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could some body explain this to me please?

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could some body explain this to me please?

Old 06-13-2012, 03:21 PM
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Turqui
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Default could some body explain this to me please?

i purchased a few weeks ago my first battery cycler, the hobbico accu-cycle pro, aniway i posted a tread and some fellows kindly answered and gave me some information; well one of the information was the measure if a bettery was good or not; well i was told that after the discharge-charge and again discharge, the numbers displayed in mah should be equal or more than 70% of the total battery capability written on the pack, bassically if the battery was 2500 nmih, to do 2500 x 0.7 and depending the number displayed on the accu-cycle i could determine if the battery was good or not.
well i did the process wich started yesterday with a battery; the brand is DaHannn(neber heard from about this brand before, it was on a plane i got); again brand is DaHann nihm RX battery 6.0v 5 cell and 2500mah written on it.
according the rule of measurement, 2500 x 0.7 is 1750 mah, so anything 1750 mah displayed on the accu-cycle and up, means its a good battery; well yesterday it did the discharge and full charge, today i started again the discharge process and its still discharging for a wile, and until now, so far the accu-cucle displays 2800 mah and continues ; is this possible?
any ideas?
i will appreciatte any information.
thanks.
Old 06-13-2012, 03:48 PM
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Default RE: could some body explain this to me please?

Yes, it is possible. Unfortunately without specc'ing out some rates and voltage cut-offs the number recorded can vary widely. I can see getting 50% easily on a good battery. I can also see gettingnumbers over 100%. The only number that is fairly reliable may be the discharge capacity at a certain rate down to a certain voltage cut-off.

Ultimately it is up to the user to decide if the pack is dong what is expected and user can slide his definition of good/bad at will. I guess to say it another way you may reject a pack , yet I may continue to use the pack for years in a different application.
Old 06-14-2012, 07:03 AM
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Rodney
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Default RE: could some body explain this to me please?

Yes your results are possible but rather doubtful. I'd check the equipment for accuracy of display. Can you measure the actual current during discharge and see if it is what you programmed? Can you double check the voltage readings with a second meter to see if they are accurate? Most times these devices are reasonably accurate but there can be an occasional miss fit.
Old 06-14-2012, 08:04 AM
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bgosselin
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Default RE: could some body explain this to me please?

Also, I would pay more attention to the amount of mAh taken out during discharge and what the termination voltage is.

During the charge cycle, the cell heats up near the end and most of that bit of charge is not being stored in the battery but dissipated as heat. So a good percentage of the mAh the charger claims is being put back in the battery at the end of the charge is not really going into the battery after all.
Old 06-14-2012, 08:13 AM
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Turqui
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Default RE: could some body explain this to me please?

Well, the battery is a 2500 mah,6.0v,5 cell, tx battery; wen started the process; the firt discharge displayes on the accu-cycle was 600, then went on full charge period for 15 hours; after the charge was completed, i started the discharge again and after the second discharge was completed, the number displayed on the accu-cycle was 3222mah, my guess is that this is the amount withrawn fron the battery. How a 2500 mah batery , showed a 3222 mah withrawn douring discharge?
Thanks again.
Old 06-14-2012, 08:18 AM
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bgosselin
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Default RE: could some body explain this to me please?

That's a pretty large variance between actual mAh and rated mAh. I would suspect that either the battery is rated very conservatively, the discharge terminal voltage is really low, or the charger is miscalculating somehow.
Old 06-14-2012, 01:57 PM
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Default RE: could some body explain this to me please?

The charger does differentiate between D and C capacities. Are you sure that was the D (discharge)? The D is the only one that is reasonably reliable . It is possible for the number to be skewed lower , but nearly impossible for it to be skewed higher.

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