Blog

What Are the Chargers for NiMH (Nickel-Metal Hydride) Batteries?

Posted by Replacement Battery Store on Apr 22nd 2019

What Are the Chargers for NiMH (Nickel-Metal Hydride) Batteries?

There are three main types of Ni-MH battery chargers. Manual -- slow chargers, controlled by integrated timer; "fast" chargers and microprocessor-controlled "ultra-fast" smart chargers.

1.Manual Slow Chargers

These chargers use a really low current. In fact, these chargers need 36 hours to charge a 2000mAH Ni-MH battery. With this type of charger, the user must manually turn them off when the charging process is over. This implies a slight guesswork about loading time. However, they remain cheap and efficient.

2.Controlled by Integrated Timer "Fast" Chargers

This type of charger loads quickly for a certain time period and then they automatically switch to a mode called "trickle charge". These “fast chargers” will charge your battery for less than half of the aforementioned “manual chargers”. The greatest advantage is that you don’t have to worry when to turn them off.
However, timer-controlled chargers can’t determine your current battery status - whether it is fully or partially charged. The charger will attempt to charge your battery to the full extent of the time set. Please note these chargers aren’t suitable for the so-called "refreshing charging". However, high-quality timer-controlled chargers include sensors that stop the fast charging process if they detect a recharge (this is called "overcharging protection").

3.Microprocessor-Controlled "Ultra-Fast"

This ultra-fast, intelligent charger is the latest type and is fully automated. They continuously monitor either the voltage or temperature of your batteries and are able to accurately determine when to stop the fast charging process. Subsequently, when required it will switch to the “trickle charge” mode.

Ni-MH batteries in any condition can be fully charged for less than 3 hours without the risk of recharging. The best chargers in this class independently monitor and charge each cell (this is also called "individual observation").

Which Charger Do I Need?

Manual - slow chargers are cheap and efficient, but charging times are long and imply guesswork. However, if you don’t find it necessary for your Ni-MH batteries to be fully charged at all times, this slow charger type is a suitable choice for you.

Controlled by integrated timer "fast" chargers have some level of automation. But they are not suitable for a "refreshing charging" because the timer will charge them for the optimum time. However, most consumers prefer to use their Ni-MH batteries instead of scrapping or replacing them with new ones instead. Refreshing charge is only needed when you want your batteries to reach their peak capacity. Hence, a high-quality, timer-controlled charger is appropriate and is excellent for the price.

If you want to be sure that your batteries have maximum capacity, a microprocessor charger with delta V or delta T control is the solution. The process is fully automated, and the batteries can be refreshed.This is the only charger that delivers battery power to its maximum power.

I already have a manual charger for Ni-MH batteries - is it suitable for 2200mAh rechargeable batteries?

It is appropriate though you need to set the charging time for 2200mAh by adding 20% to the normal charging time of 1800mAh batteries (Add 10% for 2000mAh batteries).

How long do I need to charge N-MH batteries in my handheld charger?

Always follow the instructions for your charger. The disadvantage is that you have to manually calculate the approximate charging. It is calculated by dividing the battery capacity of the charging current, i.e. 1600mAh battery charged with 160 mA current will take 10 hours. Many experts recommend adding more time (up to 40%) to make charging effective, but this is true if the battery is completely discharged. It is recommended that you discharge the batteries before charging them, so you don’t recharge them. The alternative is to invest in an automatic charger.

Note: Don’t charge different capacity batteries in the manual charger, as there is a risk of recharging the battery with a lower capacity.

What does "delta V” control mean?

Delta V Control is an advanced method for detecting fully charged Ni-MH batteries. By continuously monitoring the battery voltage while charging, the delta V controlled chargers can accurately detects when to stop the charging process and to switch to trickle charging. Due to their refinement, the delta V (and delta T) controlled chargers are able to refresh partially diluted batteries without the risk of overcharging. Full microprocessor control is required.

What does "delta T” control mean?

This is the alternative to delta V control. When fully charged Ni-MH, batteries heat up faster. Chargers that use delta T control and monitor battery temperature, determine when to stop the charging process before significant temperature changes begin to take place. Full microprocessor control is required.