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Old 01-24-2008, 11:35 AM   #16
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Originally Posted by Rick Hohwart View Post
ROAR's next rule should be no rules. You run whatever you can fit in your car as long as the car meets the minumum weight. That will allow any technology.
Oh, Heaven help us... .

Its true, George Cherry is OFFICIALLY a ROAR member now....!!!!
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Old 01-24-2008, 08:36 PM   #17
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There is no point making the A123 26650 M1 cell legal. Hardly anybody is using them for 1/10 scale racing applications. Lipo's are nearly interchangeable over NIMh in both size and voltage output. The A123 26650 and A123 18650 are not even close to fitting. Every chassis on the market would have to be redesigned and even if they were redesigned, the traditional power sources (NIMH and LIPO) would not fit right.

The A123 cell in my hand right now measures 26.7mm in diameter and 67mm long (not 26 x 65 as the specs would make you believe). A 2S2P 4 cell pack would be too big to fit properly into any 1/10 scale application.

In addition to size, the votage doesn't match up well even with a 4 cell NIMH. At 20 amps, the A123 will average about 2.8V/cell or 5.6V as a two cell series and slighly more if they are paralleled up (2S2P). A good 5 cell NIMH will average more than 6.4V at 20 amps.

If A123 is legal, they would need their own seperate class and separate chassis. The last thing we need is more racing classes.

I think the perfect application for the A123 cell would be the 1/8 scale electric truggy and buggy chassis - assuming that class takes off as projected. It's a nice big robust cell that is well suited for the bumpy and physically abusive class.
I quess you don't race 4-cell. I know that batteries are you thing, but you really missed the point. Great replacement for 5-cell NiMH!, Acceptable replacement for 4-Cell! Are you measuring the can or the paper? I'll measure your mine too. The size of 4-cell stick 26650 battery pack is roughly the same size as the 6-cell NiMH packs so not even close is your point of view. Yes they are slightly wider by about 6mm and slightly taller. If ROAR is looking to reduce speeds in the future without creating motors that are better suited for rock crawling then LiFePO4 should be lookeded at by the EXCOM. The bashers and racers are using them! These batteries are here and are showing a cheap alternative to NiMH.
LiFePO4 soft cells are in the marktplace, only time before a 4-cell sized brick shows up on MAXAMPS.
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Old 01-24-2008, 08:51 PM   #18
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Check your calipers, my cells measure:

25.78mm x 64.76mm

I guess A123 wanted to make sure the few onikers made it to your desk. I'll run the cells through a series of test to see what the average discharge possible will be for 5 and 8min. Just cause, I'll start with 20amps for 8min and 30 amps for 5 min.

Then i'll repeat the test for a 2S2P pack starting at 20amps and work higher

Remember that is per cell, 1:10 would use these cells in a 2S2p pack.
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Old 01-24-2008, 10:17 PM   #19
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I need to add this.

6-Cell NiMH volume of material ~ 90ml
New ROAR Approved LiPO bricks
volume of material ~ 160ml
2S2P A123Cell volume of matieral ~ 100ml

As you can see A 2S2P A123 pack is only 10% larger in volume leading to a slight change needed for pack fitment. The LiPO gains on volume due no voids in the pack and the brick shape.

LiPO have the advantange in being a lighter weight cell with better power density, ROAR is letting more of the power packing battery in the cars. This means flatter discharge for shorter races and greater punch at anytime. Any improvements in power density will be muliplied by the greater volume of material. In this case a LiPO brick capacity would grow by a 177% versus the same improvements power density change in Sub-C size batteries.

What will the racers do when LiPO's are 2x, 3x or 4x better in capacity than they are today? Will the batteries be smaller? Races longer? Our Sub-C's are easily four times better than the ones first used for racing, Expect the same or better for any Lithium Product.

There are no ways to compare these three power sources on the same table. Only numbers can be cruched and recorded. ROAR as already mentioned that new racers need a slower pace. Giving new racers a megawatt of power is not a slowing the pace down, it is speeding the pace up. Going with a fixed and lower volume of battery can go a long way to prevent the esclation of powers. The change to a lower voltage can also soften the effect of technology and keep the paces slower in the future.
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Old 02-05-2008, 01:55 AM   #20
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This thread is an excellent venue to show the merits of A123 cells in our hobby....

IMHO, safety is a must!!! After seeing a lot of videos of lipo batteries exploding from being overcharged, I said to myself, WHOA!! This is VERY DANGEROUS!! I won't buy that!!! There has to be an alternative battery for my needs....Here comes the A123 batteries. Well, I don't have to elaborate further on this since almost everyone knows how they perform anyway.

I was one of the first few racers to adopt them in my kits. A XX-4 and an MF2. Granted that you have to be creative in making them fit properly but once you get around doing that, you'll reap the benefits of having the best battery on the planet!!!

Why do I say it is so? The batteries have at least 1,000 cycles! They are as tough as nails. They can be used and abused and they come back for more!
If that is not durable, I don't know what is?
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Old 02-05-2008, 01:57 AM   #21
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This thread is an excellent venue to show the merits of A123 cells in our hobby....

IMHO, safety is a must!!! After seeing a lot of videos of lipo batteries exploding from being overcharged, I said to myself, WHOA!! This is VERY DANGEROUS!! I won't buy that!!! There has to be an alternative battery for my needs....Here comes the A123 batteries. Well, I don't have to elaborate further on this since almost everyone knows how they perform anyway.

I was one of the first few racers to adopt them in my kits. A XX-4 and an MF2. Granted that you have to be creative in making them fit properly but once you get around doing that, you'll reap the benefits of having the best battery on the planet!!!

Why do I say it is so? The batteries have at least 1,000 cycles! They are as tough as nails. They can be used and abused and they come back for more!
If that is not durable, I don't know what is?
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