Electrical System

Sent: Fri 4/18/08 4:02 PM
Reply-to: S2Yachts@yahoogroups.com
To: s2yachts@yahoogroups.com

Ed,

I'm pretty happy with my wiring setup.

The starting battery has its own switch, which is wired direct to the starter and alternator. The output from the switch also goes to a parallel switch. The house battery is wired direct to its own switch, then to the house loads, and also the parallel switch.

In between the two batteries is a combiners that joins them together when it detects a charge, and draws some very, very small milliamp current when not charging.

So when I want to go sailing, I switch the start and the house batteries on, start the engine, and go. When I'm done with the engine, I just kill it - the battery stays in the on position, with nothing drawing down the engine battery. When I restart the engine, both batteries get charged. If somehow the starting battery is completely dead, I can leave the start battery in the off position, house on, parallel on, and start the engine off the house load. The reverse obviously works as well - house bank can be off, starting on, parallel on, and the house feed is live. Or if both start and house switches are on, the parallel switch combines them together.

I would like to add a third bank - a second house battery. For that, I'll add one more switch to the house load/parallel switch and a second combiner that will also be fed off the starting battery. Again, each battery will charge when the engine is one, but each house battery can be used independently (one switch on), together (both switches on) or on the motor (parallel switch on). Since I already have the combiner (I bought it a few years ago on sale), I'm looking at about $240 for wiring, mounts, and a new battery - I'm looking at a group 31, 140 AH battery, and I'll probably replace the 105 AH battery I have as bank 1, so I'll have 280 AH in the house, 85 AH dual purpose on the starting.

I have the 9.2C - the batteries are stored under a seat in the aft cabin, next to the aft berth, so I mounted the inverter under the aft berth, in the section housing the steering gear. It's a dry, large locker that I can't use for much because of the steering cables and quadrant, so there won't ever be anything against it to block its ventilation, and it's a nice big box for it to heat up. I used a 48" 4 gauge negative wire direct to the battery ground, and an 18" and 32" 4 gauge positive wires. Any longer of a run and I'd definitely need 2 gauge wire. In between the positive wires is a 90 amp surface-mount breaker. Defender carried the wires for about 40% less than West Marine. I chose to use Ancor pre-made wires b/c they're very well done, the lengths worked out pretty well, and the cost savings of doing it myself wasn't worth the time it would take to figure out how to crimp something that large.

I don't plan to ever run the inverter for long or for large loads - I may use it next year to supplement the generator we'll bring along for the Parade of Lights. Also I may install a 600w microwave, but I don't know. If I were microwaving something for 10 minutes I'd kick the engine on and let the alternator take up some of the load. I really don't know what I'm going to use the inverter for - I've just had it for several years and finally decided to install it. I suppose if I mount the LCD TV it would be nice to be able to watch that at anchor.


I've also spent the past week rewiring my instrument interconnections. 61 crimp, solder/crimp, or insert wire and screw down fittings so far, and that's just the back end. But now I have a very clean instrument backend connecting the NMEA multiplexer, GPS, compass, SeaTalk interface, and transducer wires, leaving only two wires running to the displays - power and data/transducer. I don't have pics yet, but here's the electrical panel. What I installed is on the bulkhead visible on the left, much of it below what's visible in this photo:
http://midatlantictech.com/bayretriever/photos/DSC00048.JPG

Eventually I'll build a box for the displays that sits above the companionway; for my boat I think that's the best place between visibility and intrusiveness. For right now I have a replacement drop board I use - it's fine when no one else is in the cockpit, otherwise someone's foot is usually in the way ... I actually hope to have that done by the end of May.

Kevin
S2 9.2C Bay Retriever
http://midatlantictech.com/bayretriever