Battery Question

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K2KOH

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OK...just for laughs I pulled out my batteries from my BCD396T box. Yes, I had never used them. So I threw them in the rapid charger. I switched on the voltage and literally watched the voltage drop. I now have them in my MAHA charger and doing a conditioning. Is there a chance that will help or are these batteries done since they sat around for so long? Thanks
 

cdknapp

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It's going to take some time, but if you don't see improvement after the first conditioning cycle, you should probably try running them through at least a couple of more times before you write them off. If you're charger will allow it, I would also knock the recharge rate down as far as you can go, so they charge at a slower rate (I actually use the slowest rate whenever I use my top-end chargers that allow it, even in routine recharging). If nothing else, this reduces the heat generated during the charging process, and allows the charger to work via true voltage and not have it cut off ahead of time due to overheating.
Just my opinion, but I have actually 'resuscitated' some older batteries doing it like this. And the routine slower rate charge does actually extend the life of the cells.
Good luck!
 

K2KOH

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I think the MAHA does discharge them all the way. I'll run it this way now, then do the slow condition. Thanks, guys!
 

RickLeb

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I would also knock the recharge rate down as far as you can go, so they charge at a slower rate (I actually use the slowest rate whenever I use my top-end chargers that allow it, even in routine recharging).
The Maha C9000 charger uses a very slow charge rate as part of their "Break In Mode". This special charging mode can run from 39-45 hours. However MaHa says this about routine charging:

"Charging at a rate below 0.33C and above 1.0C is not recommended.
Charging too slow may prevent the charger from terminating correctly.
Charging too fast may damage the battery."

As a battery charges the voltage slowly rises. At the point of optimum charge the voltage will quickly drop a few millivolts before continuing to rise further. If the charge rate is too slow, this drop may not be detected by the charger, and the charge will continue beyond the optimum point. In the case of the C9000 the voltage will continue to rise to the point where the C9000 considers the voltage excessive, and shuts down the charger for safety reasons.
 

nanZor

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Maha has actually raised that value to 0.5C instead of 0.33C to ensure a good delta-v detection in later documents.

Super slow charging, such as done in break-in mode, is so low current that no delta-v can be detected, so it relies upon a typical timed slow charge cycle in break-in mode to quickly bring new or neglected batteries up to full capacity. You can do the same by merely using them for a few cycles. Break-in just readies them faster.

Super slow charging is usually recommended by battery manufacturers since they can not individually vouch for the accuracy of each and every fast charger out there. Fortunately Maha is very accurate with the C9000 as long as you supply 0.5C to 1C or thereabouts to get that delta-v. Super slow charging is also the easiest and cheapest way for consumer products to get batteries charged by just using simple timing.

This does not actually mean that super slow charging is beneficial with modern batteries. Batteries from this century have much less internal resistance, and can handle faster (not super fast) charging, however the urban legend about slow charging is just too established from users who used batteries in the 80's. :)

If you look at Sanyo Eneloop documentation intended for commercial users / oem's, you'll see that 1C actually nets you the best cycle life, provided you use a quality charger that detects delta-v accurately.

Since 0.5C is the real minimum, the "no man's land" between a break-in current of typically 0.1C to a minimum of 0.5C for normal charging will actually present the most risk.

Don't forget that Maha C9000 will give you a value for internal resistance upon the first insertion of the cell, and this value is shown only once - thereafter the cell voltage, and not the internal resistance value will be displayed. You can determine if you are using some cheap, damaged, or otherwise neglected cells:

1.6 - fresh new battery
1.8 - middle aged yet still usable
2.0 - old aged, high in internal resistance, lowered capacity. Time to recycle.
2.2 - Maha will refuse to charge.

Some may be tempted to get around the refusal to charge cells with high internal resistance by putting them into a dumb slow-charger. Not smart - the battery is more resistor than battery, and now you are headed for a problem. Heed the warning by Maha - it is there for a reason.
 
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