Metal for power distribution block?

[pjones]

I need to use a power distribution block to connect various components together, for the positive side, I found an old car audio block that has a few terminals that will accept 2AWG wiring, it's some sort of ferrous metal, is from the 90s I think. I don't have a matching one for the negative. I was going to go to the store today to see if I can pick something up, but I think most of what will be available is aluminum blocks.

My batteries packs are LFP, 24V and I am putting 15-20A across, with a 60A breaker. Cables are only 2-5ft away.

Any reasonable concerns with using dissimilar metals for these blocks? I don't think I am not pulling enough current to make much of a difference, but wanted to get some feedback.

I have a bunch of 6061 that I can cut, drill and tap, and maybe save me a trip to the store, and maybe make a matching set instead?

 

[chrisski]

I’m not really the right one to say, but I would avoid scrap parts unless it is truly a low draw system. I would also not mis-match the busbars, but if it does not draw a lot of amps, it may be OK.

When I see 2 AWG wire, I start thinking 50 amps.

If you were to use it, is 15-20 A all you’ll see? Not accounting for longer runs, 10 AWG may be good for those amps. I turn a coffee maker on and see a 55 amp draw, and if the micros wave goes on, I see 135 amps. For a plug in laptop, I saw up to 10 amps, although I was told to plan to 20 amps for the laptop.

Dis-similar metals can be galvanic corrosion, but pulled from a scrap pile, I don’t know.

 

[pjones]

I should clarify, the terminal block was unused from my car audio days (I had a lot of high-end stuff that I couldn't bring myself to throw away), most of my cables are 4 or 6 AWG. The thinest cables are the ones coming out of the BMS, which I think is a pair of 10AWG. Yes, I am very sure about the draw, the inverter is configure to output less than 200w, and it's only capable of 1000w.

 

[Factory400]

The distance of the cable run is unrelated to the distribution block. Each element adds its own amount of resistance to the total resistance.

Personally, I would not worry much about it if you can keep an eye out for any corrosion periodically. It is rather easy to see if the resistance of the connections is reasonable my measuring the voltage drop across it with a plain old multimeter on mV mode.

While the system is loaded with a typical load, measure the the drop by placing one probe on the wire on the incoming side and the other probe on the outbound side. You can use a hair dryer or similar to put a relatively stable load on it. If the measured drop is just a couple of mV's at 50A, not a problem. If it is 50mV, that would be unusually high, but workable [the block would start to warm up].

Above 50mV at 50A, I would start to second guess the decision to use the random block.

 

[Zil]

Blue Sea quality. https://www.bluesea.com/products/

 

[Guda]

Blue Sea quality. https://www.bluesea.com/products/

Did you notice you cant actually order from them anymore? I bought a bunch of stuff from them months ago right from their cart. Now its "where to buy". I'm looking for 4/0 in distribution block with like 3 outs at 1/0 to 8.

 

[pjones]

Thanks, all good points. I'll stop by the box store and see what's available and if nothing fits, I'll just make my own.

 

[Zil]

I only use the Blue Sea web site to identify the device I need. Then google, or duck duck go, to locate the best price from dealers. I often find them on Amazon. But there are a surprising number of marine chandlers with better deals.

 

[chrisski]

The distance of the cable run is unrelated to the distribution block.

I certainly did not word the "distance of the cable run" correctly, it's wire size and the lugs I crimp on them that determine the terminal block.