Inverter query

Cardo

Cardo

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www.yacht-tinkerbell.co.uk
When we set off in the near future we won't have much access to mains power as we intend to live untethered from the system. However, there's always the odd piece of electrical equipment that we simply can't find a 12V DC power supply for. For that reason, we're looking to get a small inverter. I realise they're not as efficient as finding a DC power supply, but sometimes it can't be helped. I've seen people say they're not too inefficient, either.

Anyhoo, onto the query.

I've stuck "inverter" into eBay and it's come up with a whole bunch of results, at reasonable prices. Now, I know some about electrickery and understand that power (watts) = Volts x Amps. So, how does this work?

http://www.ebay.co.uk/itm/1500W-Car...Home_Garden_PowerTools_SM&hash=item5d3621f9fb
This is a 1500W inverter. So it would suck up to 125A at 12V. That's a lot of amps. However, it uses 30A fuses? Also, the wiring pictured is in no way suitable to carry 125A worth of current. What am I missing here?

I've also see this one:
http://www.ebay.co.uk/itm/Car-Inver...Home_Garden_PowerTools_SM&hash=item336719631c
I quite like the look of this, being self contained and we could just plug it into a standard 12V socket. I think 150W would be plenty for items such as mobile phone chargers, laptops and other small appliances. We wouldn't be looking to run the kettle off it.

Thoughts?
 
absolutely no point in running an inverter to charge small appliances.
get from maplins a 100 watt car adaptor Ref code A73HU, it has a multi voltage output + many common phone.ipod adaptors
it you do by a 1500w inverter that is the max supply available but you may well use much less for a tv or small tool.

Cardo said:
When we set off in the near future we won't have much access to mains power as we intend to live untethered from the system. However, there's always the odd piece of electrical equipment that we simply can't find a 12V DC power supply for. For that reason, we're looking to get a small inverter. I realise they're not as efficient as finding a DC power supply, but sometimes it can't be helped. I've seen people say they're not too inefficient, either.

Anyhoo, onto the query.

I've stuck "inverter" into eBay and it's come up with a whole bunch of results, at reasonable prices. Now, I know some about electrickery and understand that power (watts) = Volts x Amps. So, how does this work?

http://www.ebay.co.uk/itm/1500W-Car...Home_Garden_PowerTools_SM&hash=item5d3621f9fb
This is a 1500W inverter. So it would suck up to 125A at 12V. That's a lot of amps. However, it uses 30A fuses? Also, the wiring pictured is in no way suitable to carry 125A worth of current. What am I missing here?

I've also see this one:
http://www.ebay.co.uk/itm/Car-Inver...Home_Garden_PowerTools_SM&hash=item336719631c
I quite like the look of this, being self contained and we could just plug it into a standard 12V socket. I think 150W would be plenty for items such as mobile phone chargers, laptops and other small appliances. We wouldn't be looking to run the kettle off it.

Thoughts?
Click to expand...
 
You haven't said what you need to run off mains. Your starting point has to be to determine the max power rating of the inverter (in watts) which you'd need to run whatever equipment you're thinking of. Then you need to find out whether that equipment needs a pure sine-wave inverter, or a quasi sine-wave inverter. Then you can sensibly choose one to suit your needs.
 
sailorman said:
absolutely no point in running an inverter to charge small appliances.
get from maplins a 100 watt car adaptor Ref code A73HU, it has a multi voltage output + many common phone.ipod adaptors
it you do by a 1500w inverter that is the max supply available but you may well use much less for a tv or small tool.
Click to expand...
Thanks for the adapter reference. That looks really handy. We already have a couple of jobbies that provide <12V supplies, but that one looks like it should sort out some of the other items that require >12V.

pvb said:
You haven't said what you need to run off mains. Your starting point has to be to determine the max power rating of the inverter (in watts) which you'd need to run whatever equipment you're thinking of. Then you need to find out whether that equipment needs a pure sine-wave inverter, or a quasi sine-wave inverter. Then you can sensibly choose one to suit your needs.
Click to expand...

The kinds of items we're thinking of are laptops, mobile phones, and our portable vacuum cleaner. We have dedicated 12V supplies for our own laptops and mobile phones, but we're thinking of guests who won't necessarily have the right 12V supplies so we wouldn't want to leave them in the dark. Also, our vacuum cleaner takes a 15V input to charge. However, sailorman's gadget above may sort that issue.

But going back to my initial question, how can a 1500W inverter work with fuses and cables that limit the current to much less than 1500W?
 
Something like this http://www.tlc-direct.co.uk/Products/TLINV1500ST.html will run a portable vacuum cleaner, or a microwave oven, or a power drill or angle grinder. However, you will want a large-capacity 12v battery bank (or need to run the engine, with an adequate-sized alternator) while using it. Wire it in with heavy-duty cable as close to your batteries as possible, the inverter includes a metre of suitable cable. You will also find a couple of useful guides on the product page to download.
 
Last edited:
greenalien said:
Something like this http://www.tlc-direct.co.uk/Products/TLINV1500ST.html will run a portable vacuum cleaner, or a microwave oven, or a power drill or angle grinder. However, you will want a large-capacity 12v battery bank (or need to run the engine, with an adequate-sized alternator) while using it. Wire it in with heavy-duty cable as close to your batteries as possible, the inverter includes a metre of suitable cable. You will also find a couple of useful guides on the product page to download.
Click to expand...

Thanks for the advice. It looks like there are proper 1500w inverters that come with suitable wiring. However, that would drain even our reasonable 500Ah bank pretty quickly! I guess the eBay jobbies are pretty much false advertising.

For now I think I'll forego an inverter and get an adapter similar to the one linked earlier on (unfortunately the linked item is not available anywhere) with one of these:
http://www.maplin.co.uk/dc-output-plug-set-expert-range-42952
That should cover us for most eventualities and if we need to use high power mains items we'll seek a marina with shore power.
 
We manage fine with a Sterling 350W inverter, although not pure sine wave it runs TV and small kitchen appliances OK and will charge computer quicker than the 12v adaptor. Have a Honda genny for heavy loads and battery charging occasionally.
 
Maplins like wot i got

http://www.maplin.co.uk/100w-laptop-car-adaptor-with-usb-charging-socket-223912

& 1/2 what they charged me :mad:

Cardo said:
Thanks for the advice. It looks like there are proper 1500w inverters that come with suitable wiring. However, that would drain even our reasonable 500Ah bank pretty quickly! I guess the eBay jobbies are pretty much false advertising.

For now I think I'll forego an inverter and get an adapter similar to the one linked earlier on (unfortunately the linked item is not available anywhere) with one of these:
http://www.maplin.co.uk/dc-output-plug-set-expert-range-42952
That should cover us for most eventualities and if we need to use high power mains items we'll seek a marina with shore power.
Click to expand...
 
Cardo said:
But going back to my initial question, how can a 1500W inverter work with fuses and cables that limit the current to much less than 1500W?
Click to expand...

If the 30A fuses are wired in parallel on the supply wire then they have a combined rating of 60A. A 60A fuse can carry 120A for about five minutes before it blows. You could (at substantial risk) operate things like big mains powered electric drills as long as you only ran for short periods and left plenty of cooling time. The same goes for the supply wiring. It would get hot but (probably) not melt! I'd get one if I just had an odd job to do on the boat but I wouldn't use one as a permanent source of mains power. You pays your money and you takes your choice, that's why they are only £38!
 
We have a small inverter (300W) and we wouldn't be without it. With so many laptops, iPads, MP3 players, hair straighteners etc to charge/use it makes sense as some laptops (my HP!)will not charge from 12V DC chargers so we would need to take it anyway. We frequently use it in the car as well.

Richard
 
Don't buy larger than you need due to the minimum current drain. It would be best to buy a small one say 150-300w max and a second high power one dedicated to whatever needs that sort of power provision.
 
RichardS said:
We have a small inverter (300W) and we wouldn't be without it. With so many laptops, iPads, MP3 players, hair straighteners etc to charge/use it makes sense as some laptops (my HP!)will not charge from 12V DC chargers so we would need to take it anyway. We frequently use it in the car as well.

Richard
Click to expand...

+1 A small inverter is invaluable at times.
 
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