Battery made of paper to charge iPhone 30 times using 2 litters of water to be sold by the end of the year

The impact of the product made the maker's stock has go up 58%

Naoki Yoshioka
Naoki Yoshioka

XAMOSCHi Chief Editor

Establisher of tempo, Inc. a web production company. Naoki has been in the web industry ever since he established the company in 2000. He specializes in tech, culture and also loves international movies and literature. Naoki is also keen on studying old Japanese material arts (Sousuishiryu-Kumiuchi-Koshinomawari: Seirenkan and Aikido: Aikikai) and continues his training until today.

The title may be somewhat confusing, so I’ll explain in order.

HURUKAWA-DENCHI, a traditional battery maker announced their new product, the MgBOX.

  • The MgBOX operates as a battery by just adding water to it
  • You will need 2 litters of water
  • There are 2 USB output terminals
  • Its capacity is 300Wh, the power voltage is DC 5.0V and the current is 1.2A
  • It is possible to switch on and off for up to 5 days, by using the reset button
  • Long life (It is said to be storable for 100 years)
  • All parts except the cell and cables are made of paper
  • Size: 233×226×226 (mm)
  • It weighs 1.6kg when stored, when there is water in it, it weighs 3.6kg
  • Initial sales will be made to municipalities only
  • Price is undecided (There is news that it should be around 10 thousand yen)



If you are familiar with batteries, then you may notice by its name that this MgBOX is actually the Magnesium-air fuel cell, whose technologies are already established. Revolutionary points of the MgBOX are:


  • It has succeeded in lowering the cost by adopting an oxygen catalyst that does not use rare metal
  • If it could actually be sold at the price of 10,000 yen, it would be an outbreak for batteries
  • Since it is disposable, a special kind of paper was used for the package so it could be disposed easily
  • Therefore, if you remove the USB and the cables, it can be treated as an combustible item
  • It would have plenty of energy to charge smartphones and lights in cases of emergency
  • It only weight 1.6kg when it does not have water in it, and you can stack up to 6 pieces. Its light, compact and easy to store.
  • It will work with tap water, sea water or even sewage water



It may seem to revolutionary to believe, but is has been proved that it works in various exhibitions. In the first place, they are a traditional maker with plenty of experience, so it shouldn’t be fake.

Japan is a country where disasters occur frequently. The convenient and high-capacity emergency battery gathered the market’s attention at once, and as a result, HURUKAWA-DENCHI’s stock has risen 58% in 3 consecutive days. In the initial press release from HURUKAWA-DENCHI, they commented that “the effect of this product to our business performance would be minimal”. They are probably dancing with joy with the unexpected effects.

I want this too! Looking back at the fuss going around these few days, the product would probably be sold to the public, too. I can’t wait to review it in XAMOSCHI.


Translated by Elena







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