STRANGE BUT TRUE CHARGING YOUR DEVICE - MINI USB

Rick GM · 09-02-2006, 03:29 PM

I have an SPV M5000, a Holux BT GPSlim236 receiver and a Motorola V3.
They all charge through the mini USB at 5.0 volts.

The V3 mains charger works with all three devices charging at 550mAmps.

The Holux mains charger works with the GPS device (obviously) and the PDA but NOT the V3, charging at 1.0Amps

The PDA mains charger works with the Holux, the PDA (obviously) but NOT the V3, charging at 1.0Amps

The corresponding car chargers work (or not) the same with the exception that those that work with the PDA only do so on occasions !!

Obviously the pins in the mini USB must differ - so QUESTION - why can't they all be the same so that I don't need several bl**dy chargers !!!!!!!!!

waveydavey · 09-02-2006, 03:54 PM

As the V3 has a lower current requirement than the other two it may have protection ciruitry to prevent over charging. Effectively preventing the higher current from the other device chargers coming through.

Rick GM · 09-02-2006, 03:58 PM

If only I'd listened all those years ago when doing electronics in the physics classes. Still doesn't get over why the PDA charges from the other chargers sometimes and not others !
Oh well !

waveydavey · 09-02-2006, 04:01 PM

You might find that the lower current is charging the PDA, but at a much slower rate due to the reduced current, hence feeling like it's only charging sometimes.

Rick GM · 09-02-2006, 04:07 PM

But the charging light doesn't come on and neither do my Today icons display 'charging' .

waveydavey · 09-02-2006, 04:14 PM

Are all the plugs the same? Sounds like a connection issue there.

Rick GM · 09-02-2006, 04:20 PM

They all look the same to me but who knows. It's the intermittent working that I don't understand on the PDA. It never fails on the PDA mains charger.

waveydavey · 09-02-2006, 04:25 PM

Maybe the collar is bigger on one than the other and the contact is flakey. Do they all feel like they fit securely?

Rick GM · 09-02-2006, 04:37 PM

Actually they don't. On the odd occasion I've wondered that myself - sometimes like the fit is tighter. But even so, that hasn't effected the charging or not. I just can't believe that they're not all standard. Mini USB = Mini USB - or maybe not !

waveydavey · 09-02-2006, 05:11 PM

Interestingly enough the Mini USB standard is for a voltage of 5v and a current of max 500mA, a standard socket and a standard plug with standard pinouts. It does seem like there are quite liberal measurements for the plugs and sockets though (proportionally obviously) and I can't find a specified plug length for Mini USB, but there is one for standard USB, and no specified collar size for either.

Remember the current specs would be for draw, so thoeretically as long as your device can survive on only drawing 500mA if it has a top range of 950mA it would still conform.

So they may well be conforming to the spec, but be sufficiently different I guess.