720i balancing problem

[zeropointbug]

Well it looks like I am not the only one with the issue then. It never used to do this up until a few weeks ago, but I thought it was the older packs I had. But I have been trying to put a few light wake up cycles on some new 6s 2200mah 45c G3's. (which, btw, are tiny!)

Some of you are saying that the cells will go up and down; I have some old old A123 packs with balance taps that I tried and the cell imbalance will continue to increase... 0.03v gap....0.06v gap....0.10v gap, it's retarded. The only way I could get them within an acceptable balance was to use a resistor through the balance tap.

I bought a HP Sentry 2, so maybe i'll just use that for balancing the pack will charging, not that a G3 pack will need much balancing anyway.

[pinkpanda3310]

Yes, I've acheived better results from an external balancer. Though I do lower the charge amps particularly with the A123's so as not to overcharge any cells. The charger will 'charge on' despite any cell differences until the desired pack voltage is reached.

I've never heard of using a resistor on the balance tap. Is that a resistor for every pin on the tap?

[zeropointbug]

No, I just use a 10W resistor, plug it into the tap and use a volt meter to watch the voltage until it reaches where I want it, then I move to the next cell.

I was thinking of getting the new 1420i charger, 550w and 20amps, whats not to like... that is, if the sentry balancer cannot keep up with the charge rate

[_paralyzed_]

It's simply an out of balance cell. When charging the charger charges all of the cells all of the time, and then stops charging and bleeds off voltage from the highest cells until they are all even.

You will see that the output is switching back and forth from 0v to full pack voltage during this process.

The "bad" or "low" cell just takes a while to reach the full 4.2v, and the "good" cells with low internal resistance easily reach 4.2v. It does take quite a bit of time for this cell balance dance to take place.

This is where a charger with individual cell charging shines and the rest fall short.

[zeropointbug]

It's not a low or imbalanced cell(s) in the pack, it is the charger. Like I said, it will UNbalance a properly balanced pack. It is doing it to brand new G3 45C packs I have hear just as bad as my old 35C G3 packs.

I just got the Sentry in the mail today and WOW, this thing is awesome, tells you everything about your pack, beautiful clear screen. I tested it out on a 4s A123 pack that had a low cell in it, total cell gap was over 0.200 volts, it balanced it out in about an hour, down to within 25mv. I will try doing some charging using this thing attached to balance port, seems to have a very decent balancing current.

[zeropointbug]

Does anyone know if you can change the tolerance for cell balancing on the 720i NET? I have heard you can do it on the new NET3, but I am not sure on mine.

[_paralyzed_]

Oh wow. I guess I jumped to a conclusion. That sucks man. I've actually had good luck with the turnigy chargers from hobbyking.