Battery Chargers – Types and Tips
No matter what type of a rechargeable battery you use, you will surely need a battery charger to replenish power to it once it is depleted or drained.
Based on the charging processes that they operate with, chargers can be divided in two main types or groups.
One process is called Timer-Controlled Charging and the other process is Smart Charging. There is a difference in price between the two but more importantly, a significant difference in the way they perform the task of charging your batteries.
TIMER CONTROL Chargers
As the name implies, these chargers operate with an automatic shut off timer that is predetermined and built in during manufacturing. Charging time for different chargers range from 4 hours for some to 27 hours for others. Regardless of how long they charge for, the point is that they stop charging automatically at this pre-defined amount of time. Timer Control Battery chargers are inexpensive but keep in mind that all they do is charge the batteries for preliminary set amount of time. This means that all the batteries receive the same amount of charge. But what happens when some batteries need less, or more? Some batteries might have been used a little bit and only require a small topping off. Respectively other batteries could be almost dead at the time of charge and need more than 12 hours of charging. If this is the case, then some batteries become overcharged and some batteries remain undercharged. Be careful because batteries that have become overcharged, are ruined. Batteries that are undercharged are not ruined – but they won’t give you the run time they were intended to deliver. And sooner rather than later, they’ll need to be charged again. With all this, less than outstanding news, why would people still choose timer-control battery chargers? Simple. The price of this type of charger is much less expensive than smart chargers and oftentimes it’s just a matter of budget.
The best part about Smart Chargers is that they have the ability to treat each battery individually. This means that each battery receives charge to the degree it requires it. One battery might be half full and only need to replenished half. Another battery might be 75% empty and would need and receive 75% the topping off power. This is quite an amazing technology! Yes, it costs more than does a timer control charger but no batteries can become over or undercharged with it. Over time, this higher price, greatly become absorbed by the preservation of batteries it gives you. Your entire battery inventory can no longer be at risk for ruin, with a smart battery charger.
TIPS when choosing a charger
- Use the correct charger for the intended battery chemistry. Most chargers serve one chemistry only. Make sure that the battery voltage agrees with the charger. Do not charge if different.
- The Ah rating of a battery can be marginally different than specified. Charging a larger battery will take a bit longer than a smaller pack and vice versa. Do not charge if the Ah rating deviates too much (more than 25 percent).
- A high-wattage charger shortens the charge time but there are limitations as to how fast a battery can be charged. Ultra-fast charging causes stress.
- A lead acid charger should switch to float charge when fully saturated; a nickel-based charger must switch to trickle charge when full. Li-ion cannot absorb overcharge and receives no trickle charge. Trickle charge and float charges compensate for the losses incurred by self-discharge.
- Chargers should have a temperature override to end charge on a faulty battery.
- Observe charge temperature. Lead acid batteries should stay lukewarm to the touch; nickel-based batteries will get warm towards the end of charge but must cool down on “ready”. Li-ion should not rise more than 10ºC (18ºF) above ambient when reaching full charge.
- Check battery temperature when using a low-cost charger. Remove battery when warm.
- Charge at room temperature. Charge acceptance drops when cold. Li-ion cannot be charged below freezing.
If you want lo learn more about battery charging, check one of our previous articles on this topic.