Portable Wii Battery

Cyan09 · Post by **Cyan09** » Sat Feb 03, 2007 2:31 pm

Hey, I was just hoping someone here might have suggestions for batteries to use for a portable wii. Obviously I'm looking for what everyone would want in a battery for a portable: small, relatively inexpensive, rechargeable, and i believe the wii uses 12v. I have been searching on my own, but I think most of the batteries I have found would have a very short life when powering a wii and 5-7" screen.

Qcanfixit · Post by **Qcanfixit** » Mon Feb 05, 2007 1:20 am

why not get a higher voltage rechargable battery and use a step down converter, it should last a lot longer that way

you can build that yourself with radioshack parts.

Or you can buy something like this

http://www.powerstream.com/12V-backup.htm

I gotta admit the powerstream battery is a nice one, you can use your portable to charge your cell. you could also charge it with solar cells

Post by **Skyone** » Mon Feb 05, 2007 2:01 am

why not get a higher voltage rechargable battery and use a step down converter, it should last a lot longer that way

Actually, it will last a lot shorter.

A few Li-Ions in series will leave you with a good few hours of life. Li-Ions are thin, but a bit dangerous to maneuver with. They are known to explode a lot, so be careful. A larger but safer route are Ni-MH battery packs. You can get a low-voltage battery and use a step-up converter from TI to boost the voltage up to ~12v.

-Skyler

timmeh87 · Post by **timmeh87** » Mon Feb 05, 2007 8:05 am

well you wouldnt be able to say whether it would last long or shorter without knowing the total capacity in watt-hours of both batteries, and the efficiency of your converter.

but there are losses in the step up/down process and you want to avoid it if you can.

Qcanfixit · Post by **Qcanfixit** » Mon Feb 05, 2007 5:04 pm

Watts = Amps x Volts

considering that information, a higher voltage, would equate to higher wattage, when a battery is used the pressure drops until the voltage is below what is needed to run the device, if the device, is a 12 volt device, the usual battery when fresh, may be running at about 13.5 volts then drops. when it hits about 10 volts, it will no longer be enough to run the device.

This process would be extended, if we start with a higher voltage battery, and provide a way to cut down, or slow down the pressure to one that is safe for the device, thats when the step down comes in. there are other options to minimize loss, but I believe when set up correctly, using a 19 volt battery such as the one I found or a laptop type battery, you would be provided with a far longer battery life, than simply using a 12v battery for a 12v device.

It is true that Li-Ion batteries have stability issues, but using less voltage, and thus less current draw than what the battery was designed for, the battery would be less likely to overheat and explode, or we could simply use a different battery type.

as you may well know, when stacking batteries, you also stack up the voltage, ( when stacking volts, you add wattage) but the current remains the same, so you have 2 reasonable options. find a higher capacity battery the higher the heavier, and more expensive, the highest I've seen are about 8000mah for a polymer Li-Ion, or stack up a few extra volts, it's cheaper and you get the same results.

timmeh87 · Post by **timmeh87** » Mon Feb 05, 2007 5:59 pm

erm. adding batteries in series to increase the voltage instead of parallel for capacity still means you are adding batteries... you say that putting them parallel adds weight, so batteries in series are what... weightless?

it comes down to the total watt-hours of your battery. that is, amp-hours times voltage. a 18v, 2000mAh battery will be much bigger than a 12v 2000mAh battery, and it will last longer. a 12v 3000mAh battery will be bigger than a 12v 2000mAh one and it will also last longer.

now some Wh calculations:

18v, 2Ah = 36Wh and big
12v, 2Ah = 24Wh and small
12v, 3Ah = 36Wh and big

you will find your portable will more or less last the same amount of time given the same Wh rating of your battery. Portables use watts, not volts.

We could also talk about energy density, which is Wh per kilogram. if you stay inside one technology like NiMh, your energy density remains basically the same, and any battery with a given power in Wh (no matter what combination of voltage and Ah you use to get the Wh) will weigh the same. this is an important result, and one you should consider.

in the end, all we have concluded is that bigger batteries make your portable last longer. the voltage doesnt matter. so just make it something compatible.

Qcanfixit · Post by **Qcanfixit** » Tue Feb 06, 2007 12:28 pm

I never said that they were weightless, just that it was cheaper than the current selection of hi-cap batteries.

Ideally, using about 4 3.6v hi cap cell phone batteries should do the trick and be fairly lighter than most other battery pack solutions.

another suggestion, the system could be designed to run on a sort of standby mode when power gets low, it could be programmed to dump a current game to flash memory or something and resume once full power is restored, that would require a lot of work, but it would be worth while.

timmeh87 · Post by **timmeh87** » Tue Feb 06, 2007 3:09 pm

4 cellphone batteries actually wouldnt last very long. if you're talking about putting them in series, it might make a N64 last 30 minutes or an hour. keep in mind that "high capacity" means from the point of view of the cellphone.

why do you think higher voltage batteries are cheaper?

Qcanfixit · Post by **Qcanfixit** » Tue Feb 06, 2007 4:57 pm

by hi cap, I mean amp rating.

3.6v 1000mah is the same no matter what type of device it is running. I suggest cell phone batteries, because they are common, small and known to work well in various conditions.

really it could be any type of battery, all I wanted to do was spark some new ideas to solve an age old problem.

vskid · Post by **vskid** » Tue Feb 06, 2007 5:20 pm

Good luck charging them and you better hope the protection circuit is on the battery itself or you could blow yourself up.

timmeh87 · Post by **timmeh87** » Tue Feb 06, 2007 5:22 pm

what im trying to say is that 1000mAh is not a high value for portable use. its actually too low for anything except maybe a NOAC

Metroid fan · Post by **Metroid fan** » Tue Feb 06, 2007 5:47 pm

Exactly portables take a lot of juice to run and 3.6v at 1Amp is not enough to power a portable for any reasonable amount of time.

Cyan09 · Post by **Cyan09** » Fri Feb 09, 2007 3:40 pm

What would you guys think about a VHS camcorder battery? 12v, 2300mAh, seems like it might not last too long though. The biggest problem I am having is I want to be able to charge the battery in the unit/play the unit plugged in, I would likely have this portable plugged in 90% of the time.

davicoro · Post by **davicoro** » Sat Feb 10, 2007 8:07 am

Cyan09 wrote:What would you guys think about a VHS camcorder battery? 12v, 2300mAh, seems like it might not last too long though. The biggest problem I am having is I want to be able to charge the battery in the unit/play the unit plugged in, I would likely have this portable plugged in 90% of the time.

all depends on the portable you will using...
if your portable needs 8v at 1ah and you have a battery that provide 9v at 2ah that need at last 5v at 0.5ah to recharge it you will need a power supply that provide 7.5v at 2ah and place 2 power regulators... one 7508(or one 8v) for the console and one 7505(or one 5v) to charge the battery. the console maybe will not need the regulator at all.

timmeh87 · Post by **timmeh87** » Sat Feb 10, 2007 11:22 am

you need a voltage supply thats at least 2v higher than the rated battery voltage to charge it. hooking a 9v battery up to a 5v power supply would drain it more.

also, you cant run a 9v battery though a 7808 for the most part, if its anything like a 7805 you would need 10.2v.

furthermore, nothing "needs" mAh, but choosing a higher mAh rating will give you more battery life. i think that you are confusing Amps with mAh. (again)