I've flown glow for a long, long time and thought I'd try electric. After reading many of the posts, I'm wondering if I've bit off more than I can chew. Anyway, to the question at hand.

I purchased a Sigma EQ Mini balanced charger and two Zippy 4s, 2700 mAh, 35 C batteries to power a Nitroplanes P 47. Having read that a cell should never exceed 4.2v, I watched the charger carefully and noticed right away that cell 1 was at a higher voltage than the other three ( 3.9xx vs. 3.8xx ) As the charge continued, cell 1 went to 4.260 before the charger reached full and shut off. The other three showed 4.191, 4.193 and 4.195. The pack total voltage was 16.84v. I was charging at 1.4A. The pack was always cool during the charge. Does this seem to be a normal situation or do I have either a defective charger or defective battery. Thanks for any help I can get. If anyone can direct me to a primer on RC electrics, I would appreciate it.

Frank T.

Your charger certainly should be able to get better balance than that. Even if the battery's not the best, the charger should at least get the cells balanced to 4.20v each. If the battery's old, it may take a bit longer for the charger to get there, but the end result should be 4.2v per cell.

I was very tentative when I first converted from glow to electric, but after a short while things became clearer. The most important lesson is that power output depends entirely on how many volts the supply is, and how big the prop is. Bigger prop will make the motor draw more amps, and if the prop's too big it will demand more amps than the motor, ESC, and/or battery can cope with, resulting in smoke somewhere.

There's "stickies" at the top of several of these forums. One thread that might help you get your head around some of the electrickery is this one http://www.rcgroups.com/forums/showthread.php?t=739069

If you're into scale, as your avatar suggests, electric sure makes it easier to get the motor in without spoiling scale detail.

I'd be concerned about the cell over 4.2V. Check the voltages with a different meter and see if the results match. If they do, I'd return the charger. The CV (constant voltage) circuitry should not let any cell go over 4.2V especially since yours are so close together.

Let us know what a "check" voltage reading shows.

Thanks for your reply, Abenn, and also for pointing me to the thread. I read it several time and will probably read it several more times.

The second battery, a twin to the first, charged in a more normal way. All the cells were very close and when they all reached 4.19x and the total was 16.78, the charger registered full. I have a cell checker being shipped to me and that may help me understand what's going on in the packs.

You're right about my loving scale and that is one of the reasons I thought I'd try electric. I've always hated the cylinder head sticking out. Also, I'm tired of cleaning up the oil mess and I've noticed how fast the electric guys move from unloading the car to flying and reloading afterwards. All in all, it should be a fun experience. Thanks, again, for your help.

Frank T.

Hoppy, I'll have to wait until my cell checker gets here. I saw one being used at Joe Nall and thought it was providing useful information so I ordered one. The only other meter I have is an analog multi tester and I don't know how to test a single cell with it.

Frank T.

If you're very careful you can check each individual cell with your multi-tester, though I don't know what accuracy you're going to get with an analogue one. You simply touch the probes carefully (to make sure you don't short anything) onto adjacent pairs of pins in the balance plug; each pair represents one cell.