Battery question

Folks, I'm sorry - this question has NOTHING to do with Windows XP. I just thought there might be an electronics guru out there who could give me an answer.

I have an elderly Ryobi engraving tool, mod. HTC18. The rechargeable battery pack is almost dead and I can't find a replacement.

My question> I have the mains transformer and docking base which all seem to work. If I were to butcher the entire rig, and rebuild it, is it possible that the engraver would run directly from the mains plug? I've just put a meter on the transformer's output and it says it's 13.32 volts DC. Oddly, the transformer itself is labelled: IN 240v-50\60hz and OUT 9v - 300ma, so I dunno why the difference between 13.32v and 9v. Never did do well on this subject at school

 

Masonite,

When the charger is not loaded, the voltage will rise to nearly the peak A.C. voltage of the transformer secondary. Peak value is defined as the rms value multiplied by the square root of 2.

That's why the output is rated with some current being drawn, in your case, 300 milliamps. If you connect the battery, the voltage will drop accordingly.

As for running the device on the charger alone, I doubt that it will support the load since 300 milliamps isn't much power at 9 volts. It is merely 2.7 watts so you can't expect much at that energy level. The advantage of using a battery is that you can get more watt/seconds of energy in a short time and then replace it with a small charger connected for a much longer period of time, often overnight is required.

Perhaps you can find a 9 volt nicad that can be jumpered somehow to sub for the old one.

 

Surferdude, thanks for that explanation, I've got an inkling of the way the charger works now.

Subbing another battery might work if I could duplicate the shape, but it's a bit bit odd, being like 4x AAs joined together in two banks of two. Guess each cell must be 2.25v? (4 x 2.25 = 9?)

So, if I understand you correctly, I COULD do what I want if I could find a 9v transformer with a gutsier output amperage? What sort of amperage would it need to be?

I should say that I rarely use this Ryobi gizmo, maybe once a year, if that. But when I need it, I need it, if you know what I mean

 

Thanks TonyT: It's always nice to deal with helpful people

 

Thanks once again, TonyT. But I'd better not pursue this thread further - I've already been castigated (as you can see) as well as being docked points (whatever that means) for a) daring to ask a question in the wrong place and b) having an unseemly expectation that someone would simply shift a transgressing post to a more appropriate location.

Nuff said, I think.

 

I'd like to hear how this turned out.