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Old 02-20-2008, 08:51 AM   #181
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Ah, a fresh new morning. Are we ready to start fighting about batteries again?! :-D

Danny, in your disclaimer you told people not to heat the packs. That's actually something that other companies have said is "okay," and most people consider safe, so long as you don't go over the top with temperature. I think for the most part, it's considered a reasonable thing to do with your LiPos. Now, your findings of more temp = more voltage are interesting. I'm curious if the things you find will be true across the board for all brands of battery. With differences in chemistry and such, some packs may respond better (or worse) to different changes. It will be interesting to see if that's the case down the road.

So I picked up a MuchMore Battery Warming Tray a while back, and I really don't recommend it. It warms from the bottom only, and really doesn't do a very good job of getting enough heat into the pack. I'm thinking my next step might be to try a reptile heating pad ('cause they're small) and roll the battery up inside of it.

Something like this looks really nice, but they're impossible to find. I like the idea, though. You guys should OEM them... I'll be your first customer if they work well. As LiPo (and warming) become more mainstream, I imagine it's only a matter of time before we see better solutions.
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Old 02-20-2008, 09:47 AM   #182
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You could probably do something with a temperature controlled heating pad. Just wrap it around your LiPo sack or some thing. At $35 it might be worth looking at.

http://www.med-electronics.com/Produ...torysingle=YES
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Old 02-20-2008, 10:15 AM   #183
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One of the problems I see is how do we get the cells warm/hot inside if they are in a hardcase and how do we make sure that all the cells get heated ?
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Old 02-20-2008, 11:00 AM   #184
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I just practice with , the heat built up from the run is perfect,. no heater really needed ...
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Old 02-20-2008, 11:12 AM   #185
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I'm sure this may work for you but what I have been testing proves that we can extract more performance if we get the pack warmer and keep it warmer.

Once again all my info is for those who are looking to extract the maximum performance from there Lipos.
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Old 02-20-2008, 11:30 AM   #186
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Run a piece of metal between the cells and out the hardcase and then use something to heat the metal?

EDIT: The metal would just be there to add weight of course. No one would ever actually apply their soldering iron to it for a few seconds to get the temps up

Last edited by or8ital; 02-20-2008 at 11:41 AM.
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Old 02-20-2008, 11:51 AM   #187
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Heat transfer from the plastic of the case to the cells is probably not great, huh? Maybe we need quick release cases so we can heat the raw cells.
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Old 02-20-2008, 12:56 PM   #188
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I think that a heat pad wrapped around the cell would be fine as long as we knew how long it takes to heat up the entire pack (all the way to the center). It's not all that hard to test as long as you're willing to pull a pack apart to measure it.

ROAR doesn't allow the cases to be opened by the racer per the latest rules.
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Old 02-20-2008, 01:00 PM   #189
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Having them in a plastic case (in this specific case) would be a benefit for keeping the cells warm longer as it will act like insulation.
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Old 02-20-2008, 02:43 PM   #190
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Quote:
Originally Posted by Wild Cherry View Post
I just practice with , the heat built up from the run is perfect,. no heater really needed ...
Not necessarily, I temp'd a hardcase Lipo at 54 deg right after a practice run with a 4wd mod at a indoor off-road track, without using any heating elements. They started off 60-70 degrees when I first brough them to the track.

Other part of the country are colder during the winter months that running it doesn't do very much to warm them up, until the spring and summer months rolls around.
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Old 02-20-2008, 06:07 PM   #191
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Quote:
Originally Posted by 4wd Racer View Post
Not necessarily, I temp'd a hardcase Lipo at 54 deg right after a practice run with a 4wd mod at a indoor off-road track, without using any heating elements. They started off 60-70 degrees when I first brough them to the track.

Other part of the country are colder during the winter months that running it doesn't do very much to warm them up, until the spring and summer months rolls around.

My pack`s come in around 110 degree`s after a practice run, discharged to 7.0v...
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Old 02-20-2008, 06:25 PM   #192
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Completely understandable and I totally agree, and I did expect your pack to be in that higher temp range of around 100+ deg since your in the part of the U.S. where the weather is warmer, and there isnít a need for a Lipo warmer at all.

I did explain earlier in another post that running Lipo's in practice, or doing partial discharges on them helps to re-activate the chemistry in them for the track, however I was explaining in response to your post that seemed to indicate that there wasnít a need for a Lipo warmer, and running them in practice was all it took to warm up to those 100 deg temps.

That isnít necessarily the case at all, because right now as the freezing winter weather is in other parts of the U.S, it is cold enough to the point where Lipo's being run indoors off-road aren't being warmed up very at all either during practice and races, (i.e. the 54 deg temp I pointed out). It is about 10 deg outside here right now, hence, making a warmer based system for Lipo absolutely necessary, since there's no way to achieve 90-110 deg temps under those colder winter weather circumstances at the indoor tracks.

That is, until spring and the summer sun comes along, which is hopefully soon! Ha ha.
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Old 02-22-2008, 05:18 AM   #193
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Quote:
Originally Posted by or8ital View Post
Danny, could you post some avg laptimes based on your charging methods and vs other packs on back to back runs? Unfortunately my charging #'s dont win me prizes Id like to see how your packs can help me on the track.
365' glass smooth paved oval

4-minute 17.5 2-cell Lipo class. No changes were made to the car other than swapping out packs as a test to compare the 3200 to the 5000.

Orion 3200
Car #4
39 4:00
5.831 fast lap
6.210 ending lap
164 degrees F.

SMC 28c 5000
Car #4
41 4:05
5.723 fast lap
6.191 ending lap
204 degrees F.

Lap Times Saturday. 2008 Feb 16th
Open the 16th
Scroll and click on R1 Race 6
Scroll and click on R2 Race 6

This will show you full lap times. The SMC pack provided a full 1/10 faster per lap thoughout the run. Now to drop 3-4 teeth and see what the difference really is.
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Old 02-22-2008, 05:31 AM   #194
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The times above were run last weekend on the track that will be holding the ROAR 2008 Paved Oval Nats.

To see the performance increase when swapping batteries opened up alot of eyes and now other racers have seen THERE IS A DIFFERENCE.


Another local racer ran the same SMC 28c 5000 in the main but broke his car while in the lead. His words and I quote:

"I was spinning tires off the corner because the pack had so much rip!"
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Last edited by Tornado_Racing; 02-22-2008 at 04:39 PM.
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Old 02-22-2008, 06:10 AM   #195
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Here are my cycle numbers for the past 5-6 months. The SMC 22c 5000 was used 15 times total in a weekend for the past 5 months or so (10 practice, 3 heats, 1 practice, and the main). That's 300+/- runs and does not include all of the testing during the week. The pack may have up to 500+ cycle/runs on it to date.

October 07' (new)
12 amp charge
8.40 GFX Lipo Peak
35 amp discharge
6.0 cut-off
sensor leads: battery side of Deans

533 runtime
7.23 voltage
11.5 IR

December 07' (3 months later)
12 amp charge
8.40 GFX Lipo Peak
35 amp discharge
6.0 cut-off
sensor leads: battery side of Deans

505 runtime
7.28 voltage
10.2 IR

February 08' (2 months later)
12 amp charge
8.40 GFX Lipo Peak
35 amp discharge
6.0 cut-off
sensor leads: battery side of Deans

495 runtime
7.30 voltage
9.5 IR

The batteries have held up just fine even with the overcharge that was done to them 4 times a weekend. Yes runtime is down but voltage is up and the IR's are lower. When you only race for 4-5 minutes runtime becomes less important (excluding Mod) and what the pack outputs (voltage) for 240-300 seconds is what really matter.

I think the packs are getting better with time.

Oh.......the pack above has a serious dent in the side from a 2nd weekend impact. Along with killer performance the durability factor is high as well. It literally "Took a Lick & and Kept on Tickin"
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Last edited by Tornado_Racing; 02-22-2008 at 04:44 PM.
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