6V MH Batteries Showing 9.35V

6V MH Batteries Showing 9.35V
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All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> 6V MH Batteries Showing 9.35V

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6V MH Batteries Showing 9.35V - 8/13/2006 4:17:37 AM

Rcpilot

Posts: 6660
Joined: 3/20/2002
From: Arvada, CO, USA
Status: offline

I've got 4 metal hydride batteries here. They are all 6 volt.

First 2 batteries are 1100mah.
Second 2 batteries are 1950mah.

These are High Discharge batteries that were originally intended for RC cars or small electrics were current demand is very high. 15 or 20 amps continuous discharge. I bought them from Radical RC for my 28% airplane because it has 7 digital servos and I wanted to be sure the batteries would deliver the amperage that all those digitals would consume.

The batteries have 14ga leads soldered directly on the pack and a mini-Deans connector. I'm using the Smart-Fly Super Switches with a mini-Deans and heavy wires to conect the battery. Then the switches have dual 22ga leads going out to plug into the RX.

I've done the initial conditioning charge on them at 125mah. About 10hrs. Charged them up and then discharged them. I did this 5 times. Then I let them sit around for about 3 months and didn't touch them. They were fully charged when I put them in storage.

Now, they are showing over 9 volts with my volt meter. But, they seam to be false peaking though. The charger shuts down and the voltage shows really high--but when I turn the plane on, it acts dead after about 15 minutes of fiddling with it on the bench.

I'm not nuts about having 9volts running through my RX and switches. Is it even possible to get that much voltage out of a 6 volt batery? Could these batteries just be junk? Maybe I left them sitting too long without doing a maintenance charge on them? Maybe a cell is reversed?

HELP!! PLEASE

_____________________________

Airplanes have expiration dates. It''s just not printed anywhere on them.
I''m not really an airplane pilot; but I did stay at a Holiday Inn Express last night.

Post #: 1

RE: 6V MH Batteries Showing 9.35V - 8/14/2006 4:48:28 PM

richrd

Posts: 797
Joined: 7/18/2005
From: Waterford, PA, USA
Status: offline

Odd no battery failure can make more voltage sooooo.
Fact full charge 5 cells maximum voltage is 5 x 1.54V so max is 7.7V peak time maybe 7.95 V at time of stopping then after sitting maybe back down to 7.5V at open cell to 7V on 200mA load drains off top charge.
Question one are these reading in plane.
2. are you using one or two packs in plane
3. do you have another meter too try.

Rich

(in reply to Rcpilot)

Post #: 2

RE: 6V MH Batteries Showing 9.35V - 8/14/2006 5:33:15 PM

Rcpilot

Posts: 6660
Joined: 3/20/2002
From: Arvada, CO, USA
Status: offline

The batteries are in the planes. I have to leave them hooked up to the switch and read the voltage through the switch because the batteries have a deans connector on them and I have no way to hook my volt meter up to that type connector.

I'm using Smart-Fly Super switches. Dual batteries in each plane.

I have another volt meter. I'll check it today.

_____________________________

Airplanes have expiration dates. It''s just not printed anywhere on them.
I''m not really an airplane pilot; but I did stay at a Holiday Inn Express last night.

(in reply to richrd)

Post #: 3

RE: 6V MH Batteries Showing 9.35V - 8/14/2006 5:45:05 PM

Rcpilot

Posts: 6660
Joined: 3/20/2002
From: Arvada, CO, USA
Status: offline

Brown is the Smart Fly switches.
Green is the 22ga dual power leads from each switch--plugging into the RX (4 total for about 12--14amps into RX)
Yellow is battery
Blue is RX
Red is power lead from battery to switch. This is where the deans connectors are. 14ga wires.

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_____________________________

Airplanes have expiration dates. It''s just not printed anywhere on them.
I''m not really an airplane pilot; but I did stay at a Holiday Inn Express last night.

(in reply to Rcpilot)

Post #: 4

RE: 6V MH Batteries Showing 9.35V - 8/14/2006 6:00:32 PM

JoeAirPort

Posts: 7288
Joined: 8/11/2003
From: Milwaukee, WI, USA
Status: offline

Is the voltage being checked with a load? The packs should be loaded when you check their voltage. A .25 to .5 amp load would be good. Will your charger discharge the pack and allow you to read the voltage and current as it discharges?

_____________________________

Joe AP

(in reply to Rcpilot)

Post #: 5

RE: 6V MH Batteries Showing 9.35V - 8/15/2006 1:41:54 AM

decay

Posts: 222
Joined: 12/11/2005
From: phoenix, AZ, USA
Status: offline

Is it possible the batt voltage is down to 4.5V
& your getting a series reading of the 2 batteries?
Meaning the sum of both batteries = 9V?
Just an idea!

(in reply to JoeAirPort)

Post #: 6

RE: 6V MH Batteries Showing 9.35V - 8/15/2006 2:52:14 AM

Rcpilot

Posts: 6660
Joined: 3/20/2002
From: Arvada, CO, USA
Status: offline

quote:

ORIGINAL: decay

Is it possible the batt voltage is down to 4.5V
& your getting a series reading of the 2 batteries?
Meaning the sum of both batteries = 9V?
Just an idea!

Ding! Ding! Ding!

We have a winner.

I unplugged each battery and checked it seperately. 4.6V in each pack. They are shot. I've tried to run them back through a slow charge. They peak out and then show about 7.3V--soon as I slap them in the plane and turn on the switch--they go dead. Pull them back out and they show 4.5--4.6V again.

Sucks because I paid big bucks for these batteries. It's my own darn fault though. I should have known better than to let them sit for months without putting a charge on them.

_____________________________

Airplanes have expiration dates. It''s just not printed anywhere on them.
I''m not really an airplane pilot; but I did stay at a Holiday Inn Express last night.

(in reply to decay)

Post #: 7

RE: 6V MH Batteries Showing 9.35V - 8/15/2006 1:26:44 PM

richrd

Posts: 797
Joined: 7/18/2005
From: Waterford, PA, USA
Status: offline

Rcpilet still got two problems.
One how you are reading in series. At the receiver must be 4.8V or no backup. Were missing something about the wiring to the switch to get a series, I am thinking a lose ground wire.
Second is bad batteries, is very odd to lose a pack just lying around we all do this every winter at least us northern’s

. Iam thinking bad peak detection, must reform before trashing them. Try five cycles of discharge to 0.9V @ 1 Amp per cell then C/10 charge or 150mA for 16 HRS. I bet this will start giving 90% rated capacity. If so then if you can wait a week or two after full charge if they are down to 60% then yes bad leaky cells not safe for flight use in ground bashing. Discharge is only 50% a month at max getting old and at 15% month new [70deg F] per Panasonic spec page 10..

Rich

(in reply to Rcpilot)

Post #: 8

RE: 6V MH Batteries Showing 9.35V - 8/15/2006 4:14:12 PM

KB9STD

Posts: 221
Joined: 4/26/2002
From: Evansville, IN, USA
Status: offline

quote:

I've done the initial conditioning charge on them at 125mah. About 10hrs. Charged them up and then discharged them. I did this 5 times.

I'm bothered by this statement,The 1100mah battery shou take at least 13-14 hours to fully charge at 125ma.The 1950 would take
21-24 hours.Did You use some type of a Cycler to discharge the batteries? and did they show full capacity?
You need to figure out how the batteries are giving You a series reading first,and correct the wiring before ever plugging them into the plane again.Then make sure that the 9+ volts hsn't damaged anything in the receiver or switches.But I don't think the batteries have ever gotten a full Forming charge.Goback to step one,and charge the batteries at the 125ma for 16 hours for the 110mah,and a full 34 hours for the 1950.Then cycle them down to 4.5 volts(.9 volts per cell). Repeat this 5 times on each battery and then see how they are performing.

(in reply to Rcpilot)

Post #: 9

RE: 6V MH Batteries Showing 9.35V - 8/30/2006 10:29:37 PM

Rcpilot

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Joined: 3/20/2002
From: Arvada, CO, USA
Status: offline

Now I'm all messed up.

I did the initial charge on these batteries at 125mah for 10hrs. They are 100mah packs. That should have put 1250mah into the packs. Are you sure it would take 13-14hrs to fully charge an 100mah pack at 125mah?

I suspect my Hobbico volt meter is shot.

I put these batteries on the cycler when I initially got them and I cycled them 5 times as a conditioning charge. That should have brought them up.

I put them on a 1amp charge last week for an hour. That should have put 1000mah into them and then they showed 0 volts 20 minutes later. I don't know if it's the bateries or the volt meter.

_____________________________

Airplanes have expiration dates. It''s just not printed anywhere on them.
I''m not really an airplane pilot; but I did stay at a Holiday Inn Express last night.

(in reply to KB9STD)

Post #: 10

RE: 6V MH Batteries Showing 9.35V - 8/31/2006 12:07:48 AM

Dudelive

Posts: 778
Joined: 4/16/2006
From: Hillsborough, NC, USA
Status: offline

You need to be sure you hve a good connection at the battery when charging. It sounds like as was already stated you have a bad connection somewhere. I would have to have both batteries on the bench where I can see what is being connected where and be sure all connections are good. Try charging each battery seperately while monitoring the voltage with a seperate meter. Good Luck

Thanks
Dudelive

(in reply to Rcpilot)

Post #: 11

RE: 6V MH Batteries Showing 9.35V - 8/31/2006 8:01:54 PM

richrd

Posts: 797
Joined: 7/18/2005
From: Waterford, PA, USA
Status: offline

quote:

ORIGINAL: Rcpilet

Now I'm all messed up.

I did the initial charge on these batteries at 125mah for 10hrs. They are 100mah packs. That should have put 1250mah into the packs. Are you sure it would take 13-14hrs to fully charge an 100mah pack at 125mah?

I suspect my Hobbico volt meter is shot.

I put these batteries on the cycler when I initially got them and I cycled them 5 times as a conditioning charge. That should have brought them up.

I put them on a 1amp charge last week for an hour. That should have put 1000mah into them and then they showed 0 volts 20 minutes later. I don't know if it's the bateries or the volt meter.

125mA times 10 hrs is 1250mAH so it must be charged some.
What are you using as a charger and/or cycler, charger will typically tell you what's up with battery. Earlier in the plane it may have taken it's toll on something but Iam not sure what. As said pull battery put on a charger that can tell you something positive, then let us know what it said
Rich

(in reply to Rcpilot)

Post #: 12

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