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1000W Inverter Help

6.2K views 15 replies 7 participants last post by  paleo  
#1 · (Edited)
<moderator, please relocate to electrical section>

Hi All,

I have searched and read many posts, but have not been able to find exactly what I need. I hope someone can point me in the right direction.

I have recently purchased the dirtyparts dual battery setup (waiting for it to arrive :rocker:)
i plan to connect most devices to the AUX BATTERY. for argument sake, lets assume i'll be plugging in a power tool through the inverter.

I notice that many people have already installed a high output inverter inside the cabin.
Where can i find pictures of 2 or 4 gauge wire going through the firewall without drilling?
is feeding the negative through the firewall better? will i have trouble if i ground it on the cabin side?

how is the wiring done if i wanted to wire the plug-ins to the center and back?
 
#2 ·
You don't need to push heavy guage wire thru the big rubber grommet plug on the fire wall...That's way to much hassle and your taking up space along the door channels to get it towards the back. I would run it outside and underneath the frame rails and then up thru a rubber plug in the back. You can keep it up and out of the way with zip ties and put it inside wire loom if you want..but not really needed. There is plenty of space in the back for the inverter. I'm installing a 2000watt 4000surge to make sure I can run bigger tools. 1000 watt won't run my portable buffer with a 8.5 amp draw. The bigger inverter will give you 15amps :cheers:
 
#3 ·
hey thanks for the prompt reply.
i was secretly hoping someone will come along and tell me that i don't need to go through the firewall.

what guage wire did you run?
will you happen to have a few pictures? especially how it is run under the car?
if i choose 2 guage, wouldn't the resistance in the wire cause it to heat up too much?

thanks in advancE!
 
#4 ·
What is the highest wattage or amperage you are going to pull with a tool. Start with this before you decide on the wire, AMP + distance determine the size wire. This is a decent chart

Wire Gauge Amps Ratings for 12 volt Automotive Systems

BTW, there is a rubber grommet behind where the aux battery is going, it is plenty big to fit any wire, you won't have to drill anything except the gromit. Take a look.

I haven't measured but the passenger side panel should have just as much space as the driver side, you can run the wire along the bottom edge of the floor.

I assume the inverter is going in the rear passenger side?

Image
 
#6 · (Edited)
Ohms law says that P (watts)= E (volts) X I (amps) or P/E=I, so if you take a 1000 watt inverter and feed it with 12 volts then I=1000/12. I=83.33 amps. To calculate wire size you need to use the wire length for both the positive and negative, if you use 12' of wire for the positive and 12' for the negative then you use 24' of wire to calculate wire size. Using the link to the chart provided in another post here, i would say you'd use the 100 amp row and the 25' column and you'll see it suggests #4 wire. You also need to realize that with a draw of 83.33 amps at 12 volts, the battery isn't going to last very long if the engine isn't running.


1500 Watt inverter= 125 Amps, #2 wire minimum
2000 Watt inverter= 166.66 Amps, 1/0 wire

The large wire size isn't just to reduce heat, it is also to reduce voltage drop due to resistance in the wire. For every volt dropped at 12 volts, 10 volts are lost on the 120 volt side of the inverter.
One last thing, 12Volt inverters usually produce a square wave instead of a sine wave. Switch mode power supplies like the ones used in computers and battery chargers for battery powered tools don't do well with square wave power. You'll need to be careful what you plug in to the inverter.
One more last thing, These calculations don't include any compensation for efficiency of the inverter itself. There is no such thing as a free lunch. The inverter uses power to convert the voltage. so, in order to get 120 volts at 1000 watts out you may have an efficiency rating as bad as 70%. That means that you have to put as much as 108.33 amps in at 12 volts to get 120 volts at 1000 watts out! That'll REALLY drain that battery fast!
Inverters are nice and convenient, but don't expect them to be an efficient replacement for a portable generator.
 
#7 ·
:cheers:eek:h that's very detailed, thank you very much

i tried to do the math, but came up with 2G wire, and i assumed less wiring

it looks like i won't have trouble wiring up the inverter.

about the sine wave, does this mean battery chargers or computers (ie laptops) won't play nice?
if so, then what are they good for?
i assumed a power tool because i may eventually get around to getting a shopvac to clean out my car with. i live in an apartment and there's no power in the garage near my spot.

realisticly, i plan to run a wireless access point and maybe fridge.
so very low drain, will the inverter still drain my battery regardless?
i'm mainly aiming to have it last 24-48 hours without running the car
assuming optima yellowtops

again, thank you very much in advance, you all have been a great help:bigthumb:
 
#8 ·
I too also ran 2 gauge wire for my inverter, front and rear remote jumper cables, and my winch. I also used it for my dual battery set up with two group 31 yellow top optimas. You can use it for your laptop but the stock inverter will even handle that. I use a DC addaptor for my laptop system. You will never want to hook a battery charger up as you can use jumper cables but it will handle it. I have a 1500 watt Xantrax and I use it for everything from a coffee maker, coffee grinder, hair dryer or just about anything you can think of. I ran mine along the frame rails and mounted it in the passenger side compartment under the sub woofer. I have even used it to power a TV and a PS3 but I really like the excessive power for anything I ever want to hook to it. Mine is a pure sine wave but a modified sine wave will still work for most everything you will use. It really depends on the length of the run but you will be fine no matter where you route your wire and locate it. It should power just about anything you want to. Just remember the more power you use the faster it will drain your batteries. I still have not been able to drain mine in the time I have used it.
 
#9 ·
I think i managed to put it all together regarding the sine waves.

in general,
If it is not a CB, HAM or similar type of radio (Electronics that modulate RF signals on the AC)
AND
If it has a transformer between the wall and unit/battery
it should be fine

a good summary was found here: Xantrex Technology Inc. - FAQ

for argument sake,
if i had a same device, lets say a cellphone charger connected to my inverter and battery

will it make a difference in my AUX (car) battery's life if it was a 1000Watt inverter compared to a 60Watt inverter?
 
#10 ·
That is a great explanation in the article you posted. Just make sure you do get a MSW or TSW inverter. The cheap ones are usually just a square wave. Yes, the larger inverter will use more current than a smaller inverter even if the loads are the same. I can't speak for every device, but typically the efficiency gets higher as you approach full load.
Calculating how long the batteries will last with a given load is complicated. One problem is that the amp-hour rating on the battery is calculated at a fixed discharge rate (load) for a fixed amount of time. As the discharge rate (load) is increased the amp-hour rating decreases fast. Check out the article below:

http://www.batteryweb.com/pdf/inverter_battery_sizing_faq.pdf
 
#11 ·
Sorry for the double post, but I think this is an important consideration. I posted this story in another thread a long time ago:


I had a trailer mounted winch to pull my boat up on it's trailer. The wire ran directly from the battery to the plug on the rear bumper, eventually the wire rubbed through against the frame and made a dead short. The truck shut down (no voltage to ignition), every inch of the wire caught on fire instantly, fortunately, after the wire became cherry red the wire melted through and cleared the short like it was the fuse. I had no significant fire (modern wire insulation is self extinguishing), battery explosion (due to the rapid release of gases from the battery) or permanent electrical damage even though there was the potential for serious damage. Unless you can guarantee that the wire running from the front to the rear for the winch cannot possibly come in contact with the chassis, even in the case of an accident, You need to install a fuse or fusible link as close to the battery source as possible to protect the wire. The fuse at the winch protects the winch, not the wire. It can be a 450 amp fusible link, but it should be something. You've got to protect the wire for your own safety.
This was a really scary thing when it happened and I want to give you the information so it doesn't happen to you.
 
#12 ·
I ran an 800 watt square wave inverter on my truck, and had no problems with any appliance I had plugged in. I did notice that my Rigid 18v quick charger for my tools, would get a little warmer than usual, but nothing excessive.
 
#16 ·
Did you use an existing power outlet or did you mount your own to plug into from the inverter? I am trying to figure out how to mount a new outlet or if I should just mount the end of an extension cord somehow. I wouldn't have direct access to my inverter outlet if I put it under the seat.
Do you also keep your inverter on at all times or did you somehow wire in a separate switch to turn it on/off? If so, how did you tap into the inverter switch?

Has anyone else done this? Pics?
 
#13 ·
Hey AA2D, that's a very good point you made there
how did it rub through and contact your chassis? was it at the cable ties (or whatever you used) to attach the cable along the frame?

TimmyD, regarding the charger, have you ever left it plugged in to your inverter with the engine off?
if so, how long have you left it there?

the most common things i plan to plug in to my car is a wireless access point (120V, .8A) and laptop (120V, 1.5A)
by my calcualtions, that's 276 watts. computer equipment should be constant draw
so in theory, if i buy a 300Watt inverter, i should be fine.

my biggest concern is, if i were to leave this plugged in without engine running, how do we think i have before the aux battery won't power my devices? start my car?
 
#14 ·
As a matter of fact, I think the only time I used my inverter with the engine off was to power my stereo at a car show in college, and after three hours I went to start my truck and got a click... No biggie at a car show with a bunch of friends and all of us had jumpers. No fancy battery tho. All I was using was a 5 yr old motorcraft.

So to answer your question, you have less than 3 hrs powering a pioneer sx 850 with two 15" subs at full blast :lol:
 
#15 · (Edited)
Baldwin,

When I ran the wire for my boat winch I ran it down under the truck and tie wrapped it along the frame to the rear of the truck. The fault occurred when the insulation rubbed through at one of the contact points along the frame. I have a 2500 watt inverter in my work truck now. I have run the wiring in a plastic corrugated tube called non-metallic flexible conduit. I also have a fuse at the battery connection point.

Ok, I'll take a shot at how long the battery will last. A D35 Optima yellow top battery has a 48 Amp-Hour rating. Now you have to remember you are stepping up the voltage from 12 volts to 120 volts, so the amperage at 12 volts is 10 times what you're getting out of the inverter, for example if your load is 2.3 amps at 120 volts, the battery is supplying 23 amps at 12 volts. I have not included any losses for the inverter itself. You should be able to go 20 hours with a .24 amp load at 120 volts before the battery is completely dead. At .43 amps it would only last for 10 hours, at .76 amps it would last for 5 hours, at 1.12 amps it would last for 3 hours, and at 2.4 amps it would only last for 1 hour. So, with your lap top and a wireless access point drawing 2.3 continuous amps the battery will last for a little over an hour. It'll last much, much less if you need that battery to start the car afterwards. Sorry for the disapointing news, but that's how the math works out.

I looked at the Optima website a little closer and they list "reserve minutes" as the amount of time the battery will sustain a 25 amp load (2.5 amps at 120 volts). For the D35 they say it has 100 reserve minutes. So, it's a little better than the calculations above. Your 2.3 amp load at 120 volts should last a little over 100 minutes with this particular battery.

Deep discharge cycles on a battery will decrease its lifespan pretty quickly, so I wouldn't continuously abuse it or you'll be buying a new battery. Inverters are great for short duration use like drilling a hole, or cutting a piece of wood, or vacuuming out the truck, but as you can see the battery just doesn't have the power density for sustained loads.