Looking to buy a generator

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AidanS

458 posts

Ultimate Geek

#249477 12-May-2019 22:41

Hi all,

After happily settling in our first home in the beautiful town of Port Waikato, we've experienced our first "small town" problem of having a fairly unstable electricity network during storms and high winds, etc. After loosing power tonight for a few hours right in the middle of a big project I"m now in the market for a small petrol / diesel generator that I can power up to keep my laptop charging, router & ONT running and the water pump working (on tank water here).

I was wondering if anyone here knows a bit about power consumption and what I'd need to actually power those things. The laptop, modem and ONT I imagine wouldn't require a high output but the water pump might be a different story.

Keeping in mind, the water pump only turns on when someone needs water, otherwise it doesn't draw (much) power. I'm also very keen for an out of the box solution that I can basically chuck fuel in, turn on, plug in and go.

The two I'm currently looking at is:

https://www.bunnings.co.nz/ryobi-2000w-petrol-digital-inverter-generator_p00088752

and

https://www.bunnings.co.nz/briggs-stratton-p3000-powersmart-series-inverter-generator_p00307850

Thanks in advance for any help!

Cheers,

Aidan

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#2235710 13-May-2019 06:36

Hi in addition to a generator I suggest you put the devices you dont want to see any actually power outage be put on a UPS or battery backed up power supply of some kind (ie stay up during momentary blips and if longer till you get the genny connected) this would include the ONT, Router and maybe some emergency LED lighting near where the genny is.

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timmmay

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#2235721 13-May-2019 07:19

I think a UPS is important as well, otherwise there will be interruptions between when the power goes down and when you run heavy duty weatherproof extension cords to the devices that need power. That also means if you buy a cheap generator the UPS might prevent it killing your electronics.

Interesting in what people recommend. I was thinking of getting on only for emergency use, but that seems like overkill. We live in Wellington suburbs, but seem to get more outages than you would expect.

EMB

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#2235726 13-May-2019 07:38

The start up current draw of the water pump is likely to be the factor you most need to take into account in terms of generator size. There's also going to be a significant amount or electrical wiring work to be done to enable safe and proper connection of the generator to the circuits you want to have running off the generator when the power is out.

Beccara

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#2235729 13-May-2019 07:51

Given that your looking at those class of generator wiring isn't going to be a problem. You'll just need to run an extension cord to the generator and manually move things over to it when the powers out.

For that class and that price bracket the Honda generators are hands down the best around, Something like the EU22i. They are built well and last a long time, You pay a little more but it's worth it. We've had that Ryobi unit before and found that the inverter EMF was so noisy that a neighbor complained his Freeview went bad when we ran it and sure enough it did.

The only question on sizing would be the pump, Do you have a make/model for it? If it's not too bad you may be able to get away with the 1kva Honda. ONT and Router are going to be 100w AT most and your laptop would only be 100-300w so the pump decides if you go 1kva or 2/3kva

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traderstu

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#2235745 13-May-2019 08:52

Yes, agree with everyone above that say that starting the pump will determine the sizing of the generator. When you think about it, all you really need water for during a power cut is to fill a pot to boil on the barbeque, and flush the dunny. My suggestion would be to take the pump out of the equation.

A couple of ways to do this. Arrange things so that the top of your storage tank is high as possible above toilet cisterns and taps in the house. Water will still flow through the pump (albeit at low pressure) and provide water in the house.

Another way would be a header tank in the roof space. Tee into a cold water pipe in the ceiling (twice). take a pipe to the top of the roof tank with a ballcock to stop it overflowing. Take a second pipe to the bottom of the tank with a check valve so that water can only flow out of the tank. When the power is on the pump works normally - you don't even know the roof tank is there. When the power goes off the water from the roof tank will back-flow into your cold water pipes and provide water to your cold taps and toilet cisterns.

trig42

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#2235750 13-May-2019 09:04

Yep, a header tank is a savior in a power cut, we had one in a previous house and were glad of it a couple of times.

I wouldn't bother with a generator for our pump, and I would probably just get a couple of decent UPSes for your ONT/Router and laptop if you really have to work through a power cut. I don't know how much an ONT and router use, but I don't imagine it is much, so a decent UPS should run them for a few hours at least (and your laptop battery should be good for at least 2 or 3 hours these days). A cut longer than say 12 hours (never happened to us yet) may mean a bucket on a rope into the water tank. If you have kids, maybe a generator for your pump might be more desirable, just for flushing the loo (though half a bucket does a good job of that too).

Myself, when I'm at home, I'm at home and work isn't at home, so I wouldn't bother too much (we get about 3 or 4 decent power cuts a year - don't know how ours didn't go off yesterday, but a lot in our area did lose power). I did fill a couple of buckets during the storm yesterday, and a big jug of drinking water in case the power went off overnight and I had to sponge bath it before work this morning (done that a couple of times).

timmmay

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#2235753 13-May-2019 09:08

Sentry Lite is a good DC UPS for ONT and router. Hook up a 12V battery any size you like. For longer cuts get a second battery and a solar panel and swap them as required.

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#2235824 13-May-2019 10:24

Note that not all UPS will charge via a generator... looks for one that says it is generator compatible.

I had a good quality UPS that monitored the incoming power condition, and the generator power was too 'dirty' for it, and the net effect was that the UPS would trip in and out every few seconds.

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EMB

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#2236167 13-May-2019 17:42

Dynamic:

Note that not all UPS will charge via a generator... looks for one that says it is generator compatible.

I had a good quality UPS that monitored the incoming power condition, and the generator power was too 'dirty' for it, and the net effect was that the UPS would trip in and out every few seconds.

If you buy an inverter generator as the OP seemed to be looking at, that is no longer an issue in my experience.

compound

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#2236944 14-May-2019 20:33

On a water pump ID plate will be the run current in amps. A rough guide is multiply the run current by 3 for the starting load. The Ryobi would suggest a starting load of 8.7 amps and the Briggs 11.3 amps starting.

kiwigander

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#2237000 14-May-2019 21:25

For slightly more than the cost of the Briggs & Stratton you can get an AEG diesel.

I have no experience with AEG generators but would suggest that if you can tolerate the noise - perhaps less of a problem if you are not in close quarters and not using the generator frequently - you're better off with a diesel than with a petrol unit.

Petrol goes stale; diesel doesn't. Also, you probably ought to be running a petrol generator for a few minutes every week or so. Diesels are more forgiving.

sqishy

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#2237012 14-May-2019 22:00

Something to consider as well is what lights you have in the house. LEDs draw very low current, no light in a dark is not good but maybe a chance to get candles out and be more romantic.

Zeon

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#2237016 14-May-2019 22:07

I've been looking at this. For a few hours can you not just use a car battery? The ONT is probably 12v right and quite possible the laptop? If not a boost converter shouldn't cost too much on Aliexpress. For the water pump a modified Sine wave inverter is still not too expensive. How important is pure sine wave for the water pump?

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Aredwood

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#2237028 14-May-2019 22:26

Zeon:
I've been looking at this. For a few hours can you not just use a car battery? The ONT is probably 12v right and quite possible the laptop? If not a boost converter shouldn't cost too much on Aliexpress. For the water pump a modified Sine wave inverter is still not too expensive. How important is pure sine wave for the water pump?

Water pumps are typically capacitor start and run induction motors. Those type of motors hate modified sine wave power. Motor will spin slower, overheat, and might not even start. Fridge compressors are the same. Modified sine wave is only OK for resistive loads, brushed type AC motors (most power tools), and older switchmode power supplies that DONT have Active Power Factor Correction.

If you are using an inverter generator or a straight inverter that has a direct electronic output stage. Get a unit that can supply at least 10X the run current of the motor.

The old 3x rule of thumb mainly applies to non inverter generators. And low frequency inverters. Type that uses a really large transformer that is directly connected to the output. Called “low frequency” as that transformer runs at 50Hz. Instead of the 40KHz or so that switchmode step up transformers normally use.

compound

88 posts

Master Geek

#2237082 15-May-2019 07:13

I would not recommend buying a diesel generator for a single electric motor load. Diesel motors need a load on them and that wont be achieved other than a second or two during the starting. The diesel will carbon up with the light loads. Petrol motors run perfectly fine with light loads in comparison.

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