Which is better? I need Lipo technology.

[aqwut]

Metalman.. I'm 99.9% sure there is lithium in there.. it's wrapped in some kind of polymer plastics...

The astroflight 109D charges the cell to a maximum of 4.2V, I've checked everytime.... I know it doesn't have a balancer... that's the cr*ppy part.. but it works well for me... it seems the less I care about the batteries, the longer they last.. :)

[MetalMan]

There is lithium, but it isn't pure lithium. It is in a compound with other elements. If exposed to water, it will not go up in huge flames. In fact, one of the ways to dispose of LiPos is to cut the outer packaging and submerge the cell in salt water.

The Astroflight 109 only sends pulses of 4.35v. It doesn't charge up to that voltage. And because of these pulses, you can charge a battery with the 109 and use a balancer. When it comes to LiPo, it is a good idea to maintain the cells. Things like storing packs at 3.7v per cell and keeping the cells in balance will make your packs last much longer.

[captain harlock]

So guys, what should I do? I want to use lipo in my touring car with the Kontronik Twist-55 and the Schulze U-force 75. The Scorpion car lipo seems good, but a little priceier. As for the balancepro, they cost a bit less than the scorpion, but the Scorpion is specifically made for usage with brushed and brushless controller( probably thats the reason why its more expensive than the BP) unlike the BP, which like other lipos, works only with controllers that operates lipos. I can always find a way to get them, but I want you people( Metal Man and the rest of the gang) to help me get the best lipo setup with a reasonable price. My eyes are set upon the FMA BalancePro 6400 pack with the BalancePro charger from Towerhobbies. What do you think of it?

[Batfish]

If you're prepared to spend the $, there is no safer, complete, all-in-one system than the FMA/Kokam systems (Scorpion or BalancePro) at this time. The difference between the two is that the Scorpion has a built-in low-voltage cutoff (LVC) and the BalancePro doesn't. You can purchase FMA's LVC for less than $20 and install it in your vehicle to accomodate whatever 2s lipo pack you put in it.
I chose to go with the BalancePro since most of my ESCs have cutoff protection and I can purchase the LVC for those that don't, which saves me money in the end over purchasing the Scorpion system.

No other systems come with such a high safe charge rate and cell balancing right out of the box. Others either have taps or require you to install taps to charge individual cells for balancing purposes. I'll take a pre-configured pack any day :)

[captain harlock]

Great. I think the U-Force75 has a 3V cutoff protection, right?

[aqwut]

Maybe ur right...

I have one dead Li Po cell.. I'm goin' to take it apart.. jsut to see.. :)

[MetalMan]

The U-Force can be programmed for Lipo, but I think you need to do it via a computer (which means a PC cable).

aqwut - There won't be any problems, I guarantee it ;). I stabbed a couple of dead (puffed) Lipo cells a couple of months ago with the back end of a hammer, and if there was elemental lithium, it would have ignited with the oxygen in the air. But it didn't :(.

ive only had experience with polyquest cells and i dont have a reason to use anything different. i understand that the fma packs have everything built in but the price seems a bit outrageous, IMHO. you can get 2 2s3100 packs for around $120 at cheapbatterypacks.com or purehobby.com. they both will ship by air. tear the shrink wrap off and shrink the two packs together, wire them in parallel and you have a 6200mah pack that is smaller than a 6 cell nimh. the polyquest packs are easy to balance yourself. starting from the red wire on the plug and going left to right, wire 1 and 2 are cell one, wire 2 and 3 are cell two, and so on. wire two small male pins on the end of a deans plug and when you find a cell a little off balance, charge it a little on its own. i have had little problems with cells out of balance, out of 6 different packs i have only had to balance a few cells. i use the ice charger and it works great. the 6200mah pack im talking about is used in a tc4 with a lehner 5300, it is a very nice setup cause it fits in the battery tray. it has the mgm 80 controller which has the lvc, i dont know if the uforce has it but i have one of the fma inline lvc devices and it works great. its nice because you have the option to set the lvc at any voltage you want. im my opinion, a lipo pack under a heavy load will need a 2.8v cutoff instead of the 3v. some think that is too low but its only for those big amp spikes that bring your voltage down.
so, if i were to spend 250 dollars, i would rather have 2 6200 mah packs than one. just my 2 cents. hope this helps.

[Batfish]

fearandloathing,
I do completely understand and agree that there are other, less-expensive options compared to the FMA system(s). This is why I prefaced most of my comments with stating that the $ amount needs to be considered. Personally, it's worth the expense to me to let the system handle it. Since my two daughters were born, my time has become more important to me than my money and I'd rather spend time with my family than to individually charge cells :)

My battery maintenance is almost completely confined to race night now, which is much better than spending hours during the week discharging and cycling packs in preparation. Since the FMA BalancePro system is fast enough to put the energy used from a race back into the pack before the next race AND keep them balanced while doing it, it's a no-brainer for me...and I need all the "no-brainers" I can get ;)

[mothman]

I just bought 5S LiPo from Cheapbatterypack.com. They are having sales rite now. I hope Polyquest 20C cells are as good as TP and kokam..

batfish, your right about the fast charge option with the fma packs and you dont have to worry about checking for yourself, if they are balanced. that is a factor i did not weigh in when comparing products. if i were a competitive racer, i would surely end up going with the fma packs, mainly because you can charge them so quickly. im just a daily basher and i have nothing but time on my hands, it can get really boring in afghanistan when there are no broken helicopters.:C:

[aqwut]

elemental lithium won't ignite in the air.. it'll ignite in water.. when expose to air.. it will just turn to ashes... depending on the humidity... if you leave them as flakes like they are in the cells they won't ignite.. but if you bunch it all up in a ball.. it's pretty dangerous stuff.. use gloves.. :)

[aqwut]

the FMA/Kokam scorpion can be charged at 3C

[aqwut]

hey fear, you can ket the kokam 2 cell from tower hobbies for $80 from tower hobbies.. and they have a 64A continuous discharge rate...20C

those packs from Cheapbatterypacks.. are only 15C max continuous.... but they're advertised as 20C.. the FMA's are true 20C continuous discharge rate.... and only $5 more.. :)

[MetalMan]

From what I have read that was posted by people that have great experience with testing Lipos is that the Kokam 3200mah cells should only be considered ~16C cells.

I just looked at a 15C graph for the Polyquest 1200mah 20C. At 15C, it delivers almost 100% capacity! At 15C, the Kokam 3200mah cell can only deliver 93% capacity. Also, at 15C, the Polyquest 1200mah puts out about 0.1v higher average than the Kokam 3200mah.