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HomeRC & Power✈️Aircraft🚁HelicopterRadio - Servo - Gyro - Gov - Batt › NIMH - Charging problem giving false reading..tried 3 different chargers
06-18-2009 09:28 AM  11 years ago
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MattJen

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UK

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NIMH - Charging problem giving false reading..tried 3 different chargers
hi guys

i just bought 4 cell NIMH batery, i plugged in a voltage checker and it went straight to red indicating flat, i charged it up and it only put in 93mah,i tried discharging it, and the same thing happend after 1 mintue it stopped, i tried this same battery pack on 3 different chargers, to eliminate charger problem. it is lucky i had the voltage checker, as i could have been fooled into thinking it was fully charged and then went off and flew my turbine..

i was recommended to charge it as a Nicad, i did this and managed to put in over 4700mah ( 4 cell 4100)

My question is why does it work when you charge it on nicad?

Is it just a case of keep recycling ? as i heard NIMH dont like to be recycled and they dont get affected by memory effect, i find them unpredictable, no where as reliable as Nicads, but it is now illegal to import them into the UK so we cannot get hold of them

I dont understand NIMH fully, and if there is a better way of using/charging them please tell me..

Matt
All The Best
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06-18-2009 11:45 AM  11 years ago
Paul Woodcock

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Dubai - United Arab Emirates

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Hi MattJen

I had an issue charging and discharging the AA sized 2000 and 2400 mAh NiMH unless i charged at 300 to 400 mA. Anything more and i would have the problems you are having.

My starter has 14 Sub-C 3300 mAh HiMH cells. I charge it at 3 A with no problem. I have never bothered cycling it. I do that at the field !!!

Regards
Paul
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06-18-2009 11:56 AM  11 years ago
Turkana

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Montreal,Quebec , Canada

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Hi
Well It is know that some Nimh batts give falls readings on chargers. I purchased a Rx pack from Spectrum last year and they had a sticker on it saying: Due to the chemistry of these batt youre charger can give a falls reading, always make sure that it is sufficiently charged???? How if the charger gives false readings??Anyway I found out that I could charge it max to 300mah then it would not give falls readings.
I changed to a Lipo RX pack and thats works just perfect for me.

Regards Pete
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06-18-2009 12:22 PM  11 years ago
Dr Lodge

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Guildford, Surrey - UK

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Matt, what chargers have you tried? I've got a few and find that my schulze chargers are the only ones that will charge NiMH packs properly, even then they can give false "charged" readings if the pack has been left for a while.

The NiMH charge detection is similar to NiCD I believe (delta peak) but is alot more sensitive, the charger looks for a much smaller drop in voltage to know when the battery is full, and this can happen in the early stages of a charge when the battery has been left a while.

If you want to send the pack to me (in Guildford, Surrey), I'm more than happy to try it on my chargers and see if they work. Alternatively, you might be able to charge it on a constant 400ma or so, that way it will charge overnight and you won't risk over charging.

Feel free to PM me with any questions.
Vibe 90, Vibe 50, Vigor CS x2,
Dyna-x, Knight 503D, Logo 10,
TRex 500, Furion, Gaui EP200
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06-18-2009 07:52 PM  11 years ago
MattJen

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UK

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Dr Lodge

many thanks, i have the following chargers
pro peak supa nova, Chameleon,bantam
All The Best
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06-18-2009 11:24 PM  11 years ago
Dr Lodge

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Guildford, Surrey - UK

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The Chameleon should work, its what I have. Try cycling it using the 0.1 amp charge function. It'll take a while (like 2 days) for a charge cycle but that should condition it.Vibe 90, Vibe 50, Vigor CS x2,
Dyna-x, Knight 503D, Logo 10,
TRex 500, Furion, Gaui EP200
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06-18-2009 11:28 PM  11 years ago
MattJen

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UK

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excellent,

thanks a lot for the info,

so for the record then, they need to be trickeled charged as i have been taught ?

Matt
All The Best
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06-19-2009 05:52 AM  11 years ago
uk sailor

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UK

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Good helpfull information here for me too.
I have a 3600 Nimh sub-c size and had given up on it as I couldn't get more than a few miliamps into it using an Ultra Duo 30 charger set to Automatic for Nimh's.
Following the information here I tried last night first with the manuel settings on 300ma and then on a main link cycler (glad I hadn't sold it yet)it has discharged 3000ma from who knows what start point and is now charging again. I will cycle it a couple of more times and see if it is usefull for more than just binding the radio and some set up on the bench thanks all.
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06-19-2009 09:51 AM  11 years ago
Dr Lodge

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Guildford, Surrey - UK

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they need to be trickeled charged as i have been taught
Well it can certainly help in two ways:
- trickle charging them at around c/10 (so 400ma for a 4000 pack) helps to (re)condition the pack and coupled with a few charge/discharge cycles in this way will help bring the pack back to life, and increase its capacity back to where it ought to be. Charging a big pack to 1.5 times its capacity at 0.1 amps and doing 3 cycles can take a week or more...!
- chargers such as the Schulze chameleon behave differently on the 0.1 amp and 0.25 amp settings compared to higher current settings. At 0.1 amps, the peak detection and capacity cut off are disabled, this means the charger will keep charging at 0.1 amps until you disconnect the battery...no false peak detection and ideal for conditioning :-) At 0.25 amps, I think the peak detection is on whilst the capacity cut off is turned off - or it could be the other way round.

If charging a 4100 pack at 0.1 amps from flat, I'd leave it for about 60 hours, then discharge at 1 amp, and repeat a couple of times. You should see an increase in the amount of energy discharged over the cycles. Then try charging at 3 or 4 amps, it should work.
Vibe 90, Vibe 50, Vigor CS x2,
Dyna-x, Knight 503D, Logo 10,
TRex 500, Furion, Gaui EP200
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06-19-2009 10:52 PM  11 years ago
MattJen

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UK

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excellent info, thanks DR and others that have taken time to reply..

I have followed your advice and suggestions and my batteries are charging to full capacity

So thanks again have a good weekend all

Matt
All The Best
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