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Brand New Nimh batteries how to treat - 8/24/2012 11:17 PM   
mikejd


 

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From: Matawan, NJ, USA
Status: offline 		So I just ordered 4 Duratrax Onyx 6s 5000 mah batteries for mine and my sons trucks.
I have a thunder AC6, an Onyx 240 and a basic 9V at 250mA wall charger.
What should I do and how should these batteries be treated  rite off the bat.(charging wise)
so they have the best possible longevity and performance.

Thanks
Mike


< Message edited by mikejd -- 8/24/2012 11:52 PM >

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RE: Brand New Nimh batteries how to treat - 8/24/2012 11:23 PM   
guver


 

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Status: offline 		Best to charge them for 15 hrs at 500 ma (if they are discharged) this is std. recommendation for new packs forming and balancing and fully charging them with 1 charge.

Neither of the first two chargers are a good choice for this. That basic wall charger though may be a good choice. Did you mean 9 V and 250 ma?

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RE: Brand New Nimh batteries how to treat - 8/24/2012 11:45 PM   
mikejd


 

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Status: offline 		Guver, yes I am sorry that is what I meant 9V at 250ma misprint. Will this wall charger work.


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RE: Brand New Nimh batteries how to treat - 8/25/2012 1:58 AM   
guver


 

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Status: offline 		Yep , but it will take a while since the current is half of what it should be. I think we can estimate the current from the 9v charger on a 7.2 battery will be about 250 ma.

5000 mah / 250 ma = 20 hrs and then multiply that by at least 2 to get 40 hrs. I'd charge this pack for 2 days while checking it for warmth toward the end of the 48 hrs if you can work that out.

Normally we use 500 ma and then multiply it by 1.5 (I'm multiplying by 2 because your rate is less than ideal) there's nothing at all wrong with using 250 ma , it just takes longer. If toward the end you can feel some warmth to all cells in the pack then you can terminate the charge , but don't be afraid to let it go a lot longer. I'd go MAX of 60 hrs even if you never get an increase in temp.

After that it is ready for immediate use with all cells balanced, formed and fully charged. Run it easy on the first run. From then on you can beat on it with 5-6 amps or whatever your charger's max current is for speedy charges.

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RE: Brand New Nimh batteries how to treat - 8/25/2012 7:52 AM   
mikejd


 

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Status: offline 		Guver thank you I greatly appreciate this info.You are a big help.
Guver one question though.I like to know why I do things. So why am I multiplying at all
If 5000/250ma+ 20hrs. Why is 20 hrs not enough to me it seems as if it would be full at that point.
I am sure i am missing somthing. But I would just like to understand the reasoning.
if you wouldnt mind.



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RE: Brand New Nimh batteries how to treat - 8/25/2012 9:59 AM   
Rodney



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Status: offline 		Guver has given you some good advice. The following web site will give you lots of good info on how to treat your batteries, well worth reading.
http://www.hangtimes.com/redsbatteryclinic.html

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RE: Brand New Nimh batteries how to treat - 8/25/2012 12:39 PM   
guver


 

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Status: offline 		Thanks Rodney. Probably the link explains.

Here's the way I see it : when charging at various speeds much of the charge can be wasted off as heat and a for some reason a slow charge needs to have a higher % of capacity delivered to the battery. Another nice thing is that at slow rates like c/10 the NI type batts can dissipate that amount of heat without damage. Surely your c/20 rate can be left on for a week without damage. Here's a chart I made up to explain , but it may or may not be accurate.

Charge at 5 amps will take 100% capacity to fully charge the pack.
2 amps 101%
1 amp 110%
500 ma will take 140%
250 ma will take 170%

The reason we can go over the % or the time at the low rates is to ensure that ALL cells are full and it doesn't hurt anything. Another method that many chargers use it to peak charge the battery at 5 amps then trickle at a very slow rate to get the benefit of balancing,fully chargeing , ect. without the waiting process. This is fine for packs with a couple of cycles on them , but for new packs generally it is recommended to do at least one c/10 charge. You'll also want to do a slow charge at the start of the season after the packs had sat for a long time of non-use.

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RE: Brand New Nimh batteries how to treat - 8/25/2012 6:24 PM   
Rodney



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Status: offline 		There is always a loss when converting one type of energy to another, on converting Nixx type batteries, this is quite high. Makes no difference in the rate at which it is done, the loss or inefficiency is about the same. Yes, this loss is usually shown up as a rise in temperature so the slower it occurs, the slower the temperature increases. If it is at the same rate as can be transfered from the battery to the surrounding media (air, metal heat sink or ???) the final temperature will stabilize at some point. The slower the charge rate, the lower that temperature will be. Usually the temperature rise of the battery when charging at 0.1C is so slight it s difficult to detect by human touch but if you use a thermometer (an IR temperature gage works great) you can detect the rise.

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RE: Brand New Nimh batteries how to treat - 8/25/2012 7:17 PM   
mikejd


 

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Status: offline 		Guys  Thanks for the advise and the lesson. Great info.
My batteries thank you for it.

Mike


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