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HelicopterMain Discussion › Battery cycle question
12-02-2005 11:23 PM  12 years agoPost 1
E30TECH

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Jefferson, New Jersey

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I cycled my new NiMH 3300mah 4.8V battery on my new Accucycle elite. Everything was programmed properly. I had it cycle 3 times - the settings were: discharge at 300ma, charge 330ma, delta 8mv. The temp peaked at about 80 degrees F.

on the 2nd cycle It charged 3720mah and discharged 3260mah. Is that normal?

On the last cycle (#3)- it charged 4400mah.


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12-03-2005 01:55 PM  12 years agoPost 2
BarracudaHockey

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Jacksonville FL

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NiMH take a few cycles to get to capacity, thats perfectly normal.

Andy
AMA 77227
http://www.jaxrc.com

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12-03-2005 01:57 PM  12 years agoPost 3
E30TECH

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Jefferson, New Jersey

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Thanks for the reply.

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12-03-2005 02:38 PM  12 years agoPost 4
Paul Hinz

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Oostburg, WI

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Yes it is normal for the charger to show more than the battery's capacity. A charger used on NiCD and NiMH is only about 80% efficient so the high charge reading is normal.

Paul

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12-03-2005 03:04 PM  12 years agoPost 5
wolfdad

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Southern Maryland

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I run the 3300 and 3700 mah NiMh batteries in all of my aircraft and, after building a group of batteries, while cycling them through, just as you did, on three cycles, it is not unusual to see "above capacity" charges as the batteries stablize. I think you are ok, especially since the temp did not become a factor. Also, I run each new battery on the CBA analyzer from West Mountain Radio, so I have a graphic display on file of the new batterie's baseline performance....something to compare to later on. I think that is about the best $100 I have spent since coming back into the hobby.

wolfdad sends...

"There are those who have...and, those who will" IRCHA #2117, AMA #70068, Turbine Waiver #105

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12-03-2005 04:59 PM  12 years agoPost 6
cessna151

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Missouri... Originally Indiana

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You should always get a higher charge capacity than the discharge capacity because of the efficiency issue mentioned above.

Just thought i'd point out i read somewhere that to see the battery's true capacity, you should discharge at capacity/5 with the cut-off at .8v per cell. For a 3300 the discharge rate would be 660ma.

--Eagles may soar high, but weasels don't get sucked into jet engines!--

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12-03-2005 05:03 PM  12 years agoPost 7
cessna151

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Missouri... Originally Indiana

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****IMPORTANT****

I've had a few NiMh batteries crap out on be, and i think i might have finally found out why.

I have the Accucycle elite too and i know the defalt is 8mv but I was told recently that NiMh batteries should have the peak detection set no higher than 4mv. Any higher would overcharge and damage the battery.

--Eagles may soar high, but weasels don't get sucked into jet engines!--

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12-03-2005 07:10 PM  12 years agoPost 8
Fullagas

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Michigan

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.
The Accucycle and Triton aren't exactlly lab quality instruments. My Triton is ususally in error by about 10% of capacity. The CBA analyzer wolfdad mentions is very accurate. I use an Astroflight Wattmeter in series to check my chargers, and have found most to be in the 10-15% error range. Good enough for who it's for.

My Nimhs do exhibit weird quirks, especially false peaks, but I've learned to work with them.

.

Flying helis since gyros had springs.

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12-04-2005 01:34 AM  12 years agoPost 9
E30TECH

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Jefferson, New Jersey

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Thanks for all the replies.

wolfdad
I may consider the CBA analyzer in the future.


cessna151
you should discharge at capacity/5 with the cut-off at .8v per cell. For a 3300 the discharge rate would be 660ma.
I have read that you do not want to 'deep cycle' NiMH batteries. I'm not 100% positive what deep cycle means, but I figured it meant don't discharge more than 1.1 - 1.0 volts per cell.
I was told recently that NiMh batteries should have the peak detection set no higher than 4mv
I asked Dave at RadicalRC and he said 3-6mv for NiMH. The manual for the elite did say a higher setting (can't recall off the top of my head). I was a little concerned about the long charge time and capacity, but the battery did not heat up.

What were you setting the mv value to when charging NiMH batteries?

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12-04-2005 06:21 AM  12 years agoPost 10
Fullagas

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Michigan

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.
I asked Dave at RadicalRC and he said 3-6mv for NiMH. The manual for the elite did say a higher setting (can't recall off the top of my head). I was a little concerned about the long charge time and capacity, but the battery did not heat up.
I've seen 4-5mv listed as correct for nimhs.

As for the heat, I've had better luck (fewer false peaks) charging my 10x3000 pack at 4 amps or so. They get a little warm, but I get more duration than a 'cool' pack.

.

Flying helis since gyros had springs.

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12-04-2005 12:55 PM  12 years agoPost 11
BarracudaHockey

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Jacksonville FL

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http://www.rcbatteryclinic.com

Andy
AMA 77227
http://www.jaxrc.com

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12-04-2005 02:59 PM  12 years agoPost 12
dgshaffer

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New Jersey

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barracudahockey

Great link! Thanks.

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12-04-2005 05:47 PM  12 years agoPost 13
BarracudaHockey

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Jacksonville FL

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I'm full of, among other things, tons of occasionally useful info.

He writes the battery colum for MA and spends a lot of time on RCU answering battery questions.

Andy
AMA 77227
http://www.jaxrc.com

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12-04-2005 06:03 PM  12 years agoPost 14
dgshaffer

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New Jersey

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tons of occasionally useful info

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12-05-2005 01:27 AM  12 years agoPost 15
cessna151

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Missouri... Originally Indiana

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I was using the defalt 8mv untill i realized my mistake. It just sucks that i only figured it out a couple weeks ago.

--Eagles may soar high, but weasels don't get sucked into jet engines!--

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12-05-2005 02:52 AM  12 years agoPost 16
E30TECH

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Jefferson, New Jersey

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I'll try it on 4mv and see if it false peaks.

Hopefully I didn't F my battery up. The pack didn't get hot, so I think I am ok.

Thanks for all the info guys

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