Batteries decline in performance, over time.
For rechargeable batteries, the decline will depend upon the battery chemistry, how the battery is used, and how it is maintained and charged.
For nickel-based batteries (NiMh or NiCd), the battery performance will decline mostly because of crystalline formation. It isn’t a memory issue (inasmuch as the battery isn’t remembering how hard it worked on previous occasions), but it is caused by partial discharging and, sometimes, poor charging.
What happens is that the crystals within the chemistry of the battery tend to group and grow into larger crystals, which increases resistance within the cell and causes the battery to seem empty before it really is.
The best avoidance practice is to “exercise” the battery every month or two with a good discharge and then a full charge or, if the cells are already delivering poor performance, to put them through a “reconditioning” programme on a suitable diagnostic device. The latter isn’t viable for cells costing a few $, but it makes a great deal of sense for power tools batteries, mobile phone batteries and similar.
For lead acid based batteries, a similar problem occurs with sulphur build up and, in this case, a multi-stage charger will often do the job and, if not, our diagnostic tools can put the battery through a thorough programme lasting, sometimes, for several days (but the batteries love every minute of it).
Modern battery chargers use fancy technology and sensors to look after the batteries in their care. For small batteries, the ideal charger will have “negative delta v cut-off” and temperature sensing. It’ll know when the battery reaches peak charge, and it will stop bothering it, other than giving it the occasional nudge.
For big batteries (lead acid), your charger should be multi-stage and, at least, should know when to go into float mode (minimal pulses to maintain a battery at peak power). Ideally the charger will also offer a desulfation stage, and might have several other interesting stages and flashing lights to entertain you.
Importantly, either you or the charger should know what type of battery you are charging and react accordingly. Both the fast charge and the float charge voltages need to change depending upon whether the battery is gel (13.8v and 13.2v respectively will work nicely), AGM (14.4v and 13.8v) or flooded/wet cell (14.8v and 14.2v). A 13.8v charge won’t hurt a flooded cell battery, but a 14.8v charge will harm a gel battery, quickly, and cost you more than a new charger would have done.
At Battery Business we test batteries for free.
If a battery can’t be restored, we will recycle it for you. You can drop off old batteries with us at your local store 7 days a week.
Contact your local store for any battery related question – we love to talk batteries.
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