Originally Posted by swopemike

I ran 3 hours of practice laps on rubber tires at a large outdoor track in mid-August this year with another racer. This was after having run an Enduro that day, so my batteries already had maybe 3 partial charge cycles apiece on them. I was using a Novak 10.5 with the standard sintered rotor and so was the other guy. I was using two IB4200 packs (1.5-1.7 IR, 1.241-1.243 V) purchased from Team Express at Paved Nats June 8th. I rested, discharged, equalized and recharged my IB's prior to running the practice session. The other guy was using Orion/Peak 3200 packs bought this season. We both had decent cars with smooth running drivetrains, and athough his was Tamiya and mine Corally, we were geared virtually the same (roughly 4.83 FDR).

We kept regrouping just before the back stretch every time we got apart. So we zipped down the backstretch over and over and over again, almost together. One following the other, back and forth. We had a great chance to see how our speeds compared.

With a fresh pack, I outpulled him by several feet (2-3 feet). Consistently enough we were sure I was faster.

After about a minute, the difference was pretty small. Maybe a foot in 100. It then evaporated and we were too close to tell. Sometimes I thought I was a little faster.

But as the run went on, I could tell I was losing ground. In a 5 minute race, I think it was almost too close to tell... I had the better hole shot, but he could pull me at the end.

This particular course is very open and flowing, 15' wide lanes, 120 x 70 or so.

When we have run at another track that is tighter and longer, there was more advantage to the LIPO. The NIMH2 seemed to fall off a little more. Of course they had another 2 months of runs on them. But the discharge curve of the LIPO clearly seemed flatter.

During the actual enduro, one of my teammates had an Orion 4800 LIPO. He went seemingly forever running his 13.5, way way longer than I could have, over 10 minutes, and with every bit as much punch as I think I had, until close to when he dumped, he finally fell off. Whereas my packs fell off much more markedly in comparison, slowing more and more through the run while pushing my 10.5 BL.

I never realized how much NiMH2 fell off in a race until I saw LIPO running. They fall off too, but the ones I have seen, do so much more gradually.

I realize it's not me running both types, but the subjective difference on the track was, although subtle, easy enough to pick up by watching the cars. Based on our club trophy races, I think in a race you could guess 2 out of 3 times (by watching) which drivers had LIPO and which drivers had NIMH2.

It would be interesting to compare the new 3600 to new 4600 cells. I imagine they are both pretty close when integrated over a 5 minute run, albeit with different discharge curves. Just a guess... actual test and track data would be nice....

Originally Posted by StephenSobottka

Linger, or possibly others;
I was pondering this today as I started to put some cycles on the new smc lipo. The charge rate governed by most chargers is a 1C rate. I was wondering, if I were to charge at .5C, would the cycle life possibly be extended?(It should I think in the long run) Would this lower charge rate cause a drop in performance? The reason I ask is because Lipo's do not get hot while charging, which is why their is no difference in power? The typical NIMH cells we run now, perform better as close to peak as possible, which is also when they are hot.
I hope I didn't open another can of worms, just looking to explore some opportunities.
Thanks!

Originally Posted by linger

Hi Stephen,
No can of worms here.
Technically, you get a tiny bit more cycle life at 0.5C vs 1C charge, but the difference is so small, that it's not worth it. The cycle life degredation seems to be exponential. For example, some of the cells I tested had fantastic cycle life up to about 1.4C and then you really start noticing a dip at 1.5C and the dip becomes huge at 2C. It's highly dependent on the battery and it chemistry on how high of a charge it can accept.
Also, charging at a higher charge rate does not make it perform any better - it just takes away cycle life..

Originally Posted by ApexSpeed

Good quality Lipo cells shouldn't need to be balanced often, if ever.


These aren't NiMh packs that need to be babysat.

Originally Posted by swopemike

I ran 3 hours of practice laps on rubber tires at a large outdoor track in mid-August this year with another racer. This was after having run an Enduro that day, so my batteries already had maybe 3 partial charge cycles apiece on them. I was using a Novak 10.5 with the standard sintered rotor and so was the other guy. I was using two IB4200 packs (1.5-1.7 IR, 1.241-1.243 V) purchased from Team Express at Paved Nats June 8th. I rested, discharged, equalized and recharged my IB's prior to running the practice session. The other guy was using Orion/Peak 3200 packs bought this season. We both had decent cars with smooth running drivetrains, and athough his was Tamiya and mine Corally, we were geared virtually the same (roughly 4.83 FDR).

We kept regrouping just before the back stretch every time we got apart. So we zipped down the backstretch over and over and over again, almost together. One following the other, back and forth. We had a great chance to see how our speeds compared.

With a fresh pack, I outpulled him by several feet (2-3 feet). Consistently enough we were sure I was faster.

After about a minute, the difference was pretty small. Maybe a foot in 100. It then evaporated and we were too close to tell. Sometimes I thought I was a little faster.

But as the run went on, I could tell I was losing ground. In a 5 minute race, I think it was almost too close to tell... I had the better hole shot, but he could pull me at the end.

This particular course is very open and flowing, 15' wide lanes, 120 x 70 or so.

When we have run at another track that is tighter and longer, there was more advantage to the LIPO. The NIMH2 seemed to fall off a little more. Of course they had another 2 months of runs on them. But the discharge curve of the LIPO clearly seemed flatter.

During the actual enduro, one of my teammates had an Orion 4800 LIPO. He went seemingly forever running his 13.5, way way longer than I could have, over 10 minutes, and with every bit as much punch as I think I had, until close to when he dumped, he finally fell off. Whereas my packs fell off much more markedly in comparison, slowing more and more through the run while pushing my 10.5 BL.

I never realized how much NiMH2 fell off in a race until I saw LIPO running. They fall off too, but the ones I have seen, do so much more gradually.

I realize it's not me running both types, but the subjective difference on the track was, although subtle, easy enough to pick up by watching the cars. Based on our club trophy races, I think in a race you could guess 2 out of 3 times (by watching) which drivers had LIPO and which drivers had NIMH2.

It would be interesting to compare the new 3600 to new 4600 cells. I imagine they are both pretty close when integrated over a 5 minute run, albeit with different discharge curves. Just a guess... actual test and track data would be nice....

Originally Posted by PitCrew

Just a thought, but did your buddies car have weight added to it so the two cars weighed roughly the same?

I'm sure if a IB4200 weighed what these lipo packs do, people would be completly shocked how they perform. (If the weight wasn't made up for elsewhere on the car)

Originally Posted by kn7671

When will SMC get updated information on their website. I hate relying on other websites for sometimes incomplete information.

If you guys would get on top of the SMC and JACO websites, you might be able to increase sales a little more. Information can be the key to a sale, or no-sale.