F32 1990 DC Rewiring - Electrical Diagram?

[bigralph]

I posted my rant in my rant thread, now I have a question for F32 owners.

I want a house battery. Last night, in my deep dive, I didn't have any schematics or wiring hook-ups to look up. It looks like my boat has 2 batteries for the engine, they are wired into a DC circuit breaker just above the bilge, between the engines. The breaker panel has leads that go to the starters, 40 amp charger, and to the panel box in the salon. Aft of the DC circuit enclosure, there is a third battery for the generator set, it's wired to a Perco switch on the wall. The Perco switch is a 2 selector switch and is wired to the 8KW genset and back to the battery bank circuit box I just mentioned. The existing charger has a needle that should indicate current, but it's pegged at 40 amps, even when all power is off in the boat. It's also directly above the port shaft log and is completely rusted out. I can't believe it works.

So, I want to add technically a 4th but really a third battery for the house. I want to replace the charger, as I mentioned before, with a 3 bank charger. I don't know if I think that Perco switch is needed and wonder if that's an add on by the PO I ranted about in my other thread. I want a deep cycle 4th battery for DC house loads(I'm a live-aboard), and obviously flooded cell since that's what all the other batteries are on the boat.

I'd like some advice on how to rewire and where to put the switch. I'm not a DC guy, very little experiene. My intution says that each engine ought to have it's own battery. It seems like I want a switch for just 2 battery banks, with one going to the existing 2 battery banks and one to the house bank. Are there any wiring diagrams available on line and has anyone else rewired/altered their system? What makes the most sense? I appreciate any advice.

[bigralph]

Partial answer to my central question about rewire. Use 2 switches and use diagram 3 in this file:
http://www.perko.com/images/catalog/pdf ... 3INS1).pdf

[yorklyn]

If your adding a 3rd bank check out "blue seas systems" pn 8689. http://www.bluesea.com/products/8689/Tr ... ment_Panel
even though I'm already set up with 3 banks im thinking about using it with the two 7610 ACR to give me total controll of all 3 banks with the battery switches (just have the two main breakers now) as well as having all three banks isolated from each other. only around $230 for the panel and $65 each for the ACR's.

[Big D]

Ideally, you want one separate battery per engine and a separate house battery bank - 3 banks not including separate generator battery. Use a smart 3 bank charger to maintain banks separately or a 4 bank charger if you feel it necessary to maintain the generator battery as well. Then you must find a way to charge all banks off the engines while underway from two alternators while still maintaining isolation between banks. There is more than one way to do this, from perhaps the most expensive such as smart alternator charge regulators, to lower tech less costly diode isolators. In the middle are ACRs. Though I prefer this technology over diodes, one must be aware of their limitations and proper installation precautions to avoid problems....do your homework before you buy. I am not a proponent of the multi bank battery selection switches ("1,2,OFF,ALL") for reasons I've described here before. If paralleling is needed for an emergency start situation for example, it should be done either by an option through the ACR or a solenoid manually activated at the helm through a momentary toggle switch to maintain bank isolation. IMO the only battery switches one should have are "ON, OFF" to service the circuit or ensure there is no drain when that circuit isn't needed. To avoid unintentionally leaving banks paralleled, switches with the "ALL" option should never be used.

One of the biggest cautions I can pass on about DC wiring is the need to be aware of the size of the load (current draw), and the distance/length of the circuit from source to load to ground, and how these relate to the wire size needed for a safe circuit. This differs considerably from AC wiring in a house for example where 14/2 can be used for a circuit that runs from one end of the house to the other for a 15 amp load. Also note that there are 10% allowable voltage drop circuits and 3% allowable drops for critical systems circuits to consider. These affect wire size sellection. Links to wire size charts have been posted before but easy to find on-line.