gjewers Posted November 4, 2008 Share Posted November 4, 2008 I keep reading that an inverter can only have 5ft. of cable. Other than resistance, why is that? Couldn't you increase the wire size to overcome resistance and solder all connections etc.? Also, would two 6v batteries power the inverter better than a 12v? Finally, my 12v battery won't hold a charge so it's time for a new one (or two), and I was wondering about what the better brands are and where to get them. I want to get the most powerful juice box I can be it 6 or 12v. Thanks again. gj Quote Link to comment Share on other sites More sharing options...
Maineah Posted November 4, 2008 Share Posted November 4, 2008 Personally I would use Trojan batteries they are the toughest. Golf cart 6 volts would give you the most current if space is not a problem. The closer you can get to the batteries with your inverter the better I would guess they say 5’ due to the lug size on the inverter but yes you can move it further away if you can use larger cables. Sizing them would depend on your inverter output. Your best bet would be use longer cables on the high voltage side and get the inverter as close as you can to the batteries. Quote Link to comment Share on other sites More sharing options...
WME Posted November 5, 2008 Share Posted November 5, 2008 I have a 7" run to the inverter. I used 0/0 cable and at 100amp draw it is staying cool Quote Link to comment Share on other sites More sharing options...
gjewers Posted November 5, 2008 Author Share Posted November 5, 2008 (edited) I have a 7 ft. run also and am using #2 gauge wire. The inverter is a cheapy but is supposed to be good for 100 continuous amps. However, it won't even power my coffee maker before shuuting down in 30 seconds. With the motor running for full voltage it runs just a tad longer but it took me 10 minutes to make 2 cups of coffee with all the shut-downs. It doesn't seem to be overheating, just can't supply the juice. Any thoughts? Edited November 5, 2008 by gjewers Quote Link to comment Share on other sites More sharing options...
Maineah Posted November 5, 2008 Share Posted November 5, 2008 I assume you are talking 100 amps at 12 volts for the cables (100 amps @ 120 volts =12,000 watts) what is your inverter output? Most coffee pots will draw 1,500 watts (12.5 amps!) at 120 volts while they brew. Sounds to me that your inverter is going into protection mode. Quote Link to comment Share on other sites More sharing options...
WME Posted November 6, 2008 Share Posted November 6, 2008 A hundred amps in is about 1000w out. As Maineh said most coffe pots are 1250-1500w. Your overtemping your inverter. Quote Link to comment Share on other sites More sharing options...
futar Posted November 6, 2008 Share Posted November 6, 2008 To get wattage the formula is Volts times Amps. The lower the voltage, the more the amperage required. The problem is that amperage is what creates heat. That same wattage formula can be expressed as Current squared times Resistance which is the formula for calculating heat loss. To get 1,600 Watts at 12 Volts would require 133 Amps. Factor in efficiency and the Amperage is higher. When there is a surge, it draws it as Current. If the Voltage drops, it wants to compensate by drawing more current. That's why the short cable. 7 1/2 feet would be 50% more Resistance. It's worse with electric motors. They draw two to three times their running current to start. This is why electricity in power lines is at very high voltage, to limit the current and heat loss. It's also why high intensity lamps run at low voltage and draw higher current, to make heat. There's been talk about going to 24 or 48 volts in vehicles to increase efficiency. It's why they moved from 6 to 12 volts. Put in a breaker if there isn't one. You can get the ones that reset themselves at any auto store. Quote Link to comment Share on other sites More sharing options...
nibs Posted November 8, 2008 Share Posted November 8, 2008 We run a 750 watt cheapie inverter on 12" cables, runs the 110v coffee maker no problem, I put in a second house 12volt batt with a #2 welding cable connecting the positives and to ground. Due to space limits went with 2 - 12 volt batts rather than the superior 6 volt golf cart batts. Last year 120 amp exide 6 volt batts were under $60 in Yuma. Bought a 1750 watt inverter in Quartzite yesterday, but had to take it back because it was too big to go under the dinnette seat, we want a bigger one so we can run the Microwave. We have been in a campground for the day, didnt even bother to plug in, 120watt solar panel keeps us fat & sassy. Tony Quote Link to comment Share on other sites More sharing options...
Maineah Posted November 9, 2008 Share Posted November 9, 2008 I just plugged in my coffee pot (run of the mill home coffee pot) into a "Kill A Watt "power meter. I would recommend this unit to any one that wants to save power or in the case of the on board inverters check power draw for your 120 volt stuff. I got the one I have from newegg.com but I'm sure a search would turn them up else where. Neat unit and not very expensive. So here is what I found, brewing, 1,040 watts or around 8.6 amps that's a pretty good hit for an inverter and the battery. If 80% is a good figure for inverter efficiency that's 108 12volt amps! Power draw mounts up fast it is surprising how much power common things use. Quote Link to comment Share on other sites More sharing options...
gjewers Posted November 13, 2008 Author Share Posted November 13, 2008 Thanks for all the input. I'll sit and digest this for a little while. Getting ready for a TG holiday trip to Bodega Bay in CA. Getting things up to snuff but still dealing with a leaking window up front. Regards... Quote Link to comment Share on other sites More sharing options...
gjewers Posted March 25, 2009 Author Share Posted March 25, 2009 Thanks for all the input. I'll sit and digest this for a little while. Getting ready for a TG holiday trip to Bodega Bay in CA. Getting things up to snuff but still dealing with a leaking window up front. Regards... Just some follow up here... When I originaly installed the inverter, it was recomended that I also install a circuit breaker in-line. I put in a 30 amp one. When I was installing the battery last time, I knocked it hard and broke it. I decided to by-pass it and give it a whirl. Lo and behold, I can brew a full pot of coffee while the inverter doesn't even get warm. The fan cycles on and off once or twice but that's it. The contacts must not be able to transfer the power efficiently enough. I got me a cuppa-mud making machine now! Here's to warmer weather and hot coffee. Quote Link to comment Share on other sites More sharing options...
WME Posted March 26, 2009 Share Posted March 26, 2009 Where was the CB between the battery and inverter or between the inverter and coffee pot????. Ive got a 150 AMP fuse on my battery leads Quote Link to comment Share on other sites More sharing options...
futar Posted March 28, 2009 Share Posted March 28, 2009 I only use the inverter when I have no alternative like my microwave. Otherwise there are plenty of 12v devices. Here's some coffee pots. http://www.12voltaccessoryoutlet.com/catal...p?idCategory=67 One of my projects is going to be to make a 12v compressor roof air conditioner. They have them for semis in Europe. http://www.dcairco.com/DC4400.html I'm looking for a used roof unit to convert. Quote Link to comment Share on other sites More sharing options...
comfun1 Posted April 2, 2009 Share Posted April 2, 2009 Simplest method for coffee, no battery drain. Take the filter basket from your home coffee maker, boil water on your stove and pour slowly through the basket/filter assembly while holding over your coffee pot. Same as electric without electricity and you don't have to store the coffee maker. Quote Link to comment Share on other sites More sharing options...
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