How does the water powered calculator work?

[paulhunn]

Can anyone shed any light on how this water powered calculator works please? http://www.thinkgeek.com/gadgets/electronic/7c17/

Thanks, Paul

 

[LURCH]

Electrodes coated with NiHM; when emersed in water, they produce ellectric charge.

 

[Pengwuino]

Electrodes coated with NiHM; when emersed in water, they produce ellectric charge.

Is this a permanent reaction or is it dependent on how much of the NiMH (isn't it NiMH?) is in there?

 

[paulhunn]

According to the article its permanent as long as you replace the water when needed. It couldn't run indefinatly because that would constitute perpetual energy i.e energy generated from nothing.

 

[Pengwuino]

According to the article its permanent as long as you replace the water when needed. It couldn't run indefinatly because that would constitute perpetual energy i.e energy generated from nothing.

I'm talking about the NiMH.

 

[Pengwuino]

Anyone know the answer to this?

 

[rcgldr]

The article is misleading. I checked eslewhere. Continuous battery life is about 2 years. So it's not really much different than a lead acid battery, just different metals, and uses water instead of diluted sulphuric acid to trigger the reaction. Buyer beware, some of these products don't provide a means for replacing the batteries.

 

[rcgldr]

I'm talking about the NiMH.

Nickel Metal Hydride batteries are one kind of recharble batteris. There are three basic type of rechargable batteries used in radio control models. The classic ones are Ni-Cads, later NiMH batteries came out and had more capacity for the same weight, but I think there was a current limit. Other than high powered electrics, which draw 80 amps or so, the NiMh batteries work in most applications. The latest technology for rc stuff is Li-Poly batteries. Li-Polys give you the most capacity for the weight and packs consist of a combination of cells combined in parallel (more current) and/or in series (more voltage). Special car is needed for these batteries, Ni-Cads are the hardiest, the main issue is not to drain them much below .9 volts per cell. NiMH batteries can be permanently damaged from overcharging (and maybe over draining, not sure on this one). Li-Poly's will explode under certain conditions. Nicads can be charged with simple brick chargerss, but you need "smart" chargers for NiMH and Li-Poly cells. When charged, Ni-cads are about 1.2 volts per cell, Ni-MH's are about 1.1 volts per cell, and Li-Poly's are about 3.7 volts per cell. Just like any battery, the voltage drops as current load increases. Capacity also is affected by the current load.

 

[Pengwuino]

Jeff, the device works by water alone. The assumption is that there is a NiMH layer inside promoting the electrolysis creating the electricity.

 

[rcgldr]

Jeff, the device works by water alone. The assumption is that there is a NiMH layer inside promoting the electrolysis creating the electricity.

Yes, but just like any conventional battery, metal is moving from one electrode to the other, eventually you run out of metal. As mentioned before, life span is 2 years for these batteries.

I don't think your getting my point about the web site. It's a salesman talking and his lips are moving.

If you want a long life span battery, nothing beats plutionium buttons generating heat to drive thermacouples, commonly used in satellites and the lunar module portion of the Apollo space craft. However, it seems to be difficult to find plutonium based consumer products. They don't use radium / luminous paint on clock dials any more. However they do have tritium / phosphor gauges now (life span also about 2 years). Now you're probably thinking hydrogen bomb, but the trick here is getting enough plutonium to set off the fusion reaction, and I can't find plutonium for sale even on Ebay.

Personally, I have my own quest for special metals. I fly radio control gliders, and it would save some space if instead of using lead weights for balancing and ballast, I could find some depleted uranium. However it's been hard to find, as we haven't had any wars over here in So Californina where the depleted urainium shells are used, and the local military surplus stores don't seem to carry the stuff.