Charging socket polarity

[DIY]

I bought a couple of wind-up dynamo LED lanterns in anticipation of the winter power cuts. They have a 6volt charging socket but there is no indication of the polarity on the case next to the socket and no instructions as to polarity. My understanding is that the usual convention is that the central pin is positive and the outer sleeve is negative on the charging plug. Is this likely to be correct?

An adaptor was not included but I have got a regulated DC adaptor that can be set from 1.5 to 12volts with either a positive or negative tip.

[Harry Bloomfield]

DIY explained :

There is no convention, but more often than not tip is positive.

The only way to be certain is to disassemble and check. If the battery is connected directly across the socket it might be possible to plug a plug into it and check its polarity with a meter, but likely there will be a diode in series to prevent wrong polarity, especially so if it is unmarked.

[Andrew Gabriel]

+ve centre is most common, but not universal. You might find that you can measure a polarity on the socket with a test meter, but it might not handle being shorted out without damage.

Another issue is if the socket is meant for a power supply or a charger, and this will depend if the unit contains its own charging circuit.

Without any details being provided, you are probably going to have to open it up to be sure what's inside, and if it needs a charger, what type and capacity battery it has.

[Laurence Payne]

You'd think so, wouldn't you? Especially on something expensive like a Sony Walkman Pro? But there isn't. Big repair bill if you get it wrong :-(

[NT]

I think thats the only way forward really, to open it and find out whats there. Good chance of killing it otherwise.

NT

[Dave Plowman (News)]

They're punishing you for not using their PS, etc. ;-)

[BigWallop]

Place a test meter on the socket. The battery is connected to the socket, so a test meter will show you which way round it is connected to the socket.

Like this <

...

[DIY]

Thanks for that tip, I tried it and the meter showed that the tip/centre pin is positive.

[NT]

If the battery connects straight to the socket you'll need a suitable charger, not a gen purp wallwart.

NT

[DIY]

"NT" wrote: If the battery connects straight to the socket you'll need a suitable charger, not a gen purp wallwart.

As stated in my original post I have got a regulated DC adaptor that can be set from 1.5 to 12volts with either a positive or negative tip, and which I have since used to charge both lanterns at 6volts. What is a wallwart?

[Laurence Payne]

What you're describing, if it looks like a pregnant 13-amp plug :-)

If there's no charging control circuitry in the appliance you'll just have to make sure you don't leave it connected too long. A proper charging system would be kinder to the batteries. But I wouldn't worry too much. It's only a gadget, not the backup power supply to a life-support system.

[NT]

Thats one way to knacker it.

NT

[Andrew Gabriel]

I guess it didn't have Lithium batteries (wrong voltage anyway), or he'd be describing the resulting indoor firework display ;-)

(Having just knocked up something on the workbench to charge up my Nokia phone's Lithium battery as the phone no longer can, that's fresh on my mind. Fortunately, it worked very well.)