Posted: Mon Nov 15, 2010 20:44 Post subject: Internal battery mod
Now that i got my wrt54gs v7.2 open with the help of barryware, I want to start modding it. The mmc mod is essential but I see theres plenty of guides on it already.
What I want is to be able to use the router without having to plug it into anything (wireless), and to have maintenance as close to zero as possible. The solution is obviously an internal (perferably) rechargeable battery.
With my elementary understanding of electricity that I gained from using Google, I hypothesize I can just attach a rechargeable battery pack in parallel to the rest of the power stuff inside the router, like maybe to the leads where the power comes in. I also think I know that the battery pack has to be of the same voltage (12 volts I think) and of equal or greater amps than what my router eats. I have the ability to measure amperage by means of borrowing a multimeter if I need to. If I used 8 small batteries of 1.5 volts each and put them in series that should add up to 12 volts, and then I'll make sure theres enough amps to work with. I also believe that if the batteries eat too many amps when charging then the router won't have enough to work and could be dangerous. I think that if I were to get a power adapter that has more amps then everything will work fine. I think I might already have a 12v 3 amp power adapter lying around.
With this setup I want my router to work like my laptop - I can unplug it and use it, and then plug it back it and use it while at the same time my battery charges. And for extra bonus maybe ave the ability to plug it in and not have it on so it would just charge the batteries.
I have already consulted somebody about this who claims to be really smart and has taken a couse in electronics and has recieved college credits for taking it. He said that this idea would not work at all because:
1) Rechargable batteries would be far too expensive, easily $60 or more. You should instead use regular batteries and replace them when they run out, and forget the idea of charging it like a laptop.
My response: my first hit on Google was http://www.zbattery.com/Maha-AA-NiMH-2700mAh-Batteries-w-FREE-Carrying-Case thats $26
2) You need a special charging circuit for the recharable batteries. Otherwise you might as well plug them directly into the wall and make them explode.
My response: Okay...
3) You cannot attach the batteries in parallel to the incoming power and expect it to charge with it plugged in and then discharge when unplugged. You would need a special circuit such as the ones found in laptops, otherwise the first battery in the series circuit will have the greatest voltage drop causing it to not function properly. When discharging and the first battery in the series circuit drains completely the battery circuit no longer has a complete path and the router won't have any power.
My response: Then, in a series circuit the first component has the greatest voltage drop. So if you were to put a bunch of lightbulbs in series the first one would be brightest?
His response: Yes.
My response: Yes, of course.
I know there must be alot of information about attaching a battery pack to a router, it seems easy enough to do, and even with recharable batteries, but I can't really find anything about plugging it in at the same time and making it work. I tried to search for information on how to attach a recharable battery into an exsiting circuit (not router related) but I was't really sure how to start searching for that. How would I go about attaching an internal recharable battery pack and making it work like my laptop does?
Thank you, but this doesn't do what I want. From the description on the website it doesn't sound like it will make my router charge like a laptop.
Plus it's a little expensive. I see that there's a charger included with that product, I may be wrong but it seems like I already have one. I understand 4.5 amp hours is very nice, especially seeing it gives me 102 mAh per usd (if you can measure it like that) but I don't think I'm willing to spend that much for this project.
1. For extended runs you need large batteries. The cheapest you can get I think are the 12V car batteries. But you don't really wanna carry one of those around and they will give you 120 hours of life (on a 0.5A power usage)
2. You need special charging circuit. Are you up to circuit design and make? Let's not forget about the added bulk
3. If you don't have the charging station close you'll have to take the router offline while charging and that would leave the area uncovered for a few hours every 120 hours (if we consider the car battery)
I'd really have to be in a VERY special situation in order to consider such a solution and getting a wire around (PoE included) would be way easier in 99.99% of the situations.
most laptops run on 12vdc and there batteries seem to work for this just fine,,, why couldnt you use one of them?? and just add a power switch to the unit and then you would have what you are wanting,, as for any special curcuitry for charging that laptop battery,, the 12vdc laptop power supply is already setup dor that...
so if you put a power switch in between the router and the power source then you can turn it on and off with the source still connected and then it will still charge when not in use and then if that laptop battery is not really big you can walk-about with it,, another idea is a solar panel to charge said battery..
Indeed, this is not a trivial or cheap task if you want a zero maintenance solution. If you are willing to forego zero maintenance you could skip any fancy charging circuits, and then your primary cost would be in the battery and charger.
This system is completely doable if you want to make compromises, but to actually say anything we need to know two things: what is your minimum uptime, and what is your maximum downtime?
