The “How-To” of Rechargeable Batteries: Part 2
Second in an occasional series on rechargeable batteries
Choosing the Right Battery Charger
Trying to figure out which charger to purchase for your batteries can be a hassle. Often you’re the one needing to be recharged. Slow versus fast, rapid versus ultra-fast – what do those terms mean, anyway? In the “How-To” of Rechargeable Batteries: Part 1, we learned the difference between NiCd and NiMh batteries. Now let’s look at some different chargers. Just for fun, we’ll illustrate the differences with a few of our favorite primetime procedural dramas. Trust us; it’ll all make sense when we’re done.
The slow charger is like an NCIS marathon on cable. The average charge time for this most basic of chargers is between 14 and 16 hours, which explains why slow chargers are often called “overnight chargers.” If speed is a priority, this one’s not for you. The slow charger specializes in charging both NiCd and NiMh batteries. However, with no light to indicate a full charge and no automatic shut-off circuit once your battery is charged, slow chargers often overcharge batteries, and an overcharged battery can be as fried as your brain after too much TV. You’ll find these chargers for cordless phones, electric toothbrushes and children’s toys.
Think of the rapid charger as several episodes of Law and Order airing back to back. Its improved technology not only has a faster charge time, it also protects your battery from overheating. Don’t let the “rapid” name fool you, though: You might argue three to six hours is not rapid at all. Rapid chargers sense the charge of the battery by the voltage and currents and then indicate when the battery is completely charged, but they may still apply a constant charge, so take your device off when it’s full. The rapid charger services both kinds of nickel-based batteries and is generally inexpensive.
Fast chargers typically take about an hour, giving you just enough time to catch a fresh episode of CSI. The fast charger accommodates both NiCd and NiMh batteries. When the battery is fully charged, the charger will enter trickle mode, keeping the battery topped off. Nickel-based batteries will slowly self-discharge when not in use, and the trickle mode keeps the self-discharge at bay while the battery awaits its turn in your power tool or walkie talkie. Typically, fast chargers are used for commercial purposes in medical, military, communication and construction fields.
To continue our theme, think of ultra-fast chargers as the opening segment of CSI:Miami. They can recharge nickel-based batteries in about the time it takes for David Caruso to take off his sunglasses. Traditionally used on large batteries, ultra-fast chargers are the bullet trains of the battery world. And just as bullet trains need special tracks, ultra-fast chargers only work with batteries equipped to handle the ultra-fast charge. Make sure your battery can handle this bad boy, or you’ll be sorry. While your battery may not be blown to smithereens, it could be ruined if it’s placed in a charger it’s not suited for. Also, ultra-fast charging only applies up to about a 70% state of charge. Past that point, the ultra-fast charger lowers its current.
So let’s recap: Slow chargers = NCIS marathon. Rapid charger = an evening watching Law and Order. Fast charger = one episode of CSI. And ultra-fast charger = the opening scene of CSI:Miami. (It’s dramatic and effective, but you still need to watch the rest of the episode to fully absorb the charge, er, plot.).
- Charging your gadget’s battery the right way (blogbattery.com)
- Overcoming the Dreaded Memory Effect (blogbattery.com)
- California to regulate ‘vampire’ battery chargers (electronista.com)