Inverters: Either of these a good deal?

[philiptompkjns]

These are both in my area, I don't really need an inverter right now but will eventually.

One is 3K Watts and does not charge for $250:
http://treasure.craigslist.org/ele/1627695176.html

One one is 2K Watts and does charge for $500:
http://treasure.craigslist.org/ele/1627986701.html


I DO plan on a 12v system for the bus, so either should work...
Are any of these deals good enough to want to jump on? Or are deals like this common or not good at all?

Thanks.

[PP]

 Hi Philip, another member but one of these a little while back and I believe they were quite happy with it, in case you want something to compare to.

http://www.tekrispower.com/inverters/product_info.php/cPath/22_54/products_id/828?osCsid=e8b22a1f0d5362d2f17efd86238b7a52

I just tried the link and it still worked. Good luck, Will

[Sean]

... I DO plan on a 12v system for the bus, so either should work...

I would advise you to think this through more carefully.

You'll need to have a whole separate 12-volt house bank to use a 3kW inverter.  How do you plan to charge the 12-volt batteries while driving?

You have a 6.5kW alternator on the bus, but it's 24-volt.  You might want to consider having a 24-volt house system, with all major loads (especially the inverter) and charger at 24-volts, and a small equalizer to run some minimal 12-volt loads such as fans, water pumps, etc..  The overall system will be much, much simpler this way.

As for the two units you looked at, I would pass on both of them.  The Duracell is a piece of junk, and the Heart is ancient.

Before you decide on an inverter, you also need to think about what you will run with it.  If you plan to run a household fridge, or anything else with an induction motor in it (such as an air conditioner), you really want a "true" sine model, not an MSW unit.

-Sean
http://OurOdyssey.BlogSpot.com

[philiptompkjns]

... I DO plan on a 12v system for the bus, so either should work...

I would advise you to think this through more carefully.

You'll need to have a whole separate 12-volt house bank to use a 3kW inverter.  How do you plan to charge the 12-volt batteries while driving?

You have a 6.5kW alternator on the bus, but it's 24-volt.  You might want to consider having a 24-volt house system, with all major loads (especially the inverter) and charger at 24-volts, and a small equalizer to run some minimal 12-volt loads such as fans, water pumps, etc..  The overall system will be much, much simpler this way.

As for the two units you looked at, I would pass on both of them.  The Duracell is a piece of junk, and the Heart is ancient.

Before you decide on an inverter, you also need to think about what you will run with it.  If you plan to run a household fridge, or anything else with an induction motor in it (such as an air conditioner), you really want a "true" sine model, not an MSW unit.

-Sean
http://OurOdyssey.BlogSpot.com

regardless of the voltage I use, you bring up a good point about the true sine wave inverter.

I HAVE run both a house fridge and A/C off a MSW inverter and they both worked... does doing this reduce their lifespan?
And I do plan on running at least a smallish fridge off inverter power.

[philiptompkjns]

Hi Philip, another member but one of these a little while back and I believe they were quite happy with it, in case you want something to compare to.

http://www.tekrispower.com/inverters/product_info.php/cPath/22_54/products_id/828?osCsid=e8b22a1f0d5362d2f17efd86238b7a52

I just tried the link and it still worked. Good luck, Will

thanks, I am now looking into a pure  sine wave inverter.... does anyone know a better deal than this? or is this about the best?
I think 2k watts will be good enough for me.

[Sean]

I HAVE run both a house fridge and A/C off a MSW inverter and they both worked... does doing this reduce their lifespan?

Yes.  It will also use more power this way.  The windings in induction motors "fight" the rapid voltage change at each stair-step of the waveform -- these motors want to see smooth voltage change, such as a sine wave.  The result of this fighting, opposing the current flow in the windings, is to heat the windings up.  Not only is the additional heat bad for the windings, but the energy used to create that heat has to come from somewhere, making the whole setup less efficient.  It will required more DC input power, and whatever the motor is running, such as a compressor for a fridge or air conditioner, will not get as much horsepower as it needs.

How bad this situation will be will depend on how many stair-steps the MSW inverter uses.  Some inexpensive units are just shy of being a square wave, and "modified sine" is something of a misnomer, like calling a hexagon a "modified circle."  Some of the better units have almost as many steps as some cheap "true sine" units, and are called "modified" mostly to ditinguish them from high-quality "true sine" units from the same manufacturer.  There is no way to tell from the name or the specs; you need to look at the waveform, either on a scope, or on the manufacturer's documentation if it is included.

I know many people have had success running fridges and A/Cs on some MSW inverters.  But unequivocally, they are using more power to do it, their appliances are not running at full output, and the windings are being cooked slowly.  This is why I recommend a true sine inverter for any induction motors other than "occasional" use.

-Sean
http://OurOdyssey.BlogSpot.com

[Jriddle]

Not sure what the budget will allow but http://www.busconversions.com/bbs/index.php?topic=15194.0this may have a potential to be a good deal?

John

[Jerry32]

I see some refridgerators say not to run on inverter or the warranty is void. I assume this is because of MSW type. I have run my houshold unit of TSW unit for three years and running strong. Jerry