12v dc to 12v ac inverter

Is there a simple way to make a 12v dc to 12vac inverter so I can run an ac pump from a car battery. ac pumps have coils in epoxy with a magnetic impeller so can run long periods continually. dc pumps break down after continous use?

Also anyone know where u can get cheap ex telecom deep cycle batteries near Penrith/lower bluemountains? They cost a fortune new. I am trying to pump water out of the dam and am killing car batteries with extended discharging.

cheers!

Reply to
lentildude
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Are you using a bilge pump? I think these would be designed for long term running.

David - who uses a bilge pump for a similar purpsose

lentildude wrote:

Reply to
quietguy

Another thought would be one of the big garden fountain pumps - these are designed for continuous running

David

lentildude wrote:

Reply to
quietguy

Hi,

No I found some 12vac pumps not a bildge pump. The ac pumps dont have much flow but dont use much current. dick smith sells 24v fountain pumps - even they would do. (some aquarium submersible pumps are 240v.) I am thinking of running them off solar panels and have it pumping whenever there is sun. Might avoid batteries alltogether.

I do have a 12vdc bildge pump that chews 10 amps and gives 6m head but this kills the car batteries if I leave it on more than `15mins or so. I want to find deep cycle batteries to run this dc pump.

quietguy wrote:

Reply to
lentildude

I'd kind of wonder about the overall efficiency of a DC-powered AC pump - depending upon what head you're pumping to and what rate you need, I suspect a DC pump is going to be cheaper and make better use of available energy. Also, depending on the water, bilge pumps are often better able to pass solid objects than pond pumps.

Have you considered trying a PWM speed controller on your existing bilge pump to wind back the power consumption?

are

Reply to
Poxy

"lentildude" wrote in news:1154445801.013565.24390 @p79g2000cwp.googlegroups.com:

Most cockys use a windmill.

Reply to
Geoff C

PWM - I might look at an oately kit for a high current pwm but I really need the full head 6m to get water from dam to vege patch. PWM might reduce current but also reduce head??? even if it drops a few amps withPWM still cant use car batteries. Maybe have to go super low tech and build a wind powered pump??

The dcpump has 19mm hose - I was wondering does reducing apeture to say 13mm hosing increase head? , might buy this

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also this chopped dc circuit might reduce current

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might be able to run an ac pump off chopped dc too!

Poxy wrote:

Reply to
lentildude

Reducing the cross sectional area of the hose will not increase the head, but it may reduce the flow rate because of increased friction through the hose. What you need to look at is if the pump is exceeding it's designed flow rate, as the power requirement can go up significantly if the designed capacity is being exceeded.

When trying to pump the most water at a specific head with the least power consumption pay attention to keeping all hose directional changes on a larger radius rather then a small tight radius. If the pump is not a submerged type, but has a pickup or suction hose, place the pump as close to the surface of the water as possible and keep the suction hose as short as possible as pumping efficiency will be increased.

Here is a link to an article that you may find of interest..

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Reply to
APR

the simplest way is to plug a 12V transfromer into a 240V inverter the wharehouse had cheap inverters a month or so ago.

Maybe you need to add a low-voltage cutout to stop your car batteries from being deeply discharged.

golf-cart and RV batteries are designed for deep discharge.

if you want to empty the dam a siphon's the most efficient way, but I'm guessing you want to use the water above the dam.

Bye. Jasen

Reply to
jasen

thanks for the comments - yeah I was going to experiement with a 100w

12/240v inverter but figure I wouldnt be able to run it directly off a solar panel. Im thinking the ac fountain pump idea will be useless for anything practical at all after researching more.

\\therfore will stick to dc bildge pump and batteries, solar trickle charged

I will try to pump water 6m "above" the dam, to either a water tank which will then gravity feed drip irrigation lines or may try to feed drip lines directly via a bildge pump but figure there wouldnt be much pressure to directly feed dripper after the 6m head.

and will look at PWM the bildge pump to reduce current (now 12v 10 amps!) . Perhaps run the pump 30mins day to top up tank that feeds drippers. I will be able to move more water in that 30min in a tank rather than feeding drippers directly. then let sun recharge batteries rest of time. Am looking for good batteries but am on a budget.

thanks for all the comments!

jasen wrote:

Reply to
lentildude

Why don't you just buy a decent pump. Bilge pumps really don't like pumping too much head. I have used a Shurflo pumps, and some of the lower power 12V ones draw only 4 amps or so.

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This will pump 8.3L/min, at 7m head, and draw only 4 amps.

David

lentildude wrote:

Reply to
David

As APR said, reducing pipe diameter will just increase friction and reduce the head it will pump to, or decrease the flow rate at a given head. If you use a PWM speed control, the reduced current will also reduce the height it will pump to, but you may find it will still pump to 6m, but with reduced flow rate.

There are things called "solar pumps" designed for pumping to high tanks at very low flow rates - I get the impression they are positive-displacement pumps and they tend to cost a bomb. One option might be a diaphragm pump, like the Shurflo pumps used in sprayers and marine plumbing. Even at reduced current, these pumps should still be able to pump to high heads.

Reply to
Poxy

Thanks for that last note; Diaphragm Pumps seam brilliant - high head, low power, long life. Brilliant! that sureflow had 28m head!!! Holy cow!

Seems perfect candidate to run off a big panel and a maximiser

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and perhaps avoid batteries. Pump while sun shines!

will now look at filters for the inlet as the dam full of tadpoles!

Thanks for that, will definately invest in a diaphram pump !

Poxy wrote:

Reply to
lentildude

That is one catch with those Shurflo diaphragm pumps - they can't tolerate any solids being passed (I think it catches in the valves and stops it from working) so they need a pretty fine filter on the inlet - you might need to use two filters, a coarse block type one over the actual inlet like they use for pond pumps, and then a fine mesh filter closer to the pump.

The other thing to keep in mind is what their duty cycle is - they might not like running for a couple of hours straight, although this may be helped by running at a lower speed. There's heaps of info around on the Shurflo pumps so you should be able to find out something via Google.

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Reply to
Poxy

Hi, I emailed the pump wharehouse and they dont recommend to use their shureflo pumps with a maximiser and solar panel, strange...

heres their reply

"George,

I do not recommend that you use any 12v DC above ground diaphragm pump without a battery - it will fail. "

I checked a solar retailer and there is a pump 5x the price that is used with a maximiser.

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I think Ill try the cheaper $200 pump and risk it..

Thanks for all the info and advice. Hopefully can make use of this dam water as its just evaperating in the hot Ozzie sun.

Poxy wrote:

Reply to
lentildude

Why does an AC pump draw "less" current than a DC pump in your application? I think it is very obvious that the DC pump is overloaded and since it is unable to generate full back EMF it will draw more current than it would if it could run full speed.

By adding PWM to the circuit you can expect to draw more current the slower it runs, and though the average power might be less, it won't be linear. The thing to avoid with DC motors is stalling them or running at near stall speeds as they look almost like dead shorts to the drive circuit.

If you want maximum efficiency you will need a motor that is rated for the job - simple. DC motors work best when they can run at optimum speed.

To convert 12VDC to 12VAC why don't you use a H-bridge circuit driven from a simple micro? Since a transformer is not involved you can do simple PWM to simulate a sine wave.

*Peter*

lentildude wrote:

Reply to
Peter Jakacki

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