09-26-2021, 01:39 AM
That's the bad news. The good news is that if you're using a rechargeable battery, you can make the chemical reactions run in reverse using a battery charger. Charging up a battery is the exact opposite of discharging it: where discharging gives out energy, charging takes energy in and stores it by resetting the battery chemicals to how they were originally. In theory, you can charge and discharge a rechargeable battery any number of times; in practice, even rechargeable batteries degrade over time and there eventually comes a point where they're no longer willing to store charge. At that point, you have to recycle them or throw them away.
All battery chargers have one thing in common: they work by feeding an electric current through batteries for a period of time in the hope that the cells inside will hold on to some of the energy passing through them. That's roughly where the similarity between chargers begins and ends!
The cheapest, crudest chargers use either a constant voltage or constant current and apply that to the batteries until you switch them off. Forget, and you'll overcharge the batteries; take the waterproof battery charger off too soon and you won't charge them enough, so they'll run flat more quickly. Better chargers use a much lower, gentler "trickle" charge (maybe 3–5 percent of the battery's maximum rated current) for a much longer period of time.
Slightly more sophisticated timer chargers switch themselves off after a set period, though that doesn't necessarily prevent overcharging or undercharging because the ideal charging time varies for all sorts of reasons (how much charge the battery held to begin with, how hot it is, how old it is, whether one cell is performing better than others, and so on). The best chargers work intelligently, using microchip-based electronic circuits to sense how much charge is stored in the batteries, figuring out from such things as changes in the battery voltage (technically called delta V or ΔV) and cell temperature (delta T or ΔT) when the charging is likely to be "done," and then switching off the current or changing to a low trickle charge at the appropriate time; in theory, it's impossible to overcharge with an intelligent waterproof car charger.
Nickel cadmium (also called "nicad" or NiCd), the oldest and perhaps still best known type of rechargeable batteries, respond best either to fairly rapid charging (providing it doesn't make them hot) or slow trickle charging.
Most people tend to put things on to charge "overnight" without paying too much attention to exactly what that means—but your batteries will work better and last longer if you charge them for the right number of hours. How long is that? It can be very confusing, especially if you use batteries that didn't come supplied with your waterproof marine charger. Never fear! All you have to do is read what it says on your batteries and you should find (often in tiny writing) the recommended charging current and charge times. If you have a basic charger, simply check its current rating and adjust the charge time accordingly. Bear in mind what we've said elsewhere about matching your charger to your batteries, however.
Lithium-ion rechargeable batteries are usually built into gadgets such as cellphones, MP3 players, digital cameras, and laptops. Typically they come with their own chargers, which automatically sense when charging is complete and cut off the power supply at the right time. Lithium-ion batteries can become dangerously unstable when the battery voltage is either too high or too low, so they're designed never to operate under those conditions. If the voltage gets too low (if the battery discharges too much during use), the appliance should cut out automatically; if the voltage gets too high (during charging), the electric transportation battery charger will cut out instead. Although lithium-ion batteries don't show a memory effect, they do degrade as they get older. A typical symptom of aging is gradual discharge for a period of time (maybe an hour or so) followed by a sudden, dramatic, and completely unexpected cut-out of the appliance after that. Read more about how lithium ion batteries work.