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Voltage question - 4 battery operated soap dispenser to AC powered awesomeness

Alright, so first time post here, I have been interested in converting my automatic soap dispenser from DC power to AC power using an old 5V cellphone charger.

Last night I did the deed, actually really simple, I followed the general idea of this instructible, though my mod didn't include a double pole double through switch, I just took the batteries out and connected the AC charger's wires directly to the battery terminals.

Here's my question though:
While it works, its not quite as powerful as I though it would be, its actually a little weaker than it used to be when I had batteries with a fresh charge.

It originally had 4 batteries, so I used a 5V charger. I have another charger setting around, but its a 7V, do you guys think thats too much of a jump? Should I wait till I can find a 6V charger? Am I going about this the wrong way?


I really don't know anything about voltage, but the concept of converting this stationary item to AC seemed like a good idea and I'll really enjoy not having to replace the batteries all the time.

Thanks for any help!

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kelseymh6 years ago
That device uses four AA batteries. Each battery is 1.5V, so the motor wants 6V. You're only providing 5V. You need a 6V or slightly higher wall wart. In fact, 7V ought to be okay. The motor will only draw as much current as it needs to run.

What you did should be fine, provided you connected the wall-wart to the correct terminals: there's going to be one positive and one negative which actually connect to the device's wiring; all the other contacts will be connected to each other to put the batteries in series.

For a different solution, you can look at my I'ble on the same topic. The baby swing version you followed is simpler, and less prone to error.

You may also find a number of I'bles on this subject where people cut wooden dowels the size of AA batteries and used them to make the connections from the wall wart.
mr_schticker (author)  kelseymh6 years ago
Ah this is great!!
I finally got around to putting another wall wart on, ended up with a 7.5V. Works amazingly well! Its as if the batteries are supercharged, I even had to turn it down to the next to lowest setting so I don't squirt too much soap out.

This is the way these things out to all work, very powerful, and more to the point, it works quickly -the whole purpose of getting an automated soap dispenser anyway.

Thanks for the comments!
Yay, congratulations on your success!

remember when soap was something you tried to hold in your hand?

L
Water and mains electricity don't mix. I don't think there is GFCI protection here.
Ummm....are you alluding to the many dangers of dropping your soap in the wrong place? And what other skeletons are lurking in your closet, eh?
mr_schticker (author) 6 years ago
Thanks for the replies, I think I'll try a 7V and let you guys know how it goes. The actual plugin is quite a ways away from the sink, and I've tried to seal the cord as best as I can with hot glue on its way out of the soap dispenser. I'm pretty sure its waterproof because I glued both inside and outside around the cord.

Its also DC at the point of the pump but I suppose we could have some trouble if it fell into say a bowl of water. The whole thing has yet to take a swim in the last 2 years I've had it, but i suppose it is a possibility, but its a risk I'm willing to take.