Somebody good with electrical tell me if I'm effing up here.

Below is a picture of a 4/0 pure copper battery connector that I have modified, beside a normal connector, in order to still be able to use the plastic terminal guards on a Renogy 3000w inverter. Kinda crap that a 3000w inverter isn't compatible with 4/0 wire connectors, but that's life. Anyway, does anyone think I am creating an even bigger safety hazard by grinding material off of the copper connector? Thanks in advance.

 

I would first try to modify the terminal guard or find a different copper lug brand that fits.

 

I’ve had a hard time finding a different 4/0 lug than the general shape you have. I’ve been able to make them work though. Just looking again and these look like they might work.

https://m.delcity.net/store/Fusion-Heavy-Wall-Copper-Lugs/p_807161.h_807165.r_IF1003

 

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It possible that the pic they have is for a smaller gauge lug though.

 

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It’s a heavy wall 4/0 lug though, crimping that probably a PITA

edit: never mind, it says solder

 

No issues, send it.

 

Yeah, you will he okay. If it makes you feel better, I frequently set up a 4000 watt directly next to my battery with even less meat clamped onto the inverter posts. Runs air compressors, worm drive circular saws, sawzall, etc. without issue.

 

The best solution is to find a lug that works. But if you must use your modified one, make sure the lug is tight to ensure a good connection, and check it after the first few heavy uses to see just how hot it gets.

 

The solder or crimp will invariably be the weak point. I would run that without any hesitation.

 

I’ve never done 3k watts with a modified terminal but plenty of 1-2k watts and all is well. I’d send it without worrying.

 

Thank you! I just bought two of them for the inverter connection. I did, however, buy the 3 crimp lugs instead of the "heat and seat" type. It'll take a few days, but I'll let you know how they work. Good find, and thank you again!

I may try to do a controlled and heavily observed test on being able to modify like that. Worst case scenario is I burn the place down. I have insurance, so that ain't so bad!

 

Do you not have a fuse or circuit breaker close to the power source?

 

Yes. A 300 amp breaker is going only 6 to 8 inches from the battery bank. I have also decided to store the inverter under the back seat and attach it to the battery bank only when needed via an SB350 Anderson Plug with 4/0 wire that will be less than 3 feet long. I'll just sit the inverter on top of the NOCO battery box in the times I use the system, which truthfully, will be rare.

 

300 amps? Sure you want to run your inverter close to maxed out? Not cheap to replace, be careful.

 

Sounds good OP. From your original post it seemed like you know what you’re doing, and you had a question that’s been answered. So as far as other details, that’s your business. That’s my take on it. You could go bigger than a 300 AMP fuse if you wanted, depends on what your inverter manual recommends and what the surge capability is. I have a 400 fuse on my Victron 12/3000. The fuse protects the wire, which I’m sure you already know. Nothing wrong with 300 but depends on how you’re pushing it.

 

I would actually have gone with a bigger breaker had I decided to only bring out the inverter when I need it instead of having it connected permanently. The original plan was to mount the inverter under the back seat and run the 4/0 cable from there t9 the bed of the truck where the battery bank and box would be, but since I will only use the inverter sporadically, it makes more sense to just be able to plug it in to the battery bank only when I need it via a flush mounted sb350 Anderson connector on the battery box. Shortening the length of wire that much will certainly allow for less voltage drop.

Gonna throw it in for the benefit of anyone reading this that the NOCO dual 8D battery box is PERFECT for housing two LiTime 230ah low temp batteries along with additional 12 volt sockets flush mounted to it. With those two batteries in there, there is a space of about 10 inches left over that I am utilizing for a battery cutoff, LiTime battery monitor with shunt, bus bars, every 12 volt plug that you can imagine, even a 12v 6.5 inch thermostat controlled fan flush mounted on the box! The box is designed to be vented already, so that fan will suck in cool air and expel it through the ventilation holes incorporated around the top rim of the box. Buying that box is what has made this easy to keep clean and neat. The DC to DC connection is also incorporated into the box via an SB120 flush mounted Anderson plug with 2 AWG wire. The summary is NOCO dual 8d battery box = good.

 

Unless you’ve already bought the 4/0 cable, another option could be doubling up on 2/0 cables, just stack the lugs back to back. This is a common practice on high current DC systems.

 

I actually never even thought about that! But yes, I have the cable already. Over $150 for 10 feet of it! GEEZ! I wanted to send an email saying "I said I wanted pure COPPER, not pure GOLD! I appreciate you sending that though. I don't why that wouldn't work for about any kind of high current connection! I wonder is they make terminals to specifically accomodate that? It wouldn't really be necessary, as you pointed out, but it would look super clean and neat!

 

Found the answer to my own question of "I wonder if they make battery connectors for dual wires?" They do, but for $45 each, they can keep them!

 

You ever seen a 3/8” 10awg ring terminal? Now those are something to be a little concerned about





been running them for years

 

In the end, I wouldn’t be concerned about using the modified lugs anyway. When it’s all set up, put some real load on it for a while, and carefully check that there isn’t any heat buildup.

 

Thanks for all the help, everyone. Got the system up and running today. Still working on getting the DC to DC charger hooked up on my truck. Had the conduit ran exactly how I wanted it earlier today, only to find I couldn't pull the 2 AWG wire through it due to a couple of bends. I had a wonderful time taking it all back out and doing it again after I straightened the conduit and pulled the wire through that way.

I did the math and think 2 AWG over about 18 feet should be big enough wire. It had me less than 3% voltage loss, anyway. That sound good on a 40 amp charger? Thanks!