Maha C9000 Help

[Albinoni]

When my C9000 is charging on the display it will cycle through different screens etc. My question here is what is MA and what is MAH ? So for eg on a battery when it shows 2500 mAh I am presuming thats MAH on the LCD screen of the C9000 if I'm correct.

 

[PhotonBoy]

MA is milliamps, a measure of current - either charge or discharge

MAH is milliamp-hours, a measure of capacity of the cell. So a cell rated at 2100 MAH could run at 2100 MA for 1 hour or 1050 MA for 2 hours, for example

 

[Albinoni]

Ok so MA is related to the one on the battery.

 

[SilverFox]

Hello Albinoni,

No. The capacity of the battery is shown in mAh.

You can think of capacity as how much the battery holds. If you go to the store and want some juice, you look at the bottle and see the amount of juice listed as 500 ml. The bottle next to is shows 600 ml. The capacity of the larger bottle will have more juice in it.

With batteries, the size of the container remains the same, because we have to be able to fit the batteries in our flashlights. However, through engineering they are able to cram more potential in. To let us know how much is in the battery, they put a label on it showing the capacity in mAh.

Now that we have a capacity, we need to fill, or empty it. That is where mA comes in. If we fill the juice bottle with a 2 mm hose, it will take a long time to fill. On the other hand if we use a 25 mm hose, it will go a lot faster.

The same applies to batteries. If you charge at 1000 mA, the charge will be completed in a shorter time than if you charge at 500 mA. This also applies to discharging. If you light draws 1000 mA, the battery will not last as long as it would if your light only had a draw of 500 mA.

The C9000 cycles through mAh (the capacity either put in or drained so far), mA (the rate the capacity is going in or being removed from the battery), min (the time spent on this cycle), and volt (the voltage of the battery).

Tom

 

[Albinoni]

Ok and a battery with a higher mAh will give a longer run time than that of a lower mAh, so say for eg 1000 mAh and 2500 mAh. Also interesting to know how true are manufactureres mAh ratings ?

Also on the C9000 when you insert a battery into it, you can manually program the mAh into it. So if I had a 2000mAh battery and slotted it into the C9000 does this mean I set the mAh to 2000 manually using the buttons on the C9000,and I'm also assuming that manual setting for mAh on the C9000 is also the charge rate setting, so if I insert a 2000mAh battery and set it to 2000 mAh this means the whole battery will charge in 1hr.

I would really like to use this charger to its full potential.

 

[PhotonBoy]

Charging the battery quickly at a MA current flow close to the capacity of the battery tends to be hard on it. The battery heats up quickly, stays hot and the battery's chemicals tend to break down more quickly, shortening the battery's overall life span.

Slower charges at lower currents (MA) produce less heat and tend to lengthen the battery's lifetime.

If you're not in a rush, slower charges performed at about .1C or .2C (10% or 20% of the battery's capacity) generally provide the best overall results.

 

[digitor]

Also on the C9000 when you insert a battery into it, you can manually program the mAh into it.

Well, that's only true for break-in mode. In charge mode, you program the charge current in mA.

I would really like to use this charger to its full potential.

Have you read the instructions that come with the charger? Also, there's a wealth of information here in the C9000 threads.

Cheers

 

[SilverFox]

Hello Albinoni,

You are on the right track.

However, keep in mind that when charging 4 cells on the C9000 at it maximum charge rate of 2000 mA, the charger heats up and that heat is passed on to the cells. If possible, it is better to limit your maximum charge rate to 1500 - 1800 mA. You can charge two cells in slots 1 and 4 at 2000 mA, and things won't heat up too bad. If you are in a hurry, go ahead and use the 2000 mA rate on all four cells, but understand that your cells will warm up a little more than normal.

To check the labeled capacity accuracy, you need to use the Break-In function. Put a cell in, select Break-In, and enter in the labeled capacity of the cell. This function takes around 39 hours to complete, so do it when you have some time and don't need to use the charger for other things. The battery manufacturers use a test very similar to the Break-In function to determine what label to put on the batteries.

Tom

 

[SilverFox]

Hello PhotonBoy,

If your charger uses -dV or dT/t to signal the end of the charge, the battery manufacturers recommend charging at a rate in the 0.5 - 1.0C range. When you charge at lower rates, the end of charge signal is not as strong, and you run the risk of missing it and overcharging your batteries.

While slow rate charging produces less heat, overcharging at a slow rate also destroys NiMh batteries. As does extended trickle charging.

The other rate, recommended by the battery manufacturers, is to start with a fully discharged battery and charge it for 16 hours at 0.1C. At the end of the 16 hours, you shut the charger down. If you want to do slow charging, remember to fully discharge your cell every time, and charge for 16 hours at 0.1C.

Initially, you will probably be able to get away with using slower charging rates, but eventually it will bite you and destroy your cells.

I might add that some battery manufacturers (Sanyo, GP, and Ray O Vac) use 1C charging when they are testing their cycle life. We ran across a Ray O Vac document that summarized the results of slow and 1C charging on cycle life. The 1C charging actually gave more cycle life than slow charging did.

Tom

 

[PhotonBoy]

Thanks, SilverFox; I'll include this information on an index card with my charger's instructions.

 

[Tatankha]

New battteries not reaching full capacity after first break-in cycle

Hello
I just purchased the MAHA C9000 with 8 2700mAh batteries. I performed a break-in cycle on the first 4 batteries and realized that the final available capacities for each batterie were lower than the 2700 mAh ( between 2570 and 2600 mAh) entered at the beginning of the process. Is that ok for brand new batteries? Do I hAve to run another break-in cycle and in that case do I have to completely discharge the batteries first?

Thank you very much for any useful answers!!!
Richard

 

[Mr Happy]

Re: New battteries not reaching full capacity after first break-in cycle

I just purchased the MAHA C9000 with 8 2700mAh batteries. I performed a break-in cycle on the first 4 batteries and realized that the final available capacities for each batterie were lower than the 2700 mAh ( between 2570 and 2600 mAh) entered at the beginning of the process. Is that ok for brand new batteries? Do I hAve to run another break-in cycle and in that case do I have to completely discharge the batteries first?

Your results seem quite normal and typical. 2700 mAh may be written on the label but such a large capacity is usually optimistic and few if any cells actually achieve this.

In light of this I would usually enter the break-in capacity as 2500 rather than 2700 just to be kinder to the cells.

 

[bbb74]

Hello PhotonBoy,
We ran across a Ray O Vac document that summarized the results of slow and 1C charging on cycle life. The 1C charging actually gave more cycle life than slow charging did.
Tom

Have you got a link for that? Thanks!!

 

[Tatankha]

Re: New battteries not reaching full capacity after first break-in cycle

Your results seem quite normal and typical. 2700 mAh may be written on the label but such a large capacity is usually optimistic and few if any cells actually achieve this.

In light of this I would usually enter the break-in capacity as 2500 rather than 2700 just to be kinder to the cells.

Thank you very much for your answer. Do you think a second break-in cycle would improve the final capacity of the batteries though?
Thanks again!

 

[Mr Happy]

Re: New battteries not reaching full capacity after first break-in cycle

Thank you very much for your answer. Do you think a second break-in cycle would improve the final capacity of the batteries though?
Thanks again!

Brand new cells often improve in capacity over the first few cycles. I think I would just use the cells rather than doing more break-in cycles. After all, you are not getting much value from them while they are still sitting in the charger.

 

[Tatankha]

Re: New battteries not reaching full capacity after first break-in cycle

Brand new cells often improve in capacity over the first few cycles. I think I would just use the cells rather than doing more break-in cycles. After all, you are not getting much value from them while they are still sitting in the charger.

Thank you for your answer. I will use the batteries as there are and see if they improve a bit after several discharge- charge cycles.
Thanks again!
Regards