running 12v pump off mains 230v power

[embecmom]

Hi there, looking for some advice from all you caravan experts out there. I have a trailer which only connects to mains power. I want to run a small water pump (bought a shurflo) for simple sink setup. I have a line run to connect it (the pump) to the mains. Obviously as I found out, 12v from 230v no go. I dont want to put a battery in place as there is no room for it and I would have to run cabling for charging it plus to the pump.. I thought about buying a pump that could run off mains but cant find any small enough (i.e their either pond pumps or central heating! and way to powerful for what I need.

Is there a converter (transformer) out there that people are using thats small enough to use inline rather than again having to run more cabling plus it wires directly into mains or does anyone have an recommendations for under sink pumps off 230v (or is it 220v now)...it would have to be on demand/self priming i.e dont have to switch it on and off...

many thanks.

 

[DaveA1]

My recommendation is. Have a word with an election and let him sort it for you.

 

[Hutch]

My recommendation is. Have a word with an election and let him sort it for you.

Dave, finger trouble maybe, an Electrician, .
A small Motorcycle battery and small battery charger would be fine I would think.
Hutch.

 

[DaveA1]

My recommendation is. Have a word with an election and let him sort it for you.

Dave, finger trouble maybe, an Electrician, .
A small Motorcycle battery and small battery charger would be fine I would think.
Hutch.

Ha. After the last four or so weeks, it's in printed on my brain.

 

[Hutch]

My recommendation is. Have a word with an election and let him sort it for you.

Dave, finger trouble maybe, an Electrician, .
A small Motorcycle battery and small battery charger would be fine I would think. 7
Hutch.

Ha. After the last four or so weeks, it's in printed on my brain.

I know what you mean, :woohoo:

 

[ProfJohnL]

Hi there, looking for some advice from all you caravan experts out there. I have a trailer which only connects to mains power. I want to run a small water pump (bought a shurflo) for simple sink setup. I have a line run to connect it (the pump) to the mains. Obviously as I found out, 12v from 230v no go. I dont want to put a battery in place as there is no room for it and I would have to run cabling for charging it plus to the pump.. I thought about buying a pump that could run off mains but cant find any small enough (i.e their either pond pumps or central heating! and way to powerful for what I need.

Is there a converter (transformer) out there that people are using thats small enough to use inline rather than again having to run more cabling plus it wires directly into mains or does anyone have an recommendations for under sink pumps off 230v (or is it 220v now)...it would have to be on demand/self priming i.e dont have to switch it on and off...

many thanks.

Hi ,
It should be possible to achieve what you describe, but what you have told us suggests the solution may be quite expensive.
You tell us you want the pump to be self priming. That means the pump will need to be a positive displacement type, that can generate enough vacuum to lift the water from its storage container. Most Sureflo are PD pumps and will self prime, these are often referred to as diaphragm pumps and there are a number of other manufacturers who produce equivalent products.

The downside is this type of pump tends to need a lot of current to start it running, Some of these pumps need a peak current supplyof 3 to 4 times their rated current to start them, and most conventional caravan supplies have trouble producing the necessary peak current to start these pumps. This is one reason why most caravans do also have a 12 v battery which acts as a current reservoir and allows these diaphragm pumps to be used.

Finding a 230v AC to 12v DC power supply with enough peak current capacity to run your pump is possible, but is likely to prove to be expensive. Such PSUs can be found on, on line auction sites, but be warey: there are vast numbers of Chinese manufactured Switched Mode units. They are mostly designed to run LED lighting, which has a benign power demand, asking some of these to power a pump motor which has a poor impedance and load characteristic may be too much even if the PSU has large current rating.

Generally water pumps run for short periods and relatively infrequently, so their daily power usage is surprisingly small, consequently running the pump of a dedicated battery as Hutch (EH52ARH) suggests does seem a reasonable proposition. You could also use a smart battery charger like the ones Aldi and Lidl sell to keep the battery charged.

 

[JezzerB]

I have a dremel type tool that runs off mains and is 12v-work were throwing out some laptop chargers and I noticed that one of them were 12v-works a treat direct.Plenty of TV's out there have transformers too-just google it or look on ebay-sure there wlll be plenty of cheap options!

Lots on there just search 240to 12v transformer-just make sure your transformer can supply more than enough amps-not sure what the pump draws!

 

[Guzzilazz]

You need to be aware that the pump will draw quite a high current at startup, which reduces quite quickly, but even so a 2.2 gall per min will draw 4-5 amps (12v) when running... You would be best as already suggested to consult an electrician, as your knowledge is limited, but a small (20AH motorcycle battery) would give you the current buffer you need when starting. It also depends on the duty cycle you expect of the pump; most 12v freshwater pumps are designed for "on then off" rather than continuous pumping

 

[ProfJohnL]

I have a dremel type tool that runs off mains and is 12v-work were throwing out some laptop chargers and I noticed that one of them were 12v-works a treat direct.Plenty of TV's out there have transformers too-just google it or look on ebay-sure there wlll be plenty of cheap options!

Lots on there just search 240to 12v transformer-just make sure your transformer can supply more than enough amps-not sure what the pump draws!

The dremel and a diaphragm pump have very different load characteristic's dremels are normally started before they are put to work, where as diaphragm pumps already have the mass and friction of the pump assembly, and when primed they have the additional load of not only the mass of water in the pump body but also the back pressure of the water in the pipe work. These factors radically increase the mechanical opposition to the motors torque, and extend the time and therefore the quantity of current required to get the motor spinning. Its doubtful a computer or TV type power supply would have enough grunt to start a loaded diaphragm pump, yet alone run it on its own.

There would be no harm in trying it except the risk of damaging the power supply, but It would have to be set up in a realistic situation with water and pipe work and tap to exercise the built in pressure switch, and to include the back pressure of the system.

There is another risk that should not be forgotten. The vast majority of computer and LED lamp power supplies are manufactured in China, and especially some of the cheapest ones do not have EU levels of electrical safety protection. I have one adjustable power supply for up to 30V @ 10A, but its output terminals sit at 115Vac above ground. For safety I would not recommend such a PSU for use on a water pump.

 

[JezzerB]

There would be no harm in trying it except the risk of damaging the power supply, but It would have to be set up in a realistic situation with water and pipe work and tap to exercise the built in pressure switch, and to include the back pressure of the system.

There is another risk that should not be forgotten. The vast majority of computer and LED lamp power supplies are manufactured in China, and especially some of the cheapest ones do not have EU levels of electrical safety protection. I have one adjustable power supply for up to 30V @ 10A, but its output terminals sit at 115Vac above ground. For safety I would not recommend such a PSU for use on a water pump.[/quote]

VERY true; beware the cheap imports but after a trawl there is some decent looking stuff-Maplins might be worth a look too.

 

[ProfJohnL]

There would be no harm in trying it except the risk of damaging the power supply, but It would have to be set up in a realistic situation with water and pipe work and tap to exercise the built in pressure switch, and to include the back pressure of the system.

There is another risk that should not be forgotten. The vast majority of computer and LED lamp power supplies are manufactured in China, and especially some of the cheapest ones do not have EU levels of electrical safety protection. I have one adjustable power supply for up to 30V @ 10A, but its output terminals sit at 115Vac above ground. For safety I would not recommend such a PSU for use on a water pump.

VERY true; beware the cheap imports but after a trawl there is some decent looking stuff-Maplins might be worth a look too.

Maplin Online not Maplins, and I have reviewed their present product range and there is nothing remotely suitable for powering a shureflow pump.

 

[JezzerB]

There would be no harm in trying it except the risk of damaging the power supply, but It would have to be set up in a realistic situation with water and pipe work and tap to exercise the built in pressure switch, and to include the back pressure of the system.

There is another risk that should not be forgotten. The vast majority of computer and LED lamp power supplies are manufactured in China, and especially some of the cheapest ones do not have EU levels of electrical safety protection. I have one adjustable power supply for up to 30V @ 10A, but its output terminals sit at 115Vac above ground. For safety I would not recommend such a PSU for use on a water pump.

VERY true; beware the cheap imports but after a trawl there is some decent looking stuff-Maplins might be worth a look too.

Maplin Online not Maplins, and I have reviewed their present product range and there is nothing remotely suitable for powering a shureflow pump.

Maplins as a shop doesn't exist any more so didn't feel I needed to state the obvious! Thought the quality might be as safer bet than an unknown off ebay-but as you say-just had a look and they really are a shadow of their former selves-have not used the online service-used to love wandering the shops but never bought much-and thereby lies the problem I suppose! If you are careful there is also a lot of quality stuff on ebay but as you say there is a lot of cheap stuff that may or may not be ok- and with few guarantees other than feedback. I have to say i have had a lot of success as China manufacture for many big suppliers and you may just cut out the middle man. I have possibly been lucky but on the odd occasion we have had an issue ie with a security camera, the refund was instantaneous and have been ripped off once-with a soup make that was replaced with another faulty soup maker. We live and learn! HOWEVER for more expensive items ie over £100 I tend to go for recognised outlets-Argos, Tesco all offload stock on there at cheaper than shop prices quite often. Of course other internet shopping sites do exist. Rs components have a huge range with pricing accordingly-but have no idea what specs you'd need to satisfy the pump draw.