Use Solar Folding Panel to Pump Creek Water

Submitted: Wednesday, Jan 29, 2014 at 10:25
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I Have a 120 watt folding solar panel, 100ah battery pack and a 750watt dirty water pump. I am wondering how long I can pump water with the battery full and solar panels connected and charging. The pump has an 8 metre lift. Delivery rate is 13000L/h , but I only need enough water for the cob hot tub in the bush. At 70years carting water up the steep embankment in buckets is getting a bit much. The battery and panel would be wheeled about 70 metres from the tub down to the embankment on a trolley. I may need to pump twice ...once from the creek to a barrel and then from the barrel to the tub near the caravan. The actual number times I may need to pump is yet to be determined. Main concern is how long I can pump each time with my very limited power. Can any one help with this calculation please?
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Reply By: jokirt - Wednesday, Jan 29, 2014 at 10:28

Wednesday, Jan 29, 2014 at 10:28
Forgot to say I also have a 1000watt pure sinewave inverter.
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Reply By: Member - wicket - Wednesday, Jan 29, 2014 at 11:05

Wednesday, Jan 29, 2014 at 11:05
At the risk of sounding a bit glib, seeing as you have all the equipment why not just try it and find out?
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Reply By: Brian 01 - Wednesday, Jan 29, 2014 at 11:09

Wednesday, Jan 29, 2014 at 11:09
The first thing to check will be the locked rotor current of the motor, this should be shown on the nameplate, probably as LRA, and for that size motor will typically be in the range of 30 to 40 amps, that's roughly 7,000 - 10,000 watts (Kva for the pedantic) or around 600 - 800 amps on the 12v side of the inverter.
This is the instantaneous current that the motor will draw on startup and even though it is of very short duration, chances are that it may be more than your inverter can handle.
The inverter may turn off due to overload or low voltage.

Next thing is the actual running current, a 750w 240v motor running off an inverter will draw in excess of 65 amps from your battery.

Assuming that it will start and run...If you allow say 800 litres to fill the tub, then at 13000L/h (depending on head height), the tub should be full in 5 to 10 minutes.
This will take roughly 6 to 12 Ah from the battery.
The solar panel will easily replace that.


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Reply By: Lyn W3 - Wednesday, Jan 29, 2014 at 11:58

Wednesday, Jan 29, 2014 at 11:58
13000 l/hr is a LOT of water (216 l/min) which is about 4 times what a home pressure system pumps. Don't think you could ever pump that amount with a solar set up, the biggest ones I have seen pump about 500l/hour.
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Follow Up By: garrycol - Wednesday, Jan 29, 2014 at 12:37

Wednesday, Jan 29, 2014 at 12:37
Agree but as it is not going to run constantly it should manage as long as there is enough time to recharge batteries between use.
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Reply By: Member - LeighW - Wednesday, Jan 29, 2014 at 12:14

Wednesday, Jan 29, 2014 at 12:14
Drawing the current required to run your pump would drop your batteries effective Ah to around 60Ah total capacity.

Using the 65A calculated above I would calculate that running for 5 minutes would effectively use 9Ah and 10 minutes 18Ah approx without any help from the solar panels.

Assuming the solar panels produce around 9A then the draw would reduce to about 8Ah and 16Ah.

Keep in mind also that you will to put more back into the batteries than you take out due to losses.

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Follow Up By: Brian 01 - Wednesday, Jan 29, 2014 at 12:34

Wednesday, Jan 29, 2014 at 12:34
Just to verify my figures..
65 amps for 5 minutes:-
5 minutes is 1/12th of an hour, therefore 65/12 =5.42Ah

I rounded up to get my figures of 6 and 12Ah for 5 and 10 minutes respectively.
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Follow Up By: Member - LeighW - Wednesday, Jan 29, 2014 at 12:55

Wednesday, Jan 29, 2014 at 12:55
Brian I'm not disputing your figures, I was just pointing out that when a 100Ah battery is discharged at 60A its capacity falls form around 100An to 60Ah.

Therefore for every 1Ah your taking out at a 60Ah rate your in reality taking out around 1.6Ah allowing for recharge losses etc.

From the quick check I did I assumed you had forgotten to allow for the lower battery amp hour capacity due to the high discharge rate,if you did I apologies.

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Follow Up By: Member - LeighW - Wednesday, Jan 29, 2014 at 14:48

Wednesday, Jan 29, 2014 at 14:48
jokirt,

Just to clarify, looking at the 65A drain you might think that you can run your pump for around 1.5 hours before your battery would be totally discharged. You can't, at 65A your 100Ah battery will only have a real capacity of 60Ah or there abouts, so in reality you can only run it for approximately an hour before the battery would be totally exhausted.

Keep in mind the above is all guess work without actually knowing the actual run current etc, you may get more, may get less.

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Follow Up By: Brian 01 - Wednesday, Jan 29, 2014 at 18:35

Wednesday, Jan 29, 2014 at 18:35
I understand your point Leigh.
A couple of different perspectives can be taken on this.

1. An amp hour is an amp hour no matter whether it comes from a 100Ah battery or a 1000 Ah battery, so the Ah actually consumed is what it is.
Watthours will be different due to the voltage variations over the runtime.

2. Peukert tells us though that the faster we take it out, the less we can take out, so that gives us a situation where, even though we have taken 5.4Ah from a 100Ah (C20 rate) battery, but at a high discharge current, in this case 0.65C, we can end up with less than the expected (100 - 5.4 = 94.6Ah) capacity remaining in the battery.

Math can help us here, as the formula:- "Capacity reduction in Ah = time in hrs x (discharge current x Pk)" tells us how much capacity we will lose from the battery in the time for which the discharge is occurring.
Pk is Peukert's constant, and while we don't know it for this particular battery, it will be fairly safe to pick the high end for an AGM battery of say 1.15.
As he said it was a battery pack then I assumed it would be either AGM or Gel.
You could use 1.25 as a constant for a gel battery if you prefer, but that will only change the answer by about 0.5Ah
The discharge current is 65 amps
The time is 5 minutes or 0.083 of an hour
So capacity = T x (current x Pk)
capacity = 0.083 x (65 x 1.15)
capacity = 6.2 Ah
Not a lot of difference from my original figure of 6Ah.
100 - 6.2 = 93.8Ah remaining
If the battery was a flooded type, then the lost capacity could be as high as 9Ah as you suggested,
Either way, the remaining capacity will still be better than 90Ah, assuming it was initially in good condition and fully charged.
Remember that the pump is only running for about 5 minutes.

By transposing that same formula you would find that drawing 65 amps out of that battery would give you 1.34 hrs to flat, or an effective capacity of 75Ah.
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Follow Up By: garrycol - Wednesday, Jan 29, 2014 at 19:52

Wednesday, Jan 29, 2014 at 19:52
Here we go again - into the minutia - trying to outdo each other with excruciating facts when near enough is good enough.

The Pedantic Thread applies.
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Follow Up By: Shaker - Thursday, Jan 30, 2014 at 08:19

Thursday, Jan 30, 2014 at 08:19
Couldn't agree more, it's making this forum tedious & boring. If you go back 10 years this was a totally different place to visit & is now being ruined by Google professors!
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Reply By: jokirt - Wednesday, Jan 29, 2014 at 16:15

Wednesday, Jan 29, 2014 at 16:15
Brian 01
The pump is a Shogun...German I think. I couldn't find anything on the LRA or start up drain in the Specs or on the unit. I see how this is the first consideration. However if it won't start I will now understand why. I had expected to run it for 5-6 minutes based on the delivery. Just wasn't sure how fast my power would drain. Thank you.

Leigh W

I will keep the drop to 60ah in mind when planning pump times. If you think I just might get 1hour, 2-3 5 minute pumps with breaks in between to recharge should get all the water I need up to the van in one day. I had feared that I would need to take a couple of days to fill the tub.

Thanks to all for making it so easy to understand


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Follow Up By: Brian 01 - Wednesday, Jan 29, 2014 at 18:47

Wednesday, Jan 29, 2014 at 18:47
I'm pretty sure that Shogun electric is owned by Mitsubishi and, as the name suggests, it certainly sounds Japanese.
The LRA is probably not critical to you now as I gave you a rough estimate of what it would be.
Some motors have the LRA shown as a letter type "NEMA code", or even just "code", and yours will likely be somewhere between J and N, with M being a distinct possibility.

If the pump will start on the inverter, then you will easily get half a dozen 5 minute runs with an hour or so break in between.
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Reply By: Ozhumvee - Wednesday, Jan 29, 2014 at 18:54

Wednesday, Jan 29, 2014 at 18:54
Might be easier to buy a 12v bilge pump and toss it in the creek as they have a pretty good lift and can shift a considerable amount of water.
Peter
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Follow Up By: The Bantam - Wednesday, Jan 29, 2014 at 22:22

Wednesday, Jan 29, 2014 at 22:22
The problem with bilge pumps is they don't push a lot of head and their flow suffers badly when there is flow resistance.

They are great little things though and cheap as chips.

cheers
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Reply By: Member - bbuzz (NSW) - Wednesday, Jan 29, 2014 at 19:43

Wednesday, Jan 29, 2014 at 19:43
I have been using a cheap bilge pump in my nursery pond to lift 2 metres to an overhead watering system.

It puts out an amazing amount of water through 3/4 inch hose broken into two branches and throttled back with irrigation sprayers.

It runs for 3 minutes and has been for 5 years.

I think I would try a bilge pump first. Cost about $20 on Ebay.


bill
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Reply By: Allan B (Member, SunCoast) - Wednesday, Jan 29, 2014 at 20:28

Wednesday, Jan 29, 2014 at 20:28
Although I can find a Shogun pump that fits the OP's description there is not a lot of specs. However it does specify "Rated Power" of 750W but this, on a pump, normally refers to the pump output power, not the electrical input demand. Accordingly, much of the power consumption reasoning above may be flawed.

An equivalent pump from Davey (D75A) will pump 13,000 l/h @ 8 metres head.
Its Output Power is 750 Watts and the 230v electrical specifications are Full Load Current of 7.5A (=1725W) and a Locked Rotor Current of 22.5A (=5175W).

Assuming the Shogun has similar characteristics, the 1000W inverter is most unlikely to support it. But as Wicket has said above, why not just try it and find out?

DISCLAIMER: No pedantics have been used in this statement. LOL
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Follow Up By: The Bantam - Wednesday, Jan 29, 2014 at 22:26

Wednesday, Jan 29, 2014 at 22:26
Shifting 13 tonnes of water 8 meters in an hour.....think about this.

Something is not adding up...750 watts consumed...yeh don't think so.

cheers
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Follow Up By: Allan B (Member, SunCoast) - Wednesday, Jan 29, 2014 at 22:53

Wednesday, Jan 29, 2014 at 22:53
No, 750 Watts output.
1725W consumed.
Davey specs:
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Follow Up By: Member - John and Val - Thursday, Jan 30, 2014 at 07:36

Thursday, Jan 30, 2014 at 07:36
Allan - love your disclaimer!
Bantam - I haven't done the sums, but that was my first thought too!

Cheers

John
J and V
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Follow Up By: Allan B (Member, SunCoast) - Thursday, Jan 30, 2014 at 08:36

Thursday, Jan 30, 2014 at 08:36
Guys, I am making no expressions re the flow capacity of these pumps other than comparing the published specs of each.
My observation was the comparison of the manufacturer's electrical characteristics, optimistic though the flow ratings may be.

And John, Einstein also said "Do not worry about your difficulties in Mathematics. I can assure you mine are still greater."
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Reply By: Member - Bruce C (NSW) - Thursday, Jan 30, 2014 at 08:59

Thursday, Jan 30, 2014 at 08:59
Hi Jokirt,
Can I suggest that you do away with the idea of using a solar setup for the pumping of your water in this instance and instead recommend one of the Honda look alike firefighter pumps from Ebay.

Such as this Fire Fighter

These units are very efficient and economical for your situation.
Solar is great but in the situation you describe I would suggest you could set it up on top of the bank so that you would rarely need to go down the bank unless you had a suction problem, which can be alleviated by a foot valve anyway at the pick up point anyway.

Having been in similar situations in the past, this is my recommendation.
You never know, you might find some other uses for the new found water supply such as a small garden, or even a big one if your intention traveled in that direction.

Your total outlay would be the pump, 100 metres of poly pipe (1" poly would do it) some fittings and a foot valve. You would then have a permanent setup, pump on top of the bank and a short walk to get it all going without climbing down the bank then back up again. A much safer alternative at 70 years of age. (I'm 68)

Cheers, Bruce.
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restless and lost on a track that I know. HL.

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Follow Up By: jokirt - Friday, Jan 31, 2014 at 10:57

Friday, Jan 31, 2014 at 10:57
I checked out the pump you suggested and think it would be ideal. Unfortunately I am not out there all the time and my van and shed were ransacked last winter. So I have to take everything out in the trailer and bring it all home again.....including water in containers. I do have a 4.4 kv generator that could have done the job, but it is too big for me to move down the hall let alone into the car. I've decided to sell it on Gum Tree and get something smaller further down the track. If I move out there to live your suggestion will be my first option.
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Reply By: Shaker - Thursday, Jan 30, 2014 at 09:33

Thursday, Jan 30, 2014 at 09:33
Forget about power have you seen these?

RIFE RIVER PUMP

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Follow Up By: Member - Bruce C (NSW) - Thursday, Jan 30, 2014 at 13:23

Thursday, Jan 30, 2014 at 13:23
You have got a good point there Shaker. I never thought of one of those.

These have been around for ever and have proven themselves time and again. In fact the last one I saw working was at Apsley Falls near Walcha NSW back in 1983. More or less work on the KISS principle as well.

So long as you have the fall they are brilliant and cost nothing to run for an unlimited water supply. Price might be another matter though.

Cheers, Bruce
At home and at ease on a track that I know not and
restless and lost on a track that I know. HL.

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Follow Up By: jokirt - Friday, Jan 31, 2014 at 11:10

Friday, Jan 31, 2014 at 11:10
Clever idea, but not suitable for my creek I'm afraid as I only have water holes to pump. Thanks for the suggestion Shaker. I really appreciate all the ideas that have been offered.
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Reply By: Bob Y. - Qld - Thursday, Jan 30, 2014 at 13:08

Thursday, Jan 30, 2014 at 13:08
Jokirt,

Have look at the Whitworths web site. They have Rule bilge pumps, 12v @ 6amps and 1920L/hr. Head of 10 metres, weigh only 500 grams and are rated at continuous duty. Outlet is 3/4". Check out cat no. 67217........$109.95

Don't know how they'd go in your case, but better than rooting around with inverters.

If you did use one of these, just put it in a plastic bucket immersed in the water, and this stops it picking up any rubbish off the bottom of the creek.

Bob



Seen it all, Done it all.
Can't remember most of it.

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Follow Up By: jokirt - Friday, Jan 31, 2014 at 11:30

Friday, Jan 31, 2014 at 11:30
This looks really interesting....and easy to move around as well. I have an 18ah battery and a 20ah battery that could be alternated with very little effort. I had thought about putting my pump in an old bird cage covered with shade cloth to act as a filter. I could double up with a bucket inside to be sure nothing gets through. The Shogun recommends also placing the pump on a brick to prevent silt being sucked up. I am wondering how durable the Rule inline pump is in dirty (sometimes sandy) water. Many of the Rule bilge pump specs that I have read say that the pump would be ruined in this type of situation. Has anyone had experience with the inline pump?
If this one works I'll be selling my Shogun on Gum Tree as well.
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Follow Up By: Bob Y. - Qld - Friday, Jan 31, 2014 at 21:40

Friday, Jan 31, 2014 at 21:40
During the 80's, we used to have a smaller version of this pump(only 1/2" outlet), and we used to use it to pump water out of waterholes in the Georgina River. The pump lasted about 5 or 6 years, with fair bit of use.

When pumping, some fine material like panty hose, would keep any abrasive stuff out of the pump.

Bob.

Seen it all, Done it all.
Can't remember most of it.

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Reply By: jokirt - Thursday, Jan 30, 2014 at 14:04

Thursday, Jan 30, 2014 at 14:04
Thanks guys I'll check out the options you have suggested and get back to you :)
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