capable of putting out just 88 amps. That motor at 12s, at stall, will pull double that. I'm not trying to be nitpicky, I just don't think this is right.

edit: that second battery link would probably be fine. Two in series would give 12s, 2.6Ah, 60C. That'd be safe, as the peak is claimed to be 120C. Whether 2.6Ah is enough for the job in capacity terms is a different matter.

[maddox10]

If each pack can supply 40*2.2=88A then both will supply 176A. All that changes is the voltage or the capacity depending on how they are wired. ie 176A @ 22.2V 4.4Ah or 176A @ 44.4V 2.2Ah.

I have the weight for 2 of these... http://www.gensace.de/lipo-battery/f...tery-pack.html

Let me put this in perspective. Each of the gensace batteries is 6S 2600mAh 60C
You can put them parallel.
This doubles the mAh value, and nothing else. Still 6S and 40C. But with 2*2600mAh=5200mah and 22.2V 60C, the rate of discharge is 312A
If you set them in series, the voltage doubles, but the rest stays the same. 2* 22.4V44.4V and 2600mAh and 40C = discharge of 156A

[Eventorizon]

Ok... so I am totally wrong. Oh well. Though now I am intrigued as to how Binky lasted on only 79.5A Cont.

EDIT: Then 2 of these will definitely cut it: http://www.gensace.de/lipo-battery/f...tery-pack.html

22.2V, 2600mAh, 60C = 156A Cont.

EDIT: And now they weigh to much.

For simplicity and reliability I think I will just stick to 10S for the time being. Shame.

[Max]

As long as they actually are 60C, bear in mind that the best optipower lipos are only 50C continuous.

[Eventorizon]

There is a high probability that Gens Ace and Opti-power lipos actually have the same internals. The company is technically Chinese but all their manufacture takes place in Germany. When Andy did has talk last November and I asked if Gens Ace were alright he said that their supplier shipped to one other company in Germany. Since Gens Ace batteries are the packs coming out of Germany that actually do what they say and more I would believe the stats.

Note: at the champs we accidentally drained 2 of our Gens Ace packs down to a crazy 2.3-2.5V per cell... and they recovered. I have no idea what it means but it can only be good.