DISCHARGE CAPACITY DIFFERENCES BETWEEN 2 CHARGERS

Hello,
I have a C9000 and an iCharger 106B+ hobby charger. I have experimented charging/discharging several LSD/non-LSD niMh D and AA cells (at the same CHARGE/DISCHARGE rates, of course). I notice the DISCHARGE capacities shown on the C9000 are always higher by about 100 - 150mah on the the 6 cells I have tested. What could be the reason for this?
Which between the two figures should be the 'real' capacity?

Different cut-off voltages, maybe? C9000 has 0.9V cut-off - try re-testing with same value on your hobby-charger.

It is also possible you are charging first on the chargers and the finish voltage of one charger is higher than the other. Another thing to consider is the discharge current used, a higher discharge current will usually give you a lower capacity as even nimh has some internal resistance to them such that higher currents incur more power loss to heat.

To Shadowww and Lynx:
I have tried all combinations. Cells charged by C9000 first, or the other way around. All values, rates, cut-off voltages are the same (since my iCharger can duplicate the C9000's fixed terminal voltage cut-off and other values). Is it because the C9000 is a pulse charger (I believe it is, isn't it?), and the iCharger is not? All my cells are marked, values recorded on which charger, etc.

I'm seeing similar differences between my iCharger 206B and a C9000.

The C9000 uses pulsed charging and discharging - if anything, this should reduce the capacity that the C9000 shows, so I'm not yet sure what the cause is either.

I've got a few ideas for tests that I'm planning to do to see if I can work out the reason.

It might come down to the fact that neither device is industrial grade and one or both are simply not as accurate as you would expect.

It might come down to the fact that neither device is industrial grade and one or both are simply not as accurate as you would expect.

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That is most likely the case. Think about it. $50.00 for a battery charger /analyzer , get real.
The real stuff would be considerably more costly.

lwknight said:

That is most likely the case. Think about it. $50.00 for a battery charger /analyzer , get real.
The real stuff would be considerably more costly.

Click to expand...

You could be very well correct there, but my concern is not the accuracy between the two chargers, but why does the c9000 consistently gives out a higher discharge capacity between the 2 chargers on the same cells.

Even if neither charger were out of calibration by much but one was positive and the other negative the spread would be more profound. It seems to me that its not really worth a worry.
The high to low is around 5% I would not be able to realize a difference in the actual use scenario. We may be talking a difference of 75 minutes vs 82 minutes run time on high or something like that.

lwknight said:

Even if neither charger were out of calibration by much but one was positive and the other negative the spread would be more profound. It seems to me that its not really worth a worry.
The high to low is around 5% I would not be able to realize a difference in the actual use scenario. We may be talking a difference of 75 minutes vs 82 minutes run time on high or something like that.

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I know what you mean. What I am trying to find out is WHAT is making the difference, the way in or of the 'discharging process' perhaps? If so, then what 'process' gives (let's say) the correct capacity? Pulsed or linear?

Although pulsed vs linear can make a difference, I don't think it will be the cause of the difference in this case.

It would be interesting if someone had an industrial level analyzer and could compare it to a C9000 to see how close it actually is. The C9000 is supposed to be accurate to about 1% from memory but there's no guarantees - inaccuracies in measuring either current or time would affect the end result and that applies to any analyzer.