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Sactom · Aug 5, 2009, 3:09 PM

The instructions for the C9000 say to charge batteries at a minimum rate of 0.5 C. This means you should charge a 2000 mAh battery at minimum rate of 1000 mAh. Doing this causes the batteries to get very warm or even hot. A call to MAHA confirmed the 0.5 charging rate. The C9000 needs this rate to determine the proper end of charge time. A lower rate might cause the batteries to overcharge due to the algorithm used in the charger.

I also own MAHA's C401FS charger which provides a much lower charging rate of 300 mAh & the batteries stay cool. When I asked the MAHA tech about this, he said the C401FS uses a different algorithm.

So I guess I'll be using the C401FS for most of my battery charging duties.

rinniethehun · Aug 5, 2009, 3:48 PM

The way I read the C9000 manual (under General Battery Education), “Charging at a rate below 0.33C and above 1.0C is not recommended.” Therefore, using your old 401 charger at 300mA would violate this basic rule of battery charging. Besides...why would you want to spend 6 hours recharging your batteries? I charge mine at the 2000mA rate, and they don’t get too hot.

the Hun

Sactom · Aug 5, 2009, 4:44 PM

My C9000 user manual, under "General Battery Education", states that "Charging at a rate below 0.5C and above 1.0C is not recommended." We must have different versions of their user manual (actually just a single sheet printed on both sides).

I use 2 sets of batteries, so charging for 6 hrs or even overnight is not an issue for me. I feel keeping the battery temp down is important to longer battery life.

Thanks for your quick response.

Sactom

rinniethehun · Aug 5, 2009, 5:07 PM

http://www.mahaenergy.com/download/mhc9000.pdf

the Hun

Sactom · Aug 5, 2009, 6:09 PM

Thanks Hun for the link. It looks like MAHA lowered the min charge rate from 0.5C to 0.33C. My charger is over 2 years old & its instruction sheet said min charge rate of 0.5C. That 0.33 charge rate should keep the batteries cooler. Next batch I'll try 0.33C.

Sactom

coppertrail · Aug 8, 2009, 6:42 AM

My cells don't get "hot" or even warm when charging at 1000 mA on the C9000. Possible these cells have high internal resistance?

Reis · Aug 13, 2009, 11:23 PM

I found this page on the Powerex website that is very helpful.
http://www.mahaenergy.com/store/mhc9000faq.asp
It answers many specific questions including charging and discharging rates for typical batteries.

Aug 5, 2009, 3:09 PM	#1
Sactom Junior Member Join Date: Aug 2009 Posts: 3	MAHA C9000 Charger info The instructions for the C9000 say to charge batteries at a minimum rate of 0.5 C. This means you should charge a 2000 mAh battery at minimum rate of 1000 mAh. Doing this causes the batteries to get very warm or even hot. A call to MAHA confirmed the 0.5 charging rate. The C9000 needs this rate to determine the proper end of charge time. A lower rate might cause the batteries to overcharge due to the algorithm used in the charger. I also own MAHA's C401FS charger which provides a much lower charging rate of 300 mAh & the batteries stay cool. When I asked the MAHA tech about this, he said the C401FS uses a different algorithm. So I guess I'll be using the C401FS for most of my battery charging duties.

Aug 5, 2009, 4:44 PM	#3
Sactom Junior Member Join Date: Aug 2009 Posts: 3	Maha c9000 My C9000 user manual, under "General Battery Education", states that "Charging at a rate below 0.5C and above 1.0C is not recommended." We must have different versions of their user manual (actually just a single sheet printed on both sides). I use 2 sets of batteries, so charging for 6 hrs or even overnight is not an issue for me. I feel keeping the battery temp down is important to longer battery life. Thanks for your quick response. Sactom

Aug 5, 2009, 6:09 PM	#5
Sactom Junior Member Join Date: Aug 2009 Posts: 3	Maha c9000 Thanks Hun for the link. It looks like MAHA lowered the min charge rate from 0.5C to 0.33C. My charger is over 2 years old & its instruction sheet said min charge rate of 0.5C. That 0.33 charge rate should keep the batteries cooler. Next batch I'll try 0.33C. Sactom

Aug 13, 2009, 11:23 PM	#7
Reis Junior Member Join Date: Aug 2009 Posts: 1	Powerex Maha MH-C9000 I found this page on the Powerex website that is very helpful. http://www.mahaenergy.com/store/mhc9000faq.asp It answers many specific questions including charging and discharging rates for typical batteries.

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Aug 5, 2009, 3:48 PM	#2
rinniethehun Senior Member Join Date: Mar 2005 Posts: 1,778	The way I read the C9000 manual (under General Battery Education), “Charging at a rate below 0.33C and above 1.0C is not recommended.” Therefore, using your old 401 charger at 300mA would violate this basic rule of battery charging. Besides...why would you want to spend 6 hours recharging your batteries? I charge mine at the 2000mA rate, and they don’t get too hot. the Hun

Aug 5, 2009, 5:07 PM	#4
rinniethehun Senior Member Join Date: Mar 2005 Posts: 1,778	http://www.mahaenergy.com/download/mhc9000.pdf the Hun

Aug 8, 2009, 6:42 AM	#6
coppertrail Senior Member Join Date: Dec 2005 Posts: 198	My cells don't get "hot" or even warm when charging at 1000 mA on the C9000. Possible these cells have high internal resistance?