EV in reverse

Do you make your own power ? be it Solar or Wind. Then this is a place for all home energy chat.
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floydster
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EV in reverse

Postby floydster » Mon Apr 13, 2009 10:20 pm

I've a sparky coming out this week to connect my solar panels to the house :)

Anyway, being excited about generating some of my power for myself got me thinking. If I was to install a switch in the mains input to my own power could I just stick a beefy inverter on my diesel van when it's running and connect it to the house instead of the mains to provide power for the lights, TV, computer etc during power cuts?

Thanks,

Floydster
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timpootle
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Postby timpootle » Tue Apr 14, 2009 9:02 am

Sounds a bit wasteful running a diesel motive power engine and tapping off its alternator. If your diesel van happens to have a generator set attached, that would be a different case.

In fact, when I read your post more carefully, I don't think a diesel van has anything that would power a BEEFY inverter. You will be taking more out of the 12v battery than the alternator is putting in, unless you manage your power consumption very carefully.

Emergency use only, I think.

*disclaimer* I am no home energy expert. It might all be alright, but I worry. Maybe someone more knowledgeable could add something?
Tim Crumpton

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floydster
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Postby floydster » Tue Apr 14, 2009 9:20 am

timpootle wrote:Emergency use only, I think.


That's all I was thinking of rather than buy a generator to take up more floor space somewhere an have something else to maintain. After Wednesday I'll have a second consumer unit installed and linked back to solar panels and battery bank to power all the constant low drain devices and computer.

I'm not a huge energy user. With the lights, TV, laptop on in the evening I usually pull about 200W from the mains, this peaks around 350W if we have a few more lights and things on. Most of the time I charge my laptop from another solar setup I have and the TV is rarely on for more than a couple of hours in the evening.

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ChrisB
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Postby ChrisB » Tue Apr 14, 2009 8:55 pm

Buy a decent full sinewave invertor though, not a cheapy chinese one, there OK but they do tend to be very noisey on the mains side as they are generally square or sudosine wave.

Also dont forget it will pull roughly 10amps on the 12v side per 100watts on the 230v side so at 300watts you'll be looking at 30+amps on the DC.


Personally I'd buy one of these little 2 stroke gennys that output about 900watts , run on a gallon of petrol/oil mix for about 8hrs or more and cost about £50 8)
Theres not a lot that needs maintaining on them really, no oil to change and just an air filter to blow out everynow and then.

Doubt you'll get a decent invertor for less than £150 ???

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floydster
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Postby floydster » Fri Apr 17, 2009 8:00 pm

ChrisB wrote:Buy a decent full sinewave invertor though, not a cheapy chinese one


I already have one feeding my emergency lights and sockets in the house. What a difference compared to the Chinese ones, they're OK for lights but only the pure sine wave one fires up mu other half's hair straighteners :)

ChrisB wrote:Personally I'd buy one of these little 2 stroke gennys that output about 900watts


It's looking like the more sensible approach, The sparky wired up the solar backup system so I have the option to switch to a genny for longer periods which happens about around once a year.

ChrisB wrote:Doubt you'll get a decent invertor for less than £150 ???


I've a 600W pure sine wave inverter like the ones in this eBay shop which works pretty well and has a built in solar charge controller.

The next step, once I figure out how, is to connect a wind generator. Does anyone else here have a solar/wind mix? Can you use a different charge controller for each input or is there a decent combined system? Also what's the best way to measure battery bank state of charge (without thinking too much :)) and is there any decent data logging equipment out there so I can see what I'm generating and using?

Thanks,

Floydster
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nino500
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Postby nino500 » Fri Apr 17, 2009 9:15 pm

For a cheap pure sine wave inverter, try one of these.
I've rarely paid more than a tenner for one (you don't need the internal batteries to work, so you can buy them as scrap).

Just remove the internal batteries and connect to your 24v pack, which can be charged by a 24v truck alternator, mounted opposite the standard unit on your van. (£30 from a scrappie)

These units give about 900w continuous. I used one with an 800w microwave on my boat and it behaved just the same as on the mains. If you check the spec on the APC site, they are listed as being pure sine wave.

The bonus with these is they also charge the pack when plugged in to the mains (albeit at a rather lowly 5amps) and give a seamless transition to battery power when the mains fails.

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floydster
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Postby floydster » Tue Apr 21, 2009 9:21 pm

nino500 wrote:For a cheap pure sine wave inverter, try one of these.
I've rarely paid more than a tenner for one (you don't need the internal batteries to work, so you can buy them as scrap).


Cool, thanks for that. I can maybe get a hold of some old UPSs to have a fiddle with.

Floydster
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