BONAI 4 Bays AA AAA Ni-MH Ni-CD Battery Charger, LCD Display Smart Charger With Unique USB Design(Micro USB Cable Included)

I bought my first one of these 2 years ago, and recently the USB socket became loose and intermittent. I looked inside and saw the small socket had become detached from the printed circuit board. Nevertheless I like the small size of this charger so I bought another one. This time I opened it to see if I could put some glue in to strengthen the socket (don't do this yourself unless you know exactly what you are doing, and also any warranty may be void). I found the printed circuit has been modified and the USB connector is mounted much more securely. This is a great little charger that fits nicely in my camera bag.

A brilliant piece of kit that operates from USB power supplies and can charge AA/AAA Batteries without frying them; the USB supplies I use are all regulated to 5 volts, so no chance of overcharge as can happen with many chargers. Could work from a power supply pack, but I would recommend that a power pack should be rated at around 25000mAh otherwise the pack would run out of power before fully depleted AA batteries were fully charged. Can be used with a computer/Laptop USB output, particularly more modern machines.

The specifications are a little misleading in that it doesn't draw anything close to 2A from the USB supply: but then you wouldn't expect it to since the output to the batteries is only 1.2V rather than 5V. So a basic 1A USB supply is all that is needed to achieve the maximum advertised charging speed, in fact. There's nothing to be gained from using a better one. This is a smart charger rather than a fast charger. I haven't measured the output, but assuming it is indeed delivering the claimed 500mA to each AA battery at 1.2V, that would make it about 55% efficient (drawing 4.36W and putting 2.4W into the cells - see picture). Far from great. But I think NiMH charging is generally only about 66% efficient anyway? Certainly, the charger electronics seem to get warmer than the batteries themselves -- but nothing gets actually hot at this charging rate (which is C/4 for 2000mAh capacity batteries). The charger seems to pulse the (input) current down and then back up with increasing frequency as the charge cycle progresses, which one can only hope is the microcontroller doing its thing to try to assess how full the batteries are... Then after the batteries show as fully charged, rather than settling down to a constant trickle charge, the input current seems to be all over the place... Hopefully that is also part of the 'smartness'... although the batteries do, strangely, stay very warm if left in the charger... I haven't done any tests yet to see whether the batteries are truly charged to full capacity, but overall this seems like it may be a useful gadget to have. Just have to bear in mind that, for use on the move, recharging a set of 4 x 2000mAh AA batteries using this charger will take around 5000mAh out of the quoted capacity of a Li-ion USB power bank (17.44Wh at 3.7V plus some conversion losses). Ideal for use with a car cigarette lighter adapter during a 4-hour journey though.

Primarily purchased this charger to recharge sets of eneloop pro batteries to use with an xbox controller, works well, the pros for me are as follows Pros USB POWER COMPACT AND EASY TO STORE DOES BOTH AA & AAA CAN CHARGE INDIVIDUAL BATTERIES, this very useful since I have 2 mice in the house that both power from a single AA battery. CONS A LITTLE SLOW AT CHARGING, not really an issue if u plan to have a spare set of batteries so you can interchange while your charging. Have already replaced all AA batteries in the house to be part of the recharging chain, plan to do exactly the same with AAA ones, of which there are several remotes around the house relying on them, so no more need of disposing of used batteries and instead can rely on a chain of recharging batteries for every device that requires them thought the entire house

This charger is much smaller than I expected as i didn't really check out the dimensions on the advert. To this extent it is perfect for travelling. However it's size does not affect its use. You add your batteries it determines what they are made of and charges accordingly. Each battery has its own LCD which displays battery and charge info. Its easy to use and charges. Its just what I needed.

We're no strangers to smart chargers, we currently use a couple of nitecore intellichargers, but these are pretty much in constant use with lithium batteries. So the decision to get this was based on the need to recharge standard rechargeable AA/AAA (Amazon brand, actually) after our old energiser charger decided it had reached the end of it's life. We aren't convinced this works as well as the listing states. Our main concern is the fact that the charger itself gets very, very warm. A read back through other reviewers remarks would indicate that this seems "normal". However, heat is energy transfer, and as you're supposedly depositing electrical energy into the batteries, any transfer of energy into heat should theoretically be within the batteries, not the charger itself! I'm not pretending to be an expert on electronics here, but if the charger itself is getting hot I wouldn't have thought it's working too efficiently (it's hard to ascertain if the batteries are slightly warm because of the charger being very warm). Our last AA/AAA charger didn't get warm and our nitecore intellichargers don't get warm so what's going on here then?! The USB cable is pretty short. How much do these things cost to manufacture? It always irks me when a manufacturer, who produces something with convenience in mind (such as ease of use for travel), cannot provide something as simple as a decent length of cable. If a longer USB cable in some way affects the performance of this charger, I would again question the quality of this charger. I'm only guessing that's the reason for the short cable. This thing needs a longer USB cable to make the actual convenience work! Once the batteries are charged, we've noticed (using our smart USB charger) that the chargers power input seems less of a trickle charge and more of a zigzag power demand. Hmmmm! It's pretty damned slow to charge compared to our previous Energizer wall charger. The display is handy enough. Overall, this charges the batteries okay, but we just aren't convinced this has the IQ of a good quality smart charger.

I already had a fast charger, but it seemed to be saying more and more of my rechargeable batteries were bad, and because that charger charges 2 batteries at once, it would kick them out 2 at a time. This charger charges batteries individually, and so assesses them one at a time. Yes I have still had to throw away 7 bad batteries, but the rest have charged OK. Only time will tell when it comes to seeing how well they have charged, but at the moment it's looking good. The charger is very lightwight, and you will need to have a USB power supply to plug it in to. The package includes the charger and a short USB cable. The only issue I have with this charger is that the LCD display is quite hard to read at times. Apart from that, it charges fine and quite quickly too.

Didn't seem to charge the batteries fully. It showed them as fully charged but when I put them into another charger they continued to charge for quite a while until full. Sorry, but I had to return it. UPDATE 10.12.2025: Following my review I was contacted by Bonai and given some interesting information as follows: ''..... regarding your mention of the battery taking a long time to fully charge after being placed in another charger, this might have led you to mistakenly believe that the charger wasn't fully charging the battery. As long as the charger's cable is connected to a 5V/2A adapter and there are no errors or other abnormalities during the charging process, and the battery can be fully charged from empty, it means the charger is working properly. Let me explain the reason for this situation: A 1.2V battery has a maximum voltage of 1.45V when fully charged. After removing the battery, the voltage will drop back to around 1.2V~1.3V. This is the battery undergoing a voltage reduction process. Therefore, putting it back in the charger or placing it in another charger will trigger a recharging detection. However, this is not recommended. If the battery is not used after being fully charged, do not repeatedly charge it in a short period of time. If the battery will not be used for a long time, you can charge it once every two months.'' Excellent follow-up and pleased to find a helpful Company who obviously take pride in their products. Thank you.