Educate me on Inverters ?

[Maximus Ram]

ok, I searched and there are threads about inverters, but nothing that give specifics on what size is good for what uses or install tips and tricks.
So , I am open to being educated on these. What I am looking at is instaling on in the Dodge. It would be there for possibly running one of those small twin tank cambell hausfeld compressors and the occasional power tool. Maybe an Engle or similar fridge at some point. So where to start ??...



Thanks,
Matt

 

[cnynrat]

ok, I searched and there are threads about inverters, but nothing that give specifics on what size is good for what uses or install tips and tricks.
So , I am open to being educated on these. What I am looking at is instaling on in the Dodge. It would be there for possibly running one of those small twin tank cambell hausfeld compressors and the occasional power tool. Maybe an Engle or similar fridge at some point. So where to start ??...



Thanks,
Matt

The Engel, ARB and other similar fridges run off of 12 VDC directly - no need for an inverter for those.

 

[NLXTACY]

If you are using something like a fridge that has both 12v and 110v capabilities, its more efficient to use the 12v option.

There are two types of inverters: Mod Sine and Pure Sine.

Mode sine inverters can be used for pretty much anything EXCEPT NiCad rechargeable batteries, laptop batteries and really high-end professional camera equipment. The charge you get is considered a dirty charge.

Pure sine inverters are very clean charging inverters and thus are recommended for use for sensitive medical equipment, computers and NiCad.

Pure sine inverters are 10-20x the cost of its comparable Mod sine brother.

I have a mod sine inverter that I use for charging lithium-ion batteries, DSLR battery, cell phone, PSP etc. I have a Xantrex Pure sine that is yet to be installed but that is for the Mac laptop plus other mods I have planned.

Note: I have personally seen a cheap mod sine inverter toast a dell laptop. Luckily neither were mine.

 

[NLXTACY]

In case it helps, here is my particular mod sine inverter install:

http://forum.ih8mud.com/80-series-tech/239781-how-power-distribution-part-3-inverter-install.html

Also when installing make sure you go direct to the battery. Be sure you consider the length of the wire run and what the maximum amperage is for that run length and wire size. And of course be sure you install a circuit breaker AS CLOSE TO THE BATTERY as you can and be sure its rated for what the manufacturer recommends.

 

[762X39]

It would be there for possibly running one of those small twin tank cambell hausfeld compressors and the occasional power tool.

You will want a 1.5kw inverter to run the compressor and 2/0 cable between the battery (+ and - leads) and the inverter.
Don't forget to ground the inverter chassis with a #8 ground wire to the chassis.
The fuse between the battery and the inverter will be about 200 amps (I use forklift fuses and fuseholders).
I too have toasted an IBM thinkpad with a modified sinewave (more like a squarewave) inverter.
Still, my 1kw inverter in the work truck gets used every day for a grinder and other non-critical loads.

 

[mhiscox]

Before deciding on the inverter size, you need to figure out the AC watt-hours you'll use up before you get to recharge the batteries attached to the inverter.

Watt-hours is simply the sum of each AC load you'll have in watts times the number of hours you have that load. Then you need to find the DC amp-hours that represents.

You convert the AC watt-hours to DC amp-hours by dividing total watt-hours by 10. For example, if you plan to use 1000 watt hours, that's equivalent to 100 battery amp-hours. (Since it's a 12-volt system, you'd think you'd divide by 12, but dividing by 10 adjusts for the inefficiencies in the conversion.)

It'd seem like you'd then need 100 amp-hours worth of battery bank, but you want to discharge your batteries only 50% AT THE MOST, and 60-70% would be better, particularly if using lead-acid batteries. So you'd need a minimum of 200 amp-hours of batteries to cover the 1000 watt-hour load.

In addition, to make sure your batteries last for years instead of days, you have to limit the discharge rate to a certain percentage of the capacity. For lead-acids, you'll kill them off if you routinely draw off more than 25% of their amp-hour capacity. With our example of a 200 amp-hour battery bank, that means a maximum of 50 amps draw, which is (at 12 volt with inefficiencies) about 500 AC watts. Fortunately, AGM batteries are OK with 35-40%, which means as much as 800 AC watts available at a time.

Anyway, you can find more cogent and detailed explanations of this stuff all over the internet, but the overall point is that the size of the inverter isn't all you need to know, since a big inverter with a small battery bank is not going to work for you.

 

[762X39]

Oh yeah, I forgot...when using my 1kw inverter, I leave the engine running.

 

[Heimz]

You convert the AC watt-hours to DC amp-hours by dividing total watt-hours by 10. For example, if you plan to use 1000 watt hours, that's equivalent to 100 battery amp-hours. (Since it's a 12-volt system, you'd think you'd divide by 12, but dividing by 10 adjusts for the inefficiencies in the conversion.)

Just curious, a 12V system is 1/10th the voltage of of a 120V system. Maybe thats why you divide by 10?



And what does AGM mean, is that a reference to Gel batts?

 

[Martyn]

For your compressor requirements why not go with something from Extreme Outback http://www.extremeoutback.com. The ExtremeAire Magnum will run your air tools all day.

 

[BigJim]

Not True

Pure sine inverters are 10-20x the cost of its comparable Mod sine brother

Inverter prices have come down. You can purchase pure sine wave inverters at the inverter store in Reno. They do Ebay as wll.

A pure sine wave inverter is the only way to go. All your equipment will run cooler and as designed. Some modded sine waves are near DC. That is there is no sine wave to speak of.

Do you really think you are getting a quality 1000 W inverter for $50?

Motors run way way hotter with a moded sine wave.
You can and will eventually damage your electronics with a modded sine wave.
Been there done that.

If you are using something like a fridge that has both 12v and 110v capabilities, its more efficient to use the 12v option.

There are two types of inverters: Mod Sine and Pure Sine.

Mode sine inverters can be used for pretty much anything EXCEPT NiCad rechargeable batteries, laptop batteries and really high-end professional camera equipment. The charge you get is considered a dirty charge.

Pure sine inverters are very clean charging inverters and thus are recommended for use for sensitive medical equipment, computers and NiCad.

Pure sine inverters are 10-20x the cost of its comparable Mod sine brother.

I have a mod sine inverter that I use for charging lithium-ion batteries, DSLR battery, cell phone, PSP etc. I have a Xantrex Pure sine that is yet to be installed but that is for the Mac laptop plus other mods I have planned.

Note: I have personally seen a cheap mod sine inverter toast a dell laptop. Luckily neither were mine.

 

[R_Lefebvre]

Any device (such as a laptop) which uses an AC/DC converter really shouldn't require a sine wave inverter. These device chop up the AC and turn it right back into DC. I've gotten in an argument about this with others, and pointed out that for example Apple sells an expensive Mac branded inverter which they recommend for use to charge one of their laptops, and it is in fact a simple inverter, not a Sine wave.

Or, go to a construction site where the men are using electric power tools all day long, and ask them if their generator makes pure sine. They'll look at you funny.

Pure sine is useful and necessary for some things, but there is a lot of hype surrounding them and they're not always necessary.

 

[spencyg]

I ended up just buying a DC charger for my laptop....it jumps the 13.5V up to 18V or something to that effect. Cost me like $30, and everything else can run off the inverter if necessary.

There are options!

Spence

 

[spencyg]

The unit I found was from ebay....Chinese from all indication. No idea about a Mac...sorry.

Spence

 

[M.Bas]

This pdf document is from a Dutch inverter/charger manufacturer (Victron Energy, yes those very expensive bright blue boxes), eventhough it is more based on yachts I think most of it also applies to our vehicles.

It handles stuff like battery's, charging of battery's, extra power generation, monitoring, consumption etc etc. Because it is from a manufacturer offcourse it uses all their equipment and all their examples are perfectly suited for their stuff.

I think one can answer most questions about what they need on their own after reading it.

 

[kenallwine]

Just thought I would throw my .02 in here. I have attached a scope shot of what the output of the most common modified square wave inverters looks like. Most people on here commenting are mostly right however, over time this will damage your equipment. If you look at this scope shot, every time the voltage changes, you will see a very small negative or positive spike. This is called over shoot or under shoot and is effectively a surge event. Over time, each of these surge events slowly damages your equipment. Ever hear the term "death by a thousand cuts". That applies here. If you can afford it, use a pure sine wave inverter. In the long run, it will pay off.