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buckybuck
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# Posted: 19 Jan 2013 10:39am
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I recently got a power inverter. It came with nice, 2 gauge cables. I kinda like to do things the right way unless it's too much effort. According to the manual that came with the inverter, it's important to put a 200 amp fuse near the battery. Okay, I'll buy that, even though it would have been nice if the inverter came with that very important fuse. Whatever. So I bought a 200 amp ANL fuse and fuse holder.
Now what? As near as I can tell, my options are to either hack through that perfectly good positive cable that came with the inverter, and then either:
A. Buy a $18 impact crimper I'll never use again and about two dozen terminal lugs to practice on, or
B. Buy a $60 eBay hydraulic crimper I'll never use again and two terminal lugs.
What's my other options? I can buy a six inch inverter cable online for around $28 including shipping, but frankly, it annoys me to pay $28 for a six inch cable.
For that matter (and before anyone jumps, I'm really not planning to do this; I'm just curious), why do you need a six inch cable between the battery and the fuse when you're hooking up an inverter in a permanent, non-moving location? Why can't I just bolt the ANL fuse to the battery terminal and then bolt the positive cable to that? It seems to me that by eliminating all the added terminal connections (I count four) you need when inserting a short cable from the battery to the fuse holder and then back to another length of cable, you'd lessen the power loss you might incur each time you send power through a terminal connector.
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toyota_mdt_tech
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# Posted: 19 Jan 2013 10:53am - Edited by: toyota_mdt_tech
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I own 2 of those impact crimpers. So its a non issue for me. I would get some waterproof shrink tube to install over the crimped eyes. Dont use solder. You need a mechanical connection before a soldered connection. Solder only can let go in a heat conditionwhile a mechanical ones remains well connected. Solder can make the wire "break" too as it deletes it flexibility. There is a marine shrink tube, I know Borg Warner makes some too. It shrinks and seals it literally water tight. But make sure the eyelet lugs are not opened on the end (see the cross section of the wire), but instead, wire goes into a "blind hole" or water/corrosion can or will set in.
$18 for a tool to do it right seems reasonable. And you may need it again, especially if you expand a system. It will work on wire sizes down to 8 gauge real nicely and makes for a very professional crimp. But crimp the underside of the lug, not the top or it will look silly. Of course, I'm one of those super perfectionist guys who wants the professional look on absolutely everything. My buddies tells me "there is medicine for that you know"  
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MtnDon
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# Posted: 19 Jan 2013 11:05am - Edited by: MtnDon
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Go to Solarseller.com. Pages 42 thru 50 for fuses and breakers for DC
Read. A Type T fuse is the best type for fusing an inverter. athey explain why. They have holders you can use by cutting the cable, stripping the ends and clamping in place with a set screw.
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Steve961
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# Posted: 19 Jan 2013 11:14am - Edited by: Steve961
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The Easiest way I have found to add a large fuse to a battery is with a Blue Sea terminal fuse block. They have 1 or 2 stud block versions for fuses that range from 30 to 300 Amps.
Blue Sea Terminal Fuse Block
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TomChum
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# Posted: 22 Jan 2013 12:10pm - Edited by: TomChum
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Impact Crimper? Searched it on Google images, First time I ever saw one, thanx for that. Looks like you just whack it with a hammer. Would be great to have one that had a bunch of dies for all size wires. I wasn't about to pay $5-$8 for terminals so made terminals out of copper tubing, it was very easy. Making my own crimper was a lot more work than buying one, but I was able to make it for the wire that I had.
Here's a pic of my sliding battery drawer, you can see the 300A fuse connected directly to the battery terminal. If you look around at my other thread you will see my "old" temporary wiring, using 6 ga cables. With this arrangement, my inverter/charger would not charge the batteries. I thought there was something wrong with the charger. When I put cables of sufficient size, it charged at 57Amps! Which you can imagine, reduces my generator runtime considerably. You can make a fairly large cable by using all 3 conductors of a 12/2 Romex as one wire. Or all 4 of a 12/3. Don't underestimate the amount of copper needed to move 12vDC, 12v likes lots of copper!
Battery drawer, 300A fuse at far right on the battery post.
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Moving Pictures
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# Posted: 22 Jan 2013 04:26pm
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Have you considered a heavy-duty DC breaker?
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MtnDon
Member
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# Posted: 22 Jan 2013 06:25pm
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Quoting: Moving Pictures Have you considered a heavy-duty DC breaker?
The positive lead from the batteries to the inverter needs a class T fuse. This is a fast blow type and is meant to break the circuit flow in times of a dead short. That is different from an overload condition caused by somebody putting too many devices on a circuit.
A DC rated breaker can actually have the contacts fuse together if the battery bank has a high enough amperage capacity and if the dead short is more than a skinny piece of wire or something that itself would melt fairly quickly. Many DC rated breakers like the Airpax and Eaton Heinemann can be used as a convenient on-off or disconnect for the inverter. I have a big Airpax for that with a class T fuse between it and the batteries. A DC breaker will also act as the overload disconnect.
A DC rated breaker should also have an AIR (Arc Interrupt Rating) of 10,000 amps if there is more than just a couple of golf cart batteries. Batteries really do not have a very large capacity but they can release a whole lot in a very short time. Enough to melt insulation and fuse breaker contacts or the contacts of AC Only breakers and switches. I've see clouds of smoke from the insulation on cables.
The Square D QO breakers are rated at 5000 amps AIR. Lots of folks use them in low voltage DC applications. In a case of a dead short with a number of batteries pushing current their contacts might fuse. I have the QO in the DC service panel and have a class T fuse before it to serve as the dead short, catastrophic failure device.
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buckybuck
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# Posted: 17 Feb 2013 09:26am - Edited by: buckybuck
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What great information! I really love this forum.
I had put this project on the back burner because of a more pressing winter project involving a generator that would run just fine for 20 seconds and then quit--unless the generator were tilted about 20 degrees to one side. After weeks exploring and tearing into the generator to check on things like a stuck carburetor float, or a wire somewhere in the innards that somehow shorted when the generator was positioned upright (and I could go on), here's my tip of the day--if you have a engine with a low oil cutoff feature and the engine shuts off even when you can see oil in the crankcase, check to see if maybe there's a little too much oil.
TomChum, that's an interesting idea of making terminals out of copper tubing. That's the way I may end up going. Since I've already got it, I'm still planning to use my ANL fuse, even though some of you have convinced me there are better choices. Interestingly, I did Google a number of inverter manufacturer installation instructions and they all specifically say to use ANL fuses, so I dunno. In any case, I suspect that there are probably a lot more inverters being used without any sort of fuse protection than there are inverters with fuses.
I am curious about using Romex wire. What's the wire gauge equivalent of ganged three conductor 12/2 or four conductor 12/3 Romex?
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creeky
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# Posted: 29 Aug 2013 09:37am
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search youtube. there's a guy who show's you how to crimp terminal lugs with two nails and a vise. I did all my lugs that way and the technique works. Plus. You can do any size lug just by changing the space between the nails. I used drill bits.
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