Charging NiMH for the first time??  
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All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> Charging NiMH for the first time??
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Charging NiMH for the first time?? - 10/22/2007 9:26:00 PM   
gapple12


 

Posts: 317
Joined: 1/20/2006
From: San Antonio, TX, USA
Status: offline 		Ok, I have two 6volt 2600mA NiMH 5 cell batteries that are new and I want to charge them for the first time. Now I have heard that the first initial charge is most important, therefore I don't want to screw them up. The only chargers I have are a Hobbico Quick Field Charger MKII and a couple of the stock Futaba wall chargers for receivers and transmitters. Do I need a discharger or can I just charge them? Please help, I would like to try them out this weekend.
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RE: Charging NiMH for the first time?? - 10/22/2007 10:09:46 PM   
guver


 

Posts: 8975
Joined: 3/7/2003
From: LaGrange, OH, USA
Status: offline 		The MKII isn't a good choice for the first charge, but might do fine later on. The wall charger might be ok.

You won;t have to discharge them, but charge them at a rate close to 250 ma for 15 hrs . The rate and time don't have to be exactly 250 and 15 (just have to be close) , but when multiplied together they should equal 150% of capacity.

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RE: Charging NiMH for the first time?? - 10/22/2007 10:38:28 PM   
TLH101



Posts: 5513
Joined: 12/27/2001
From: Corpus Christi, TX, USA
Status: offline 		http://members.aol.com/davthacker/nimhfaq.htm

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"Old Fart" in training. (not to be an R/Cer, but to be an "Old Fart")

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RE: Charging NiMH for the first time?? - 10/22/2007 10:46:31 PM   
guver


 

Posts: 8975
Joined: 3/7/2003
From: LaGrange, OH, USA
Status: offline 		"bookmarked" for future linking. That's a great article.

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RE: Charging NiMH for the first time?? - 10/22/2007 11:05:03 PM   
Jazzy



Posts: 1106
Joined: 1/8/2002
From: Erie, PA, USA
Status: offline 		Since you are limited on your chargers: wall warts only putting out 50 mA and the MK II putting out... wait, the MK II will work just fine!!!
Just set it to between 200 and 250 mA and let it go. It will peak charge the packs at or just below the C/10 rate and be perfectly safe. It would be WISE however to frequently check the temperature status of the packs after the first few hours. If one or both packs peak early (perfectly normal with new and aged NiMH packs) put them on the wall warts for 4 -10 hours to try to complete the forming charge. If one or both packs get more than comfortably in-your-hand warm, reduce the charge rate 50 - 100 mA. After putting them on the wall warts they should not get much more than room-temperature-warm. Even if they peak out with an input of around 2600 mAH, put them on the wall warts for a few hours. It will not hurt them.

Don't worry about "hurting" your packs. They will be just fine! They are tougher than you think they are. Just remember to keep the charge rate around or below the C/10 rate for the first couple cycles.

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Aww $#!^.... I left the )@#& transmitter at home!

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RE: Charging NiMH for the first time?? - 10/22/2007 11:48:26 PM   
gapple12


 

Posts: 317
Joined: 1/20/2006
From: San Antonio, TX, USA
Status: offline 		Ok, I will do that. I appriciate your help. Thanks!!

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       Post #: 6

RE: Charging NiMH for the first time?? - 10/23/2007 12:09:56 AM   
guver


 

Posts: 8975
Joined: 3/7/2003
From: LaGrange, OH, USA
Status: offline 		The only way the MKII will work is to set the rate high enough to do the job in 2 hrs or less since it has a 2 hr limit. OR you could keep restarting it. Then trickle as stated above to equalise/balance.

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RE: Charging NiMH for the first time?? - 10/23/2007 12:32:11 AM   
rcairflr


 

Posts: 627
Joined: 9/2/2004
From: Wichita, KS, USA
Status: online 		If you want the most out of your NIMH batteries get a good battery FORMER charger and properly form your battereis, you'll be glad you did. The one I chose was the Sirius Pro Former, it can also be used as a regular charger. Regardless of what anyone tells you, you cannot properly form a new battery with a peak detect charger and a 50mA wallwart cannot form a 2600mA battery.

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RE: Charging NiMH for the first time?? - 10/23/2007 1:09:25 AM   
gapple12


 

Posts: 317
Joined: 1/20/2006
From: San Antonio, TX, USA
Status: offline 		I dont know if it makes any difference, but my wall Futaba charger says 4.8 volt 100mA.

rcairflr, where can I get a FORMER CHARGER like that or similar?

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       Post #: 9

RE: Charging NiMH for the first time?? - 10/23/2007 1:17:54 AM   
rcairflr


 

Posts: 627
Joined: 9/2/2004
From: Wichita, KS, USA
Status: online 		You stated that your battery is a 5 cell battery, so a 4.8 volt wallwart charger will not work. Chief aircraft sells the Sirius chargers or you can directly to the Peak Electronics website. I was able to get mine at the local hobby store. If you ever get any of the new low impedance NIMH batteries, Forming becomes even more critical.

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       Post #: 10

RE: Charging NiMH for the first time?? - 10/23/2007 2:37:46 AM   
gapple12


 

Posts: 317
Joined: 1/20/2006
From: San Antonio, TX, USA
Status: offline 		So do I still need a discharger? Would a cycler/charger/discharger do the same thing? Thanks again for all the help.

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       Post #: 11

RE: Charging NiMH for the first time?? - 10/23/2007 2:50:18 AM   
rcairflr


 

Posts: 627
Joined: 9/2/2004
From: Wichita, KS, USA
Status: online 		I am making assumptions here, I assume you are now flying big enough airplanes to require higher capacity batteries. With this in mind we put several hundred to several thousand dollars into our airframes, engines and servos. It doesn't make any sense to not put some money into good chargers/dischargers to properly take care of our batteries. With that said I would not be without a good peak detect charger that can also discharge a battery. If you do not fully charge and then discharge a battery once in a while, how can you tell the condition of your battery? Also keep in mind that a NIMH does not have a memory like a NiCd, but NIMH also gain from being cycled once in a while, plus you can use it as a opportunity to check the condition of your battery. Just my $.02 worth.

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       Post #: 12

RE: Charging NiMH for the first time?? - 10/23/2007 3:32:29 AM   
gapple12


 

Posts: 317
Joined: 1/20/2006
From: San Antonio, TX, USA
Status: offline 		Oh, I am for sure going to spend a little more. These batteries are for my 33% Yak that I am not taking any chances with. I had 4.8 Volt 2000Ma and I think I screwed them up. I could only get two or three flights on them before they would get to low. I am running two receivers on it. I will be shopping around if any one wants to get rid of one.




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RE: Charging NiMH for the first time?? - 10/23/2007 11:14:55 AM   
rcairflr


 

Posts: 627
Joined: 9/2/2004
From: Wichita, KS, USA
Status: online 		Nice looking airplane....

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