I have been trying to use a LidlAldi car tyre inflator to pump up a large child's
'play pool'. I realise the pressure/volume match is not a good one, but I'm
being a cheapskate...
I have been trying to power the inflator from the mains via a 12V adapter,
instead of a car battery/lighter socket. I tried two different PSU adapters: one
rated 12V/1.5A and the other 12V/4A.
Neither was much of a success; the inflater barely worked and kept 'conking out'.
It runs fine from the 12V car socket.
I am guessing that least part of the trouble is that both supplies were
switch-mode, intended for fairly linear loads. From the 'put-put' noise of the
inflator I imagine it is an impulse type design with highly varying load.
I'm really musing if anyone else has done anything like this, and whether it is worth me trying a different (linear) adapter? I have probably thrown a few
Transformer-based 12V adapters away recently ;-(.
(I have pumped up the pool regardless, this is for 'next time').
I don't imagine a linear wallwart is going to help - taking large gulps of
current is likely to just cause the transformer to saturate, so it still
can't deliver the current.
You could try some chunky capacitors across the output of your 12V/4A supply
- they might be able to buffer the current gulps. Some linear PSUs (eg in
bench supplies and hifi gear) already have such large capacitors, while
wallwarts probably don't.
Also, power supplies from the Playstation 3 go up to 32A @ 12V, are fanless,
and available on ebay for under a tenner:
(similarly power supplies from old servers, but they tend to howl)
It's not a problem with switch-mode or not, it's simply that those
little tyre pumps take a *lot* of current. When I measured mine it
was taking about 15 amps. So your 1.5A or 4A PSUs simply can't cope.
What I do if I want to run a pump away from a car is use a small car
battery (it's actually a garden tractor one) and have a charger to
keep it charged.
After serious thinking jkn wrote :
That needs considerable volume, at low pressure - well beyond a tyre
The PSU needs to be able to cope with starting and surge current, much
bigger than what you have.
In message , Theo
I know this is d-i-y but I have been very impressed with a ?12.00 pool
inflator from Homebase but I guess elsewhere as well. Faster than using
my workshop compressor!
Ozito by Einhell 130Watt.
When I run my tyre inflator from the socket in the car, a) I had to
fit a heavier-duty fuse on the board under the dash otherwise it just
blew (forget how big, it was a few years ago, maybe up from 15 to 25
amps) and b) I need the car engine running otherwise the compressor
motor just stalls.
Interesting, thanks. I hate the fact that they have to be plugged directly
the Appliance to be pumped up - especially since IMO they all have differen
diameter adapters etc. But then I also hate faffing with pipes and all the
incompatible adapters otherwise!
Most cheap car inflators will take up to about 15A max.
If that is within spec for the PSU, go for it
As for the volume thing, to fill a car tyre to 3 bar is the same volume
as filling 3 car tyres to atmospheric and considerably less work
Id say a tyre inflator would do that pretty well on a paddling pool, if
you don't mind letting it run for 20 minutes
Its certainly less than ideal though
A 10 amp fuse will take a *long* time to blow at 15 amps, like many
minutes. I only decided to check the current my pump was taking when
I found the cigarette socket plug (horrible things) was running very
hot, much too hot to touch.
Where possible I install Torberry Powerpole connectors on
car/boat/bike, much neater and smaller than cigarette lighter, carry
more current without getting hot, are they are 'genderless'. (See
Y3es, you really need something like a car battery charger that is meant to
fast charge a battery for that kind of thing, as long as the volts are not
more than 14v and its not too ripply.
Linear supplies, the old ones that break your toe if you drop it on your
foot were much better at this sort of thing, but remember the limiting
factor could be the thermal cut off or killing the rectifier!
Some older train and slot racing car units seemed to work.
On Fri, 7 Aug 2020 14:19:07 +0100
I started using a cigarette socket plug from CPC, but part of the
circuit was a pressure spring, which heated up and turned the whole
thing into a molten mess.
'8 Amps' was for a few minutes only.
I had a similar kind of experience with mine.
You tried your wall adapters and had a lack of success.
When I plugged mine into the car, it blew the fuse
on the lighter socket. But, I was holding a spare in
my hand, because I expected this to happen.
The two page "instruction manual" was a shambles,
the printed one in the box. It didn't say anything
about power requirements.
However, I just tried a Google, and a later model
(that looks identical on the outside at least),
lists 105W, which is very approximately 9 amps.
Power Requirement: 12V DC Neg. Gnd
Maximum PSI: 200 psi blocked head pressure
Duty Cycle: 15 min. on/30 min. off
Power: 105W @ 12V DC
Maximum Air Flow: 0.7 CFM (high pressure)
1.4 CFM (low pressure)
Now, that's not a surge rating for the first
100 milliseconds when you switch it on. That's
after it's spinning and pumping. It might draw
more than 9A at the very first, then settle
down to 9A after that. I think my lighter
socket fuse might have been 25A or 30A or so. *******
They make Ham Radio supplies as battery eliminators
for mobile rigs being run in a shack. The quality of these
varies all over the place. Some are linear (quiet - but inefficient
and run hot), some are SMPS (efficient, but not electrically quiet,
create hash on the radio they power). For your pumping
project, the type probably doesn't matter quite as much,
but the OverCurrent detection might be just as
"precise" as your wall adapters. This particular one
weighs 30 pounds, so it's obviously got a giant
transformer inside. SMPS ones could be a bit smaller.
It costs as much as half of the purchase price,
for the shipping on it.
That's just to show the absurdity of "trying to beat the system" :-)
Mine was definitely not drawing 9 amps when it blew
the fuse in the car. And that's the excessive current
the motor draws when it first starts up. When you operate
from a car battery (and without a too-small fuse in the way),
the battery can handle a larger load. I measured my car
one day, and the starter motor drew 150 amps peak,
and the battery voltage dropped down to 9V while
doing so. That's why the battery is a bit dangerous.
It's got more capability than that Tripplite thing. *******
This example of a line-powered air mattress pump is a lot cheaper.
high power 130W
Winding the motor for line voltage, doesn't seem to be affecting
the price all that much. And at least, they've selected a motor
in the same wattage class. It's not an underpowered motor which
further slows down the pumping process.
I don't think that one has a pressure gauge.