Rapid Roy

I don't do much electric except for my micro so please be nice while I ask some basic questions.

I have a pack of 6 cell GP1100's. I originally had a Tekin BC67 charger to charge them. I know its not NIMH compatable, I just kept my eye on the temp while it charged. Now I have a BC112c with the H31 software. With the new charger, I thought it would charge to a higher voltage and capacity, but it hasn't.

The peak voltage is 8.6 or so and I can't seem to get anywhere close to 1100mah worth of charge into the pack. I am using the P0 profile which is reccomended for the Nimh batteries and charging at anywhere from .7 amps to 1.75 amps.

I have tried discharging the pack using a 2 amp bulb. I have also tried to equalize the cells by discharging each cell and measuring the voltage. Should I consider dead shorting the pack? Will this improve the numbers I get while charging? Can I do the same things I read about that are done for the sub C packs?

When I discharge and measure voltage, do I measure the voltage while the bulb is connected or without any load? Without load, the voltage just keeps creaping up.

Am I trying to do the impossible? Are my current peak voltage and charge capacity numbers okay? I get plenty of run time, I thought that a higher voltage would give me better punch.

Pat Clark

This what I would do... Discharge pack to 5.4 volt if it is 6 cell or 4.5 if it is 5 cell... Your 2 amp bulb should be fine for this.... Next discharge each cell to .9 with a smaller load... I guess you are using a automotive 1157..?? I would use a tray but I know you can't because of the smaller pack... I would just use the "low beam" of the bulb... Your trying to use somewere around .5 amps... Once each cell is "equalized" then charge at 1.1 amps... Hope this helps, I think I confused myself..

P.S. And yes take the voltage reading with the bulb connected in both steps..

Rapid Roy

Thanks!

That clears up most of my questions.

Anybody know how much the peak voltage and Mah capacity I should be looking for?

Also, these batteries are supposed to have a 20A to 30A discharge rate. Should I use my 10 bulb discharger to discharge, or use a single bulb for 2 amps?

micros_rock

That 20A or 30A rating is only good for a split second, not continous current. I wouldn't discharge over 10A

Rapid Roy

Thanks!!

I'll just continue to use the 2 amp bulb then. Anybody out there know what the peak voltage and MAH capacity I should be getting? Again, I use a Tekin BC112c on PO at bewteen .75 to 1.5 amps

newracer

Those cells are rated for 10-20 amps continuous, 30 amps spike, You could discharge with your 10 bulb if you want. They should peak in the mid 9v or low 10v for a 6 cell pack. If they are fully discharged you should put close to 1100 mah into them, that's why they are GP1100's.

Itchy

iTrader: (1)

You wont charge 1100mha in them until u REALLY discharge them. That cant be done with automotive bulb because that discharges the whole pack. Some cells will be gone, others will have some juice in them.

I dont know any equalizer tray that works on those cells but you can build one easily with 6 diodes, six resistors and something to conect to the cells. If u want info on that say something...
i have the link somewhere on my bookmarks.
I can take a picture of my "equalizer" although its a messy job

Rapid Roy

Good observation on the capicity thing.
I figured I was not getting enough charge into the batteries even after I discharged and equalized. One of my problem is I don't run the car often enough. May be once every 2 to 3 months. I usually just put the car away after the 5 minute main figuring that the partial charge left in the pack is okay for long term storage. I try waking up the pack a few days before I'm going to race. This time, with some new info, maybe I'll get better results.