Inverter/ Alternator Question

[Jason Moreland]

I'm probably gonna have a 1000W inverter hardwired to the battery soon. My truck has a 130 amp alternator. I should be fine right? I'm not worried about the battery so much since I don't plan on running everything without the truck running.

 

[Wes Carter]

Jason, when I bought my inverter I found a site that had a lot of useful information about inverter sizing, battery options, wiring, and cable sizing. I think it might answer your question and many others you might have.
DonRowe.com Inverter FAQ's

Also, here is an inverter sizing chart to help you figure out how much inverter you need. You can always use a larger inverter but downsize the fuse to protect both your equipment and your vehicle.

 

[david diehl]

If I were you I would add a relay between your battery, and invertor. This way if you forget to turn it off you don't kill your battery.
I have two extra relays in my van. one for my radios, and the other for my inverter.

 

[Joe Dorn]

I'm probably gonna have a 1000W inverter hardwired to the battery soon. My truck has a 130 amp alternator. I should be fine right? I'm not worried about the battery so much since I don't plan on running everything without the truck running.

Out of curiosity, why do you think you need a 1KW inverter?

I have two loaded vehicles with no inverter. They are a significant source of RF, and sometimes audible, noise. I have gone out of my way to make everything work on 12 volts.

 

[David Wolfson]

I'm working on some mobile equipment that uses about 35W. However the power meter says it's actually drawing about 70VA. In other words, the equipment I expected to draw about .25A at 120V was actually drawing .5A. How can this be? The answer was new to me and AFAIK not mentioned in any of these ST discussions about mobile power.

Many small power supplies have a lot of reactive impedance that results in a low power factor. It's common for up to half the power to be wasted due to the mismatch. Public utilities eat the difference because your standard electric meter doesn't measure the waste, and it's not huge for most households. It can get significant when you're drawing off a limited 12V supply.

My advice is not to trust the consumption charts, but rather to measure it yourself with a meter like the "Kill-a-Watt" available for less than $50 from Costco, Amazon, etc. You may be surprised like I was.

 

[Lou Ruh]

I'm working on some mobile equipment that uses about 35W. However the power meter says it's actually drawing about 70VA. In other words, the equipment I expected to draw about .25A at 120V was actually drawing .5A. How can this be?

I believe the difference is explained by how Watts and VA are computed in AC circuits. VA is the typically peak value and Watts is the RMS value. 70 vs. 35 seems a bit off ... the difference would be a factor of the square root of 2 (about 1.414), but, allowing for some variation in everything being used, is probably close to right.

 

[D. Hayes]

Jason you probably won't come close to actually pulling 1000w through that inverter. Just make sure you have a quality battery like a sears platinum. Down side it you'll need to run some 0/1 gauge wire with inline fuses for both the power and ground. At least that's what the manufacture recommended for my 1000w. You can find kits online on ebay or any stereo shop. I bought my kit from knukonceptz.com.

If you have a good inverter it will auto shut off when the battery power gets low so you can still start up in the morning. Then you won't need to do a relay setup.

yes yes, 1000w is way over kill but who can pass when it's 75% off.

 

[David Wolfson]

Lou, the meter uses RMS values for voltage and current, and for the device I mentioned showed about 35W of real power, 70VA apparent power, and a PF of 50-55%.

The PF seemed low to me, too, but is apparently not out of line for small switched supplies. NIK.

 

[Joe Dorn]

Out of curiosity, why do you think you need a 1KW inverter?

I have two loaded vehicles with no inverter. They are a significant source of RF, and sometimes audible, noise. I have gone out of my way to make everything work on 12 volts.

I received a PM about how I avoid inverters; my response may be of interest to others...

"The laptop was my problem for years then I found out that 12 to 19 volt converters are available. Dell had one for my laptop but other's are available. RAM Mounts has one. The Dell converter fits nicely into a tray on the back of my RAM amount computer table.

I use a CB radio with WX channels for my NOAA radio source. The weather radio you have might take 12 volts and the adapter plugs are available at Radio Shack.

I also use Anderson PowerPoles for my 12 volt connections with an eight position distribution panel. This allows me to readily move all of my 12 volt stuff (a bunch) to different locations as needed.

I am very active in amateur radio with two road worthy vehicles loaded and ready, an ATV ready for search and rescue, and multiple radios for connection to the NWS in Fort Worth and local spotters.

I have had no problems with voltage spikes. I wire my distribution panel directly to the battery with fuses in both legs. The battery acts as a capacitor to help eliminate spikes I have been told.

Ham radio operators connect a lot of stuff to automobile systems with little trouble reported.

Hope this helps..."

 

[Tyler_Costantini]

[FONT=&quot]I think you will find that you will never get close to 1KW! If you do then turn off the heater or remove the short in the wire . I have 2 laptops and a few other things the rest all runs right off the DC. I tested the load with a Kill-A-Watt meter and it’s around 26w when the batteries are charged and 70 or so when charging the laptop batteries.

BTW I would highly recommend a Kill-A-Watt meter.

[/FONT]

http://www.amazon.com/P3-Internatio...1?ie=UTF8&s=electronics&qid=1255926412&sr=8-1

Tyler.

 

[Jason Young]

Well I use two batteries in my truck,
One for my Truck and Ham. The other ( deep cycle ) for my Scanner , CB , side mount light's and a 750 watt inverter. BUT , I mainly use it for long road trip's with the kid's and ( WARNING : Redneck Alert ) I have used it while the power has been out in my house.