How can I convert a rechargeable beard trimmer to strictly a/c?

First of all, I love this trimmer. I've had it for probabaly 15 years. The settings are so precise and I'm so used to it that I would hate to replace it. It is a rechargeable model, which plugs into a cord, not a charging stand. The battery hasn't charged in probabaly 10 years. But since it stopped charging, I was able to keep using it by having it plugged in. I was able to do this for a long time until several days ago. When I'd turn it on while plugged into the outlet, the motor would barely even run. So I took it apart, looked around, and figured I would try to replace the rechargeable battery inside. I sourced a battery, installed it, and the trimmer worked again. I charged it overnight and went to use it the next morning. I got about halfway through when it just completely died on me. So I would turn it off for a few minutes, let it maybe charge a little and try to finish my trimming. At this point, I could maybe get 30 seconds of really weak performance before it would grind to a halt. I tried plugging it in and using it that way, as I had done so many times before, but that wouldn't work either. Can anyone advise me as to what's going on here? Why was I able to use it for so many years with the a/c/ cord and a dead battery, but now with a fresh battery, the a/c cord is useless for operation and obviously useless for charging as well? So I'm wondering if there might be a way to convert this trimmer to strictly a/c, remove the battery from the eqation, and operate it that way? I'm no electronics guru, by any means. But If instructed, I'm sure I could get this thing operational again. I don't care about it being battery powered anyway. I use it in the bathroom where there are a couple of very handy outlets. Thanks.

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it sounds like your new battery doesn't have enough juice to keep your shaver powered longer or maybe the new battery isn't compatible with the old charger. are you sure the battery is only 1.2V my electric razor is 15V and my trimmer is 3.6V. On the wall power cord it should say what the voltage its rated for. and might say on the shaver itself. or Google might have the answer! Then in theory you would just need to wire a wall power supply that can match the batter to the battery terminals and you should be good to go.
NachoMahma7 years ago
.  This may not be an electrical problem. After 15 years, especially with no maintenance, the gears and bearings are probably worn out. Probably a lot of hair, skin, and dirt accumulated, also.
.  If you are good at putting things back together after you take them apart, disassemble the mechanical works, clean, and lubricate.
.  While you have things apart, wash out the motor with WD-40 (or equiv) and blot up as much of the excess as you can (a few shots of compressed air may help). Check all the wiring, switches, connections, insulation, &c for corrosion and/or breaks.
.  Put it back together and see what happens.
chinaski (author)  NachoMahma7 years ago
i diassmbled the whole thing, as my first suspicion was the motor since it had let me run it with the cord for so long. that's when i disconnected the rechargeable battery and stuck a regular AA to the terminals to see what would happen. it ran fine, so i knew that the motor was not the problem. i haven't detected any problems with the innards of this thing. and it was amazingly clean inside. it was well designed in that area. i maybe found three or four little whiskers that had worked their way into where they shouldn't have been.
.  It sounds like it might be the charger, as Re-design mentioned, or you may have gotten a bad battery (or one that is not the right type).
.  Can you check the voltage at the motor when the unit is running (and preferably with a load on it) and verify that it is close to what it should be. To get you in the ballpark, a NiCd will put out about 1.2V per cell and an alkaline around 1.5-1.6V - use Google to find the voltage of other type batteries.
Also there may be something going on with the charger. It's meant to charge the battery overnight. Running the motor direct may have used more current than it was meant to supply. But you could just figure out what the voltage is and directly wire the proper sized wall wart to the motor and switch.
chinaski (author)  Re-design7 years ago
that leads me to another question. being as i'm not so well versed in electricity, would the voltage output of the batter (1.2V) be what is required to run the motor? or is there a chance that the current post-battery would be either increased or decreased before hitting the motor? the charging circuitry is all internal, so i wouldn't even know where to begin diagnosing that or even how to do it. but if i were to be able to figure the proper voltage, i assume that i could completely remove all circutry before the switch and motor and use the properly rated wall adapter wired directly to the switch, correct?
I wouldn't think that there is any thing to increase of decrease the voltage of the battery to run the motor. If you have a friend with a variable power supply you could have him hook it to the motor and slowly bring the voltage up to whatever you think sounds like the proper speed and that should be pretty close to right.