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Old 02-11-2018, 22:27   #1
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Inverter

help , is it possible to run a 1.5 hp motor off a inverter and if so how big inverter would I need , taken in account the starting power of a 1.5 hp motor , also how many amp would it take out of my batteries bank ?
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Old 02-11-2018, 22:44   #2
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Re: Inverter

1.5HP is about 1100W (roughly). Allowing for large startup draw, I'd be looking at a 2-3kW inverter.



As for Amps, figure about 100A draw to allow for inverter efficiency.
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Old 02-11-2018, 22:48   #3
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Re: Inverter

One HP = 750W/24V = 31Amps. So a 1.5HP motor will use 46Amps so that would flatten (say) a 24V 150AH battery bank very quickly. (But of course there would be losses)

I'm sure someone will tell me if I have gone wrong!

How much wattage of the inverter is needed to run a 0.5 HP single ...
https://www.quora.com/How-much-watta...run-a-0-5-HP-s...
Oct 3, 2017 - Don't forget that a motor takes 6 times full load current on starting unless some form of current reduction ... ... 2) Once you have data, now take start looking at inverter specs. ... Can I run a 1.5 HP motor on a single-phase electricity? How can I ...
How much wattage of the inverter is needed to run a 3 HP single ... 20 Mar. 2018
How much electricity is consumed by a 1.5 HP motor if it is ... 31 May 2017
How much battery does a 1 HP motor require? - Quora 25 Oct. 2016
How much wattage of the inverter is needed to run a 2 hp single ... 2 Oct. 2016
More results from www.quora.com
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Old 02-11-2018, 23:40   #4
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Re: Inverter

Maybe this link will work?

https://www.google.com.au/search?ei=....0.IKgAwbabYb8

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Old 03-11-2018, 14:43   #5
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Re: Inverter

Quote:
Originally Posted by coopec43 View Post
One HP = 750W/24V = 31Amps. So a 1.5HP motor will use 46Amps so that would flatten (say) a 24V 150AH battery bank very quickly. (But of course there would be losses)

I'm sure someone will tell me if I have gone wrong!

Why do you assume 24V?



(OK, I made the same mistake and assumed 12V, but that is much more likely for the vast majority of people here - I should have explicitly said about 100A @ 12V nominal).
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Old 03-11-2018, 15:45   #6
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Re: Inverter

Just a quick note that the inverter needs to be sized for twice the motor capacity to allow for starting inrush current.

Edit: oops I miss that stum already covered that. Carry on...
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Old 03-11-2018, 15:45   #7
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Re: Inverter

Have to ask the obvious question: it's an AC motor, right?
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Old 03-11-2018, 16:01   #8
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Re: Inverter

Most cheap inverters from China will not allow for peak draw beyond the rated output, but higher end inverters can handle that for short bursts.

This particular inverter is WAY overkill for most boat owners, but showcases this feature well. It's a 24V 6000W inverter, but capable for sustained 18,000W for 20 full seconds (well above the startup time of pretty much anything). I'd look for a 2-3kw inverter with similar overhead.

https://www.amazon.com/PICOGLF60W24V...inverter+6000w
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Old 03-11-2018, 16:58   #9
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Re: Inverter

Quote:
Originally Posted by sailorchic34 View Post
Just a quick note that the inverter needs to be sized for twice the motor capacity to allow for starting inrush current.

Edit: oops I miss that stum already covered that. Carry on...

most inverters will have a 1.5-2x surge capacity.
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Old 03-11-2018, 17:29   #10
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Re: Inverter

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Originally Posted by StuM View Post
Why do you assume 24V?



(OK, I made the same mistake and assumed 12V, but that is much more likely for the vast majority of people here - I should have explicitly said about 100A @ 12V nominal).

Good question.

If you are running a 1.5HP motor (plus other loads?) you need a larger inverter which probably means 24V. (I don't think that many people here would be running a 1.5hp motor off their batteries)

https://www.rpc.com.au/information/f...2v-or-24v.html

Clive
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Old 03-11-2018, 17:35   #11
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Inverter

The real key is, what size is the bank, or does he have a large alternator and plan on running the engine?
Iím thinking Watermaker, and if so then you need 150 amp alternator or bigger to supply a continuous 80 or 90 amps to run it without discharging the bank. ( 1hp motor)
My Mark Grasser Alt will easily run my high output Watermaker through my Magnum MS 2812 inverter / charger
All at 12 VDC.

1.5 HP is going to be tough
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Old 03-11-2018, 18:56   #12
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Re: Inverter

Quote:
Originally Posted by coopec43 View Post
Good question.

If you are running a 1.5HP motor (plus other loads?) you need a larger inverter which probably means 24V. (I don't think that many people here would be running a 1.5hp motor off their batteries)

https://www.rpc.com.au/information/f...2v-or-24v.html

Clive
I don't now about that. It depends on how long you are going to run it.


I run quite a few 1kW+ appliances through the inverter on on 12V system inverter since everything except aircon and water heater go through it.
(That includes things like an induction plate in the galley.)
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