As rechargeable batteries continue to grow in popularity, more and more people are picking up packs of NiMH batteries at the supermarket or online to put an end to the never-ending cycle of disposable batteries. When purchasing NiMH rechargeable batteries for the first time, however, many people overlook the importance of choosing the right battery charger for their specific lifestyle and needs. The following article explores the different features and options you can expect to find when shopping for battery chargers and will help you to make the right choice for your specific needs.
Basic Chargers vs. Fast Smart Chargers
Basic chargers are designed to be slow chargers that you leave on all night while your batteries recharge, and are typically the least expensive style of battery charger. However, their affordability sometimes comes with a caveat: basic battery chargers tend to either undercharge or overcharge your rechargeable batteries. This is because they apply a set charge rate and then shut off with a timer. As a result, high-capacity batteries may not receive a full charge before the timer switches off. Conversely, batteries that are only partially discharged will receive the same timed charge overnight. This can cause your batteries to overcharge and lead to overheating and potentially permanent damage to your batteries, which will reduce their lifecycle. Additionally, basic chargers do not have protection features to prevent overcharge, such as temperature and voltage drop sensors. Also, if there is a power interruption during charge, the timer will start over and result in your batteries being overcharged.
Smart chargers, on the other hand, have advanced microprocessor controls called Delta V Control, which allow you to safely charge your batteries without worrying about overcharging them. Smart chargers will charge your batteries more consistently because they can sense when your batteries have reached full charge by measuring the rise in voltage. At full charge, they switch to a “trickle charge” mode, which keeps rechargeable batteries fully charged until ready for use. Smart chargers also protect your batteries from overcharging and overheating, which will prolong the life of your batteries. If the extra cost of these features is within your budget, it is well worth the extra expense, as it will save you money due to longer battery life and more battery cycles.
If you’re looking to go one extra step beyond smart chargers, you can also opt for a battery manager. A battery manager offers the same functionality as a regular smart charger, however it is also capable of other useful tasks, such as conditioning, discharging, and analyzing battery capacity. Most battery managers deal with each battery individually, allowing you to perform different functions at the same time. If you use rechargeable batteries for work-related tasks that rely on an optimally charged set of batteries, having a battery manager is the best option.
1-Hour Chargers vs. 4 to 6 Hour Chargers
The best battery chargers on the market will balance speed with gentleness and completeness of charge. Charge speed is always an important feature, but the faster the charge rate, the more internal wear on the battery, which will ultimately shorten the battery’s life. The ideal battery charger will charge fast, but also provide a relative, gentle charge rate and a smart Delta V chip to protect the charger from overcharge / overheat damage, while at the same time provide a complete charge to maximise run times between chargers.
If you do choose to go with a fast charger, you should know that the maximum number of charge cycles your rechargeable batteries can endure will be somewhat reduced. Battery manufacturers claim their batteries can attain up to 1000 charging cycles, but this is dependant on several factors, including the rate of charging and discharging as well as the depth of discharge between charge cycles. In other words, if you want to attain the highest number of charge cycles, use a slow overnight charger and begin charging them before they are 50% discharged (even though this isn’t always the most convenient option). In my opinion, a charger that can charge in about 4 to 6 hours is the best trade off between convenience and not frying your batteries during each charge.
2-Channel vs. 4-Channel Battery Chargers
While speed and “smart” features tend to be what consumers look for in a high quality battery charger, choosing the right amount of channels for your charger is also a critical decision. As a rule, 4-channel chargers are always a better choice than 2-channel chargers. This is because a 2-channel charger only charges 2 sets of 2 batteries at a time. What this means is that, if 2 batteries of differing charge (1 flat and 1 half charged) are charged together on the same channel, only one of them will get fully charged. However, with a 4-channel battery charger, all 4 batteries are charged independently, so that they each receive a full, even charge.
Which Chargers Can Be Used Overseas?
If you like to travel and take your electronics and gadgets with you, then you have to be careful about recharging your batteries overseas. There’s a simple yet critical rule to observe: only use your charger overseas if the charger’s AC adaptor plug is rated to accept 240V. There should be a sticker on the adaptor near the plug listing the power specifications. If it says 100V – 240V 50-60Hz it can accept other countries power as long as you have the applicable adaptor to allow the plug to fit in that outlet. The sticker should also have a tick symbol on it to show that it has been approved for use in Australia. Many battery chargers purchased from overseas do not have any approval for sale or use in Australia and may not meet Australian Safety Standards.
Should Batteries Get Hot When Being Charged?
Yes, when charging Ni-Mh and Ni-Cd batteries, they do increase in temperature substantially due to internal resistance. The batteries will feel warm to hot when charged. According to specifications, they can heat up to 55 deg C (131 deg F) during rapid or fast charging. Allow your batteries a few minutes to cool down before using them. Also, it is a good idea to leave the dust cover down when charging to allow airflow and help dissipate the heat.
How Long Will It Take To Recharge My Batteries?
This is like asking how long does it take to drive from Melbourne to Sydney! Unless you know how fast you are going, you will have no idea how long it will take. The same is with a battery charger: unless you know how fast it will charge, it is impossible to guess how long it will take to charge. The Vapex VTE 2000 charger, for example, has a charge current of 500 mA and will charge 2900mAh batteries in just under 6 hours. As a general rule, charge time is calculated by charge current / battery capacity. In this case 500 / 2900 = just under 6 hours.
So to sum up, for most people and for most uses, a charger that can charge in 4 to 6 hours and has Delta V microprocessor controls and 4 independent charging channels is the best choice for safety, convenience, and wear and tear on your batteries and will get the most out of your batteries.
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