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Old 08-18-2015, 03:35 PM   #1
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inverter wire gauge question

Installed 1500 watt PSW Ramsund. Used 0 gauge stranded copper for a 3 1/2' run on the 12v dc side to batteries. . Question: I have 6 gauge connecting the two batteries. About 8 or 10" long. Will this be OK? Or should I get heavier gauge for the Bat. to Bat. connection?...Oh, and I used 10 gauge direct burial romex for a 20' run on the 110v A-C supply side to a receptacle next to shore power cord.
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Old 08-18-2015, 04:11 PM   #2
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#6 NM-B or UF-B is rated at 55 amps or 660 watts. You're going to have to decide if the battery to battery current draw will be more than that. I'm using #10 for a run from my 200 amp service 60' to my outside 30 amp outlet. It's adequate to run the AC as the voltage at the rig is still 115VAC when running.
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Old 08-18-2015, 04:30 PM   #3
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#6 NM-B or UF-B is rated at 55 amps or 660 watts. You're going to have to decide if the battery to battery current draw will be more than that.
is that rating over any particular given distance? I'm wondering if it makes a difference that the initial draw from the inverter will be adequate from the one battery (with the proper 0 gauge to the inverter) and the second battery will leak over slower to make up the current loss to the first battery. Or will the inverter draw from both right away. In which case maybe the 6 gauge will be inadequate at the full 1500 watt load
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Old 08-18-2015, 07:26 PM   #4
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Actually the chart I drew from doesn't include distance in the ampacity. Here's the site I went to.
Ampacity Charts
I can't imagine where you would ever go to the full 1500 watt draw. Those batteries would last no time at all. I would hope the #6 is large enough. Current draw from each battery would be approximately equal. The battery that the load is hooked to would get a slightly larger draw because of the line loss of the wire between the batteries but not enough to make any difference.
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Old 08-19-2015, 05:15 AM   #5
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Great, thanks. I guess I'll give it a real world test here at home. The bigger loads I would use it for would only be for a short time. Like the coffee maker or a few minutes on the microwave. Most of the time will be just the television and reciever box for a few hours plus an electronic sound machine after that. digital clock, and maybe charging a cell phone and computer. I'm anxious to see how long it takes the converter to get the batteries back up the next day. Gen. run time.......Also, do you agree with what someone said about not mixing older and new batteries? The one I have is about 6 months old and the other a year or more. I would add 2 6 volt golf cart batteries to them http://www.batteriesinaflash.com/dee...ud0aApRD8P8HAQ But they say the new batteries would take on the age of the older ones. Or that the older ones would decrease the life of the new ones? I wouldnt want to do that to fairly expensive batteries.
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Old 08-19-2015, 06:47 AM   #6
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OK, seems to be a problem. Just tried out the inverter. (1500 watt) Microwave pins the led watt meter on the inverter and the blue "on" light turns to red and the inverter beeps. Than resets. (auto reset breaker?) OK, thats fine. Even with microwave set at half power it does that. I dont really need the microwave. But heres the real problem, the coffeemaker (small 5 cup) does it too. And the kicker is the led watt meter is only reading 750. It trips and resets about three or four times as the coffee brews. ...Any idea why it should trip when the watt meter is only reading 750? Seems to do it when the inverter cooling fan come on. Batteries are at full charge (13.5v )........update: coffee maker draws 650 watts which is what the led bar reads on the inverter. So why does it trip and reset? Converter breaker is off. If anything else was drawing in the camper wouldnt it show on the watt meter?
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Old 08-19-2015, 06:58 AM   #7
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I ran into the same difficulties on my old trailer.


The solution was to place the 1,500W inverter under 12" from the battery. Very short, heavy leads. I think I used #4 wire.


The 750W microwave could warm up (room temp to drinkable) an 8oz cup of coffee in 1 minute on the inverter. 30 seconds on shore power.


Forget about running a coffee maker on batteries! 8 minutes @ 700W. The CO detector will complain about low volts before the pot is brewed.
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Old 08-19-2015, 07:26 AM   #8
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I used 0 gauge wire for a 3 1/2' run to batteries. Why wont it run a 650 watt coffee maker for 4 minutes with two freshly charged batteries? Its a 1500 watt unit. I read some reviews of this on amazon (BTW its $80 cheaper now and I bought it a week ago) and someone had the same complaint. Is the inverter just a POS?
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Old 08-19-2015, 07:54 AM   #9
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Quote:
Originally Posted by rick danger View Post
I used 0 gauge wire for a 3 1/2' run to batteries. Why wont it run a 650 watt coffee maker for 4 minutes with two freshly charged batteries? Its a 1500 watt unit. I read some reviews of this on amazon (BTW its $80 cheaper now and I bought it a week ago) and someone had the same complaint. Is the inverter just a POS?
Do the math: How many amp-hours in your battery?

650 watts @ 12V is over 50 amps per second.

So 50 times 60 seconds in a minute times 4 minutes equals 13,000 amp minutes. Divide by 60 minutes in an hour about 217 amp hours are needed to do a batch of coffee.

The problem isn't the inverter, it is in how much absolute energy can be stored in a battery. Gasoline is over 300 times more energy dense. Propane is close at 270x.

Why do you think electric cars are so pointless in this era of cheap hydrocarbons?

If you want to make coffee and don't have access to lots of electricity (grid, genset, etc.), buy a stovetop unit.

But keep the inverter. I haven't found a 12V coffee grinder yet.
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Old 08-19-2015, 08:28 AM   #10
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My batteries are tethered together with 0 ga.. no sense having a choke point
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