Rechargeable batteries: How to choose the best battery charger

Battery charging technology is constantly improving and many modern smart chargers promise to charge your batteries in under an hour.

We’ve tested five of these smart chargers in the Which? lab. You can find out how the Duracell, Energizer, Uniross and Maplin chargers fared and which scored high enough to become a Which? Best Buy in our battery chargers review.

Here we explain a little more about the pros and cons of smart chargers, what to consider when choosing the best battery charger and how we put fast chargers to the test.  

Why use a smart charger?

Smart battery chargers, also known as delta-V chargers, monitor charge levels in each battery and stop charging just before it’s full.

They are usually the best choice for keeping batteries in good shape, because they prevent overcharging, which can reduce battery lifetimes.

How to choose a smart charger

There are several questions to ask yourself when choosing a smart battery charger, including:

• How fast do you want your batteries to be charged? Do you have time to charge batteries overnight, is charging in an hour or two quick enough or do you need a big boost in 15 minutes?
• Is it important to you that your batteries are fully charged every time? (if they are not fully charged then you’ll need to charge them more often)
• Do you want a charger that comes with rechargeable batteries? And is it important to you that these are high-capacity batteries? (The higher the battery capacity the longer the battery will last per charge).

If you decide you want a fast battery charger, check out our battery chargers review to find the smart charger that matches the rest of your needs. And if you need new batteries too, make sure you choose some Best Buy rechargeable batteries.

We tested five smart battery chargers including the Duracell 15-minute charger

How fast is 'super fast'?

We’ve only tested very fast smart chargers – those that promise to charge batteries in an hour or less. These offer maximum convenience as you don’t have to plan your battery usage in advance, however they do tend to be more expensive than slower models.

If you don’t mind charging your batteries for longer – such as overnight – then you might be happier with a slower, cheaper charger.

We have not tested the long-term effect on batteries that are charged in very fast smart chargers, but believe the convenience is likely to outweigh any long-term detrimental effects.

Smart charger prices

We’ve tested the Duracell 15-Minute charger, Energizer Accu Recharge 1-Hour charger, Uniross High-Speed charger, Maplin 30-Minute Ultra-Fast charger and Maplin 1-Hour Extra Fast charger.

When we bought these smart chargers in November 2011, the prices ranged from £27.99 to £39.99. However these are top-of-the-range fast smart chargers and you can buy slower, more basic models for less. The cheapest chargers we’ve seen cost less than £10.

All the chargers we tested can charge four batteries at once, but you can get bigger models that can charge eight batteries simultaneously.

Where to buy smart chargers

High street shops such as Argos, Asda, Homebase, Maplin, Robert Dyas and Sainsbury’s usually stock some smart chargers and there is a wide range available online on websites such as Amazon.co.uk and Play.com.

How we test battery chargers

In our test lab, we measure exactly how long it takes each charger to charge four batteries. We then run down each of the batteries in our computer-controlled test rig to see whether they have been charged to their full capacity.

We carry out this test with the batteries that the charger is supplied with, and then again with our own 2,600mAh high-capacity batteries. We also test the capacity our batteries achieve after being charged for just 15 minutes in each charger.

On top of this, we assess each charger for ease of use – including how easy it is to insert and remove batteries, noise, build quality and bulkiness of charger and ease of knowing when batteries are charged.  
Our total test scores ignores price and are based on:

• Charge achieved in 15 minutes - 30%
• Charging supplied batteries - 25%
• Charging generic (2,600mAh) batteries - 25%
• Ease of use - 20%

More on this...

• Visit our battery chargers review
• See full test results for all rechargeable batteries tested
• Check out our Best Buy disposable batteries