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Old 03-11-2008, 06:01 PM   #361
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We just got our first shipment in - Thanks Danny... Took 2 for myself to test
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Old 03-11-2008, 07:34 PM   #362
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LiPo @ 70deg
528 - 7.44 - 4.9 at 70 degrees.

LiPo @ 140deg
527 - 7.53 - 3.4

Matched EnerG 4600
448 - 7.39 - 10.7

So would you say, then, that your LiPos are definitely faster than the EnerG 4600's? That seems like a pretty clear advantage all the way around.

Will your racers be running the packs at nats?

You know, and interesting test would be to run your LiPo packs through a bunch of hard cycles, and do the same to your NiMH, while giving them the proper maintenance they require to stay in top form. I'd be interested to see how capacity/voltage/IR is affected across both types of packs as the cycles pile up.
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Old 03-11-2008, 08:27 PM   #363
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Originally Posted by Thugs Bunny View Post
Danny et al.
Just to let those interested know, I bought a 28c 4000 and 28c 5000 and have managed to fit both into the Losi JRXS R. It is a very tight fit for both and the 5000 will only fit when placed sticker side down. The slight taper on the one side of the pack is enough to clear the topshaft. So far I've been happy with the performance but I do wish the wiring solution was different. As it is my wires come out on the left front of the car through the drive belt. Just makes me a little nervous but so far so good.
Thanks for the info and I'm glad to hear they fit in your car. As far as the wires we had no choice but to make them come out on the side.
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Old 03-11-2008, 08:36 PM   #364
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Originally Posted by syndr0me View Post
LiPo @ 70deg
528 - 7.44 - 4.9 at 70 degrees.

LiPo @ 140deg
527 - 7.53 - 3.4

Matched EnerG 4600
448 - 7.39 - 10.7

So would you say, then, that your LiPos are definitely faster than the EnerG 4600's? That seems like a pretty clear advantage all the way around.

Will your racers be running the packs at nats?

You know, and interesting test would be to run your LiPo packs through a bunch of hard cycles, and do the same to your NiMH, while giving them the proper maintenance they require to stay in top form. I'd be interested to see how capacity/voltage/IR is affected across both types of packs as the cycles pile up.

Due to the low IR of Lipos the voltage gain at lower amp loads will be less than NiMh so they may not be better.

So far I have gotten feedback that they are faster and that they are slower so it's still not clear.

I think that motor setup/gearing may need to be altered to run with Lipos. The fact that a Lipo pack will have less voltage at a lower amp load may require a bit more gear assuming it doesn't overheat the motor. I think the low IR would be able to pull more gear but I maybe wrong.
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Old 03-11-2008, 08:44 PM   #365
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Originally Posted by Danny/SMC View Post
Due to the low IR of Lipos the voltage gain at lower amp loads will be less than NiMh so they may not be better.

So far I have gotten feedback that they are faster and that they are slower so it's still not clear.

I think that motor setup/gearing may need to be altered to run with Lipos. The fact that a Lipo pack will have less voltage at a lower amp load may require a bit more gear assuming it doesn't overheat the motor. I think the low IR would be able to pull more gear but I maybe wrong.
I've always had to gear my LiPo higher than NiMH to get the same speeds, even with Core packs that have pretty good voltage. I did have to drop a tooth or two when I started heating them, though. The motor was getting too hot, presumably from the increased voltage.
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Old 03-11-2008, 08:45 PM   #366
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You've been putting discharge numbers on all your packs, right? How much variety are you seeing between them? Are they all fairly close?
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Old 03-11-2008, 09:04 PM   #367
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When you say you gear more with your Lipos how many teeth do you go up ?

Are you getting better results by warming up your Lipos and going back down on gear ?

I think that the key to doing a good test to make sure the car is setup/balanced properly for Lipos and then the proper gearing/motor setup needs to be found. I think once these two things get figured out we will have the answer is Lipos are faster , the same or slower.


I did post some numbers from random 4000s on the previous 1 or 2 pages. I will get some numbers from some 5000s tomorrow. I think voltage and IR is very consistent and there is some fluctuation on runtime.
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Old 03-11-2008, 09:45 PM   #368
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Unfortunately, my tests on the track were pretty subjective, so I'm not sure they should be used for anything definitive. But, as a general rule, I've found that when running LiPo (Core, decent voltage) I had to gear up about 3-4 teeth higher than I did with NiMH to get comparable lap times. This was with a 13.5 brushless running rubber tires on a small carpet track. When I started warming the packs, I noticed my motor was getting too hot by the end of the race, and fading. Lap times were faster up front, but the stator got saturated. I dropped down 1 or 2 teeth to get the motor closer to its desired temp, and the lap times stayed the same without the excess heat and fade toward the end. In order to do a more scientific test, I suppose I would need to compare a new NiMH (I was using IB4200 at the time) against the warm LiPo to be absolutely certain. Also, my car is a bit lighter with LiPo (legal limit) which could throw the whole thing completely out of whack, since lighter cars pull more gear.

So... I suppose the only conclusive thing I can say is that you might need more gear with LiPo than NiMH, depending on your situation. I think, rather than trying to come up with a definite formula, it might make more sense to just let people know they may have to adjust their gearing, and then let them do their normal routine to find the gearing that works best for them. There are probably too many variables, however, to swap a NiMH directly for a LiPo and expect the gearing to be exact. It will be a moving target, like always.


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Originally Posted by Danny/SMC View Post
When you say you gear more with your Lipos how many teeth do you go up ?

Are you getting better results by warming up your Lipos and going back down on gear ?

I think that the key to doing a good test to make sure the car is setup/balanced properly for Lipos and then the proper gearing/motor setup needs to be found. I think once these two things get figured out we will have the answer is Lipos are faster , the same or slower.


I did post some numbers from random 4000s on the previous 1 or 2 pages. I will get some numbers from some 5000s tomorrow. I think voltage and IR is very consistent and there is some fluctuation on runtime.
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Old 03-11-2008, 09:49 PM   #369
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That was really wordy.

Yes I geared up with LiPo. Yes the car is faster when the LiPo is warmed, but I had to gear down to account for the voltage. Still faster overall. There are a lot of other variables that make this unscientific.

Gearing between LiPo and NiMH will probably be different. Normal procedures for finding the right gearing should be done when changing battery types. We can't expect them to be the same.

It's good to hear you're seeing so much consistency between packs. That's been a topic of much debate in the past.
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Old 03-12-2008, 06:29 AM   #370
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We feel this consistency is a result of having one single manufacturer producing and monitoring all the packs. Some other brands may change between manufacturers due to availability/price, etc. and this results in numbers that fluctuate somewhat. Just my opinion.
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Old 03-12-2008, 09:21 AM   #371
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Jack, with all due respect... I think given how SMC is new to the lipo game, you aren't in a good position to be making such broad claims about other mfgs and their products at this point.

The biggest dog in the game (orion), we know uses Kokam cells and that does not change. Obviously some companies have switched vendors as happens in every industry. But I doubt they just flip flop based on the best current price among suppliers as your post suggests.


SMC has invested in tooling to get a product that fits your requirements for the new packs.... so it's not like you could (or would want to) simply switch to a different vendor on the next order. I'm guessing SMC isn't the only company to do that.

BTW, it's good to see SMC invested in the lipo market. Now get off the nimh bandwagon...
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Old 03-12-2008, 09:50 AM   #372
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I imagine with the new ROAR rules, changing the origin of your cells on a whim would be somewhat problematic.

I can't think of anybody making batteries for cars that has switched in the manner described. Well, maybe MaxAmps at some point, but they seem to be sticking with those copper tab cells (HECELL I think).

I don't know if there's a correlation between quality control and cell consistency, but it sees reasonable that would be the case. If so, I suppose that's a testament to the quality of the cells you guys found.
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Old 03-12-2008, 10:48 AM   #373
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Danny and I have discussed this and it is just a theory. Perhaps it is just a matter of buying different part numbers within a cell manufacturer's product line. How else can these disparities be explained? We have cycled multiple packs from numerous companies and there is quite a large variation among SOME brands.
Glassdoctor- us being new to the lipo scene does not in any way diminish our ability to speculate on why packs show variation. I believe we have learned enough about these batteries and their sources over the last 6 months to make a legitimate guess and not be called out on it.
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Old 03-12-2008, 12:51 PM   #374
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Quote:
Originally Posted by Jack Rimer View Post
We have cycled multiple packs from numerous companies and there is quite a large variation among SOME brands.
Thats not really newsworthy....but if you included the names of the companies that had the worst / least variation, that sure would be.
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Old 03-12-2008, 03:21 PM   #375
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where I can find in stock the 5000???
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