Cheap Inverters...

[Doodlebug]

Hi all,

 

I am after a 1kw inverter for the washing machine and dishwasher and was wondering what might be the problem with cheap inverters. They start on ebay at 22 pounds for a 1000w inverter but it doesnt mention anything about the surge rating, so I then looked through and found this one.

 

http://www.ebay.co.uk/itm/1000W-INVERTER-USB-Car-Power-Inverter-DC-12V-to-AC-220V-2000W-SURGE-/221284070260?pt=UK_Home_Garden_PowerTools_SM&hash=item33858ef374

 

I know its modified sine but what else should I be looking out for?

 

Having said that both run fine on our 300w inverter without use of the heating elements. I want to be able to run the proper heating cycles when on the generator (which is 1kw but can't cope with the heating elements) and so I am assuming if the machines run ok on modified sine, then adding the heating element will still work fine.

 

Not explaining too well - basically what I am saying is that modified sine usually affects the timing circuits and so if the programs run ok on modified sine the whole machine will be ok, and that modified sine doesn't affect heating elements?

 

Thanks

 

Doodlebug

[Alan de Enfield]

I'm a little confused, You say your 1Kw generator will not run the washer with the heaters connected, so I'm wondering why you think a 1Kw Inverter will work ?

 

Apologies if I've misunderstood your post.

[Phil Ambrose]

The heating element should be OK on a semi/quasi sinewave and you are correct to assume if the M/C runs OK on modified 300watt it should be OK on the same modified invertor of a higher wattage. Cannot help with the surge rating but you do need to look at the draw of the heating element, are you sure 1kw will be enough?

I assume you are going to run the M/C from battery bank while charging bank from the genny.

Also why would a 1kw invertor run the M/C while a 1kw genny won't? That's the question I would be asking myself

Phil

[Doodlebug]

Hi, sorry, I wasn't being very literate! I've just finished an essay so brains abit frazzled!

 

The generator is a 1kw yamaha but the continuous current is around 800w and doesn't seem to work.

If you suddenly try to draw a large amount of power in economy mode the genny cuts out. Which would mean I would need to have the generator running full blast which isn't ideal.

 

If I had a 1kw inverter with a 2kw surge it should run fine, -the generator wont cope with the inverters current draw but the batteries will then act as a buffer. If thats making any sense?

 

But looking at inverters there is a huge price difference. Maplin sell one for 110 pounds. Ebay I could get one for 22. I just feel like i'm missing something.

The heating element should be OK on a semi/quasi sinewave and you are correct to assume if the M/C runs OK on modified 300watt it should be OK on the same modified invertor of a higher wattage. Cannot help with the surge rating but you do need to look at the draw of the heating element, are you sure 1kw will be enough?
I assume you are going to run the M/C from battery bank while charging bank from the genny.
Also why would a 1kw invertor run the M/C while a 1kw genny won't? That's the question I would be asking myself
Phil

 

The heating element is 850w so should run ok, and yes you are correct that the genny would be running at the same time.

 

Its down to the economy mode on the generator. if the dishwasher is running an hours cycle I would need to have the genny running at full revs for the period its on.

[Alan de Enfield]

What washing machine is it, and what does the 'plate on the back' say the max wattage is ?

 

Ive not come across a washing machine that will work on 1kw.

 

Most of the threads on here re washing machines moan (comment) that a 2kw inverter is marginal.

 

Just remember that the 'surge' rating is just that - fractions of a second at that wattage, not minutes.

[Pykebird]

An old candy small machine will run off a modified 300w inverter. But they are hard to get hold of. As said most will need 2kw at least.

[Chalky]

The 1kW inverter. How is it rated and at what temperature?

Is it 1kW for 3 seconds at room temp - more like 10W continuously.

Is it 1kW for 30 seconds at room temp - more like 100W continuously.

Is it 1kW for 3 minutes at room temp - more like 300W continuously

or is it 1kW contiunously at some higher temperature e.g. 40 degrees C. If its the latter then its a proper 1kW inverter. Inverters get hot and one of the major issues with power electronics is heat management. That and good quality design don't come cheap.

[Alan de Enfield]

Did anyone notice that the seller of Dodlebug's potential inverter is a company called :

 

Thorneycroft Engines of Preston

[jonathanA]

Did anyone notice that the seller of Dodlebug's potential inverter is a company called :

 

Thorneycroft Engines of Preston

don't know if they are any relation to the well known thorny croft, but they seem to sell various boat bits, most of them are not 'brand' items but chinese knock offs. I've had a few odds and ends off them and they are what they are - worth the money i paid.

 

to answer the OP's original post - the spec does say 1000W continous 2000W surge, obviously the weedy croc clips are not a viable connection method for full load. I've had a maplin 1000W MSw inverter (not on boat) that had loads of abuse over the years and works just fine despite spending a fair amount of time bouncing around in the back of a landrover.

 

i don't quite understand how you intend to use the genny - is this powering a battery charger of some sort and your intention is to charge the batteries whilst the washing machine is running off the batteries via the inverter ?

Edited January 22, 2014 by jonathanA

[Alan de Enfield]

jonathanA, on 22 Jan 2014 - 9:02 PM, said:

 

i don't quite understand how you intend to use the genny - is this powering a battery charger of some sort and your intention is to charge the batteries whilst the washing machine is running off the batteries via the inverter ?

 

The OP states :

"the generator wont cope with the inverters current draw but the batteries will then act as a buffer. If thats making any sense?"

Maybe the generator is going to provide some of the power to the inverter and the batteries make up the rest that the inverter needs ?

I'd be interested to see how that would work

 

I dont recall the OP mentioning a battery charger - if the OP is intending to use the generators 12v output (6 amp ?) then its going to be a losing battle.

 

 

A battery charger powered by the genny (800w continuous) will not be very big - 800w at 240v is only about 3 amps

 

The 1000w inverter will be taking 100 amps out of the battery (I dont remember the OP saying how many batteries he had) but they are going to take a beating, it would probably be more beneficial to run the engine and use the alternator (50 amp ?) when the washing machine is in use.

Edited January 22, 2014 by Alan de Enfield

[smileypete]

There was a thread on this the other day:

 

http://www.canalworld.net/forums/index.php?showtopic=63249

 

Is that any help?

 

cheers, Pete.

~smpt~

[Alan de Enfield]

There was a thread on this the other day:

 

http://www.canalworld.net/forums/index.php?showtopic=63249

 

Is that any help?

 

cheers, Pete.

~smpt~

 

Thanks - thats relevant but I was trying to remember if amongst the many threads that Doodle has started if there was any mention of his battery / battery charging situation and capabiliies.

[frangar]

Just as long as he doesn't try running the inverter and generator in parallel to provide more AC amps.......that would be entertaining!!

 

Cheers

 

Gareth

[Doodlebug]

Haha true, I have started far too many threads recently - but the boat is going through its final phases of being made perfect for living in and so there are lots of questions to ask.

 

I know about not running AC in parallel, although I swear there must be a machine that can match the two up. Hondas can be connected together using a special lead.

 

We have a 40a sterling battery charger so with the genny running at the same time and 4 110ah batteries I figured we should be ok. Ill try and find out about the wattages of the dishwasher, its a bit difficult to get to the back at the moment.

 

Thanks for the advice though, I can see that cheaper models get hot and might not cope as well over long periods but the heater wont be on for long.

 

Thanks

 

Doodlebug

[Chalky]

Just as long as he doesn't try running the inverter and generator in parallel to provide more AC amps.......that would be entertaining!!

 

Cheers

 

Gareth

 

It can be done. A similar method is used on some aircraft however there's a lot of electronics and software involved to make sure the voltages and phase relationships are aligned.

[jckm2000]

I recently bought a cheap (£20 ish) 1500w inverter from ebay for my camper and it lasted a day just running a tabletop fridge, the build quality was very poor and weighed nothing. Having booked a ferry ticket to France for the following day I had to get a replacement PDQ so got one from Toolstation which is still working fine.

 

Having said that I also bought a cheap (£150) 1500w pure sinewave jobby from ebay 6 years ago for my yacht and it's never let me down.

 

I guess just don't go too cheap!