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Charging NiMH batteries

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Charging NiMH batteries

Old 09-15-2008, 09:26 PM
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kbailey45
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Default Charging NiMH batteries

I just bought a used plane and for the rx there is a NiMH battery. I have the stuff to charge it with (Trion Jr and adapter) but was curious as to which rate to charge it at. The battery is a 4.8V 2200mAh. The manual that came with the triton says to use a rate that would charge it 1-2 hours thats either 1.1 or 2.2A. Is it ok for these packs to charge that fast if not what is a good charge rate.
Old 09-15-2008, 10:06 PM
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MustangBY6
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Default RE: Charging NiMH batteries

I have been using Hobbico's Accucycle Elite for a few years now. I have several 4.8v 1650mAh packs and a few 6v 1700mAh, all NiMH. The charger is set at .65 amps for peak charging and .3 amps for trickle charging. These rates have been satisfactory for me. Hope this helps!
Old 09-15-2008, 10:11 PM
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MustangBY6
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Default RE: Charging NiMH batteries

Correction!
My trickle is set at 3mA.
Old 09-15-2008, 10:53 PM
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Default RE: Charging NiMH batteries

The usual recomendation is 1/10C for charging then 1/100C for trickle.

In your case that is 220mah [ 14 hours from fully discharged ] and 22mah trickle.

They will last longer charged at these rates.
Old 09-16-2008, 01:17 AM
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kbailey45
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Default RE: Charging NiMH batteries

also this is the battery that came with the plane how can you tell if a battery is getting old or weak
Old 09-16-2008, 10:23 AM
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Rodney
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Default RE: Charging NiMH batteries

Since this is a battery that you do not know the history of (it may be old or abused) the first thing you should do it charge it for 16 hours at 0.1C and then do a discharge test by discharging at 0.2 to 0.25C down to 0.9 volts/cell and measure the capacity. If it is about 80% of the stated capacity, it is probably safe to use; i.e. won't cause your system to fail. Also, on NiMh is not recommended to do a trickle charge as that will shorten the lifespan of NiMh. Contrary to much of the comments here in the forums, NiCad batteries still rule over NiMh in all respects except mass per unit of energy. If you can stand the slightly increased weight, you will get twice the life and more immunity from minor abuse such as overcharge and trickle charging by using NiCad versus NiMh.
Old 09-16-2008, 11:01 AM
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kbailey45
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Default RE: Charging NiMH batteries

I will be using for 4 hobbico standard HT servos 69 oz/in each and 1standard for throttle what size would be good for 4-5 10 minute flights in NiCd
Old 09-16-2008, 04:47 PM
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Default RE: Charging NiMH batteries

1000 Mah 4.8 should be ok for 5 flights PROVIDING all your servo linkages are free and no servo is stalling at full travel.
Old 09-20-2008, 08:19 AM
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Default RE: Charging NiMH batteries

I have a Triton Jr charger and the manual states 1.1A-2.2A for a 2200mAh battery is that way to much I would like to be able to charge in at least 4 hours or would that put the pack at too much of a risk. Im thinking of just gettinga NiCd for it since I feel more comfortable with them and they are more tough.
Old 09-20-2008, 11:12 AM
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Default RE: Charging NiMH batteries

Hi!
As has been said before. NiMH cells doesn't like to be fast charged in the long run. It can be done but don't expect them to be too long lived.
Then there is the problem with "False Peak detecting" All fast chargers use Delta peak charging and NiMH cells often false peak when you fast charge them. It's therefore wise to slow charge them with 0.1C (in your case 220mAh) now and then and don't rely on the alarm signal the charger puts of when the fast charging stops. The battery pack isn't always fully charged.
Old 09-21-2008, 05:31 PM
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Default RE: Charging NiMH batteries

the thing with the triton jr. is that it has a time limit of 90 min. so you can't charge your battery in 0.1C. I'm using Ni-Mh batteries too. I usally charge them with 0.4C. But as Rodney said Ni-Cd is always a better choice
Old 09-21-2008, 09:31 PM
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kbailey45
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Default RE: Charging NiMH batteries

You can turn the safety timer off on the Triton Jr. or at least the newer ones you can.
Old 09-22-2008, 03:43 AM
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Default RE: Charging NiMH batteries

ohhh I didn't know that. I'm using a triton II rigth now.

As an answer to yout question: in my opinion you don't have to charge your ni-mh batteries with 0.1C. I am charging my 2200 mah ni-mh with 1amps and using that battery for about 1.5 years now. It still can hold 2200 mah so there is no problem.
Old 09-22-2008, 11:00 AM
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kbailey45
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Default RE: Charging NiMH batteries

Thats good to here. The thing is my triton jr only has a 12v input and I dont want to have to leave it on my car battery that long and dont rally want to purchase an 80 dollar power supply. Ive been looking at getting the Accu Cycle elite since it has ac and dc input.
Old 09-23-2008, 05:46 AM
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badguy
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Default RE: Charging NiMH batteries

I wouldn't do that. you can buy a simple power supply. like : http://www3.towerhobbies.com/cgi-bin...&I=LXRJN7&P=ML

or you can buy a computer power supply (the atx ones which has an on-off switch) and use it. This way it is cheaper. A 150-200 watt power supply is enough for your triton jr. That's what I'm doing for years.
Old 09-23-2008, 06:30 AM
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kbailey45
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Default RE: Charging NiMH batteries

Thanks I havent seen that one the only one I had seen was the one that was 90 bucks I will look into that one.

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