Wiring problem. Battery to Inverter

cswaite · July 2009

Ok.

So, I currently am using a 19" 2 Gauge battery cable to connect battery to my 2000W/4000W inverter. I have the one end that connects to the battery with the screw down battery terminal, the end that goes to inverter I have attached to alligator clips.

I bought wood and supplies last night to build a cabinet to store the battery(s), that the top reaches to the bottom of the window so I wont have to run much wire from battery to inverter (plan to put the inverter mounted on the wall right next to or below the window in the room). So I figure maybe 2-3 feet max wiring from battery to inverter.

The problem is the alligator clips cant fit the large 2 gauge wire correctly for a firm connection, I have it temporarily underneath the insulation of the clips to hold the wire in place.

I would love to be able to find ring terminals or some other sort of clean connection (preferably not alligator clamps), that I can screw down on the back of the inverter. I have searched Home Depot, Lowes, Harbor Freight and haven't been able to find anything large enough. Biggest thing I found was at Home Depot, they had a terminal for #4 Gauge wire, but the ring end was too small, I need the ring end to be about the size of a quarter almost.

I searched eBay and online to see if I could find anything, but no luck (maybe im not searching good enough).

Should I use 4 Gauge wire instead of the #2, and would I be able to find a terminal to fit the back of the inverter (ring size about the size of a quarter)?

Any suggestions would be appreciated.

Thanks much.

mike95490 · July 2009

Re: Wiring problem. Battery to Inverter

Can you describe the terminal provision on the inverter? Are they wire clamps, where a screw mashes the wire into a socket? Screw w/ tapped buss bar, where you are supposed to place a ring terminal under the screw.

An alligator clip will not work, for more than a few amps. Not enough contact area, under heavy load conditions, it will heat up.

What kind (Brand/model) of inverter is it, most good ones have easy provisions to connect to them.

cswaite · July 2009

Re: Wiring problem. Battery to Inverter

It has large screw downs, like the nut screws down on the bolt (the bolt is built into the back of the inverter). The bolts coming out are a little smaller than a quarter (money quarter) around.

It is one I got from Harbor Freight. The Brand is Chicago Electric.

Wish I had it with me i'd take a picture.

Here is a link to it online, but doesnt help much because it doesnt show the back of it.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95596

BB. · July 2009

Re: Wiring problem. Battery to Inverter

Try looking here (is wholesale only -- but if you can find somebody with a small business--it is easy to sign up and purchase single items).

Another place to look is for grounding hardware at your local home supply or electrical supply warehouse. Frequently, it is big pieces of copper that you can figure out how to modify for your needs.

-Bill

cswaite · July 2009

Re: Wiring problem. Battery to Inverter

In the manual it said to use #1 Gauge, im not pulling a large load (at least not at the moment), so #2 should be fine.

You would think they would make something to connect it properly and not be so hard to find.

cswaite · July 2009

Re: Wiring problem. Battery to Inverter

If I cant find a round eyelet, What are those eyelets that arent completely round, but u shaped, if i can find one of those i could push that down around the bolt on the back of the inverter.

That or just jam the wire directly between the nut and bolt and screw it down, not so clean though.

Cariboocoot · July 2009

Re: Wiring problem. Battery to Inverter

Your inverter connections are studs (bolt ends) with nuts on them right?
The connector you're looking for is called a "lug end" or "lug terminal". This is a standard wiring connector that should be available at any electrical supply store, larger hardware outlets. automotive shops & RV supply, and welding supply stores. They look like this:

http://lindequipment.net/siteimages/B+G-CLAMP-LE18C-WEB.jpg

There is another thread on this forum about hammer crimpers, which is how they are fastened. There shouldn't be any difficulty getting these. You might want to take your wire in and have them crimp the ends on, though. RV service or welding store should certainly be able to handle this.

cswaite · July 2009

Re: Wiring problem. Battery to Inverter

Cariboocoot wrote: »

Your inverter connections are studs (bolt ends) with nuts on them right?
The connector you're looking for is called a "lug end" or "lug terminal". This is a standard wiring connector that should be available at any electrical supply store, larger hardware outlets. automotive shops & RV supply, and welding supply stores. They look like this:

http://lindequipment.net/siteimages/B+G-CLAMP-LE18C-WEB.jpg

There is another thread on this forum about hammer crimpers, which is how they are fastened. There shouldn't be any difficulty getting these. You might want to take your wire in and have them crimp the ends on, though. RV service or welding store should certainly be able to handle this.

Would Home Depot or Lowes have these? I was looking in the electrical section last night and didnt see any, maybe I wasnt looking in the right spot or missed them. Or would I have to go to one of those other types of stores mentioned?

Cariboocoot · July 2009

Re: Wiring problem. Battery to Inverter

Since the wire size involved is quite large, your best bet is an auto/RV place as they would install these fittings for exactly this purpose: powering inverters. And they'll have the tool to crimp them on with.

n3qik · July 2009

Re: Wiring problem. Battery to Inverter

I got these from Homedepot. They have a hole for a 1/4" bolt.

RandomJoe · July 2009

Re: Wiring problem. Battery to Inverter

Another possibility is a battery supply store, if you have one available. I had never thought of them for cabling, but when I went to buy my T105s for the battery bank I found they have all kinds and sizes of wire and lugs and will build cables to suit. (Have the proper crimpers too, which can be pricey.) Prices weren't bad either.

cswaite · July 2009

Re: Wiring problem. Battery to Inverter

n3qik wrote: »

I got these from Homedepot. They have a hole for a 1/4" bolt.

Did they have these in a larger size hole? Where in the store did you find them?

cswaite · July 2009

Re: Wiring problem. Battery to Inverter

You all have given me plenty of places to check that I would have never imagined. Thanks for the input.

n3qik · July 2009

Re: Wiring problem. Battery to Inverter

They are in the electric section next to the fuse/CB. I do not know if they had bigger. They are for grounding to the box.

homerramirez · July 2009

Re: Wiring problem. Battery to Inverter

How about have a piece of 1/2 or 3/4 copper pipe, smash one end, drill a hole as needed then stick and crimp your wire on the other end?... it might work:cool:

BB. · July 2009

Re: Wiring problem. Battery to Inverter

Copper pipe is not that much copper mass (closer to sheet metal probably).

Forgot to add earlier--but our host has a wide selection of parts need to wire up your DC system.

I would recommend something designed for the job... Here is one from NAWS:

Power Distribution Block 1 x 4 circuit, 175 Amp
Item# 16220-1
$30.00

Also, I kind of like the Integrated Bus Bar + Fuse holders--Here is one company that supplies some pretty large bus/fuse blocks intended for large audio systems.

Remember that every wire that leaves the + bus connection should be protected by an appropriate sized fused for the wire that leaves the battery bus. Normally, the negative leads are not fuse protected.

-Bill

Kamala · July 2009

Re: Wiring problem. Battery to Inverter

I, too, have had difficulty finding lugs in the proper gauge/stud size combination at my local hardware/home improvement stores. I was looking for #6 in 5/16" and 3/8" and found them at West Marine. NAWS does carry #4 in 3/8" and I have decided to go with this heavier gauge. I may still want the 5/16 stud size though. I will also be getting the hammer crimp tool from NAWS,

BB. · July 2009

Re: Wiring problem. Battery to Inverter

Remember, you can use heavier gauge cable and trim some extra wires out at the ends to fit the swage connector (get the advantage of low voltage drop for "long runs" of cable).

However, the fusing/breakers should be rated for the size of the connector (not the size of the original cable--i.e., #2 cable going into a #4 connector).

-Bill

nigtomdaw · July 2009

Re: Wiring problem. Battery to Inverter

Bill having looked at the link you gave for the ICE fuses bus fuse boxes Im going to warn people not to go down this route from real life usage on at least one type of these products that use the FSG 5AG fuses The GP-0155, GP-0160 and GP-0165.

I fitted two of the four to 1 way fuse boxes show on the link GP-0165. The actual fuse holders are good well made and easily up to the job.

The problem lies with the fuses, unless I got a dodgy batch on two different occasions from different sources they do not handle the continual current from PV arrays . The glass fuses didnt blow due to over current or anything. They physically failed. The gold end caps became detached from the metal fuse strip. After 6 failures in two years I replaced them with Midnight solar buss bars .

I can not comment on the ANL and other fuses but avoid the glass FSG 5AG types

nigtomdaw · July 2009

Re: Wiring problem. Battery to Inverter

A simple search on Cable Lugs on ebay US has the answers if NAWS doesnt have the size you need

http://shop.ebay.com/?_from=R40&_trksid=m38.l1313&_nkw=cable+lugs&_sacat=See-All-Categories

BB. · July 2009

Re: Wiring problem. Battery to Inverter

Nigel,

Sounds like a good recommendation/feedback--I will stop giving these as examples of fused/bus-bar circuits.

-Bill

cswaite · July 2009

Re: Wiring problem. Battery to Inverter

Thanks again for all the advice and recommendations.

After deciding to randomly browse an Ace Hardware store here in town, I happened to come across some lugs, exactly what I was looking for. Only $1.50 each.

They are for 2 Gauge, and have a 1/2 inch hole, which I believe should fit well around the lugs on the back of the inverter (haven't tried yet). Was so excited to be able to find them in town.

Also, as far as a fuse goes, can just use a fusible link that I saw at Pep Boys?. Would an 80AMP fuse be good for the 2 Gauge wire?

Cariboocoot · July 2009

Re: Wiring problem. Battery to Inverter

Fuse size is dependent on amperage draw and voltage (it has to be able to interrupt the voltage of the system - a 12V fuse won't 'break' enough to handle 80V coming from a PV array, for example). So it's wattage/voltage = amperage. I can't remember what your system is, so this is a "guessample":

2000 Watts / 12 Volts = ~166 Amps. The fuse has to handle that (probably a 200 Amp in this scenario). Fuse should also always be the weakest link, so if you're running smaller wires only capable of handling the current for, say, 1/4 your inverter's output then the fuse has to be down-sized accordingly.

Good thing about 12 Volt systems: lots of Auto & RV stuff readily available to do many of the jobs.

cswaite · July 2009

Re: Wiring problem. Battery to Inverter

I bought 2 Gauge wire, for battery to inverter. My inverter is 2000W but I dont plan on even eventually pulling that much. What would be recommended. Think I was told elsewhere 2AWG is rated at 181AMPS, so any fuse smaller would work?

Or am I reading the wrong spot on this wire chart. Am I looking at Chassis, or Power transmission. What is the difference?

Cariboocoot · July 2009

Re: Wiring problem. Battery to Inverter

It looks to me like you've got it right for your approx. 1000 Watt max usage: 80 Amp fuse. Be sure the fuse connectors are designed to take 2 gauge.

If I recall correctly, "chassis" refers to an auto-type application where you have a large 'chassis ground' and hot wires running to devices whereas "power" refers to a 'wire loop' where you have wire going from battery to device and back. The substantial mass and thus conductivity of the 'ground' side is "chassis" allows greater current limit on the 'wire side' then a loop of wired circuitry can handle.

Gosh, that was a pretty poor explanation. Anyone want to tell me what I'm talking about?

cswaite · July 2009

Re: Wiring problem. Battery to Inverter

dwh wrote: »

Here's what the fuse that you need looks like:

http://store.solar-electric.com/infubr.html

The fuse protects the wire. What size fuse you need depends on the rating of the wire you are protecting.

For a "chassis wiring" situation, where you use #2 to connect from the battery to the inverter, then the wire is rated for up to 181 amps. Thus the fuse has to be 181 amps or less. The fuse has to burn before the wire does.

So the perfect fuse would be 180a. But you might find that hard to get, so you might go with a 150a. Fine, but if you do, then you might as well go down to #3 wire since it is rated at 158a - which means a 150a fuse will burn before the wire.

Ok, above is what I copied from one of my other threads. I was told from battery to inverter is Chassis, so im confused. Am I to use a fuse under 181AMPS (Chassis), or one rated under 94AMPS (Power)?

icarus · July 2009

Re: Wiring problem. Battery to Inverter

When in doubt,, use a too small fuse for the wire size,

T

Cariboocoot · July 2009

Re: Wiring problem. Battery to Inverter

icarus wrote: »

When in doubt,, use a too small fuse for the wire size,

T

Yup. Err on the side of caution.

I still think my explanation is right. But then again, I think I'll win the lottery some day.:p

dwh · July 2009

Re: Wiring problem. Battery to Inverter

cswaite wrote: »

Ok, above is what I copied from one of my other threads. I was told from battery to inverter is Chassis, so im confused. Am I to use a fuse under 181AMPS (Chassis), or one rated under 94AMPS (Power)?

Think of it this way - Chassis would be like if everything were in one box. Power would be like if you were running the wire between boxes.

If you are putting everything in one box (even a box with a divider, or two boxes bolted together with a hole to run the wire through), then that's chassis and you could rate the wire up to 181.

If you are running the wire between two boxes - even a foot or two apart - then that's power and you have to use the lower rating.

Wiring problem. Battery to Inverter

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