MiMh Cycling on ProPeak

[Steve]

I suspect one of my NiMh flight packs is of dubious condition, so I put it on a 5 time discharge/charge cycle last night to see how it shapes up. The pack is a 4200 mAh Sub-C NiMh 4 cell at 4.8V. My charger is a ProPeak Sigma EQ which basically has the same screen and very similar software to the popular Prodigy 2 charger.

I've checked the read out this morning and noted down all the figures but don't have the instructions to hand (have got them at home but really could use an answer sometime today if poss).

Here's what came up on the screen and the blue is my guess at what it means - please correct me if I'm wrong:

ChgPeak = 6.16V The maximum fully charged voltage during the whole cycle
DchgAvg = 5.11V The average voltage at which the discharge process was stopped
ChgCAPA = 990 mAh The Charge Capacity Average - the average mAh that went into the pack during the 5 cycles
DchCAPA = 2607 mAh The Discharge Capacity Average - the average mAh that came out of the pack during the 5 cycles
Input = 11.87V Not sure about this one
Output = 5.55V Final output voltage or average output voltage maybe?

Thanks

[glen_j]

ChgCAPA = 990 mAh The Charge Capacity Average - the average mAh that went into the pack during the 5 cycles

are you sure this one is correct? i would have though this should be 2990 to coincide with the amount discharged, if so its most likely ok, what ampage are you dischaging /charging it?

[heliphil]

It could be just magic batteries - 990 in 2607 out !!!!!

[Steve]

Not sure what the titles mean - I've copied them as they appear on the screen.

Discharged at 1A, then charged at 4.2A, 5 times.

[glen_j]

at those charge/discharge rates i'd say its fine if its putting in around 3000mah

[Steve]

It was fully charged when I went to the field yesterday and was seriously low (down to 4.65V) and well into the orange/red on the led indicator) after just 2 minutes hovering.

Hence, I suspect it's mullered, but I'd like to understand the numbers that tell me so, if you know what I mean.

[glen_j]

the two number to look at are these.
ChgCAPA = 990 mAh The Charge Capacity Average - the average mAh that went into the pack during the 5 cycles
DchCAPA = 2607 mAh The Discharge Capacity Average - the average mAh that came out of the pack during the 5 cycles

they should be very close to the actual capacity of the battery or at least 3/4 of it, anything below and its worth considering replacing them. it is possible that the charger false peaked when you charged it last and said it was full when it wasn't giving you the problems you had. make a note of how many mah goes into the pack. nimh batteries start getting warm when they are nearing a full charge so another way to ensure the pack is charged is to feel it and see if its warm, its one of the ways i check my batteries for the glow clip and tx to make sure they haven't false peaked and seems to be going well.

[Steve]

Thanks, but I still don't understand what the abbreviations used on the screen mean. I've now checked the destructions and it simply doesn't explain them at all - shows a page with them on but no explanation of what each abbreviation stands for.

Things like ChgCAPA - I would assume this stands for charge capacity, but is it an average over the 5 cycles, or the best result of the 5, or the worst result or what? Same questions for DchCAPA?

Also Input and Output voltages? Could the Input be the voltage that the unit is working on after step down from the mains supply? Is the Output voltage measured right now, or an average over the 5 cycles, or a maximum, or even a minimum?

If it's the 990 and 2607 figures that are important, then I guess 990/2607 = 38% would be my guess at the condition of the pack = poop!

Instructions are a crock!

[Brian Gifford]

Steve, the only one I know for sure is the input voltage. That's the DC volts to the charger provided by the charger's internal power supply, which you woukd expect to be 12v, as that's the same as the external input for a battery, etc. I'm away ATM, but I'll dig the charger out tomorrow evening & see if I can help any then.

[Wayne's World]

Aging NiMh cells will peak early if you charge them too quickly. At 4200mAh charge current a good pack will be okay, but not an aging one. Set the charge rate at 1A or lower and leave it over night. Then see what the total charge capacity is. If it is still low, then one (or more) of the cells has got a high internal resistance (poorly).

[Brian Gifford]

I suspect one of my NiMh flight packs is of dubious condition, so I put it on a 5 time discharge/charge cycle last night to see how it shapes up. The pack is a 4200 mAh Sub-C NiMh 4 cell at 4.8V. My charger is a ProPeak Sigma EQ which basically has the same screen and very similar software to the popular Prodigy 2 charger.

I've checked the read out this morning and noted down all the figures but don't have the instructions to hand (have got them at home but really could use an answer sometime today if poss).

Here's what came up on the screen and the blue is my guess at what it means - please correct me if I'm wrong:

ChgPeak = 6.16V Maximum volts in
DchgAvg = 5.11V The average voltage during the discharge
ChgCAPA = 990 mAh ?
DchCAPA = 2607 mAh ?
Input = 11.87V DC Input to Charger from internal PSU
Output = 5.55V average output voltage

Thanks

Steve, had another look, and these are my best guesses till I can have a look at my charger.

HTH

[Steve]

Aging NiMh cells will peak early if you charge them too quickly. At 4200mAh charge current a good pack will be okay, but not an aging one. Set the charge rate at 1A or lower and leave it over night. Then see what the total charge capacity is. If it is still low, then one (or more) of the cells has got a high internal resistance (poorly).

Yep.

I've got my trusty old MainLink Systems cycler out to do a discharge and trickle charge on the pack. This will probably take 24 hours to complete as I can't alter the charge current, but at least I understand the number that it spews out at the end of the cycle.

Just seems a shame that you buy something more modern that has all the bells and whistles and it's let down by the paper work.

[Steve]

Steve, had another look, and these are my best guesses till I can have a look at my charger.

HTH

You may well be right. But it's the current values I'm interested in, not the voltages as they will give me useful info about the state of the pack.

[Wayne's World]

As far as I know;
ChgCAPA = Last charge capacity
DchCAPA = Last discharge capacity

[Steve]

As far as I know;
ChgCAPA = Last charge capacity
DchCAPA = Last discharge capacity

That would make sense.