paint chipping off mixing elbow

[rmeador]

I finally got around to installing my new battery charger yesterday, which means I spent about 9 hours in the engine space of my boat. While I was down there, I more than once banged against what I believe is the mixing elbow on my engine. It's a metal 90 degree turn that connects to the exhaust and has what appears to be a water pipe going into it. The engine is a Perkins 4-108 that was "completely rebuilt" about 400 hours ago, and looks practically new. The beautiful blue paint chipped (or maybe flaked) off in large pieces every time I hit my head on the mixing elbow. It came off clean, revealing bare metal beneath (no rust). Should I be worried? Should I repaint it?

[arf145]

Worried about the elbow? No. Showing bare metal is good. Not much of a paint job on it, though, or you've got one hell of a hard head. From my experience, worrisome rust in a mixing elbow happens from the inside. My mixing elbow looked beautiful right up until it perforated and broke off

[mitiempo]

9 hours?

[rmeador]

Yeah, 9 hours. I have no idea why it took so long. It seemed like everything went wrong. I didn't have a big enough drill bit to run the wires, bolts wouldn't come undone on the electrical panel, the AC wires wouldn't fit into the terminal block on the charger, I didn't have wire strippers or crimpers that were big enough... it's not even done. It's an inverter/charger, and the inverter circuit is completely disconnected. Next weekend's project. At least all the wires for that one are already run, so I figure it will be 2 hours, with about an hour and a half of that being jamming the AC wire into the terminal block on the charger (since now there is already another wire in there, it will be twice as difficult!)

[sailingdog]

Sounds like a lousy paint prep job.

As for wire crimping, what size wires are you using???

[rmeador]

I used the size wires recommended in the installation guide. The DC inputs are 2/0 AWG, the ground wire is 1/0 AWG, and the AC wires are 10 AWG. I bought them through GenuineDealz, which someone here on SailNet recommended, and I had them make up the big cables for me (cutting to length, crimping, and heat shrinking). There's no way I could do those myself. The 10AWG was what I had trouble cutting, stripping and crimping. I'm an electrical engineer, so all my tools are for tiny circuit boards... my crimpers only go up to 14AWG, which I didn't find out until during the installation.

Hmm... it just occurred to me that I probably would have had a much easier time running the AC wires into the charger if instead of trying to feed the ones from a given port to the terminal block on the same side, run it across to the other side... that would prevent the nasty S bend that was giving me so much trouble. Too late now... and this is totally off topic!

I guess I won't worry about the flaking paint, and if I ever get through the stuff on my todo list I'll repaint it.

[mitiempo]

The terminal blocks will accept up to 10 awg. As well there are separate knockouts for the AC input and outputs on either side of the connection points so there should not be much problem wiring it.

[rmeador]

mitiempo, I know they accept 10 AWG. I did eventually get it in there. And I am using the knockouts (we're talkling about a Xantrex Freedom HF 1800, for those of you not in the know). My realization in my last post was that it would have been fewer small-radius bends of the wire to go in a knockout and connect to the opposite terminal block (the inputs to the European-style terminal block are oriented in that direction). Still, even marine-grade stranded 10AWG wire doesn't like to bend.

[mitiempo]

I strip the outer sheath off just inside the knockout for more flexibility. Depending where it will be mounted I sometimes find it easier to mount the invertor and make the DC cables to length but not attach them. Then remove the invertor to attach the AC wiring (pre-measured) and then reattach it to the bulkhead. Then add the DC cables.

This is what we are discussing.

[rmeador]

You're nearly exactly describing the steps I took to install it. When you did it, did you put the AC input in through the left or right knockout in the diagram? I put it in through the left one, but I'm now thinking it may have been easier to go through the right one.