ReZAP – recharge Alkaline batteries and save heaps


ReZAP wants to let people know that you can recharge single-use Alkaline batteries – AAA, AA, C, D, 6V and 9V as many as 15 times. No, it is not a con!

ReZAP is the brainchild of Managing Director Wilson Lee who started Digital Works in Melbourne in 1991. He has a bachelor’s degree in Electrical, Electronic and Computing Engineering. He released the predecessor LazerCharge in 1998 that proved you could recharge up to four Alkaline batteries at once for about 1 cent in power costs.

I have used a ReZAP Battery Doctor (model RBC883) since not long after its release in 2003 – 17 years ago. It is as good as the day I bought it and has recharged thousands of batteries without fuss.

Why did I buy a ReZAP way back then?

Well, at the time, we had kids in the nest. That means multiple TV remote controllers, torches, bicycle lamps, Dolphin Lanterns, battery operated salt and pepper mills, clocks, transistor radios/Walkman, smoke alarms, cameras, toys, mice, and many more items. We were probably spending $10-20 a month on batteries.

AA and AAA ‘Energizer’ Alkaline batteries cost over $1 apiece, 6V lantern batteries $13 and 9V over $10 each. Sure, you could buy cheaper ‘house’ brands or you could get rechargeable nickel-metal hydride batteries for about $5 each plus a charger for $20 or more. Batteries were a constant drain on the budget.

Recharge, reuse, recycle

Since then I could count on one hand the number of times we have bought new batteries. For two reasons!

First, you can safely recharge an Alkaline battery about 15 times using ReZAP’s patented AlkalineMax technology. The only time you may not get that many is if the battery starts leaking – and believe me that happens to the best brands as much as the cheapest low-cost ones!

Second, perhaps it is my somewhat Scottish nature, but I started collecting used batteries from friends and office colleagues. I had an unlimited supply of batteries paid for by others!

And the ReZAP Pro will also recharge NiCad (Nickle-Cadmium) and NiMH (Nickel-Metal Hydride) up to 1000 times, RAM (Rechargeable Alkaline Manganese) and Titanium batteries.

It does not do Lithium coin and camera style batteries currently, but there are plans for an add on module.

The original ReZAP battery Doctor (RBC883) costs $79.95. That is equivalent to recharging about 80 AA/AAA batteries and an awful lot less if you count 6V lantern and 9V fire-alarm batteries. I estimate I saved the purchase price in well under a year!


The new ReZAP Pro (RBC889) costs $119.95, and it quite a lot more things. That is what we are reviewing.

Catch – none

ReZAP uses a slow pulse charge system – it can take from four-to-sixteen hours, but that is gentler on the battery. An LCD readout tell you when its charging and finished.

When you insert a battery, the ReZAP computer analyses the cell to find its type.

If it is Alkaline (Zinc-Manganese Dioxide Zn/MnO2), then the AlkalineMax technology kicks in. If it is rechargeable, then it slow charges to avoid overcharging and prolongs the life of the battery.

You can mix different sizes and charge 1-4 batteries at once.


ReZAP will fill the battery to its ‘analysed’ capacity. For Alkaline that varies from 1700-2850mAh. NiCad is usually 600-100mAh, and NiMH is between 600-2750mAh.

Over time that capacity may reduce a little. I have seen no material degradation – it either works or not. ReZAP will indicate if the battery is dead, the wrong type or you have it in backwards!

ReZAP Pro RBC889

  • Website here (note this is the new US site. The old Australian site is here)
  • Country of Manufacture: China
  • Developer: Digital Works Melbourne
  • Price: A$119.95 but shop around
  • From ReZap online
  • Warranty: 12-months

ReZAP calls this the next generation and apart from not charging 6V lantern batteries it does mostly the same as the original Battery Doctor.

Although Wilson Lee, Inventor did ask me to clarify the above statement. The Pro adds (over the original Battery Doctor)

  1. The recharged alkaline batteries have up to 30% better in performance than before.
  2. Has a better and improved battery detection algorithm.
  3. Supports higher capacity batteries.
  4. The LCD allows users to check and see the exact voltage strength of each battery while recharging. No more guessing and uncertainty based on flashing lights.
  5. It supports up to four 9V batteries instead of one.  
  6. There are more safety protection schemes built-in to eliminate bad batteries and incorrect user operations to ensure absolute safe operation of the device.
  7. It employs universal 12V/2.5A 30W switching power adapter with changeable plugs for world travellers and can operate in caravans or on boats (compared to fixed AC power of either 240V/50Hz or 120V/60Hz).
  8. Full US Patent

OK Sorry Wilson – the Pro is streets ahead!

It will charge an AA up to 3000mAh and C and D to 8000mAh

We note that it has 4 x 500mA charge slots versus the Battery Doctor at 4 x 250mA. It also has two USB-A ports BC 1.0 (5V/.3A/1.5W) and a DC-Out 4.2/6/8.4V/.3A port.

Now BC 1.0 is long outmoded, and few USB-A/micro-USB devices use as little as .3A so keep this in mind. Here you would be better with a dedicated USB-A charger like the HPM that has 2.4A ports.

Similarly, there are few DC ‘plug’ devices that draw .3A. Take these ports as a bonus.

The LCD panel grew up

From individual LEDs to a graphic panel may seem to over complicate things. But for the techie, it also shows battery health. For example, a AAA battery should recharge to 1.68V (or higher), but an older one may only get to 1.5V.


ReZAP uses a new Active Charge Monitor technology that senses the characteristics of each individual cell and controls its charging cycle to custom charge each battery to its full capacity. It also senses if there is a chemical breakdown in the cell and will not charge it.


We placed four Coles brand Advance+ AAA (expiry 11-21) in the unit. These had been used approximately four times in remote controls. According to our battery tester, these were “inefficient”.

Note every ReZAP users should buy one. Jaycar have a digital one for $39.95 and a simple bad/good version for $13.95. It took under an hour to top them up.

We charged a 100% dead 9V battery – it took just over three hours. Based on our prior use of the Battery Doctor version, it is a similar time.

GadgetGuy’s take – ReZAP rezaps dead Alkaline batteries

If you are continually buying Alkaline batteries – more than a few dollars a month – then this will pay for itself in under a year. Plus, you are delaying sending batteries to the landfill.

We think it is a must for any sized home or business – savings in mice and keyboard batteries alone would cover its cost in a few months.

The older ReZap RBC883 got 4/5 on, and this is an evolutionary improvement over that. The fact that mine is still going strong attests to that.

And it works so well! It gets our unreserved recommendation. While this review gives it 4.7/5 (Excellent) it only lost a few points due to usefulness of the lower mA rating of the rear USB and DC ports. Had these even been 1A it would have been perfect.

We would like the inventor – Wilson Lee – to think about the next model. It would be perfect if it supported 18650 (and variants) Lithium-ion batteries as well as the later USB-C PD standards to at least 5V/3A. And it would probably cost twice as much!

Value for money
Ease of Use
Reader Rating1 Vote
Pays for itself in a year if you use $10 of batteries a month
Very safe and analyses each battery
USB-A and DC output ports are old tech