Batteries Won't Charge

[Monkey Wrench]

I am not a battery expert, not by a long shot, so hoping to get some help here.

I have several battery packs I use in my RC18T. They are six cell, 7.2 volt, 1200 maH packs.

I admit, they have sat for awhile, so they may be DOA, but before I replace them, thought I'd ask the experts here first.

When I connect them to my charger/analyzer, I get a voltage high message and it won't cycle or charge. How can the voltage be high if I know there is.no charge on the pack? Are these packs just dead?

Any tips most appreciated!

 

[Greywolf74]

I am not a battery expert, not by a long shot, so hoping to get some help here.

I have several battery packs I use in my RC18T. They are six cell, 7.2 volt, 1200 maH packs.

I admit, they have sat for awhile, so they may be DOA, but before I replace them, thought I'd ask the experts here first.

When I connect them to my charger/analyzer, I get a voltage high message and it won't cycle or charge. How can the voltage be high if I know there is.no charge on the pack? Are these packs just dead?

Any tips most appreciated!

This may seem like an obvious question but are you charging them using a NiMH charge setting? Most chargers can charge up to 15+ cell NiMh packs so theres no way a 6 cell NiMH pack could be too high of a voltage.

What charge do they have when you put a multi meter or battery tester on it?

 

[Monkey Wrench]

This may seem like an obvious question but are you charging them using a NiMH charge setting? Most chargers can charge up to 15+ cell NiMh packs so theres no way a 6 cell NiMH pack could be too high of a voltage.

What charge do they have when you put a multi meter or battery tester on it?

Yes, I am sure I am using the NiMH setting. I have a Hobbico Accu-Cycle Pro Series Elite charger.

As for the multimeter, ashamed to admit, not entirely sure what setting to use and what number I should see. This is the multimeter I am using.

 

[Greywolf74]

Yes, I am sure I am using the NiMH setting. I have a Hobbico Accu-Cycle Pro Series Elite charger.

As for the multimeter, ashamed to admit, not entirely sure what setting to use and what number I should see. This is the multimeter I am using.

View attachment 157482

Use whatever DCV setting that makes the screen read 0.00. I wanna say thats going to be the 20 setting but I can't remember for sure cuz I've been using autosensing meters for a long time now.

 

[tudordewolf]

not entirely sure what setting to use and what number I should see.

Under the "DCV" section, pick "20", to indicate that you're measuring less than 20 volts DC. The number indicates the maximum for that range.

 

[Monkey Wrench]

Pack 1: .02
Pack 2: 5.04
Pack 3: 5.04

If I'm reading this right, none are over 7.2. Wonder why my charger gets pissy when I try to cycle or charge.

 

[Greywolf74]

Pack 1: .02
Pack 2: 5.04
Pack 3: 5.04

If I'm reading this right, none are over 7.2. Wonder why my charger gets pissy when I try to cycle or charge.

Pack 1 is toast. thats never going to hold a proper charge. The other 2 should be ok. Can you snap a pic or two of the charger set up and your charge settings?

 

[Monkey Wrench]

Pack 1 is toast. thats never going to hold a proper charge. The other 2 should be ok. Can you snap a pic or two of the charger set up and your charge settings?

Ok, going through the charger screens:

1. Type: NiMH
2. Cells: 6
3. Volts: 7.2
4. Capacity: 1200 mAh
5. Peak charge current: 0.50 A
6. Trickle current: 30mA
7. Peak sensitivity: 8mV/cell
8. Discharge current: 0.30A
9. Discharge cutoff volt: 1.1V/cell
10. Number of cycles: 1

Connect the battery, start a "cycle" cycle, immediately starts a 1 min delay. It'll act like everything is peachy, then I get this.

 

[Greywolf74]

Instead of cycling it does it do the same thing if you just try and charge it?
I hate to say it but I think your charger is suspect at this point. How long has the charger been sitting and was it stored inside or in an attic/garage?

 

[Monkey Wrench]

Yep, same for just charge or just discharge.

Charger lives in my finished basement with my rigs.

Could be the charger, except, it is charging another pack and my glow starter without issue. I'm going to see what it charges for a 5-cell receiver pack.

Truly appreciate all the help!
I know it may be unlikely, but could it be a connector issue?

 

[Greywolf74]

Yep, same for just charge or just discharge.

Charger lives in my finished basement with my rigs.

Could be the charger, except, it is charging another pack and my glow starter without issue. I'm going to see what it charges for a 5-cell receiver pack.

Truly appreciate all the help!
I know it may be unlikely, but could it be a connector issue?View attachment 157486

That is strange indeed. I mean I wont say it couldnt be a connector issue but the fact that both of the batteries are doing would lead me to believe that it probably isnt? hard to say for sure.

One thing I would try is changing the charger to a 7 cell setting and see if that will let it charge and if not then Id try it on a 5 cell setting and see what that does.

 

[Monkey Wrench]

That is strange indeed. I mean I wont say it couldnt be a connector issue but the fact that both of the batteries are doing would lead me to believe that it probably isnt? hard to say for sure.

One thing I would try is changing the charger to a 7 cell setting and see if that will let it charge and if not then Id try it on a 5 cell setting and see what that does.

Will do, thanks for the advice! I'll give it a shot and let you know.

 

[leyla1989]

Just been reading your thread monkeywrench, interested to see if you found out the cause of the problem ??

 

[bill_delong]

just a guess, if the 6 cell NiMh battery is over drained, the charger might think the voltage is for a 4 cell pack which might explain the voltage too high issue.

Regardless, if any of the cells have sat for too long then changes are shunts have formed inside the battery making it extremely unstable, I would discard the pack and replace with new if it were me.

Batteries are expendable in this hobby, I tend to abuse my packs in extreme summer heat out here in Texas, very rarely do I have a pack last longer than a year before significant IR fade and pack swelling begins to occur.

 

[Greywolf74]

just a guess, if the 6 cell NiMh battery is over drained, the charger might think the voltage is for a 4 cell pack which might explain the voltage too high issue.

I bet your right. I'm surprised that never occurred to me.

Regardless, if any of the cells have sat for too long then changes are shunts have formed inside the battery making it extremely unstable, I would discard the pack and replace with new if it were me.

What if they sit but you periodically charge them? and by periodically I mean like once a year or so

 

[Monkey Wrench]

Just been reading your thread monkeywrench, interested to see if you found out the cause of the problem ??

I didn't. I tried changing charger settings as suggested...no joy. New pack I bought works fine and when I fully charged it, little truck ran like a spotted dog!

just a guess, if the 6 cell NiMh battery is over drained, the charger might think the voltage is for a 4 cell pack which might explain the voltage too high issue.

Regardless, if any of the cells have sat for too long then changes are shunts have formed inside the battery making it extremely unstable, I would discard the pack and replace with new if it were me.

Batteries are expendable in this hobby, I tend to abuse my packs in extreme summer heat out here in Texas, very rarely do I have a pack last longer than a year before significant IR fade and pack swelling begins to occur.

I think you're right, I think the packs are just spent. They're well over five years old and I didn't charge them at all. I'd rather not risk causing a fire or something so going to clip the Deans plugs off, get some new packs and go from there.

 

[bill_delong]

What if they sit but you periodically charge them? and by periodically I mean like once a year or so

I don't think there's a time limit on packs sitting, just a time limit on when the voltage drops below the given threshold

more info here:
https://batteryuniversity.com/article/bu-808a-how-to-awaken-a-sleeping-li-ion

In the OP's case for NiMh, it's possible to restore it with "Priming", more info here:
https://batteryuniversity.com/article/bu-702-how-to-store-batteries

As a racer, I prefer to discard older packs for performance reasons, for bashing around, I think NiMh is relatively safe from causing any fires so it may be worth a try with priming.