Catalina 350 International Association

I know that this has been discussed in some detail but I cant seem to figure out what is the best way to wire / connect a separate starting and house battery configuration. Unfortunately, my understanding of this kind of thing is almost at the "don't stick your finger" in an outlet level. I have read all of the posts, printed numerous wiring diagrams that folks were very kind to post, scoured Calder and I am still stumped. I want a fool proof system (I'm the fool) with both circuits separate so that I don't have to touch the switches except in an emergency.

I have Hull number 383.

I have installed a starting battery and an Echo charge unit. So far so good. Where I run into trouble is the BIG question (for me) of how to arrange all the wires and switches I have. I think I have the Echo charge unit installed and wired properly and the black ground from the New Start Battery to the Black ground for my 4D's.

My question is where to connect the Red wires so that the alternator will charge the house bank and the Echo charge will charge the Start Battery?

My first attempt was to take off the short red wire connecting the Common post on the 1,2,Both, Off switch to the Engine Off /On switch. I then connected the Start Battery Red to the Engine On / Off switch. This proved to be incorrect as I drained my house bank down to Alarms sounds (the worlds going to end) level during a long day of sailing and motor-sailing in unfamiliar waters. I figured out (with the help of a FRIEND) that my wiring arrangement wasn't sending the alternator output to the house bank at all. The motor started great, all the other electronics, not so much. Alternator output was OK, checked with a multi-meter.

At this point I am considering running a cable (what size?) from the alternator output to the Common on the 1,2,Both, Off switch. I am concerned though that I will probably blow something up by doing so.

Please help. I can follow Step by Step instructions; "See Jane Run" type instructions. Thanks in advance

Dave on Ventosa on Vandemere Creek, Off the Bay River, off the Pamlico Sound, North Carolina.

Dave, I'll take a stab at your question.

The main problem with adding a starting battery is that the boat is only wired with 2 positive (red) leads that run from the battery switch (1,2,Both, Off) to the 4D batteries. There is no quick way to accomplish what you want without some rewiring and possibly adding another battery switch.

Here's what I did when I added a starting battery and it only required 2 cheap, simple modifications to the wiring:
In order for this to work, you must locate your starting battery under the settee next to the battery compartment.

- Take the longest red large (~1/2" diameter) wire off one of the 4D batteries and run it to the positive terminal of the starting battery. I can't remember which battery it comes off but only 1 red wire is long enough to reach.
- Leave the other large (~1/2" diameter) red wire connected to the positive terminal of the 4D other battery.
- Go to a battery shop and have them make another large red cable with lugs on each end that is long enough to go from the positive terminal of one 4D battery to the positive terminal of the other 4 D battery. What this does is makes your two 4D batteries into one large house battery bank. The advantages are that you will draw down both banks equally and you can still use your battery switch to switch between the house and starting battery.
- This should leave you with a large black wire on the negative terminal of one of the 4D's and a short black cable that bridges the negative terminals of the 4 D's. There should also be another large black wire that goes from the negative terminal of one of the 4D's to the windlass. As you have already done, there should be another large black wire running from the negative terminal on one of the 4D's to the negative terminal of the starting battery.
Now for the battery charger wiring.
- There should be a smaller (~3/16" diameter) red wire that runs from the positive battery terminal post on each 4D back to the battery charger. This lead should also have a fuse near the end that connects to the battery. Take one of these leads off and run it to the positive post of your starting battery.

You now have to determine which battery bank will be active with the battery switch set to "1". The easiest way is to disconnect the positive lead from the starting battery, turn the battery switch to "1" and then check the battery monitor on the electrical panel to see if voltage is present. If so, position"1" on the battery switch is your house bank. If not, "2" is your house bank. If I remember correctly, the red lead that you move from the 4D to your starting battery was from battery #1 therefore with the switch on #1 you are running from your starting battery . If you switch to BOTH then your are combining your house and starting battery.

Your battery charger will now charge the house bank (4D's) and the starting battery. The alternator will charge which ever bank the battery switch is set to. I relabeled my battery switch with "HOUSE" and "START" so that I know where I'm drawing from and where the alternator is charging. Having said that, I always have my switch on the HOUSE position. Your mileage may vary depending on how you use your boat.

I'm not sure I've laid this out in a "See Jane Run" fashion but hopefully this will give you a start. Given your admitted level of electrical expertise, I think this is your best bet to add a starting battery. I did this several years ago and it has worked flawlessly for me. In fact I only use my starting battery once a year just to make sure it's working. By combining the 2 4D's into one large bank, I've always had enough power to start my engine on the house bank. But it's reassuring to know that the starting battery is there.

Wow, Thanks, Ken.

Seems like a simple, elegant and inexpensive solution. Pretty hard to come by all 3 at he same time. I did put my Start Battery under the port side settee as you suggested so this should work. I guess that I can leave my Echo-charger in place as it will draw a small charge off of the now, larger House bank when it is being charged by whatever source is available.

Thanks, again.

Dave