2000 Excursion LTD 7.3 4x4.

I would like to install a power inverter to run a freezer we take hunting to Idaho from Minnesota. We also bring a 6000 watt generator to power the freezer while we are there so the inverter would only be used to power the freezer while we are on the road. I'm thinking about a 2000 watt inverter. I've seen coleman makes one with 4500 surge capacity which should be plenty to power our chest freezer.

Looking for advice or experiences related to installing inverters on the 7.3 PSD. How much can the alternator handle? Have any of you guys with work trucks had them installed? As I will probably only use it when we go west each year it will see very little use but I would mount it permanently under the hood.

Any advice would be appreciated.

Thanks - Dan Ward

 

How much power does your freezer pull?????

 

I would mount the inverter where some cool air can get to it, not under the hood, especially with such a large inverter. Our stock alts. are 130 amp rated. the 130 amp rating is at about 1200 rpm for the alternator, not engine rpm. So if your truck is idling your alt. might not put out enough power. This will overload the alt. drian the batteries and possibly ruin the inverter when the freezer starts up. So I would keep my idle up when you stop for a rest, and/or turn off the electrical load until you are driving again.

 

I assume your freezer has a standard motorized compressor. If so, you will have to purchase a true sine wave inverter, the reason is the cheap inverters use a stepped square wave which will not work on purely inductive loads.

Rule of thumb that I use in sizing inverters for resistive loads is to take the number of watts output required and divide by 10, that will give you a good approximation of worst case input amps that your car will need to supply.

So to take your alternator question, assume you have 75 amps or remaining alternator capacity, divide that by 10 and you will have 7.5 inverter output amps, we can round that to 8 for easy math and multiply by the output voltage of 120 to achieve 960 watts. Therefore your alternator could support a 1000 W inverter at 100% load providing the engine is turning sufficient RPM to allow for max output.

Hope this helps.

 

I've posted the add for the 2000-4000 watt coleman generator below. It advertises that it can start refrigerators so I assumed that it would start our freezer. I think the freezer draws about 600 to 700 amps when running but I've heard it takes 3-4 times that to start it. I also assumed with a 2battery system that the initial surge could be supplied by batteries and the alternator would recharge once operating amps are reached. I also htought when running that enough air would get under hood to cool. Anybody have one installed on their truck?

Thanks for your feedback - Dan Ward (below is add)

This is a super-efficient inverter with the highest surge capability in the industry, which allows it to start even the most difficult loads, including color televisions, TV/VCR combinations, microwaves, refrigeration units, and much more.

2000 watts continuous power
4000 watts peak power
Run power tools and work lights.
Run refrigerators and microwaves.
Run space heaters or cooling fans.
Power computers, printers and peripherals.

 

I mean't inverter not generator in last post. Sorry

 

Dan,

If the inverter's manufacturer states that it will run a refer, then I'd say you have a pretty good match.

You are correct that the surge would be handled by the batteries, but remember to wire for the increased amperage. These wires must be able to carry the surge amperage with minimal voltage drop. Most inverters shutdown at about 11 volts so if you are starting your refer with the car off, then you will have 12.6 volts minus the voltage drop of the supply circuit. In other words you cannot drop more than 1 volt in the supply circuit or the inverter will shutdown. I'm certain that a quality inverter will give you directions regarding the proper sized wire to use.

As far as mounting the unit a cool and dry location is expected unless the manual states otherwise. This is usually under 90F, and cannot be found under the hood of any engine. If you want to mount forward and outside, providing it is a weatherized unit you may be able to mount on the leading side of the radiator mount.

On my expedition I have a 700 watt inverter stashed underneath the middle seat. That allows enough air to flow through the unit and close enought to the load(s) that I will run in the rear cargo area. However I do not have the power requirement that you do which would require running large guage wire from the battery through the passenger compartment.

Good luck!

 

I have used my 1500/3000 watt inverter to run a skill saw (by it self), two TVs, a satellite, and an industrial fan (all at the same time--good for about 3-4 hours between needing to start the truck), and finally I have ran my fullsize refrigerator and chest type freezer both at the same time while our power was out during the recent storm.

Granted, my truck has the dual alternators, but I would be more than comfortable running just a freezer off of it with only 1 alternator.

And definitely keep it in a cool location or at least where air can circulate around it.

 

Agreed, a single freezer on an inverter shouldn't pose a problem for any competent charging system as it should be less than a 50A draw.

SkillSaws are not induction motors and will run on anything from DC thru high frequency (400Hz) AC and are tolerant of wide voltage fluctuations and the like.

It is the sealed induction type motors like you have in your freezer that are touchy about having sine-wave power.

 

Thanks for all your input guys. I ordered the 2000/4000 inverter knowing I'll not need it but I've been told the invertor will only provide the load required. I paid 173 plus shipping for the invertor which seemed reasonable.

I have a question related to the alternator output. Specifically if its a 130 amp alternator, what level of output can it comfortably provide over a 12 hour period and what is the best way to measure how many amps the alternator is pumping out.

I ask this because I bought my Ex used and it came with an amp wired in to the sound system. I planned on disconnecting the amp while running the freezer, but I think there will probably be plenty of power to run both, and once the freeezer is running and I turned the radio on I would get an accurate read on alternator draw.

Thanks - Dan Ward

 

Heres an update to my amp use question. I work with a Chev dealership and we hooked their diagnostic amp meter to the alternator. Idling with nothing turned on it was drawing 20 amps. When I turned the AC on (no fan) 26 amps. Turning fan to full added 14amps (low fan setting only added 3 amps) - so now we are to 40. Turning on the lights added another 15 amps. My concern for the amped up sound system was unfounded as turning the radio on to normal levels only added two amps. Cranking the volume up to ear blasting levels could get the draw up a maximum of 10 amps.

So it looks like I'll be able to keep the draw without the freezer to a maximum of about 45 amps (at night with lights, low ac and low radio on) and mimimum of 25 during the day.

I spoke to an electric shop that we have rebuild alternators and he thought a load under 100 amps with good air curculation ( driving down freeway) should be ok. Today I am going to get an appliance amp meter from our power company to test exactly how many amps the freezer draws, both starting and running.

Does anyone have any feed back on the amp readings I listed?

Thanks - Dan Ward

 

Thery only comment I have is good job! It is nice to see someone trying to do a job the right way for a change. It gets so fustrating readin about people doing things half @$$ and then crying about how their stuff isn't working right.

 

The meter I got from the electric company is basically the same thing you have on the out side of your house. It measures accumulated kilowatt hours and not amps, which makes sense for someone trying to figure out how much an appliance is costing them. I ended up buying an AC ammeter which I'll be able to use at home now. Bottom line now is that my kitchen refrigerator, two freezers in our garage, and the freezer we will take to Idaho all draw between 1-2 120volt amps after they are started and running. The freezer we are taking is the newest and actually only draws 1 amp after it has run for a while. The units in my home draw about 15 120volt amps when starting, but the freezer we bring hunting only draws about 9 120volt amps when starting. I'm now fairly certain a 1200 watt invertor would have been plenty but as the 2000 watt is on its way - better too much than too little.

Thanks for the feedback and hopefully my little learning session will help someone - Dan Ward