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Old 03-24-2008, 12:13 PM   #436
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I posted this in the 416 thread. But I thought I'd post it here as well. SMC 4000 pack. Car has been running great with this setup. Lipo Lead weight and PPD plate under the pack makes it weigh 443g. I can make it weigh less if I use a thinner lead plate. So I have full control of how much weigh goes on battery side. Balances great with the brushless setup. Thinner weight for brushed. 2 packs ran all day long. I'll play with high discharge and high charge rate later on. But so far so good.

Am I the only one that noticed the 7.2V on the decal attached to the pack shown in this picture? I thought all Lipo packs were 7.4V - especially the SMC 28C packs????
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Old 03-24-2008, 12:19 PM   #437
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It was talked about a few pages back. It's a typo made by my friend who got the stickers printed for us. Lipos are 3.7v per cell so our packs are 7.4v guess he was use to the sub-c packs which are 7.2v
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Old 03-24-2008, 12:21 PM   #438
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It was talked about a few pages back. It's a typo made by my friend who got the stickers printed for us. Lipos are 3.7v per cell so our packs are 7.4v guess he was use to the sub-c packs which are 7.2v
Thx.... didn't do a search.

Looking forward to trying these cells out.

Martin
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Old 03-24-2008, 05:43 PM   #439
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just so everyone knows, the 5000 hardcase will fit the tc5 with no problems.

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Old 03-24-2008, 05:57 PM   #440
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Follow what Tony is reccomending as I have no actual data on warming it up prior to charging or only on the discharge.

Thanks for the info Tony as this is actual ontrack testing which is better than my GFX testing but that also means improvement on GFX numbers results in better ontrack performance.
No problem Danny. Just wish "someone" would come up with a Lipo Warming Sack!
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Old 03-24-2008, 06:05 PM   #441
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<--- jealous 008 owner

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just so everyone knows, the 5000 hardcase will fit the tc5 with no problems.

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Old 03-24-2008, 06:20 PM   #442
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<--- jealous 008 owner
Yea, but slammed top decks are SOOOOOOO sexy!

I bet the EU 08 would take LiPo okay. :-)
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Old 03-25-2008, 06:15 AM   #443
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Danny YGM!
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Old 03-27-2008, 10:59 AM   #444
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Here are the graphs for our 28C cells/packs. These graphs were done by our manufacturer and done on a single cell which is the industry standard when testing C rate.

Our 5000 pack uses four 2500mAH cells which means a single 2500 cell was tested. Our 4000 uses two 4000 cells thus a 4000 cell was tested.

To specify the C rate the industry standard is that a cell must be 90% of it's rated capacity at maximum C rate discharge.

The 2500 cell is 93% at 30C and the 4000 is 88% at 30C so the cells used in our packs do have a true 28C rate as advertised.
Attached Thumbnails
SMC 28C 4000/5000 Hardcase Lipo part 2-2500mah-graph.jpg   SMC 28C 4000/5000 Hardcase Lipo part 2-4000mah-graph.jpg  
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Old 03-27-2008, 09:57 PM   #445
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delete me
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Old 03-27-2008, 09:58 PM   #446
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Originally Posted by Danny/SMC View Post
Here are the graphs for our 28C cells/packs. These graphs were done by our manufacturer and done on a single cell which is the industry standard when testing C rate.
Danny, those are impressive curves. (Not quite like Jessica Alba though... lol)

I haven't been looking at discharge graphs for a while... (so I have missed all the latest 25-30c+ cells) but I don't think I've seen any that good.

Do you have the temp data from those tests? That's another factor that is normally taken into account when testing/determining a cell's rating.
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Old 03-27-2008, 11:05 PM   #447
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The 2500 cell is 93% at 30C and the 4000 is 88% at 30C so the cells used in our packs do have a true 28C rate as advertised.
Danny--please don't misunderstand, but that is absolutely NOT the conclusion your data shows re: the 4000 pack. I've no doubt at all that it is, as you claim, a true 28C pack but what your data shows is only that it is NOT a 30C pack based on the industry standard you quote. The graph clearly shows the 4000 pack meets spec at 20C but 28C (nor any quantity between) is not addressed.

Also, the statistician in me is curious how many cells were tested (how many tests) as to whether a statistically significant sample size has been examined, but that becomes an exercise. If the industry standard allows a single data point (or limited data points), as seems to be the case, then you've certainly met that standard.

BUT, to truly back the claim quoted above, please have your friends test a 4000 pack at 28C and provide you with the resulting data and graph.
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Old 03-28-2008, 01:41 AM   #448
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Danny, those are impressive curves. (Not quite like Jessica Alba though... lol)

I haven't been looking at discharge graphs for a while... (so I have missed all the latest 25-30c+ cells) but I don't think I've seen any that good.

Do you have the temp data from those tests? That's another factor that is normally taken into account when testing/determining a cell's rating.
What do you mean by temp data ? Is it the temp at which the cells were tested at or the temp when various cycles were completed ? I'm pretty sure I can get this info if you tell me what your looking for.

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Old 03-28-2008, 02:01 AM   #449
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Scottrik: Before we released our new packs we made sure that our manufacturer tested the cells so he can give us the true C rate. He told us that we could advertise them as 28C based on the test result.

I'm not sure what else we have to do to prove that our packs are truly 28C.

Anyone is welcome to buy one of our packs and have the C rate tested as we have nothing to hide and we won't claim a higher C rate just to try and make our packs look special.

Based from the feedback we have gotten our packs truly have the performance we claimed they had plus now were showing the graphs to back up our claim of 28C. As far as I know SMC is the only company offering 28C packs for RC racing. I really would like to see other companies graphs and maybe we will purchase packs from every company on the ROAR approved Lipo list and have them graphed to see what they look like.
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Old 03-28-2008, 05:59 AM   #450
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If you think about it, why would our manufacturer choose an obscure number such as 28 to reflect the C rating if it wasn't 28C? Why not just use 30C? Well...because it isn't a 30C, it is actually a 28C. I'm sure many other companies are abusing this much worse than anything we could ever be accused of. The cell is 88% at 30C. I don't think it such a stretch to assume that it would be 90% at 28C.
The fact remains- when we came out with our packs we were blasted for not supplying data and told our claims of high performance were bogus. Now, since the packs have been released and we have empirical and real world proof, I somehow don't feel vindicated. Perhaps instead of debating whether the packs are as claimed on a machine, we should be comparing them to other packs on the track where it counts. I think our packs will hold their own on both accounts.
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