Power to the robot people

March 9, 2012 6:07 PM

Does anyone have any experience using a wall wart battery charger, one for battery packs, as a power source wired direct to the machine that the batteries usually are installed in? I have a Wall-e and it has a dead batttery, one is ordered to replace that but I got to thinking of running the little guy off a long cord for the motion portion of his performances. The battery has a unigue connector to make the + and - stay correct and I could work around that part.
posted by Freedomboy to sports, hobbies, & recreation (4 answers total)

You could probably wire up a wall wart to supply the appropriate voltage, but just using a battery charger is not going to get you what you want - battery chargers can (and do) supply more voltage to batteries than they usually output, which is why they can recharge faster than they drain.
posted by spaceman_spiff at 6:09 PM on March 9, 2012

yes and no.
There are Instructables involving direct-wiring a wall wart to replace standard AA batteries (example), and even one talking about how to match the wall wart to the battery/device. But there's definitely no guarantee that the charger you have will substitute for the battery you have. You may be able to examine the devices and figure it out.
posted by aimedwander at 6:53 PM on March 9, 2012

As mentioned, what you want is a wall-wart, not a battery charger. Battery chargers put out variable amount of power, usually more than the battery it is charging. And probably won't put out anything if there is no battery inserted since it needs that to

Look at the dead battery to see how many volts you need, and find a power adapter that has the same voltage. It will probably require at least 200mA, but you can go as high as you want. Just not lower.

A good power supply will have a little diagram showing which part of the plug is positive and which is negative. (If it doesn't show, the center of the plug is generally positive.) Don't guess on this since hooking it up the wrong way can ruin the widget since most cheap widgets don't have reverse current protection. A cheap multimeter can make sure you're connecting it the right way.
posted by Ookseer at 8:56 PM on March 9, 2012

[Fragment....] A charger probably won't put out anything if there is no battery inserted since it needs to read from it to make sure it's not over charging the battery.
posted by Ookseer at 8:57 PM on March 9, 2012