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davidwf
Active member
Re: Inverter Power Calculation
assuming its a 220V AC motor its approx 2.09kw so a 2.5kw invertor is needed.
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assuming its a 220V AC motor its approx 2.09kw so a 2.5kw invertor is needed.
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LadyInBed
Well-known member
Re: Inverter Power Calculation
Useful link <A target="_blank" HREF=http://www.onlineconversion.com/>http://www.onlineconversion.com/</A>
They say 3 horsepower [electric] = 2.238 kilowatt, so as has been said 2.5 kW will do the job.
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Useful link <A target="_blank" HREF=http://www.onlineconversion.com/>http://www.onlineconversion.com/</A>
They say 3 horsepower [electric] = 2.238 kilowatt, so as has been said 2.5 kW will do the job.
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charles_reed
Active member
Think again
I don't know if you're using 12 or 24 volts - but for a 12v system you'll need to pull about 220 amps (allowing for a fairly efficient inverter), which is rather more than many starter motors.
Why not drive it direct from a generator?
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I don't know if you're using 12 or 24 volts - but for a 12v system you'll need to pull about 220 amps (allowing for a fairly efficient inverter), which is rather more than many starter motors.
Why not drive it direct from a generator?
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ccscott49
Active member
Re: Inverter Power Calculation
I agree with charles, an inverter is not the way to go, the starting current would be enormous only for a few seconds, but i do nnot know an inverter which could handle it, plus 220 amps from your batteries to run it is just not feasible, unless you have a huge battery bank, Think again for a smaller watermaker, (pur 80e) or only run one this size with a seperate generator or engine driven mains alternator or pump. The same goes for running air conditioning from an inverter.
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I agree with charles, an inverter is not the way to go, the starting current would be enormous only for a few seconds, but i do nnot know an inverter which could handle it, plus 220 amps from your batteries to run it is just not feasible, unless you have a huge battery bank, Think again for a smaller watermaker, (pur 80e) or only run one this size with a seperate generator or engine driven mains alternator or pump. The same goes for running air conditioning from an inverter.
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tcm
...
Re: Inverter Power Calculation
no idea. But it soujnds fairly flaky for fresh water, in that you wd be dependent upon the engine, alternator, batteries, water maker, inverter and the tank all working nicely for water supplies. Is it not feasible to just load up lots of bottles of fresh water?
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no idea. But it soujnds fairly flaky for fresh water, in that you wd be dependent upon the engine, alternator, batteries, water maker, inverter and the tank all working nicely for water supplies. Is it not feasible to just load up lots of bottles of fresh water?
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ongolo
New member
Re: Inverter Power Calculation
as it is stated 220 to 250 A from your battery for the operation then about 6 times the Amps for starting will be about 1500A that the inverermust handle. If it is overload protected or input current limited, the motor will just not start.
You cannot succed in this one. Drive it from an alternator or generator or drive it directly.
regards ongolo
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as it is stated 220 to 250 A from your battery for the operation then about 6 times the Amps for starting will be about 1500A that the inverermust handle. If it is overload protected or input current limited, the motor will just not start.
You cannot succed in this one. Drive it from an alternator or generator or drive it directly.
regards ongolo
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G
Guest
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+ extra for start-up
So really is impractical.
<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I came - cos they said was FREE Guinness !
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So really is impractical.
<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I came - cos they said was FREE Guinness !
/forums/images/icons/cool.gif
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ccscott49
Active member
Re: Inverter Power Calculation
9.2 amps at 230volts, is 2116 watts. (amps x volts = watts)
2116 watts at 12 volts is 176.33 amps.(watts / volts = amps)
176.33 amps @ 95% efficiency is 185 amps (176.33 / 0.95)
So you will need a 2.2 kw inverter to run the watermaker. You will be drawing 185 amps continuously from your battery bank, no battery bank fitted to a boat, will last long enough to make a decent amount of water. then you have flat batteries!
You will need twice that size to start an AC motor. lets say 4.5 kw, so you are now seeing, I hope, the futility of this exercise, runing a mains watermaker from an inverter is a no no. Re-think smaller watermaker, battery powered and only run it when the engine is running or power the pump from the engine, or have a mains watermaker with a genny. But think if your genny packs up? No water! Battery powered is a much better idea for a smallish cruising boat. I hope this now makes sense. All of course IMHO.
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9.2 amps at 230volts, is 2116 watts. (amps x volts = watts)
2116 watts at 12 volts is 176.33 amps.(watts / volts = amps)
176.33 amps @ 95% efficiency is 185 amps (176.33 / 0.95)
So you will need a 2.2 kw inverter to run the watermaker. You will be drawing 185 amps continuously from your battery bank, no battery bank fitted to a boat, will last long enough to make a decent amount of water. then you have flat batteries!
You will need twice that size to start an AC motor. lets say 4.5 kw, so you are now seeing, I hope, the futility of this exercise, runing a mains watermaker from an inverter is a no no. Re-think smaller watermaker, battery powered and only run it when the engine is running or power the pump from the engine, or have a mains watermaker with a genny. But think if your genny packs up? No water! Battery powered is a much better idea for a smallish cruising boat. I hope this now makes sense. All of course IMHO.
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ccscott49
Active member
Re: Inverter Power Calculation
The power lead will need tobe fairly thick, to reducce volt drop then it will sink by its own weight. but if you are prepared to go to these "lengths" why not just tow a watertank /forums/images/icons/wink.gif
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The power lead will need tobe fairly thick, to reducce volt drop then it will sink by its own weight. but if you are prepared to go to these "lengths" why not just tow a watertank /forums/images/icons/wink.gif
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tcm
...
Re: Inverter Power Calculation
but then his water maker won't work!
a small point brian has omitted to relate is the voltage of his AC watermaker, likely to be 110 volt i bet. Typical! [sighs and shakes head slowly]
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but then his water maker won't work!
a small point brian has omitted to relate is the voltage of his AC watermaker, likely to be 110 volt i bet. Typical! [sighs and shakes head slowly]
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ccscott49
Active member
Re: Inverter Power Calculation
in that case its also likely to be 60 hertz............oh! Dear. Wheres me calculator?
still eed a shed load of amps at 12 volts, still the same outcome overall.
Even at 100 amps, with a 1000 ah battery bank 50% discharge max. = 5hours = not a lot of water and need to charge batteries with genny or engine????
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in that case its also likely to be 60 hertz............oh! Dear. Wheres me calculator?
still eed a shed load of amps at 12 volts, still the same outcome overall.
Even at 100 amps, with a 1000 ah battery bank 50% discharge max. = 5hours = not a lot of water and need to charge batteries with genny or engine????
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jimi
Well-known member
Re: Inverter Power Calculation
Would'nt it be sensible to tow a turbine alternator to power the watermaker and the electric engine?
<hr width=100% size=1>.. when's that again, but ..
Would'nt it be sensible to tow a turbine alternator to power the watermaker and the electric engine?
<hr width=100% size=1>.. when's that again, but ..
ccscott49
Active member
Re: Inverter Power Calculation
No, it would not! Go back to hibernating!!! See you at the Do?
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No, it would not! Go back to hibernating!!! See you at the Do?
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jimi
Well-known member
Re: Inverter Power Calculation
Humph! Try to diseminate some tight to the heathen and end up in the pot .. gerumph .. how's about hooking the alternator up to the propshaft with a fanbelt then?
<hr width=100% size=1>.. when's that again, but ..
Humph! Try to diseminate some tight to the heathen and end up in the pot .. gerumph .. how's about hooking the alternator up to the propshaft with a fanbelt then?
<hr width=100% size=1>.. when's that again, but ..
ccscott49
Active member
Re: Inverter Power Calculation
No, not enough oomph! Back doon yer hole, wee timourous beastie!
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No, not enough oomph! Back doon yer hole, wee timourous beastie!
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wiggy
Well-known member
Re: Inverter Power Calculation
Why not to a small power station to power the watermaker, but then you need the staff and accomodation, I ve got it! Tow a small country, maybe Ireland, behind you..........!!!
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Why not to a small power station to power the watermaker, but then you need the staff and accomodation, I ve got it! Tow a small country, maybe Ireland, behind you..........!!!
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