And I thought my ancient Trackpower 5400 mA-h LiPo was doing a great job pumping out that 675 W with the LRP X 12 3.5, also pumping out in excess of 220 ampere bursts.
I thought I would discuss this c rating. At 16C the Trackpower can be discharged at an average of 86.4 amperes. This means the connectors that connect the multiple cells, and the very thin conductor which is sandwiched onto each layer of the cell will not flash vaporize with this much average discharge starting in a relatively cool lab and discharged on a machine.
So how can I build a 32 C cell. I take the thin conductor sandwiched onto each layer and double its thickness, and I take the stainless steel ribbon which is about 1/2 inch wide and joins the cell ends to your terminal block and either double its thickness or double its width. I make sure the terminals in the battery can withstand 168 amps. Now when I do this I reduce the resistance from conductors in the battery a little, but just a little. Like adding a couple inches of 12 gauge instead of 14 gauge. This does not amount to much. For mod this is of little use. In fact I leave the 14 gauge for mod. The chemistry in fact may need to be changed to tolerate the additional heat from the higher discharge rate. It is not neccesarily changed in a manner that produces more voltage although that probably is a goal as well. The chemistry in the cell is what makes the car go faster. I would rather see you reporting the average voltage on a 35 amp discharge. That is what will make your stock motor sing. More volts. If you look at my battery test, the only difference between the new and old pack is the new pack delivered more volts once the motor got to peak power. The increased voltage (about .12V) was worth 50 Watts. Both packs had identical voltage at the start of the test. 8.21 V.
I agree that you will lose fewer volts in the cell connectors with a higher c rated pack, but it would be nice if it also produced more volts to start with.
I am running mod TC. My highest average amps is about 45. It might be 50 amps with my new motor and great traction. This means I am well within the capabilities of the Trackpower. Any higher and the motor will catch fire in Houston. The lifetime and performance on any new pack I try is such a gamble. I have tried many.
I did think about purchasing the 40c pack from SMC for a second pack. I am not doing it because it is 40c. I would be doing it to test the voltage on discharge, performance in the mod TC, and maybe another run on the dyno and long term performance. Give me time. My dyno is out of commission for a week awaiting an amp sensor. Matt's should be ready to fire back up in a few days.
Here is a quote from Danny at SMC to finish up this post. Comparing a lower c to a 40c pack.
"I'm not saying that it's better but were seeing that it's as good and I know it's confusing and trust me we find this strange but that is what were seeing on the track.
When we test higher C rate packs in higher amp draw conditions the higher C rate is better but in the 13.5 class it seems like theres not enough amp draw to make a difference. This means you can save 35 bucks and get a 6000 and be very competitive.
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