When performed correctly (and as soon as possible after using the scooter), charging a set of scooter batteries is about as complicated as plugging in the right amperage trickle charger with automatic cut-off and disconnecting it at the end of its proper recharge cycle. However it may be nearly impossible to fully charge an old battery that is nearing the end of its usable lifespan, or perhaps has seen too many seasonal extremes of hot summers and cold winters. It may be tempting to try and force a charge that the marginal battery doesn't want to take, but this is a self-defeating and often a dangerous thing to do.
An inherent issue with almost any type of rechargeable battery, whether it sparks your Jazzy, your Vespa, your car or your MP3 player, is the problem of overcharging. Too much charge can cause heat and pressure to build up to inside of the battery until it deforms the exterior case. Automotive and marine batteries --which are in fact just larger versions of scooter batteries -- have been known to burst after being grossly overcharged. Although I wonder if the tales of overcharged iPods and mobile phones causing house fires are more urban myth than fact; even these small lithium-ion examples might reach combustion temperature under the right circumstances.
There are several ways your battery may try to tell you that it has been overcharged. Depending on your scooter model, very often the batteries themselves are hidden away under decks and panels, so it is a good idea to visually inspect them at the time of every recharge session. If your scooter battery is exhibiting any of these four symptoms, overcharging is probably the culprit.
- Won't Hold a Charge
Overcharging a battery will degrade the lead plates between the cells, causing the electrolytes to evaporate, reducing its ability to hold the charge. Reduced electrolytes further increase the heat inside of the battery, which boils off even more electrolytes in a vicious cycle ad infinitum.
As the lead plates degrade from the overcharging process, internal electrical resistance increases. This resistance is felt as excessive heat on the batteries' plastic case. This increase in heat further evaporates the electrolytes, causing even more destruction to the cells.
- Leaks & Residue
Scooter batteries are supposed to be fully sealed and all but leak proof. The heat and pressure from overcharging can cause the outer case to crack and leak acid. Often corrosive "salts" are visible around the seams.
- Warped, Swollen, & Busted
The most obvious sign of severe overcharging is a battery's case that has been warped, rounded, bloated or bulging. Excess heat and pressure inside of the battery can eventually split the case wide open, spilling acid. In extreme cases, a single spark from a bad electrical connection or even static electricity can ignite the explosive gas and spoil your whole day.
The best charge for almost any battery is a slow trickle charge which cuts off automatically when the desired charge is reached. On the other hand, the worst charge for a scooter battery is a boost or jump from one of those high-amp automotive chargers. A boost charge is far too "hot" for the relative low-amp batteries found on most small scooters, and will probably damage the batteries as much as rejuvenate their power.
It cannot be stressed enough that getting a good scooter battery recharge starts with having the correct battery charger for your scooter. If in doubt, read your ownwer's manual.