Recommended battery charge rates in MH-C9000

We sometimes get asked: “what is the best charge rate to use in my MH-C9000 for my batteries?”.

We recommend 0.5C as a standard charge rate. That is 0.5 multiplied by the battery capacity. Here is an example:

0.5C charge rate x 1000mAh battery capacity = 500mA charge rate.

If you are in a hurry, you can use a charge rate up to 1C without concern of damage, but at 0.5C charge rate you will get a more complete battery charge. A slower charge will result in a slightly higher capacity, and it is easier for the battery to absorb the energy at a slower rate, which will contribute to a longer battery life. So why not charge even slower and get more charge capacity and more battery cycles from the rechargeable batteries?

Using a slower charge rate has a diminishing marginal benefit. Going any slower than 0.5C does not result in much difference to energy capacity or battery longevity.Futhermore, we recommend a minimum charge rate of 0.3C. Below 0.3C it is more difficult for the MH-C9000 to detect the change in voltage and know when to terminate the charge.

As a guide, here is a chart for our main battery models:

5 Comments »

1. I totally agree with charge rates. I tend to stick to 0.3C, rounded up to the nearest 100mA, so for a 1000ma, it would be 333 mA, rounded to 400mA, or 700mA for a 2000mAhr battery. I find the charge completion excellent, the batteries dont get warm, and the C9000 works well there.

   I do use a 1C charge if necessary, but that tends to make the batteries pretty warm. They are not too hot, but hotter than I personally like to get them. I have had too many chargers in the past which tend to “cook” batteries, as well as massively overcharge them, so the C9000 is a welcome charger which has cycled my batteries faithfilly for the last 2.5 years pretty much in your above guidelines and the batteries are still testing at well over 90% of their original capacity!

   Comment by David — March 6, 2010 @ 9:31 pm

2. I received my Maha Charger C9000 yesterday and successfully put two Duracell 2650 mAH through the Refresh Analyse mode. Today I am doing the same exercise with another two and they are in the charge cycle and reading 3349 mAH (1.46V) and 3351 mAH (1.46V). I am feeling a little nervous! Are there situations when the charger should be turned off?

   Comment by Mary — March 26, 2010 @ 12:47 pm

3. Hi Mary, are you sure it is in ANALYZE mode rather than BREAK-IN?

   While the capacity measurement of 3349mAh is very high, a voltage reading of 1.46V is normal. The charger will automatically terminate when the voltage stops increasing, or if the temperature of the batteries is too high.

   Comment by Jeff Servaas — March 26, 2010 @ 2:04 pm

4. Great table. But what about discharge rates?

   For example when using the refresh and analyse mode, should the discharge rate be the same as the charge rate?

   Comment by chewbot — May 22, 2010 @ 4:07 pm

5. My recommended discharge rate is 0.25C. So for 2700mAh AA batteries, discharge at a maximum rate of 700mA. For 1000mAh AAA batteries, i recommend a maximum discharge rate of 200mA.

   Comment by Jeff Servaas — May 23, 2010 @ 1:19 pm

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