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Old 07-13-2006, 11:38 PM   #1
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A quick battery question I hope - I have some 4 cell packs that I haven't used for...

6 months and I've decided to make some 6 cell packs out of them and try off-road.

When I put the first pack on a trickle charge after a minute or so it went to 12v and pushing the charge button (rate set at 5 amps) it jumped to over 16v in less than a minute.

So after unpluging it because "that can't be right surely"...I discharged the whole pack until it read 5.4v and let it rest for a few seconds and plugged it onto the charger. This time the voltage while trickling was around 11.5v but when I pushed fast charge (again at 5 amps) it went to just over 12v but was going up very very slowly from there.

I unplugged the charger as I wanted to check here first before giving a full length charge.

But as it stands now, after discharging the pack to 5.4v volts again, and letting it rest, I'm getting approx a 1.75 volts reading out of each cell.

Which should be a reading of around 10.5 for the whole pack but it's reading over 11?

As these are my first 6 cell packs in ages, I used to run 1500 mah in 540 stock in NZ before switching to 4 cell 12th (19 turn), I'm wondering are these numbers normal when bringing nimh cells back to life so to speak?

Or does it indicate they are toast?

Almost forgot...they were stored as 4 cell packs with 3.6 volts left in each pack.

Last edited by Mabuchi540; 07-14-2006 at 03:11 AM.
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Old 07-14-2006, 12:40 AM   #2
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High voltage means the IR is ridiculously high.
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Old 07-14-2006, 01:00 AM   #3
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Quote:
Originally Posted by Mabuchi540
I decided to make some 6 cell packs out of them and try off-road.

When I put the first pack on a trickle charge after a minute or so it went to 12v and pushing the charge button (rate set at 5 amps) it jumped to over 16v in less than a minute.

So after unpluging it because "that can't be right surely"...I discharged the whole pack until it read 5.4v and let it rest for a few seconds and plugged it onto the charger. This time the voltage while trickling was around 11.5v but when I pushed fast charge (again at 5 amps) it went to just over 12v but was going up very very slowly from there.

I unplugged the charger as I wanted to check here first before giving a full length charge.

But as it stands now, after discharging the pack to 5.4v volts again, and letting it rest, I'm getting approx a 1.75 volts reading out of each cell.

Which should be a reading of around 10.5 for the whole pack but it's reading over 11?

As these are my first 6 cell packs in ages, I used to run 1500 mah in 540 stock in NZ before switching to 4 cell 12th (19 turn), I'm wondering are these numbers normal when bringing nimh cells back to life so to speak?

Or does it indicate they are toast?

Almost forgot...they were stored as 4 cell packs with 3.6 volts left in each pack.

Maybe a few more cycles can bring down the resistence somewhat...But never back to the good old day....

Can be used for practice though...
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Old 07-14-2006, 01:02 AM   #4
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good packs should peak at 9.5 volts or less. the higher they are the higher IR. you need to cycle them at a high amperage a few times at 20+amps. hopefully the IR will drop after a few cycles.
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Old 07-14-2006, 01:09 AM   #5
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Default Thanks guys.....

I assume that this is because they were unmatched random cells to start with and that the numbers should be much better when I turn my 6 x 4 cell matched packs into 4 x 6 cell packs (as the numbers on their labels are very close across all three packs)?

Last edited by Mabuchi540; 07-14-2006 at 01:20 AM.
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Old 07-14-2006, 01:18 AM   #6
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Default Just to clarify.....

the cells came from an Epic unmatched zapped brick from TowerHobbies last year.

While I think about it, should I run the 4 cell packs through a cycle or two before pulling them apart?

Update on the first converted pack after first full charge:

Time to reach full charge at 5 amps: 42 min 53 sec
Discharge rate: 17.5 amps (only one I have available)
Time to discharge down to 5.4 volts: 15 min 6 sec

Are the number good/bad/indifferent for an unmatched pack made from random cells?

Last edited by Mabuchi540; 07-14-2006 at 06:41 AM.
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Old 07-14-2006, 02:25 PM   #7
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These seem like magic batteries. You are putting 3583 mah charge into them and getting almost 4400 mah out of them.
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Old 07-14-2006, 02:41 PM   #8
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Default Honestly I wouldn't know.....

Quote:
Originally Posted by Iceracer
These seem like magic batteries. You are putting 3583 mah charge into them and getting almost 4400 mah out of them.
The charger is a Duratrax Intellipeak Digital pulse charger and the voltage on both the charger and discharger are measured by seperate volt meters I had to wire into them.

The amp setting is just made by the turn of a knob with no way to tell for sure, but the mark on the case indicates it's set at 5 amps.

During the charge the volt meter said the pack peaked at 14.4 volts. But as someone said, that means the ir is way to much, so I ignored that and just went by time.

The voltage reading on the pack as soon as I plugged it into the discharger started at 8.6 volts and took the time mentioned to go from there to 5.4 volts at a 17.5 amps discharge rate.

Magic numbers...I wish I'm sure there's a mistake in my process somewhere that makes them magic?

The fact they're zapped batteries wouldn't have anything to do with the funny numbers would it?

Last edited by Mabuchi540; 07-14-2006 at 04:07 PM.
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Old 07-14-2006, 10:36 PM   #9
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Lightbulb Doh.....

Well it turned out that one of the volt meters had a stuffed battery . So after replacing it I got the following:


Charge time: 41 min 45 sec
Fully charged voltage: 9.1 volts
Time to discharge from 9.1 to 5.4 volts: 14 min 45 sec
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Old 07-22-2006, 06:54 PM   #10
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Default Yet another update.....

Quote:
Originally Posted by Mabuchi540
Well it turned out that one of the volt meters had a stuffed battery . So after replacing it I got the following:


Charge time: 41 min 45 sec
Fully charged voltage: 9.1 volts
Time to discharge from 9.1 to 5.4 volts: 14 min 45 sec
I've just finished testing out another of the converted packs but this time instead of unmatched GP 3700's it's a pack made up from matched Intellect 3600's (all the cells from both donor packs were very close in their numbers).

Anyway this one only took 35 min to charge (approx because I got called away from the room) and was quite hot to the touch.

So after a quick repeak to get a peak voltage reading (9.35v) I put the battery on the discharger (17.5 amps).

But this time it only took 12min 5 sec to reach 5.4 volts.

Is this normal for Intellect cells?
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Old 07-22-2006, 07:11 PM   #11
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that seems like good voltage. how much amperage did it peak at?
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Old 07-22-2006, 07:21 PM   #12
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Default Not sure what you mean.....

Quote:
Originally Posted by recklessryan
that seems like good voltage. how much amperage did it peak at?
My charger doesn't have a built in amp meter (it's a Duratrax but their last best model that doesn't have the read out )

If you mean what did I charge at, that was 5 amps.
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Old 07-22-2006, 08:35 PM   #13
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Did you set your charger up to charge 6 cells? Just asking since you said you used to run 4 cell. If the charger is still setup to charge 4 cells and you hook up a 6 cell pack, the voltage reading will be extremely high.
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Old 07-22-2006, 10:25 PM   #14
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Default The charger I use.....

Quote:
Originally Posted by EricO3
Did you set your charger up to charge 6 cells? Just asking since you said you used to run 4 cell. If the charger is still setup to charge 4 cells and you hook up a 6 cell pack, the voltage reading will be extremely high.
only has a variable amp setting dial, it doesn't have a 4/6 cells setting.

This is the charger here....

http://www2.towerhobbies.com/cgi-bin...?&I=LXHJB4&P=7
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Old 07-22-2006, 10:50 PM   #15
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Hmmm, I know I had problems with the first Duratrax Charger I had. My problem was like it didn't have enough "oomph" to charge the battery, and this was a 3300. Try charging a newer battery and see what happens.
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