I want to buy a small 12v diesel transfer pump (Amazon.com product link shortened)
I won't always have it close to a car to allow me use the car battery. So the question is could the Bosch 12v batteries used in their cordless equipment be used to drive this pump and if so for how long.
I hesitate to buy a small 12v lead acid battery as it would inevitably be discharged when I wanted to use it.
Or could I get a 240v to 12v transformer to drive it as access to 240v isn't a problem
Many thanks for all assistance
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Batteries are usually marked in amp.hours. Multiply that figure by the voltage to get watt.hours. Divide that figure by how many watts the pump takes to give a rough idea how long it would run for. You won't get that full amount, though.
If the pump says how many amps it takes, the calculation is easier.
If the pumps says 0.5 amp, and the battery is 2 amp.hr, the theoretical time would be 4 hours. But in practice, perhaps 3.
--
*Fax is stronger than fiction *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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fred wrote:

160W / 12V = 13.3A
Assume (since you didn't mention capacity) a 4Ah battery, that gives you a theoretical maximum battery life of
4 x 60 / 13.3 = 18 minutes
but will be lower in practice.
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On 27/02/2018 11:11, fred wrote:

Probably needs DC, not AC. Drawing about 13 amps. So you would need a fairly meaty transformer, but a medium sized car battery charger would be OK (except that these give around 14 volts on load). The standard 12 volt wall warts used for CCTV only give an amp or two.
Cordless power tools these days are commonly 10.6 or 14.4 volts rather than 12 volt. I think my 14.4's are about 1.5 amp-hour so that would give you about six minutes pumping. Mobility scooter batteries (about a third of the size of a small car battery) are typically 15 AH (so an hour of pumping).
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Ebay usually had a fair selection of 13.8v power supplies designed to run car accessories (radios, etc) off mains.
--
*A conscience is what hurts when all your other parts feel so good *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On 27/02/2018 13:19, Dave Plowman (News) wrote:

He'll need a lot of amps though for a pump.
Bill
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On 28/02/18 08:26, Bill Wright wrote:

10A and 25A units are common

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Climate Change: Socialism wearing a lab coat.

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Yes - not given for the actual pump when I replied. I was thinking of a small pump like you'd use to empty the car sump. Wonder if a decent PC power supply would do it? Some older ones produce a lot of amps at 12v for HDs, etc. And can be very cheap used.
--
*A conscience is what hurts when all your other parts feel so good *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On 28/02/2018 10:57, Dave Plowman (News) wrote:

Er. He put a link to the pump details in the very first post!
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Cheers,
Roger
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Don't do links. Surely not too difficult to post its details in text here?
--

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On 01/03/2018 11:22, Dave Plowman (News) wrote:

You must miss an awful lot of details, then! What about when people post links to photographs? They're often vital for understanding what is being discussed.
--
Cheers,
Roger
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On 27/02/18 11:29, newshound wrote:

best way to get 12V DC is a cae battery replacement PSU sold for e.g., CB radios in a fixed base unit
Dozens on ebay. I got a really good one for under £30 and there are often even cgheaper ones
--
“A leader is best When people barely know he exists. Of a good leader,
who talks little,When his work is done, his aim fulfilled,They will say,
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On 27/02/2018 11:29, newshound wrote:

Why? Even if you don't use it for months it will still be 90% OK. After use put it on slow charge for a few days. Then put it on the shelf. I have two 15Ah deep discharge batteries that are used maybe once or twice a year and they have been fine.
Bill
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On 27/02/2018 11:11, fred wrote:

The link says it's 130 watt - which is over 13 amps at 12v. A typical 12v power tool battery has a capacity of 2 amp-hours - so would only power your pump for about 9 minutes, assuming that it could deliver 13 amps (which it may not be able to).
I know you said that you didn't want to buy a small battery - but how about something like this https://www.maplin.co.uk/p/maplin-jump-starter-digital-500a-150psi-compressor-n63nk which has plenty of uses other than just powering your pump? I always carry a similar in my car, but I do make sure I top up its charge every now and then.
If you want a mains power supply, your usual wall wart won't be anything like powerful enough. Something like this (Amazon.com product link shortened)HREVKM1S062Z0W5CWJ may well do the job. You'd have to modify the connections on your pump, of course.
--
Cheers,
Roger
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On 27/02/2018 11:58, Roger Mills wrote:

If its like the one I bought a few years ago they lie about the capacity. Mine had a 7ah SLA battery in it and it only weighed half of what other 7Ahr batteries did.
A 7Ahr sla battery is much cheaper.
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On 27/02/2018 12:03, jim wrote:

And when the fuel is cold or there's a big lift it will be a lot more.
Bill
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On 27/02/2018 11:11, fred wrote:

Loads of these, for example... https://www.ebay.co.uk/itm/DC-12V-24V-5V-10A-12-5A-15A-20A-30A-Universal-Regulated-Switching-Power-Supply/181881169501?hash=item2a58f6665d:m:m3_-EzXHf5rrCZ9TAbHXjXA
(Ebay no 181881169501)
Chose a 12V 240W (20A) one, why not, it's under a tenner. It needs connecting and putting in a safe place.
Cheers
--
Clive

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On 27/02/2018 12:35, Clive Arthur wrote:

Agreed, if mains really is not a problem and you feel competent to make a safe box for your environment (is it wet? the PSU may need some ventilation) then that is the cheapest and most reliable way to go.
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On 27/02/2018 12:45, newshound wrote:

Make sure the neg output lead is bonded to mains earth via the PSU's mains lead. Some of them float so a fault could put 240 leakage on the output.
Bill
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On Wednesday, 28 February 2018 08:30:50 UTC, Bill Wright wrote:

Class II supplies are generally safer than class I, but if you're pumping fuel, earthing it would eliminate those tiny sparks.
NT
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