12v dc to 12v ac inverter

[lentildude]

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!

 

[quietguy]

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

 

[quietguy]

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

David

 

[lentildude]

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.

 

[Poxy]

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?

 

[Geoff C]

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!

Most cockys use a windmill.

 

[lentildude]

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
http://www.oatleyelectronics.com/kits/k098.html
http://www.oatleyelectronics.com/pdf/k098.pdf

also this chopped dc circuit might reduce current
http://www.voltscommissar.net/minimax/minimax.htm
might be able to run an ac pump off chopped dc too!

 

[APR]

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

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..

http://www.otherpower.com/danf_waterpump.html

 

[lentildude]

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!

 

[David]

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.

http://www.pumpwarehouse.com.au/prod179.htm

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

David

 

[Poxy]

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?

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.

 

[lentildude]

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
http://www.voltscommissar.net/minimax/minimax.htm
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]

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
http://www.voltscommissar.net/minimax/minimax.htm
and perhaps avoid batteries.
Pump while sun shines!

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

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.

 

[lentildude]

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.
http://www.ecosouth.com.au/solar_pumps.htm

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.

 

[Peter Jakacki]

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*