I recently had occasion to charge my central heating expansion vessel
(qv!), and tried to use the little 12V pump which I carry in the car for
inflating tyres. As we have a 240V-12V PSU for use with a camping
fridge. This device states that its output is 13.6V DC / 5A /68W -
surely more than adequately rated for the pump? (or maybe not?) Anyway,
plugged in, the pump simply cycled weakly at about once per second.

So purely from curiosity, why would the pump have failed to work on the
transformer?

David

Lobster wrote:
I recently had occasion to charge my central heating expansion vessel
(qv!), and tried to use the little 12V pump which I carry in the car for
inflating tyres. As we have a 240V-12V PSU for use with a camping
fridge. This device states that its output is 13.6V DC / 5A /68W -
surely more than adequately rated for the pump? (or maybe not?) Anyway,
plugged in, the pump simply cycled weakly at about once per second.

So purely from curiosity, why would the pump have failed to work on the
transformer?

The pump takes 5A to start, and the power supply is switching itself
off to prevent damage.

In article ,
Lobster wrote:
I recently had occasion to charge my central heating expansion vessel
(qv!), and tried to use the little 12V pump which I carry in the car for
inflating tyres. As we have a 240V-12V PSU for use with a camping
fridge. This device states that its output is 13.6V DC / 5A /68W -
surely more than adequately rated for the pump? (or maybe not?) Anyway,
plugged in, the pump simply cycled weakly at about once per second.

So purely from curiosity, why would the pump have failed to work on the
transformer?

Probably can't supply the peak current needed. Although the motor may be
rated at 5 amp continuous it may take a great deal more for a very short
time each compressor cycle or whatever.

--
*Can vegetarians eat animal crackers?

Dave Plowman London SW
To e-mail, change noise into sound.

On 21 Nov 2006 18:42:35 GMT, Ian Stirling
wrote:

Lobster wrote:
I recently had occasion to charge my central heating expansion vessel
(qv!), and tried to use the little 12V pump which I carry in the car for
inflating tyres. As we have a 240V-12V PSU for use with a camping
fridge. This device states that its output is 13.6V DC / 5A /68W -
surely more than adequately rated for the pump? (or maybe not?) Anyway,
plugged in, the pump simply cycled weakly at about once per second.

So purely from curiosity, why would the pump have failed to work on the
transformer?

The pump takes 5A to start, and the power supply is switching itself
off to prevent damage.

ISTR that my 12v car tyre pump took about 9amps !

Its not alot slower using a footpump

Robert
Robert

lid wrote:
On 21 Nov 2006 18:42:35 GMT, Ian Stirling
wrote:

Lobster wrote:
I recently had occasion to charge my central heating expansion vessel
(qv!), and tried to use the little 12V pump which I carry in the car for
inflating tyres. As we have a 240V-12V PSU for use with a camping
fridge. This device states that its output is 13.6V DC / 5A /68W -
surely more than adequately rated for the pump? (or maybe not?) Anyway,
plugged in, the pump simply cycled weakly at about once per second.

So purely from curiosity, why would the pump have failed to work on the
transformer?
The pump takes 5A to start, and the power supply is switching itself
off to prevent damage.

ISTR that my 12v car tyre pump took about 9amps !

Blimey - wouldn't have guessed. That would explain it...

Its not alot slower using a footpump

You want to try using a footpump when the valve you're inflating through
is 6 feet off the ground (and you have to pump an 18-litre volume up to
4 bars. (But job done - good fun!)

lid wrote:

ISTR that my 12v car tyre pump took about 9amps !

I'll second that. I got sick of mine blowing the 10A cigarette lighter
fuse every other time I used it, so lopped the plug off and fitted a
pair of crocodile clips for direct connection to the battery.

Given a spare car battery, this means I'm all set up for topping up an
expansion vessel 6ft off the ground, thus ensuring that my expansion
vessel will remain happily inflated until about a week after the pump
spontaneously combusts.


Kim.

In article tq60ke.47c.ln@willow,
kimble wrote:
I'll second that. I got sick of mine blowing the 10A cigarette lighter
fuse every other time I used it, so lopped the plug off and fitted a
pair of crocodile clips for direct connection to the battery.

Given a spare car battery, this means I'm all set up for topping up an
expansion vessel 6ft off the ground, thus ensuring that my expansion
vessel will remain happily inflated until about a week after the pump
spontaneously combusts.

With Xmas coming, one of those jump start packs with compressor built in
is worth a punt. It's also a convenient easily portable source of 12 volts
for testing car bits, etc - better than a spare battery. I got one from
Lidl for 20 quid and didn't expect it to last. But it's done ok.

--
*The most common name in the world is Mohammed *

Dave Plowman London SW
To e-mail, change noise into sound.