Hi There,

I just purchased (based on popular net info) a maha battery charger. The question I have is:

When do you condition your batteries?

Do you condition (I assume fully drain them) them when your batteries still have a charge in them (i.e. 50%), so that you can recharge them to their full capacity?

What happens to a (i.e. NiMH 1550mAh) battery when you charge (without conditioning)it when it still has a strong charge present? Does it just tap the charge up, or does energy get wasted? A friend told me that sometimes a battery will think that it is drained, when in fact it still has a charge on the account that the battery was recharged when it still has an i.e. 60% charge intact? - Does this make sense.

Thanks,

Haskell :^)

-- Haskell (haskell@squareusa.com), May 09, 2000

Answers

memory-effect is what they call it i believe... when the battery is half drained and then charged, the battery might think that it's lower limit (even though it's only half depleated) and thus shorten the capacity of the battery and the result becomes permanent... supposedly NiMH batteries are less succeptible to this memory effect...

-- Keat Lim (keatlim@my-deja.com), May 10, 2000.

Haskell:
Yes - it's called memory. NiCD (Nickle-Cadmium) batteries are vexed with this affliction. It's caused when you repeatedly charge the battery after only partially draining it in use. The battery will then remember this pattern and, while the overall current available from the battery remains constant, the voltage drops more quickly - which makes the equipment not work properly or report the battery as dead. In the past some manufacturers tried to override the memory effect by adding cells to raise the initial voltage - so a memorized battery with an early voltage decrease would not be noticed. This required larger packages, and equipment that knew about the scheme. Nowadays it's typically worth avoiding NiCd batteries in favor of the newer alternatives such as NiMH (Nickle Metal Hydride)which don't typically suffer from this problem.
It's worth noting though, that recharable batteries do not last forever. There is a finite limit to the number of times a battery can be charged. Frankly claims of a thousand charges are exagerated in my book - 300 to 600 times is more likely
So - when do you condition your battery? If you have NiMH - don't. It's not necessary. If you have NiCd then it depends on what your conditioner does. Some chargers will offer to discharge the battery for you before it charges it. This simply takes longer. Some conditioners actually pulsate the charge on the cells to reduce crystalization effects that overcharging can cause. Others drain the battery way-way down before charging - and this kind of conditioning is really one you don't want to do very often - it's a kill-it or cure-it step. My guess is that your unit (if it's a normally priced consumer unit) only discharges the battery nominally prior to charging. Use it only when you have not fully discharged the battery (only NiCd) before you charge it.
Be aware that dumb chargers are nasty little creatures. A dumb charger is one that just keeps on charging long after the battery has had enough. This blows more then the batteries credit limit - it uneccisarily heats the cells, and breaks down the chemistry that makes the battery work in the first place. Don't overcharge your batteries. Smart chargers know when to back off. They're also more expensive. Given the choice of a rapid charger, and a slow one - the slow ones are safer and will allow your battery to last longer. Rapid chargers are handy - but your batteries will not last as long due to the heat and assocated breakdown. In any case it pays to heed the recommendations on the charger and batteries for how long they should remain coupled.

Des

-- Dan Desjardins (dan.desjardins@avstarnews.com), May 10, 2000.

Please, please read the 'Digital camera batteries' article on www.dansdata.com, including the 2 links to www.repairfaq.org, if you want to know the facts about cells, batteries, charging, and 'memory effect'. Seems there's no such thing any more except the lower- maximum-voltage result of overcharging nicads.

-- Jeffrey Behr (behrjk@uswest.net), May 13, 2000.