with what distance of wires can 12v battery be used?

SniperGaulois

SniperGaulois

10 kW
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I need a battery to run a 25W pump from a spring 50 meters away from a battery that is being topped up by solar power in the sunshine...

given a 12v, 5ah battery, for examble, and using nice 3mm^2 household wire... how much power would i lose because the wire is too long?

the solar charger is just a 5w trickle charger, would it be unable to send power to the battery if it was 50 meters from it? is it best to send the distance current from the battery straight to the pump?
 
Well it's a volts drop issue. You need to see the resistance of your wire per meter. Calc the total resistance. Use ohms law to see how many volts you loose. I imagine you will be fine

1.344V lost through 50 meters of 2.5 carrying 2 amps.
 
Maybe the real question is how good does the pump run on 10v? Or whatever the v drops to.

The test should be pretty easy, buy the wire, and without really uncoiling it, run the test. If it fails, you can return the box of wire and rethink. I don't see much benefit from a second battery near the pump, unless you can send that battery enough voltage to charge fully.
 
Thankyou very much, i searched as you say and found this page http://www.bulkwire.com/wireresistance.asp, and it says that i should place the solar panel far away have the trickle charge current going the long distance and the higher amps distance traveling a short distance. i have to read why high amps encounters more resistance than low amps :)
 
Its not that higher amps makes more resistance, but it does take heavier wire- shorter is better too. You want the higher amp load on the shorter thicker wire. You still want heavy wire from the panel to the battery so you don't end up with so much voltage drop. Can you test voltage? If you test near the panel and at the battery and pump you will start to see. Keep in mind the solar panel will likely show 17 to 20 volts in full sun when no load is hooked to it, when hooked to the battery it should hopefully show 13.8 v or a little more if the battery is good.
 
My curiosity is getting the best of me. What are you building (besides a water pump and power generator) :?:
 
Putting more Amps thru a small wire size(not designed for high amps) and using low voltage will increase Heat, hence resistance.
Volts is "Pressure" (speed) and low volts = low pressure (slow speed) and the "Amps" (Coulombs) will build up in a small wire because they
can't move fast enough.

Picture a Subway Turnstile. 50 people moving slowly toward the Turnstile can easily make it past without running into each other.
50 people moving fast towards the 1 turnstile and "BANG" there is a build up "resistance" and they can't make it thru quickly.

Want to get amps thru?
Two things can be done:
1 up the voltage (the speed at which the coulombs can move faster)
2 up the size of wire (this is like opening more turnstiles for the 50 people to pass)

You said 50meters...... That's a long distance for 12v to travel.

There would be losses in many designs. Stepping up the voltage thru a transformer would allow small wire over the
longer distance, then a Step Down Transformer would be needed at the other end.

Best: Move Panel and battery over to the pump.
Another Option: Change pump to 120v and put inverter on battery to change the Low volt DC to High Volt AC and
run 50 meters of #12 gauge extension cable.

Tommy L sends.....
mosh.gif
 
melodious said:
My curiosity is getting the best of me. What are you building (besides a water pump and power generator) :?:
Click to expand...
it's for a holiday home, there is a spring near the house, but it's too much work to bring water home for showers and cooking, so am going to get a diaphragm pump that can output 60psi and a 10w solar panel and a battery and a cmp12 solar regulator and place the panel in the sun, 10w of solar panel can actually provide 500 litres of water a week to the house :) i ll set a timer on it (cn101a) to send the water up in the evening when the battery is full :) it seems that i should have one battery, placed beside the pump, and the solar panel which is 18v, to send the low amps charge current over a long distance.
 
gotta ask why you decided on diaphragm pump and not a regular circulator. if you are pumping up to a storage tank that is unpressurized then you don't need 60psi.

you should be pumping water during the day when the panels are active rather than using stored energy to make it more efficient to move the water to storage.

you intend for this to operate during the week when you are not present and have the storage tank filled when you arrive on the weekends from what you said so you could have a small generator for when you are there to drive the pressure pump from storage when you wanted to shower, and recharge the battery then too so you would have lights. leds that is.
 
I found these tables. You might find them very useful for projects.
Studying these charts will give you a better Idea of the volts/amps/wire size/length relationship.
Note that there is a chart for 12v, 24v and 120v.

It's neat to compare 12v and 120v:
120v 15amps #14wire 56feet max 1800watts
12v 15amps #14wire 6feet max 180watts

http://www.solar-electric.com/wire-loss-tables.html

Tommy L sends.....
mosh.gif
 
Carrying water 50 meters sounds pretty hard. But maybe carrying a lithium battery that far would be pretty easy. Set the pump up to run on a bms protected battery that charges all day, then you stroll over and start your pump about dinnertime?

Or, for a morning workout bike power a pump?
 
why not get a pump with a decent suction head (one that can suck water from a long way away, and is self bleeding... your diagram pump will probably work tbh)

and then put it at the house/tank end ?
 
knighty said:
why not get a pump with a decent suction head (one that can suck water from a long way away, and is self bleeding... your diagram pump will probably work tbh)

and then put it at the house/tank end ?
Click to expand...
Yep, with a one way valve (diode) lol
 
he does not have much power to work with. that was why i asked him why he was gonna use a diaphragm pump. for low power setups you have to use a circulator in the water source, which is what submersible pumps do. he has to pump to atmospheric pressure storage if he wants it to pump enuff water with a little panel to make it worthwhile then use a generator if he wants to get high pressure by driving another high pressure pump from storage. this is basic design stuff.
 
dnmun said:
he does not have much power to work with. that was why i asked him why he was gonna use a diaphragm pump. for low power setups you have to use a circulator in the water source, which is what submersible pumps do.
Click to expand...

A diaphragm pump is positive displacement. You don't waste power circulating water about. You can hit 97% efficiency. A typical centrifugal pump (such as a submersible sump pump) is closer to 50%

I wonder what 60psi is going to drop to after a 50m delivery. I can't remember the last 50 meter hose I used, but it's quite slow compared to straight from the tap iirc. I'm sure someone will be quite used to such hose lengths..

Could a siphon be used or are you up hill from the spring? You might have to dig if your on level ground, but the pump would then just need to get things going. Stored water has it;s own problems though. I would like to fetch it as I needed it if possible
 
also, the pump will only run at 60psi if there's 60psi of back pressure from the hose/restriction at the end

maybe it's an auto on/off pump, which will trip off at 60psi when the ball valve on the other end closes ?

either way, it'll (normally) only run at whatever back pressure there is in the pipe ;)
 
Thanks all! there are lists of decrease of psi for different pipe diameters due to friction, it is relative to water speed and pipe width, a half inch tube is about .25 psi loss for 50' / 30m... there are an amazing diversity of water pump designs and i am learning about them, diaphragm pumps are very reliable and are used for most boat bilge things and boat plumbing and it seems like a safe bet, they are very efficient i think?

it's fun stumbling into different disciplines of engineering and having to learn all about them.

Thanks!!!!!!!
 
yes, boats use them and they are used by excavators and sewer repair workers to dewater holes in the ground too because in both cases the pump can handle large pieces of debris which will clog a normal pump. that is why they are called trash pumps or sewage pumps because they can move large pieces of material through the pump and out the other side of the check valve.

of course now that we have an expert on circulators he can document how inefficient they are but it sounds like you already decided. there is actually a large body of info out there because of the use of solar to drive low voltage submersible pumps in the third world. it is useless for me to repeat since you already know what you want but you can google up a lot of stuff that others have done with solar driven pump systems.

you will find that high pressure is not part of it. bol.
 
dnmun said:
of course now that we have an expert on circulators he can document how inefficient they are.
Click to expand...

You are the only one talking about circulator pumps.
When you talk about a circulator pump, you are talking about it's duty, not a type of pump.

Is english your first language?
 
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