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Small Cabin Forum / General Forum / Converting AC to 12V DC
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spencerin
Member
# Posted: 19 Nov 2021 01:34
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There are multiple converters for sale on Amazon that'll convert AC to 12V DC. The pigtail end is for whatever you want to power with DC, and the other end is plugged into an outlet.

They're advertised primarily for lights and other electronics. But, is there any reason why it wouldn't satisfactorily power a 12V RV water pump? I'm looking at a 200W converter for my 120W max pump.

toyota_mdt_tech
Member
# Posted: 19 Nov 2021 08:06 - Edited by: toyota_mdt_tech
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I have a 60A power supply in my trailer, its made for RV's, much cleaner power than a battery charger (which are almost always only half wave rectified vs full wave rectification) and it also charges and maintains a battery. I think you would want a battery to act as a cushion or shock absorber/capacitor.

Mine was an Intelli-charger 9100 and I added the "smart wizard" on it. Now you dont need the 60 amps, they come in 40 and even 30 amps too and smaller. So when plugged into "shore power" as my trailer is doing now, it maintains the battery and gets me all my 12V needs.

Smart Chargers

OK, loads of chargers, best bet is to get the ones with built in smart charger, but more steps is more money and of course, more amps, more money and larger leaded needed between charger and battery. So locate battery first, put charger close to it.

Nobadays
Member
# Posted: 19 Nov 2021 08:25
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I use a power supply transformer to convert 120vac to 12vdc for that exact purpose. THIS is like the one I've been using without issue for 3 years on a Shurflo 2088-554-144 pump. I am actually using a 10amp transformer without issue. My Shurflow doesn't specify watts but I'm pretty sure they pull a max of ~10 amps. The linked transformer says 180w so close.

Brettny
Member
# Posted: 19 Nov 2021 08:44
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They make these RV/diaphram pumps in 120vac. Just get the correct pump, they dont really cost any more than the 12v versions.

travellerw
Member
# Posted: 19 Nov 2021 10:55
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Although watts are a good way to look at it, in this case amps might be better..

A 120W water pump will draw 9.52A when running. However, it has an inrush current as well (less than a second at startup). I would guess the inrush is 1.5 times the running draw 14.25A. So to be safe you need a power supply that can deliver that 14.25A (a 180W supply).

but like Brettny pointed out. I would just buy a 120V version of the pump and not worry about a power supply.

spencerin
Member
# Posted: 19 Nov 2021 12:24 - Edited by: spencerin
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I know there are 120V models, but I already bought a 12V model and tested it and it works well. I didn't want to send it back for a 120V only to find out it wasn't as good. Plus, keeping it 12V opens me up to a lot of other models should I need to replace it later on. There aren't a lot of 120V models out there.

I ended up buying - (https://www.amazon.com/Supply-High-powerTransformer-Waterproof-Adapter-Outdoor/dp/B0 7SB2WY7Z?th=1). Based on your responses, it looks like it'll work and that I bought enough power coverage. The pump itself says 10A max.

gcrank1
Member
# Posted: 19 Nov 2021 14:07
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Run a hidden 12v battery close by the pump and recharge it as needed. The intermittent pump use wont draw it down fast.

Nobadays
Member
# Posted: 19 Nov 2021 18:46 - Edited by: Nobadays
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Quoting: travellerw
but like Brettny pointed out. I would just buy a 120V version of the pump and not worry about a power supply.


I don't know if things have changed with these pumps but there is an older thread on here somewhere... couldn't find it... where folks have had poor service from the 120vac models, the 12vdc pumps have apparently proven to out last them by a lot.

spencerin
Member
# Posted: 24 Nov 2021 22:01
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I recently received the converter and it worked great. However, I had to return it due to poor-quality manufacturing (not shipping damage). One guess as to the manufacturer's country of origin.....

Nobadays
Member
# Posted: 24 Nov 2021 22:46
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Too bad.... mine has been ticking along for 3 years but I do keep a spare one!

Brettny
Member
# Posted: 25 Nov 2021 06:40
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Quoting: Nobadays
don't know if things have changed with these pumps but there is an older thread on here somewhere... couldn't find it... where folks have had poor service from the 120vac models, the 12vdc pumps have apparently proven to out last them by a lot

We run the 120v version of these in..let's say public bathrooms. They last for years and years. Usualy they fail because of a water leak or freezing not the motor.

spencerin
Member
# Posted: 1 Dec 2021 22:05
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Brettny, what 120V version(s) have worked for you? I'm looking at Seaflo and DC House on Amazon and the reviews make it seem like they don't last long.

Brettny
Member
# Posted: 2 Dec 2021 06:07
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I believe there shurflow, mine is 150mi away right now.

https://www.amazon.com/Shurflo-2088-554-144-Fresh-Gallons-Minute/dp/B00C1M6B1C/ref=as c_df_B00C1M6B1C/?tag=smacab-20&linkCode=df0&hvadid=167130592685&hvpos=&hvnetw=g&hvran d=957438480704369853&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9004 885&hvtargid=pla-310543981177&psc=1

If I had 120v available though I would be getting something more in the 5-6gpm range...but then again a real 120v shallow well jet pump is $100.

jhp
Member
# Posted: 2 Dec 2021 09:31
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This is exactly how I power my out door shower. I have a cheap no-name 120v-12v converter rated at 10amps, powering a Flojet style knock-off that is rated at at either 5 or 7 amps max draw...I forget. Works great, the converter doesn't get hot when under load...everything seems fine.

I wanted to keep it 12v so when the pump dies I can get another cheap one or use one i scrounge up.

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