Need some help to choose LiPo

[MetalMan]

Usually balancing is done through some for of "taps" that are just wires that connect to each individual cell. A pack can be balanced through taps. The voltage of each cell (or cells in parallel) can be monitored through taps. Taps come in different forms - some packs use a single connector (Polyquest, Thunder Power, and the Scorpion packs). Others use an individual JST connector for each cell (Maxamps [if chosen], Tanic). I use the JST connectors for ease of use. I am always balancing my cells, so I can attest to their advantages. The only problem with the JST connectors is that they shouldn't be used for more than 5 amps (although can handle 10, but the resistance will cause quite a voltage drop).

[coolhandcountry]

Thanks metalman. You and batfish helped out alot. I like the sound of lipo in a lot of ways but don't in others. I will wait a little longer though. Thanks alot. Knowledge is power and you just made me stronger.

[Serum]

For my T i use maxamps lipoly's with homemade taps and a polyquest balancer. (the maxamps tabs are 2 wires for 3 cells, this is not the way imo, i used 4 wires for the balancing, just a principle...) i would not use lipoly without balancer, but perhaps i'm just paranoid.. I thought Mike charged his FMA/kokam3200's
thousands of times without a balancer..


The balancer is capable of dividing the power of the charge input, meaning it can flatten a max. difference af about .1-.2 volts of the cells.

Am imdividual cell discharge monitor would be a nice feature as well.. though in my opinion the charging ballancing is adequate enough allready... Because, normally the difference will get bigger and bigger every time you charge/discharge the packs. Using a balanced charging, makes the cells allmost equall after every charge...

Balancing is good, safe and with a proper charger and some extra care, like a metal charge case, lipoly is a nice way to get your truck light and nimble..

If you want to go to 6S on the 9920, i would recommend a 8XL or 9XL though.. This was your first brushless right? 16 cells is a blast allready! (5S)

[MetalMan]

I too use Maxamps Lipos, and not only did I use my own taps, I even assembled the packs myself! I have made another pack with 10C 2000mah cells from Dymond-RC, which also has taps.
Serum, do you mean you use the Polyquest Charge Guard? If so, I hate to tell you that it isn't a balancer. It just stops the charge if any cell reaches 4.35v, which is too high. No cell should be allowed to go over 4.25v, as that is where instability begins.

[Serum]

What thing should i get to balance the cells?

i got my knowledge from this site, it seemed like a balanced way of charging.. It takes away difference in voltage, so i thought that it was a balancing function..

http://www.toddsmodels.com/Lithium/pcmguard.htm

[MetalMan]

There are several choices out there. There are 2 Thunder Power balancers, one for 2-5 cells, the other for 2-10 cells:
http://www.thunderpower-batteries.co.../chargers.html
Astroflight will be coming out with their own Lipo balancer, discussed here:
http://www.rcgroups.com/forums/showthread.php?t=396343
Another choice (that is much cheaper) is to monitor the cells during the charge. If one cell is higher than the other(s), then stop the charge, and charge each individual cell. This is what I do since I don't yet have a balancer. But, I will make one sometime using this schematic:
http://www.rcgroups.com/forums/showthread.php?t=409659
It stops the charge if it takes more than 600mah to balance the pack, but this capacity can be changed R10 to a larger value. This device acts like a Polyquest Charge Guard that will not only stop the charge if there is a large imbalance, but will also balance the cells.

EDIT:
Serum, I looked at that website, and here is where you can tell that the Polyquest PCM Guard is not a balancer:
"If and when any cell exceeds 4.35 volts, the LED will start blinking and the charge circuit will be disconnected automatically. The LED will go off which would indicate cell metering/balancing needs to be performed. PCM does not guarantee that cells will be charged evenly but will prevent cells from being overcharged causing rupture or fire."

[Serum]

Hey! i allmost forgot! i even got the samples for a balancing IC.... (i wanted to make one too, untill i saw the polyquest)

but the polyquest does do something of balancing..

that 4.25 volts is the peak, 4.15 is the cutoff i thought..

That 2-5 cell TP balancer for about 50 dollars is not really expensive.. I personally won't boughter building one when that one is available.. If you are interested in those IC's..? (smd if i remember correctly, i will dig them up and check the type if your interested)

That TP has got a 4.3V overvoltage warning, i thought 4.15 was the maxximum..?

[MetalMan]

4.20v is the standard cutoff, and 4.25v is the point where no more charging should be done.
I am not too sure on the specs of the TP balancer, as I would rather build something for cheap than buy something like that (being 16 does have its disadvantages).
I suppose I might be interested in those chips you have.