a123 or lipo.... and other ?s

[starscream]

I'm not sure what you mean by a "flat" pack. Are you referring to the A123 3S packs?

I am testing a prototype 3S flat pack from modelelectronicscorp.com (same size as the 4S pack)
I am running 7S on my maxcim system and am happy with the the initial results. I charged them in series using my Lipodapter and Astroflight 110D. The funny thing is that the 110D cuts off the charge before the LipoDapter.
I am going to really put them to the test this weekend when I head down to the track so I'll have a better idea on actual track results then.

I really don't know why anyone would want to solder these cells together.
The Solderless Power Tubes are, IMHO, the best way to go. The M1 cells stay in balance very well so using a balancer on every charge is really over kill and not necessary IMO.

[BrianG]

I meant A123 should make flat packs like lipos are so they'll fit better and make more efficient use of the room they do take. Probably wouldn't have a metal shell, but that would save weight.

[starscream]

I don't think it wise not to have these in a metal casing. It seems like an expensive and messy risk and I'd assume much easier to puncture than LiPoly.

The A123 "round" casing is quite light, I think its something like .5oz at most
I've held an empty cell and its almost un-noticeable.

[MetalMan]

Originally Posted by starscream

I really don't know why anyone would want to solder these cells together.
The Solderless Power Tubes are, IMHO, the best way to go. The M1 cells stay in balance very well so using a balancer on every charge is really over kill and not necessary IMO.

I chose to solder because of the extreme (IMO) cost of the SPTs. I just made up a shopping cart of everything I would need to do one 4s2p setup (2 x 2s2p), and it would cost $40 without shipping. The current setup on my Revo is 5s2p (3s2p + 2s2p), and to make a pack like that using SPTs would cost $52. Obviously the Silver Power Paste is a one-time buy sort of deal, but for me to make another 5s2p pack it would still cost $36.

The only cost for my soldering method is the copper braid, which cost something like $7 and will make almost two packs (the cost of the solder is almost negligible). And with as many car projects as I have on the budget I'm on (12hrs/week at $6.75, half of that goes to savings, and then $20/week allowance), the method I'm using is so much easier to afford.

A123 cells aren't perfect, and won't perfectly maintain balance. When using the Dewalt packs, sometimes (even with brand new packs) there might be a low cell or two. One cell in one of my Dewalt packs was at something like 1volt while the rest were at ~3.30v. Even if you don't use the Dewalt packs, balancing is a very good thing to at least be able to do.

[starscream]

Originally Posted by MetalMan

I chose to solder because of the extreme (IMO) cost of the SPTs. I just made up a shopping cart of everything I would need to do one 4s2p setup (2 x 2s2p), and it would cost $40 without shipping. The current setup on my Revo is 5s2p (3s2p + 2s2p), and to make a pack like that using SPTs would cost $52. Obviously the Silver Power Paste is a one-time buy sort of deal, but for me to make another 5s2p pack it would still cost $36.

The only cost for my soldering method is the copper braid, which cost something like $7 and will make almost two packs (the cost of the solder is almost negligible). And with as many car projects as I have on the budget I'm on (12hrs/week at $6.75, half of that goes to savings, and then $20/week allowance), the method I'm using is so much easier to afford.

A123 cells aren't perfect, and won't perfectly maintain balance. When using the Dewalt packs, sometimes (even with brand new packs) there might be a low cell or two. One cell in one of my Dewalt packs was at something like 1volt while the rest were at ~3.30v. Even if you don't use the Dewalt packs, balancing is a very good thing to at least be able to do.

I tested out my 7S setup (with a SPT phantom cell) at the track yesterday and am very pleased with the performance. The extra cell made all the difference in the voltage drop I saw with the 6S setup and I plan to use the 7S config for racing.

Budget restrictions are always a factor. The SPT kit is a one time purchase and gives you the ability to make x-1 cell configs (x being the max cells for the kit). These packs are easy to take apart and put together, so if/when you chose, you can replace or balance cells. In terms of balancing, I don't see these cells much different than NiMh packs. After 20+ cycles, I believe Pete's 6 cell pack was within a few one hundredths of a volt of each other.

I got my Eagle Tree system the other day so I am eager to do some testing, if it ever stops raining that is. I didn't realize they are based right over in Bellevue :027: I could have saved a few bucks on shipping. :007: