Electrical System Upgrade - Yorkshire Rose

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By Mark Elkin, Yorkshire Rose #133

Interestingly, I had already started my own electrical upgrade plans (and even purchased a few components) when John Gardner and Jim Moe submitted their own electrical system upgrade projects. This gave me an opportunity to sanity check and fine tune my plans, and even borrow any better ideas they implemented.

My upgrade plans included:

  • Replace alternator bracket (yes, I still had the old one)
  • Replace original alternator with higher output model
  • Add external smart 3-stage regulator
  • Add replace battery combiner with a smart starter battery charger
  • Replace main battery cables with larger diameter and shorter cables to minimize voltage drops
  • Eliminate one unnecessary battery selector switch (go from 3 switches to 2 switches)

First and immediate, replace that old alternator bracket. Much has been written in both the Project pages and the Message Board about this. I won't bore you with repeated details here. Let's just say I felt relieved that it was done.

Next came the new alternator and regular. I had to choose between a wide variety of factors, with the major factors being cost, output current capability, and regulator complexity. After studying and researching lots, I came down to two alternative manufacturers: Ample Power or Balmar Marine. I had a couple questions for both and sent email to both after thoroughly scouring their web pages for the information first. Balmar responded within a day; Ample Power never responded. That settled it. I purchased a Balmar 712-110 Alternator, MC-612-H Regulator, and MC-TS-B Battery Temperature Sensor. I found a good package price for these on the web. Yes, the 110A alternator output is probably overkill, but I justified it as follows. It should output sufficient current (amps) at lower RPM and will probably increase the reliability since I'll rarely ever operate it anywhere near it's capacity rating. px250]]

The -H version of the regulator means that Balmar provided a prefabricated wiring harness. Overall, this is a good thing, with only 2 minor drawbacks. The harness length is fixed (about 3 feet long). And the stator and field connections were attached to a molded plug connector that didn't match the 7 series alternators -- emailed Balmar and they said "Just cut the connector off and attach the correct ring lugs. Your warranty is still valid even though you do this modification." (I gave Balmar another "plus" for that.)

I had a difficult time deciding where to mount the regulator. I wanted to be able to see it's display easily. The owner's manual said to avoid mounting in hot places (like next to the engine) and avoid wet places (just not good for anything electronic). A reasonable good place might have been the bulkhead wall under the sink separating the head from the engine compartment, but that was already too cluttered (as you'll soon see) and it still limited the visibility of regulator's display. Ultimately, I put the regulator against the aft wall under the sink. Yes, the engine exhaust hose runs very close but that was the trade off I made. border|250px]]

I also installed a Balmar Digital Duo Charge to provide smart charging of the engine starter battery. It was more expensive that other options, but gives me the luxury of mixing battery types for the house bank and starter battery. It too has smarts built in so the battery gets topped off efficiently. It will operate whenever the input side is at or above 13VDC; so it works fine when the shore charger is plugged in. And because it has a simpler, but still useful display that I wanted to be able to see, I mounted it side-by-side with the regulator.

Finally, it was time to redo the wiring. The existing 4 gauge wire ran from the alternator to the starter battery via the starter motor and then back to the house batteries via a battery combiner using an 8 gauge wire. This would not work with the new high output alternator. And it certainly wasn't what Balmar (and many others) recommend.

So I blended Balmar's suggestions with the aforementioned upgrade projects from John and Jim. Seasoned that with my own desire to minimize voltage losses in the cables. A finishing touch was minimizing the number of cables running back and forth between various points in the system. The battery cables now run directly from the engine/under-sink space through the bilge to the battery box. The cable bundle is protected by a water proof sleeve -- actually a soft 3" diameter hose, the kind that are used to drain swimming pools.


The wiring changes also required some re-arranging of stuff in the battery box. Here's some before and after pictures.

I eliminated the main DC panel switch as the combining point for cross connecting the house bank and starter battery. The new combining point is the starter battery on/off switch itself now. I replaced the existing on/off switch with a 1-both-2-off switch. This enabled me to also reuse the alternator-output-to-house-battery-charging-input cable as the house-bank-as-starter-boost cable. 9starter-battery-selector.jpg

The final result is what you see in the schematic below.

I also created a spreadsheet with more details to keep track of the wiring.

By the way, I didn't take on all this work just because it was fun, or because I needed more to do. It all really started because I'm adding an electric anchor windlass that could truly drain my house bank. Upgrading the alternator and wiring would insure I could provide enough power for the windlass. But that's another project (wink)

Coming soon

2010 - 2011. I've made more changes. Here's a look at the new "schematic". I will post the project details soon.