Need help on wiring inverter and charger to 4 six volt batteries

[270S]

Also, a real biggie overlooked by 99.99% is wire size. I will be using 0000 (said "4 aught"). It is 3/4" in diameter with insulation. There will not be any voltage drop and efficiency will be as close to 100% for transmission as possible.

[ScottBrownstein]

[QUOTE=spock123;1158553]I wish I had not took the pictures of the batteries. ... I don't need any advice on the batteries

It's the political season and no one actually answers the question posed! You can always put more than one lug on a battery terminal, done all the time. I don't however understand the "drilling holes"part of the question. I assume that inside the inverter, both of those lugs go to the same bus bar anyway.

Now what was the question again??????

[Kenny kustom]

Originally Posted by spock123

I wish I had not took the pictures of the batteries. That was not what I was asking about. I have been hooking up batteries for ten years or more. Just forget the batteries. It was really the inverter because of the two positive cables. I don't need any advice on the batteries


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Don't be snooty.

Members saw the knife switches, lack of fusing, scary wiring and thought you needed some help.

2016 Sabre 36QBOK
2015 Ram 3500 CUMMINS

[spock123]

Originally Posted by Kenny kustom

Don't be snooty.

Members saw the knife switches, lack of fusing, scary wiring and thought you needed some help.

2016 Sabre 36QBOK
2015 Ram 3500 CUMMINS

I have did it before I just had more battery post to work with. I like the knife switches. If everything is hooked up right you don't ever get a short. I check all my wiring three or four time before I hook up the negative post. I may go on Amazon and find some 2 AWG. I'm going to hook up the inverter two positive cables to one post on the knife switch, then I'll only have three cables on one battery post. The camper came with four six volt batteries and the cable on them is four or more. They worked after I wired them up correct.


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[Big Bill]

I cant see the terminals, but it looks like the batteries are in series giving 24 V , wire like the previous posts

[boondocking]

Originally Posted by Big Bill

I cant see the terminals, but it looks like the batteries are in series giving 24 V , wire like the previous posts

They are 6 volt batteries wired correctly, series/parallel giving 12 volts.

[ScottBrownstein]

Put as many on one post as you want, as long as they fit it's no problem.

[270S]

NO it is Not correct to load up ANY post with more than a single wire, 2 if continuing on, but even then ....The proper way is to use a bus bar. Connect each item on the bus bar that is part of the same parallel circuitry. To do otherwise invites galvanic corrosion (shows up as green slime). Is what you were asking answered?

[ScottBrownstein]

Now I know why you were asking the question. I don't know where you got that as I certainly have never seen it. "If you are going on..." where else would you be going. There are standard battery schematics that have 3 wires on one post otherwise you cannot get equal length circuits for parallel batteries, like say 4-12 volt batteries.

Obviously you can get galvanic action on any lug and post combination.

[The_Rhino]

Originally Posted by Kenny kustom

Don't be snooty. Members saw the knife switches, lack of fusing, scary wiring and thought you needed some help.

Yes, folks are just trying to help you create a safe, efficient setup... Accidently drop a tool across all those knife switches & the sparks will fly! Also, the wires are too small to handle the amps possible from (4) 6V batteries... IMO you need to see a good (4) battery installation on a MH & use that as your build guide... Much heavier 12V wires are used, fuses, and everything absolutely secured so that a fender-bender does not cause a fire...

I have a good understanding of DC voltage from my RC aircraft & Ham radio hobbies... DC can push the amps & do a lot of damage so it's important to always use fuses immediately after the batteries, install heat shrink tubing over bare wires, etc. You need to be SAFE around DC w/amps just like 110V AC... It can kill ya...

However, I also still have a lot to learn when it comes to RV applications. As I am planning to install a residential fridge powered by an inverter, I had no idea I would need to consider using welding cables for the DC side until I read these forums... So I plan to gather as much info from others on these forums before I finalize my build plans.

[palmetto rogue]

You are beyond help. You need bigger than no 2 wire and you are just looking for trouble. Get some good local help.

[spock123]

I have did this before and I didn't blow anyone up, there will be a cover over the batteries. The batteries are strapped down. I bet anyone that has a residential refrigerator will not have 0000 gauge on the battery bank, mine did not.


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[The_Rhino]

I like this guy's setup, although I would use even bigger cables for (4) batteries paired with a larger inverter:



Found here:

http://www.forestriverforums.com/for...ml#post1158047

Notice the use of heat shrink tubing so there are no bare wires - just the uncovered battery posts. So... some folks were stating that he could cover the battery posts for additional safety & use something other than the thin stock covers for the unused posts.

Remember, you are camping only a few feet away from other families with kids, pets, etc. Also, you may have to fix an issue with your battery box when it is dark & stormy, wind blowing, etc. and you don't want to drop a flashlight or tool into the box & short it out...

[spock123]

Once I get everything set up I will not have to open the battery box. On my residential refrigerator the battery box I hardly every look at, those batteries are hard to get out. Cedar Creek did not put 0000 gauge cables in my Creek. Someone at the dealer could not even hook up the cables right, I had four six volt batteries but they were hooked up in a way that I had two 12 volt batteries and one 12 volt was not getting charged. The dealer couldn't even follow the diagram that was posted behind the batteries. I'm a safe person, I double and triple check what I do with batteries. Right now I can't afford solar, Alaska trip and all.


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[B and B]

Hello OP

To answer your first question. You can parallel the wires out of the inverter. I would buy two new switches and eliminate the knife switches. Also you do need a fuse in the positive line. I would also make sure the batteries are clamped tight not just a ratchet strap holding them together. A plastic battery box could be used to mount the switches and fuses to make a neat install.

Switch http://www.harborfreight.com/media/c...mage_16035.jpg

Make sure you size any wiring for the load and drop a size. Bigger is better. Lower resistance will mean better performance.

[spock123]

I really like the knife switches, I have used them for a long time and at a glance I know if they are off or on. You buy what you like. I am going to order a TM-2030 and they sell fuses. I needed some more cables so I plan to get 2/0. The cables in my other bank of batteries will stay the same. I needed some new cables anyway and I try to keep the cables as short as possible. I still wish I had not took a picture of the batteries.


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[270S]

The HF website does not give the switch specs, but I have seen similar and they are only capable of 250 amps sustained.




Depending on your inverter sizing & loads, that may be exceeded. Like everything I do, I design/plan on using above minimums for best results. Typically I use Perko, Guest, Blue Seas, Marinco, or similar with a minimum of 350amp ratings. They are obviously significantly more expensive, but ... Up to each to decide.


My new favorite is the Marinco 770-ez. Wire from front and has a continuous 400 amp rating that will probably never be reached in most applications. There are others in the 500+amp range if necessary.

[ScottBrownstein]

You guys are spending too much time reading specs and building for the edge. 250 amps is a lot of current even with a big inverter. In fact, on the Trojan discharge curve for T-105 deep cycle batteries, 250 amps is at the very high end of the curve and can only be sustained for maybe 30 minutes!

A 21 cubic foot residential reefer only draws 80 amps or so for maybe 10 minutes and a 1500 watt microwave maybe 120 amps.

Let's get real, we are not driving nuclear power plants. Sure heavier cable will cut the voltage drop but don't go into the ampacity calculators with 200 amps! Let's not confuse fuse ratings with continuous loads. They are for shorts and catastrophic situations, not average loads.

[270S]

Instead of dismissing those that try to assist, some should think further. I am able to run EVERYTHING (including AC for cooling) at the same time off my inverter as if I was pluged into a 30 amp shore cord. 250 is not enough. There should always be an excess when doing electrical design or efficiency and safety will be compromised. The only disadvantage of upsizing is cost and weight. If managed correctly, those are not issues either.

[ScottBrownstein]

Originally Posted by 25FKS

... If managed correctly, those are not issues either.

Perhaps but 250 is all there is! Look at the specs for your spanking new T-105s. Sure you can run everything...for how long? Looks to me like about 35 minutes per pair...and that is to 10.5 volts...i.e. totally discharged...totally dead...0% SOC! Both banks together would be 70 minutes and that is really an optimistic number. Then how you gonna charge them cause if you don't do it right away they will be permanently damaged.

And that is only at 250 amps or the equivalent of 25 amps of shore power.

Look for yourself. http://www.trojanbattery.com/pdf/dat...ata_Sheets.pdf