Power Inverter Info Needed

[HSpiering]

I need to charge an RV battery. I know nothing about an inverter. If I am in the sun I use a solar panel. In the rain I need something else. I think a generator is rather inefficient. So how best to do that with my truck? I would be driving some every day anyway. I see Cabela’s has a 400 wt inverter that will plug into a power outlet in the truck and what if I plug in a battery charger . Run the plugin through the back window and use a battery charger. Just run it when I am driving the truck as not to run the battery down. Or is there a lot better way? I think I would need to drive the truck about 10-12 hr over a 5 day period to charge what I need.

 

[surfbeetle]

You could just run some heavy gauge wire back to the trailer battery from the truck's battery and get a charge controller. To me, it makes no sense to convert from 12v dc to 120v ac and then back again.

 

[AABEN]

The 400 will not run your battery charger!! Watts time 120

 

[HSpiering]

Ok,if I use a charge controller I might as well use a generator.

Not sure how what a battery charger takes to charge 10amp. A 1000 watt generator will do a lot more than a battery charger. So I'm thinking a 400 watt inverter would work.

 

[ToolManTimTaylor]

Many of todays "heavy duty" inverters are hell on batteries anyhow. Talk about inefficient, many have a sine wave that is a rather dirty "square" wave. This method keeps cost low and will do the job but has high harmonic distortion that will and can destroy motors, capacitors, transformers and much much more.



A "Modified" sine wave has the closest resemblence to line power found in your home. Looking at a scope it is like looking at the letter "S" on its side with a line going through the middle of it. When compared to the square wave it has less heat and not a drastic rise and drop which is how clean the power produced is.



Using an inverter to draw a load, produce a charge and dump into another battery is not such a good idea with a cheap wallmart inverter. Both truck and trailer batteries will suffer. HOWEVER if gone through the right steps with the right inversion unit there can be some pluses like now having onboard 110 volt or more for high load things like worklights, and tools.



Now things like startup load and Peak wattage need to be figured out and are simple formulas.





To Convert AMPS to WATTS:





Multiply: AMPS X 120 (AC voltage) = WATTS

This formula yields a close approximation of the continuous load of the appliance

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FORMULA to convert AC Watts to DC Amps:



AC Watts divided by 12 x 1. 1 = DC Amps

(this is the size vehicle alternator you would need to keep up with a specific load; for example, to keep up with a continuous draw of 1000 watts, you would need a 91 amp alternator)





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To Calculate approximate Startup Load:





Multiply: WATTS X 2 = Starting Load

This formula yields a close approximation of the starting load of the appliance, though some may require an even greater starting load. NOTE: Induction motors such as air conditioners, refrigerators, freezers and pumps may have a start up surge of 3 to 7 times the continuous rating.

Most often the start up load of the appliance or power tool determines whether an inverter has the capability to power it.



For example, you have a freezer with a continuous load of 4 amps, and a start up load of 12 amps:



4 amps x 120 volts = 480 watts continuous

12 amps x 120 volts = 1440 watts starting load



You would need an inverter with peak-surge rating greater than 1440 watts.

 

[Hoefler]

It would require more power from your altenator to run the inverter than to just run a charge line from the truck. In a nut shell; if your charger draws 10 amps A/C, it will draw 100 amps 12 volt D/C.

 

[surfbeetle]

Ok,if I use a charge controller I might as well use a generator.

Not sure how what a battery charger takes to charge 10amp. A 1000 watt generator will do a lot more than a battery charger. So I'm thinking a 400 watt inverter would work.

What I meant by charge controller is this: You run a charge line that is heavy enough to carry enough volts/amps to charge the rv battery in short order. You also need the controller that allows the system to charge the truck's batteries first and then allow the rv battery to be charged otherwise the rv battery constantly being connected will cause issues with your truck batteries.

 

[Skydiver]

Running a wire from Battery to battery. is the best way. Never run a wire off a battery more than a few feet if it is not protected by a Fuse or Breaker. Major NO NO.



A diode will allow the current to flow in one direction. Might help.

 

[HSpiering]

And I thought this was going to be simple.

 

[RJWEST]

relay continous duty RV type, controlled by the ign on fuse through a sw on the panel, ( diodes have a voltage drop ).

heavy wire back to aux battery, heavy wire has less voltage drop, faster charge time... . ( 8-10 wire)

install a voltmeter on dash , run sense wire back to battery being charged, now you can check state of charge of aux battery. .

Now that you have a Voltmeter installed, We add a rotary sw
with wires running to all batterys, Now we can check charging state of all batterys, busses, what ever,
( screw in + post of battery makes sure Voltage is read at the battery, not the input to the battery )

I guess you figured out "I like switches, Gages"
Really, Nothing worse than dry camping and find that your Aux Batterys did not charge. BUMMER, Wife is not a happy camper,
BAD Thing. .

 

[kenny61]

Mine Charges right thru the seven pin trailer plug. When I get where I'm going to I unplug it if battery goes dead plug it back into the truck and let er charge with the truck running for a little while

 

[icman95]

I assume you mean just the battery as if it's being used in the back of your truck. If it's in an RV it will charge off of the hitch wiring. Otherwise:



JC Whitney catalog has a battery isolator setup for just such occasions. Will wire to your truck's system and to the aux battery. It will let the juice flow in one direction only. This way the aux batt. charges, but when in use will not draw down the truck batteries, leaving you d. o. a.



Try this link to that product:



Automobile, Truck & Motorcycle: Parts & Accessories



By the way, I wouldn't try the battery charger off the 400w inverter. I tried to run a Dewalt drill charger on it and fried the inverter and the truck's fuse. You won't be able to get enough power for a battery charger. They draw way too much juice.

 

[HSpiering]

As RJWEST said "wife unhappy. ":-laf The Cabela’s add said it would run a drill. So thanks for that info.

 

[icman95]

There are inverters out there that will do what you want, but they are mucho $ and will mess up you truck batteries in a quick way. I had one on a big rig I used to own that was 1000 watts and it would run a small microwave. The difference here is that there were 4 HUGE batteries on board that it was drawing from. Even so, you couldn't draw at maximum for too long before the batts gave way. The best way to do what you need is to charge directly off the truck. Any of the suggestions posted here will do.

 

[HSpiering]

I understand the 5. 9 started out as a generator motor. So I have a 40K 325 hp generator that someone forgot to add the plugin. :-laf

 

[JVantreese]

I have found that a 1000 watt gas generator is handy when camping. Most of these units have a built in 12 volt output that can be used to manually charge your aux battery. Some trailers have a built in charger for the aux battery that will work anytime you plug into AC. The newer gernerators are also quite and gives you the option of running the generator during the daytime hours and saving the aux battery for the evening. My aux battery is also charged through the 7 pin connector but it is not cost effective or neighbor friendly to have an oil burner ideling for several hours a day. These small output generators will not run your air conditioner or microwave but will handle your water pump, lights, and your TV.

 

[Arctic Taco]

Try either Honda 1000 or 2000 EU, lightweight and charges about 8A dc

 

[jakprince]

If you have any mechanical ability you can make a 12 volt charger out of a 5 hp engine and an alternator out of an 80's model chevy. It should be able to put out 30 amps or so.

 

[JoeHutchinson]

Here my two cents,





For reason I don't understand I have never been able to get a Inverter to run a battery changer, Even the 1600 watt inverter I bought would not run a charger





When you hock up your trailer it should charge the battery, to check leave your truck running and check the voltage across battery before and after hocking it up. It should jump two volts when hocked up. If it doesn't check your fuse box in the engine compartment. My truck came with a dummy fuse in the slot which I changed to a real fuses and then it all worked good.



Good Luck



Joe



PS. I love my honda EU 2000 generator