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rachelsdad
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# Posted: 16 Sep 2024 09:13am - Edited by: rachelsdad
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Spent four full days at cabin. I lost my second set, (4), of Volt batteries early this season to what I assume was an idiotic mistake on my part...but we won't go there!
So I did have two extra 1kwh 24 volt VOLTS I bought on ebay for less than $100 each and had been using them most of the summer for fairly light use, long sunny days, moderate evening activity.
So here are the issues:
One, I mounted the pump directly to a frame in the cabin....It's LOUD, and it rattles the whole place.
Two, I had to use it rather frequently as I was doing a lot of cooking and dishwashing, but being relatively frugal with the water use. So....night two, my stairwell light, which is always om, (4watt LED), was off. I rushed to the CC and it was off with a red fault light. My MagnaSine CC read 20 volts but I'm not sure it truly reads SOC from what Creeky told me years back. I did have lights on more than usual as it gets dark very early but they are all LED bulbs drawing 4 watts.
Luckily they were back up to a 24 volt reading by 11 a.m. and were fine the rest of the weekend but I was very cautious of water pump usage.
So I'll remount the darned thing isolated from the frame of the house but I'm wondering do the AC versions of the Shurflo use much more power than the 12 volt versions?
And how would I do the math based on the specified
0.53-0.94 Amps @ 0-50 PSI?? How much is this drawing from my battery bank? Is there a formula?
Yes, I'm only running on 2kwh bank until I pull the trigger on the new LiFePo's, but was hoping to be able to get by with 2x 24volt 100 batteries. 4.8 Kwh
I have less than 20 lights, all 4 watt LED and hoping to use an energy efficient fridge with the new battery bank. But this pump has me worried.
Mayber get a 12 volt pump and a 12 volt LiTime w/supplemental panel??
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FishHog
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# Posted: 16 Sep 2024 12:10pm
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cant imagine its your pump drawing too much power, but if its 120v you must be running it through an inverter. It there a large parasitic drain from that inverter causing you issues.
I'd start with a volt meter on the batteries and have someone run the pump and see what happens. If you have a clamp on volt meter measure the current going to the pump. But they aren't high use items especially if your not running it continuously.
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gcrank1
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# Posted: 16 Sep 2024 01:24pm - Edited by: gcrank1
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The amps stated for a device either charging or draw is Per Hour so it is pretty mathematical. Just for good measure add in another 25% for 'system inefficiencies'; ie, that inverter draw.
Btw, too large an inverter can have Huge, constant draw even when it isn't doing anything. If you always have it on it is draining the bats. I have 3 inverters, a 300w psw, a 750msw (runs my 600w toaster) and a 1000w psw, each are off until needed but the 300w gets the most use. Point? match the inverter size to the load.
My guess is you aren't running all the lights at the same time, probably only a few where you are at, and LEDs are so efficient/low draw that I don't even factor them, or USB charging, etc anymore.
And that water pump is only on X short hours in total in 24hrs so I don't see it as the culprit.
If you decided to go with a 12v pump just get a step-down transformer (cheap) to run off your 24v system.
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ICC
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# Posted: 16 Sep 2024 01:45pm - Edited by: ICC
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I doubt there is much difference in watts used between running a 12 vdc vs a 115 vac Shurflo. A quick look at the available spec tables coupled with mental calculations doesn't wave any red flags.
Are the LED lights AC? If they aare the inverter is on or idling 24/7 just for the lights, so I don't think swapping to a 12 or 24 vdc pump would be any real improvement. Yes the 2088 is made in a 24 vdc version.
Off hand no ideas to suggest.
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paulz
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# Posted: 16 Sep 2024 02:00pm - Edited by: paulz
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Just checked my 12v pump (13 at the bank). The ammeter at the bank measured 6 amps change when on, about 80 watts. No idea what the spec is, and it’s a Flojet not Shuflo.
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Brettny
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# Posted: 16 Sep 2024 02:33pm
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Quoting: rachelsdad Mayber get a 12 volt pump and a 12 volt LiTime w/supplemental panel?
You could do this but I would look into the cost of a 120v pump. Generaly there not going to be much more money.
The power difference between running a 120v vs 12v pump off a 24v system is really the difference between your inverter loss and a 24-12v converter.
I'm running a mini fridge off 8kwh of FLA batteries. I couldn't imagine trying to run one off 1/4 my capacity. Have you tried freezing bottles of water durring the day and putting them in the fridge at night? It's a free simple test to try and move some energy around to help the system not run as much when theres no sun.
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Grizzlyman
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# Posted: 16 Sep 2024 09:50pm
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rachelsdad
how would I do the math based on the specified
0.53-0.94 Amps @ 0-50 PSI?? How much is this drawing from my battery bank? Is there a formula?
……..
Power usage should be the same theoretically between 12,24,110, or even 220 volts. Wattage is power. A pump needs to do x amount of work and needs Y amount of power or wattage to do it.
Not sure I understand your question and trying to be helpful so sorry if you were looking for something more advanced. but yes the formula is W=AxV. Or W/V=A.
You can pretty much do any electrical calcs with this basic formula.
Hope this helps.
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gcrank1
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# Posted: 16 Sep 2024 11:03pm
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Just so on the watts rating being consistent across voltage. Divide the watts rating by voltage and you get the amps (which is amps used in an hour).
If you have no watts rating you use the amps rating x the running voltage to = the watts.
So, that .53 - .94 amps is just over 1/2 amp to just under 1 amp draw BUT that is at the 120vac the inverter makes.
The next step is often missed, it tells you how many amps (approx) is drawn off your battery when making the 120vac. You Must multiply the amps draw at 120vac by the battery voltage of your system.
Then there is the conversion inefficiency of the inverter, say 85% (or 15% is 'lost').
So, your .53-.94A at 120vac is 12.72-22.56 + the 15% or 14.62 (round up to 15A) - 25.94 (26A) drawn off your battery bank per hour of use (at the 50psi).
There are some math shortcuts but I used all this to take it through the process hopefully in a logical way.
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rachelsdad
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# Posted: 17 Sep 2024 12:48am
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Wow guys thanks!!!!
So:
. but yes the formula is W=AxV. Or W/V=A.
Ok let's round up: .94A (1 A) x 24 volts equals 24 watts?
So if I run the pump for an hour I'm pulling 24 watts?
Sorry to sound so dense but thi is confusing to me!
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rachelsdad
Member
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# Posted: 17 Sep 2024 12:51am
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What would I use to measure how much energy is being used by the pump?
It sounds like a jack hammer. This really "feels" like it's eating up gobs of power
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ICC
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# Posted: 17 Sep 2024 01:38am
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A Kill-a-watt meter would be ideal for any 110-120 VAC device
If you a a multimeter than can measure AC current, use that, then multiply the amps x volts to get watts
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gcrank1
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# Posted: 17 Sep 2024 02:25am - Edited by: gcrank1
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Yes, 1 amp x 24v is 24 watts
1 amp at 120v is 120w
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Grizzlyman
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# Posted: 17 Sep 2024 02:55am - Edited by: Grizzlyman
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rachelsdad
No I don’t think so. 24 watts is not much . what voltage is your pump? It’s not a 24 volt pump right? Is it a 110v pump through an inverter?
If so it’s pulling 110 watts+ invertor loss - call it 125 watts.
My shurflo is a 5 amp x 12 v= 60 watts. Yours must be quite bigger.
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rachelsdad
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# Posted: 17 Sep 2024 06:02am
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Ok...here is more info om the pump.
So "ignoring" the inverter loss for a second Grizzlyman seems spot on
Power Source ?ac
Maximum Flow Rate ?3.3 Gallons Per Minute
Maximum Lifting Height ?3 Feet
Voltage ?115 Volts
Manufacturer ?Shurflo
Wattage ?104 watts
Amperage Capacity ?0.9 Amps
Soooo....it uses as much of my capacity as a 100 watt bulb would?
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ICC
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# Posted: 17 Sep 2024 12:52pm
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Quoting: rachelsdad Soooo....it uses as much of my capacity as a 100 watt bulb would?
Yes, a true 100 watts for as long as the pump runs.
Which, going by memory more or less matches my 12 volt DC pump. IIRC it is rated at about 8 amps. 8 x 12 = 96, or about 100 watts. I have a small conversion loss for the DV-DC 24 v to 12 v converter.
So I doubt you would save much by going to a 12 vdc pump.
The "thumping" pump noise is the nature of the beast..Eliminate any hard connection between pump and cabin frame or panels. Try suspended it on bungee cord?
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Brettny
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# Posted: 17 Sep 2024 01:52pm
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Your missing the fact that a 120v 1a pump is not the same pump as a 12v 1a pump. The 120v pump would pump 10x the water in theory. This is also such a small intermittent draw I would look else where to save power. LED bulbs or lower watt bulbs..
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paulz
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# Posted: 17 Sep 2024 02:01pm
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As I mentioned above, my 12v pump measured around 80 watts. But, my water tank is 20ft above the pump and will gravity feed even with pump off, so it’s not working very hard.
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rachelsdad
Member
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# Posted: 18 Sep 2024 09:27am
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Quoting: ICC The "thumping" pump noise is the nature of the beast..Eliminate any hard connection between pump and cabin frame or panels. Try suspended it on bungee cord?
Really??? I was thinking of setting a 4 x 4 post and mounting it on that but if it can operate like that....PERFECT. I'll try this weekend, thanks!
Oh and for the record all my bulbs are LED 4watt 110 volt, I just wanted to make sure the pump wasn't a huge power hog.
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FishHog
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# Posted: 18 Sep 2024 11:59am
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Quoting: rachelsdad Really??? I was thinking of setting a 4 x 4 post and mounting it on that but if it can operate like that....PERFECT. I'll try this weekend, thanks!
They definitely vibrate, and if hard mounted to the building you will hear it very well. Flexible hoses to the pump help, rubber feet between the pump and mount help, but the more you isolate it the less you will hear it. But even your water lines will pulse and if that will make some noise. Great for leak detection though.
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Brettny
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# Posted: 19 Sep 2024 07:33pm
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Your water lines will pulse until you put a pressure tank in.
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scott100
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# Posted: 22 Sep 2024 02:18am - Edited by: scott100
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Quoting: gcrank1 The next step is often missed, it tells you how many amps (approx) is drawn off your battery when making the 120vac. You Must multiply the amps draw at 120vac by the battery voltage of your system. Then there is the conversion inefficiency of the inverter, say 85% (or 15% is 'lost'). So, your .53-.94A at 120vac is 12.72-22.56 + the 15% or 14.62 (round up to 15A) - 25.94 (26A) drawn off your battery bank per hour of use (at the 50psi). There are some math shortcuts but I used all this to take it through the process hopefully in a logical way.
Not quite (at least here's where you lost me 
To go from current in amps from 120v to 24v, you multiply by 5 because that's the conversion (120/24=5). That's just shortening the power equation where power in watts= current x voltage. The power is the same 100 watts for either the 120 or the 24 volt systems (so plug in the voltages and power and solve for current if you want to go about it the long way). Note that I'm using 100 watts here because it was mentioned in this discussion and sounds about right for that pump. 100 watts at 120v is .83A, which is pretty close to the specs for the pump. You also aren't getting the math right for a 15% loss, so I'll ignore losses in my comments below to simplify things.
To the OP...I like to think in terms of amp hours when talking about batteries. If your pump runs around 100 watts, that would be .83 amps at 120v or about 4.16 amps at 24v. Run it for 1 hour and it uses 4.16 amp hours. You mentioned having a battery bank that was 24 volts and 200 amp hours. In a perfect world with no losses and no power use to run your inverter, you could theoretically run that pump for 48 hrs. Now, that's not real world, but what I'm getting at is that the pump is not your problem, and switching to a 12v pump won't help. If you want to think of losses at this point, just figure you'll get 15% (or whatever loss you want to use of 48 hours) less run time than the 48 hours calculated.
The pump noise. I had the same issue when I tried installing my 120v sureflow pump onto my cabin. I built a stand that sits on the ground and put the pump on it. I ran my pex plumbing down to the pump, and it's now quiet enough you hardly hear it running inside.
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gcrank1
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# Posted: 23 Sep 2024 09:51pm
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Yeah, the math gets weighty....
That is why we are probably better off using watts and watt hours, but as an old 12vdc guy I think in amps and amp hours too. Its an affliction 
One of my main points is that is too easy for someone to just use the watts @120vac because they have it running on an inverter and think it is only that small draw when in fact it is pulling far more out of the battery.
Even so, the 'problem', as you state, is not the pump.
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