Power inverter what size

MM53 · **Posted:** Tue Mar 17, 2015 9:42 pm

Going to mount a power inverter in the rear of the liberty for camping and such wondering what the biggest size I can put back there and use the pre-existing wires that are already ran to that power outlet by the back tailgate thank you in advance

Drewd · **Joined:** Mon Feb 06, 2006 12:24 pm **Posts:** 902

Find out what is the amperage of the fuse going to the 12 volt outlet.

For example: If the fuse is 10 amps than P=IE (Power in watts = current (amps) x Voltage (volts)

At 10 amps, you have 120 watts of power (10 amps x 12 volts) that can be used at that outlet and your inverter should not exceed 75-80% of this value since inverters are not 100% efficienct, i.e. a 100 watt inverter may use 120-130 watts.

Typically you want to minimize wiring length to an inverter because of losses; thin wiring also worsens the effect of wire length voltage losses.

Inverters should be mounted/wired as close as possible to the 12v power source and use a wire that can handle the current. There are charts that show what voltage losses you can expect with length and wire gauge. For example, on my camper I have 2 batteries feeding a 2000 watt inverter. in order to minimize losses, I run 000 cable (as thick as my thumb) and run it as short distance as possible, about 5 feet to my inverter.

If you are needing more power, might I suggest a small generator or a portable setup with a battery/inverter?

If you draw too much from your battery while camping your trip may be extended until you can get a jump start.

If I was in your situation, I'd get a cheap 4 stroke generator. They are reliable, provide plenty of "camping" power, and won't risk a dead battery. Here is a good link to one on clearance: http://bottomlinetrading.com/DS1000P3.html

If you want something quieter, may I suggest one of these: http://www.earthtechproducts.com/goal-z ... r-kit.html

You can easily build a portable power station with a battery, battery case (marine or even a rolling toolbox form Home Depot) and an inverter of your choice. http://www.instructables.com/id/The-Gri ... Generator/ or https://www.youtube.com/watch?v=O95TSa2nBLU If you need clean power for electronics, you should get a full sine wave (or true sine wave) inverter and NOT get a modified sine wave which can damage sensitive electronics.

PALiftedKK · **Posted:** Wed Mar 18, 2015 10:16 am

don't you dare reuse any factory power loom for an inverter. with no load, an inverter draws 3 amps. all manufacturers use about a 5 amp rated line at a given distance.

run your own line back there. easier this way! 10 gauge is the smallest id recommend for a 10 ft. run at a constant draw of 20 amps.

no way would it be possible to "reuse" the factory lines for an inverter that almost already maxs out the system with no load.

there's a few KK owners on here that wrote up a how to on this potential fire hazard mod.

Drewd · **Joined:** Mon Feb 06, 2006 12:24 pm **Posts:** 902

PAlifted,
I think you are a little misinformed. How can you make a blanket statement on the no-load amperage draw of an inverter? How much an inverter draws depends on its size and who makes it. For example a Samlex 300 watt full sine wave inverter draws <500 mah at idle (no load). http://www.samlexamerica.com/documents/ ... 4-0413.pdf That converts to 6 watts max which is a very low load. 300 watt would be too big for any cig lighter outlet anyway.

However, I will agree with you that using factory wiring is not a good idea. Its not a fire hazard as you stated because vehicle's circuitry is fuse protected. It just can't handle the load. '

This link has a good calculator to determine what gauge wire should be used for load of inverter and distance from battery. www.google.com/url?sa=t&rct=j&q=&esrc=s ... 8373,d.cGU It is interesting that the thicker the wire, the less resistance/losses it has than a wire of the same length that is thinner.

Any decent sized inverter should be mounted close to the battery with wire able to handle the current. Any decent output inverter would require engine to operate at a high idle so battery wouldn't die. Hence, a generator is a good option or a portable power back.

Original poster, how much power do you need? That's the most important question. Do you need 50 watts, 100, or 1500 watts so your wife can user her blow dryer while camping? Don't laugh, I have an inverter in my camper trailer so my wife can use the blow dryer first thing in the morning after a shower and I don't have to go outside to start my generator for it.

PALiftedKK · **Posted:** Thu Mar 19, 2015 11:08 am

Drewd wrote:

PAlifted,
I think you are a little misinformed. How can you make a blanket statement on the no-load amperage draw of an inverter? How much an inverter draws depends on its size and who makes it. For example a Samlex 300 watt full sine wave inverter draws <500 mah at idle (no load). http://www.samlexamerica.com/documents/ ... 4-0413.pdf That converts to 6 watts max which is a very low load. An inverter that is 3000-4000 watts would probably draw the amount you mentioned and we both know that is not a wise idea to wire into a CRD since the battery doesn't have capacity to power that inverter at max load for a long time.

However, I will agree with you that using factory wiring is not a good idea. Its not a fire hazard as you state because vehicle's circuitry is fuse protected. It just can't handle the load. A 75 to 100 watt inverter should be ok but the whole inverter in a vehicle thing is a bad idea unless the car is running at high idle to provide power to it.

sorry, typo. id just highly recommend MM53 on running their own wire. a 75-100 watt inverter is tinny for any instance. id say their best bet is to use a 400-600 watt inverter. so that way they are not limited to 75 watts.

and the goal zero products are great! their the best AIO.

if MM53 is intending on running the inverter off the car battery while off; bad; bad idea!

check out my "how to" on solar panels on jeeps. http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=104&t=81430

Drewd · **Joined:** Mon Feb 06, 2006 12:24 pm **Posts:** 902

I agree, drawing any measurable load off of a car battery for an inverter is bad idea!

Great link on the solar stuff and I'm going to reference it for my upgrade to solar this summer on my camper.

I'm limited on how much gas I carry when we go camping and I need all of that gas for our ATVs. We typically burn 4 gallons apiece each day riding. Saving 2 gallons a day of gas by not running the generator would save us 15 gallons over the course of a typical camping trip.

I'm looking at cramming 400 watts of panels on top of my camper roof. That should give me plenty of power when it is shady outside to recharge my batteries that are typically very low after running the heat all night. We camp at 10,000 feet and higher in the summer and it gets down to mid 30's at night at those elevations.

A separate battery pack or small quiet generator is original poster's best bet.

PALiftedKK · **Posted:** Thu Mar 19, 2015 11:29 am

Drewd wrote:

I'm looking at cramming 400 watts of panels on top of my camper roof.

that's impossible. unless you plan on having 4 panels over hang the jeeps roof. my panel is rated at 210 watts and it is roughly about 4 ft by 3 ft. from the factory its out put is max 180 volts. I brought that down to a max of 90 volts since the panel has 2 rails each rail has 2 sub rails if that makes since. basically my one panel has 4 panels on it.

and unless you have very good sources, you aren't going to get much more then a 100 watt panel on your roof.

the only reason why my panel is that rated that high is because its a commercial panel that a family friend gave to me because it was an extra on site.

mass-hole · **Posted:** Thu Mar 19, 2015 1:57 pm

If you have the 7 Pin towing harness, I know the 12V power line is solid(not sure of the exact gauge) and should be a direct connection to the battery. I assume there is a minimum spec that it can be to be able to feed trailers so you could probably figure it out form that.

geordi · **Posted:** Thu Mar 19, 2015 4:24 pm

At one time, I used my CRD as the power source for some film sets. I was able to run a coffee maker (1200 watts) off my 3000 watt inverter, BUT I had to have the engine running and it fed from the alternator and the battery at the same time. A 1200 watt coffee maker is pulling 100 amps at 12 volts, which is close to the limit of the alternator itself, without accounting for the losses in the cables and the inverter.

Inverters are also not 30% inefficient, they have gotten a LOT better in recent years. Still not 100%, but nothing ever will be. The electronics need some for themselves.

That inverter setup I was running was also on 4 gauge cables that were only 18 inches long, and the inverter sat on the hood or the fender while it was being used, directly connected to the battery.

Shorter cables are better.

Drewd · **Joined:** Mon Feb 06, 2006 12:24 pm **Posts:** 902

PALiftedKK wrote:

Drewd wrote:

I'm looking at cramming 400 watts of panels on top of my camper roof.

that's impossible. unless you plan on having 4 panels over hang the jeeps roof. my panel is rated at 210 watts and it is roughly about 4 ft by 3 ft. from the factory its out put is max 180 volts. I brought that down to a max of 90 volts since the panel has 2 rails each rail has 2 sub rails if that makes since. basically my one panel has 4 panels on it.

and unless you have very good sources, you aren't going to get much more then a 100 watt panel on your roof.

the only reason why my panel is that rated that high is because its a commercial panel that a family friend gave to me because it was an extra on site.

I can squeeze 3 Kyocera 140 watt panels on my camper roof. 3 x 140 = 420 watts

thermorex · **Posted:** Thu Mar 19, 2015 6:55 pm

geordi wrote:

At one time, I used my CRD as the power source for some film sets. I was able to run a coffee maker (1200 watts) off my 3000 watt inverter, BUT I had to have the engine running and it fed from the alternator and the battery at the same time. A 1200 watt coffee maker is pulling 100 amps at 12 volts, which is close to the limit of the alternator itself, without accounting for the losses in the cables and the inverter.

Inverters are also not 30% inefficient, they have gotten a LOT better in recent years. Still not 100%, but nothing ever will be. The electronics need some for themselves.

That inverter setup I was running was also on 4 gauge cables that were only 18 inches long, and the inverter sat on the hood or the fender while it was being used, directly connected to the battery.

Shorter cables are better.

holly cow, you took with you McDonald's coffee makers? That's a lot of juice for a coffee maker, that's about 10-ish amps in ac world? My deep freezer, which is medium sized, has 5 amps.

geordi · **Posted:** Thu Mar 19, 2015 10:11 pm

Have you ever looked at the rating sticker on one of those classic Mr Coffee 8-10 cup pot brewers? The heating plate on those (like most resistive heaters) sucks down a LOT of juice.

Size matters not, powerful, the heaters can be. </Yoda>

FYI, one of those McDonalds or truckstop industrial brewers that heats a tank of water instead of the pot, could easily be rocking a 3500 watt element.

PALiftedKK · **Posted:** Fri Mar 20, 2015 8:02 am

Drewd wrote:

I can squeeze 3 Kyocera 140 watt panels on my camper roof. 3 x 140 = 420 watts

I failed to see you had a camper. whats their specs?

thermorex · **Posted:** Fri Mar 20, 2015 8:54 am

geordi wrote:

Have you ever looked at the rating sticker on one of those classic Mr Coffee 8-10 cup pot brewers? The heating plate on those (like most resistive heaters) sucks down a LOT of juice.

Size matters not, powerful, the heaters can be. </Yoda>

FYI, one of those McDonalds or truckstop industrial brewers that heats a tank of water instead of the pot, could easily be rocking a 3500 watt element.

You're right, my "modern" home use brewer with warmer has 900w, 12 cups size, also mr coffee. Didn't even realized this till today, lol.

To go back on Drewd idea with solar panels, for "non pickup truck camping", there is a portable, non breakable, foldable solar panel that's advertised at 24w, I believe brunton is the company name, for about 400 bucks...

95Z28A4 · **Joined:** Sun Mar 30, 2014 9:53 am **Posts:** 297

For the money, the 1000 watt Bestek inverter is hard to beat - $72. You'll need at least 4 gauge wire for this inverter on a short run. You'll need 2 gauge wire if you locate it in the back near the tailgate.

http://www.amazon.com/gp/product/B007SL ... UTF8&psc=1

Below are links to a 4 part youtube review of the Bestek 1000 watt inverter.

Part 1: https://www.youtube.com/watch?v=iE7W1lZNEDg

Part 2: https://www.youtube.com/watch?v=a5xJMiAXtfg

Part 3: https://www.youtube.com/watch?v=YZXQsq8xrWo

Part 4: https://www.youtube.com/watch?v=Cx_pcogNGOo

PALiftedKK · **Posted:** Fri Mar 20, 2015 10:36 am

for those of you wanting to run sensitive electronics form an inverter ( TV, computer, phone, compressor based refrigerator, or anything that involves dropping voltage and supplying it to a digital product a pure sine wave inverter is recommended.

if the inverters use is primarily for high load applications ( heater, ac, coffee maker) modified sine wave are the better and cheaper alternative.

geordi · **Posted:** Fri Mar 20, 2015 12:20 pm

Anything with a switching power supply (laptops, etc) should be just fine with a modified sine wave. Modern electronics are getting better at protecting themselves, and a switching power supply is denoted by the designation that it can handle from 100-250 volts AC incoming. That means that if the shape of the plug is changed to match the UK outlets, then the device will work just fine being directly connected without a voltage converter (which those are usually also just modified sine wave) and the device can handle the 50 Hz power instead of the 60 Hz that is used in North America.

Modern LCD TVs are also mostly switching power supply too - for the same reasons, then the manufacturer can sell the same device to the whole world and the device itself will adapt to whatever the incoming power tastes like, and do its own smoothing and converting.

PALiftedKK · **Posted:** Fri Mar 20, 2015 1:22 pm

geordi wrote:

Anything with a switching power supply (laptops, etc) should be just fine with a modified sine wave. Modern electronics are getting better at protecting themselves, and a switching power supply is denoted by the designation that it can handle from 100-250 volts AC incoming. That means that if the shape of the plug is changed to match the UK outlets, then the device will work just fine being directly connected without a voltage converter (which those are usually also just modified sine wave) and the device can handle the 50 Hz power instead of the 60 Hz that is used in North America.

Modern LCD TVs are also mostly switching power supply too - for the same reasons, then the manufacturer can sell the same device to the whole world and the device itself will adapt to whatever the incoming power tastes like, and do its own smoothing and converting.

why make the device work harder? your making a lets say $600 TV work the way it was manufactured plus try to make up for the poor frequency and waveform from the $75 inverter.

I have a $500 or so sound system for my desk top and I can tell when it gets switched to back up power. you can hear the buzzing. that is not good at all for the electronics.

electronics these days and since day 1 were produced to run off of 50-60 Hz 120 or 240 volts pure sine wave form.

buy a good pure sine wave inverter to prolong the devices power delivery system. and like I said above, if the inverter is just for heating or cooling something, go crazy with a modified waveform inverter.

SC RIGGR · **Posted:** Mon Mar 23, 2015 3:37 am

Remember folks, Motors are round, they do not like square wave forms. An of-the-shelf supply for pure sine wave inverters is your neighborhood Marine supply store. It always costs more for marine, but you get watt you pay 2^2.

MM53 · **Posted:** Mon Mar 30, 2015 3:07 am

Thank you for all your help I want A head and got a solar powered generator just seemed easier than running all the wires and I don't want to keep the jeep running when I'm using it and the solar powered ones portable and quiet

Power inverter what size

Who is online