Alfalfameister

Caring for "stick" battery packs (Newbie questions)

First off, I am NOT a racer/competitor, but I do like reading all the new-fandangled gadgetry that racers use (top end battery chargers, dischargers, equalizers, etc). This topic is about stick battery packs for r/c cars and trucks.

Equalizers are used in side-by-side packs, which is supposed to be for equalizing (duh!) voltage in each cells. Supposedly, this brings them all to an even/equal state of discharge, so the starting point of the charge would be about the same for each cell.

Obviously, stick packs (not side-by-side) can't be equalized. So what's the next best thing for them?

I have heard differing opinions about "dumping" the cells: some say don't do it for fear of cell reversal, and yet there is now the practice of dead-shorting the cells.

A. Exactly what is "dumping"?
B. Isn't dead-shorting the same thing?
C. And what is the best-practice?

Racers tend to charge at 5, 6, or even 7 amps for "more punch". If I'm not looking for more punch, but rather more runtime and more battery life, would 3 amps be good? Or is there some other advantage of charging at higher amperage (say 5)?

And how about slow-charging (C/10)? How often should this be done? Some say, after about every 5 cycles, it would be good to equalize the cells (obviously not for stick packs) and slow charge them. Why would this be done?

Sorry for the numerous (noob) questions, but I was reading Red's www.rcbatteryclinic.com and I don't remember if these particular/specific topics were addressed. And THANKS for any info!

--Alf

guver

My Feedback: (325)

It seems that I agree w/ everything you have heard about batts. The only thing I think is different is that dumping is usually a reference to "when the battery runs out" If you were to look at a discharge graph it would be nearly flat until the last bit of mah and then all the sudden (if all cells are matched) it would take a dive in voltage and show up as a "knee" . On to you questions:

It is not adviseable to dead short stick packs unless cells are exactly equally/evenly discharged. This is possible, but not worth it. I am not even sure that dead shorting any nimh cell is good. The best practice for run-time is to do exactly what you've stated and charge at 3 amps. The c/10 charge for 15 hours should be done for the first few cycles if it isn't too late already. This will form and equalise the cells. This should also be done with a pack that has been setting for many months also.

The stick pack will also be equalsied with a c/10 charge. Red's is a good site and good info. There are 2 other ways that I use to equalise stick packs. One way is to use them until it dumps then let it set for a month. The other way is to use the trickle function on the peak charger for an hour. Lots of chargers do this automatically to equalise the cells.

Alfalfameister

So, tell me if this method is okay for stick packs:

1. After running the R/C, I won't "dump" the batts -- i.e., as soon as vehicle slows down, remove the pack and let cool;
2. Put in discharger (my friend has a MuchMore CTX Charger), and discharge to 5.4v (.9v per cell) at ??? amperage (is lower better, such as C/5, or should it be at high amperage? The CTX Charger I think can discharge up to 10/C.
3. Let cool.
4A. If to be used again, charge normally (I plan on using 3/C or 4/C);
4B. If to be stored, charge about 50%

Then once every 10 cycles or so, discharge to 5.4v (again, at what amperage?), and charge at C/10 for 14-16 hours.

Does that sound good?

Thanks!!!

--Alf

guver

My Feedback: (325)

1 good
2 unnessecary
3 good
4 yes
4b yes if storing over a week - month (I am not sure exactly)

Alfalfameister

Thanks for the info, U-dUd! Very helpful of you!

Cheers!

--Alf