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Old Jul 25, 2014, 11:10 AM
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Joined Jul 2014
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Question
Charging my battery pack

Hello all, I have a fairly simple question.

Recently I purchased some Hi-Capacity power products D-Type 11000mAH 1.2V Ni-MH Rechargeable Batteries.

I am connecting 10 of them in series to make my own compact 12 volt rechargeable solution. Because getting them in and out will be a slight pain, I want to be able to charge them in place once I finish making the pack.

I dug around and found a nice charger I had for use with sealed lead acid batteries:
12V dual stage charge
Screw terminals
1000 mAh
14.8V fast charge

Its worked great for my SLA batteries and shuts off once the pack is charged.

Do any of you foresee any issues with using this charger or charging in this manor? Or should I take each one out and place in the D cell battery charger that I have?

Thank you very much for the responses!
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Old Jul 25, 2014, 11:53 AM
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Joined Jul 2014
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What I have found online is:
"The cheapest way to charge a nickel metal hydride battery is to charge at C/10 or below (10% of the rated capacity per hour). So a 100 mAH battery would be charged at 10 mA for 15 hours. This method does not require an end-of-charge sensor and ensures a full charge."

So with that being said, a 1000mAH charger should charge the 11000mAH batteries and stay with the C/10 charging range.

The charger I have has a DC voltage output of 14.8V. If I am thinking correctly the D Cell charger I have charges at 1.5 each volts so this would be equivalent to charging each 1.2 volt battery separately, right?

So the big question is charging Ni-MH batteries in series. Is there anything wrong with that?
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Old Jul 25, 2014, 12:17 PM
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I found this on eHow:

"If you have a group of NiMH batteries that all need a charge, there is any easy way to do it. Instead of putting each one to charge individually, you can connect them one to another in a series joining with a charger for a complete charging circuit. You can use any charger and number of batteries as long as the combined total voltage of the batteries equals the voltage of the charger."

Has anyone else done this before?
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Old Jul 25, 2014, 05:22 PM
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USA, GA, Marietta
Joined Aug 2005
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Your numbers are correct. Charge at 1/10 of the rated capacity.
Yes charging in series is correct.

Glen
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Old Jul 25, 2014, 07:19 PM
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United States, WA, Woodinville
Joined May 2014
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Many lead-acid chargers don't really limit the current though so depending on the charger they may push too much current through the cells. In a pinch a small incandescent bulb or a resistor calculated to limit the current to 0.1C in series with any voltage source at least a few volts higher than the fully charged voltage of the pack will work.
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Old Jul 25, 2014, 09:46 PM View Post
leveezengxi
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Old Jul 26, 2014, 06:24 AM
homo ludens modellisticus
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near Nijmegen, Netherlands
Joined Feb 2001
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Quote:
Originally Posted by leveezengxi View Post
You can use any charger and number of batteries as long as the combined total voltage of the batteries equals the voltage of the charger.
Don't bother, it's spam, several messages peddling for helthusb. Quote opening post, select 'underwater' screen , end of message: the alturl image link refers to helthusb.
Messages borrowed from the internet, in this case from
www.ehow.com/how_7507187_charge-nimh-batteries-series.html

Indicators:
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* out of the blue message trying to look as if part of discussion

Vriendelijke groeten Ron
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