Battery Powering a Wireless Router

[airman00]

Sort of related to robotics.....

I want to make my wireless router battery powered ( dont ask why , ) . Now on the router it says that its powered by 3V 2A adapter.  Should I assume that the router is drawing all those 2 Amps every hour or should I assume a lower value ?

I also want the router to last at least 12 hours before needing another recharge . So what would you guys suggest , lithium pack or just two NiMH battery packs to increase current supply ?

Btw I will be using a switching regulator to get to the 3V.

Thanks,
Eric

[TrickyNekro]

You can assume that it drains 2A every hour....

MMmmmm, I'll make a lucky guessing and I'll say you need them for a close circuit camera system....

Well, I suggest lithium ion as far as you provide a protection circuit....

Why, because it has a lot better power output graph (time - voltage) than NiMH...

The router would malfunction with a low battery supply... and you would not even notice with NiMH

And you say 12 hours.... hell... 24A/h !!!! Hell again... but cause of the regulator I suggest 26 - 28A/h....

That's all from me....

[airman00]

I was afraid it was gonna be 24 ah .....

Can I just hook up two 12ah lithium batteries in parallel?

[ArcMan]

I wouldn't assume that the router draws 2A.  That's what the wall wart is capable of producing, but the router will use somewhat less than that.  The load might vary based on network traffic as well (if the router's is not transmitting all the time).  I suggest sticking an ammeter in the circuit and measuring the current load during various network traffic conditions.

[airman00]

I wouldn't assume that the router draws 2A.  That's what the wall wart is capable of producing, but the router will use somewhat less than that.  The load might vary based on network traffic as well (if the router's is not transmitting all the time).  I suggest sticking an ammeter in the circuit and measuring the current load during various network traffic conditions.

where would I connect the ammeter to? Which part of the circuit?
Btw I am using the router as a portable repeater . I will be using DD-WRT firmware on a compact linksys router.

Anyways I was thinking of getting 10 of these in parallel: http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=505
Total weight would only be 3 lbs.

[Webbot]

Assuming that its currently powered by a transformer that plugs into the wall socket, with a lead that plugs the 3v into the router then:
can't you snip the wire for the 3v plug and then place your ammeter in the way to measure the actual current. Seems a bit radical but you can always use a soldering iron and some masking tape to put the connector back on afterwards. I know its not a very 'scientific' approach - but will give you the real numbers!

[airman00]

Thanks for all the replies guys

I don't even think its necessary to measure the current. I realized why. On the actual router ( not the wall adapter) it says that it consumes 3V @ 2 A. If it was on a adapter that would be a different story.

I'll post up some designs soon for my device.

[airman00]

I found a router that consumes less amps and is more hacker-friendly
This router: http://www.linksys.com/servlet/Satellite?c=L_Product_C2&childpagename=US%2FLayout&cid=1149562300349&pagename=Linksys%2FCommon%2FVisitorWrapper&lid=0034939789B01
With these batteries:  http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=1349

   +    + 

My router (Linksys WRT54G) is powered by 12V .5A and my battery pack is a 12V 5AH pack.
So theoretically my setup should run for 10 hours straight - I can't find a 12V 6AH battery  so I'll just settle with the 5AH one. 10 hours is enough for me.
Also I have a feeling that the router will not draw .5 amps continuously . Am I correct to assume this? Is there some way to modify the router to draw less current?

I will use the Open WRT to burn the wifi repeater firmware into the router.

[dunk]

see if you can get a WRT54GL rather than a  WRT54G as it is far easier to put your own firmware on, has more RAM, etc.

the WRT54GL is similar to the old WRT54G and is made by Linksys after they changed the specs of the original WRT54G so people could continue modding the WRT54GL.

more info here: http://en.wikipedia.org/wiki/Linksys_WRT54G_series


dunk.

[airman00]

Thanks dunk that router looks better

According to this : http://forum.openwrt.org/viewtopic.php?id=2162
I can even power it with 6V(since its above 4.5 volts) and use less than the 12V that the wall adapter gives

Also , I found out that the router draws an average of 5.5 watts.
Time to look for a cheaper combination of batteries .

[pomprocker]

did you see this:

http://curiousinventor.com/kits/spk_wrt

[Admin]

I remember reading somewhere that routers use an insane amount of power (probably mostly wasted, too). 5.5W is more than most of my robots even use!

I'm willing to bet inside the router is a really cheap voltage regulator sapping 30% of your power . . .

If you open it up, you can probably change out the regulator for a switching regulator or an LDO.