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German Wiring and American Rewiring

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cbsura

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Jun 7, 2004
27
Bavaria 32 Branford, CT
Last August I posted about a problem I was having with my batteries. (See “House Batteries Boiling – Suspect Battery Charger Wiring” in the Bavaria forum.) I thought about this all winter long and have just finished tracing though all the original wiring and the aftermarket add-ons. I have a pretty good idea what I want to do, but I thought it might be best to get some fresh eyes on the design before I start ripping everything apart and make it worse ;-)

For those who aren’t familiar with the German wiring in Bavarias, they use black for DC positive and blue for DC negative. (This kept confusing me since I’m used to seeing black for DC negative. I ended up taping the lines red and yellow to follow the new ABYC standard.) The boat’s wiring diagram is in German, so it helps to know that “schwartz” and “blau” mean “black” and “blue” since they are abbreviated as SW and BL. Also common to German practice, the original main switch isolates the negative battery lead, not the positive. I plan to leave the original switch intact but always leave it in the ON position.

So here are the modifications I am planning: (1) Adding a new OFF/ON/COMBINE battery switch (Blue Sea 5511e) to allow me to use the house batteries to start the engine if my starting battery fails. (2) Moving all the aftermarket equipment, which is currently wired directly to the house batteries, to a separate fuse block (Blue Sea 5025). (3) Replacing the battery charger with a 50A, 3-bank ProMariner ProNautic 1250P with a battery temperature sensor. (This is similar to the Sterling Power unit recommended by Maine Sail.)

I have attached a diagram of the plan. I have a few questions already: Is it OK to leave the 125A house battery fuse where it is (before the battery switch)? If I ever need to combine the batteries to start the engine will that fuse blow? Do I need a fuse between the house battery and fuse block? And please let me know anything else you see that might need improvement!

Thanks,
Chris
 

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Jan 22, 2008
597
Oday 35 and Mariner 2+2 Alexandria, VA
The only issue I see is that I thought EU standards use a positive ground vice a negative ground in a lot of 12V applications so with that in mind, just make sure you keep convention and it should work just fine. The fuse before the switch should be fine. I do not think you should not need an additional one between the house battery and the fuse panel.
 
Feb 26, 2004
21,327
Catalina 34 224 Maple Bay, BC, Canada

cbsura

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Jun 7, 2004
27
Bavaria 32 Branford, CT
Thank you, Stu and Dan, for your replies! As near as I can tell, the boat is wired for negative ground. The (blue) negative cable is attached to the engine iron. The only backward part is that the original battery switch was on the negative lead which is common to both battery banks. Now, there is currently a second battery switch that is attached only to the house battery positive lead. (This is the switch I want to replace.) When I bought the boat, the first switch was labeled "engine" and the second was labeled "house." Indeed, the engine would only start when the "engine" switch was on, and either the "house" switch or the battery charger had to be on to power the panel.

Stu, I had actually read those excellent posts of yours earlier and, thanks to your reminder, I am still on the fence and agonizing over this choice! First, I don't have the ACR but I do have a working battery isolator between the alternator and the 2 banks. It always charges the starting battery first before the house bank. The starting battery is small (55 AH) and the house bank is two 4D's good for 240 AH. I like having one circuit dedicated to starting and the other dedicated to house loads because the two banks are not equally sized. If I understand your main warning correctly, it's generally a bad idea to combine batteries because a bad one will drain the good one. The only reason I would ever combine the two banks would be in the case of a dead starting battery, and I would combine them only for the 30 seconds it would take to start the engine. (I suppose in the rare case that doesn't work I could still pull the leads off the bad starting battery if necessary.) Given this one rare use case, is it still a really bad idea?
 
Feb 26, 2004
21,327
Catalina 34 224 Maple Bay, BC, Canada
Yes, for that very reason. Why have to pull wires off a bank when you can just use a switch?
 
Sep 5, 2010
74
Yamaha 25 Hebe Heaven
Stu's post was just great. I've been curious for long on how to arrange the circuit for 2 banks correctly using the 1/BOTH/2/OFF switch.
 
Jan 28, 2008
10
Bavaria 47 Tenerife, Canary Islands
On my boat I have a single pole switch that joins the positive terminals together, a jump lead would do the same thing in an emergency.
 
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
the layout looks great the way it is... but in my opinion there should be an appropriate sized fuse just before it goes into the house distribution panel. (added to it, not moved from one spot to another) if you should have a problem in the house, it will blow the fuse before it does damage to the charger to the charger or the starting battery.

using the white wire as the ground is becoming more popular in this country as well. on a system where you have black wires and white wires, it always pays to check the circuit. if it is a factory job, after the distribution panel, the white wire will almost always be the ground and the black wire will be a hot wire....
BUT, the main power leads from the battery TO the distribution panel will always be red and black..... but very much larger wires.
 
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