Re-Wiring a Really Old Boat

[Minggat]

Originally Posted by Rugger8

Any other thoughts on the battery arrangement and the Odyssey batteries in particular. ....

I understand that Sears Die Hard sell the Odyssey battery re-labeled and much cheaper.

[S&S]

Originally Posted by Rugger8

S&S - the Balmar centerfielder, what is the purpose of that? To combine 2 alternators and provide one source of power to the batteries?

Thanks,

Jeff

Yes, it synchronizes output.

[GordMay]

From the literature:
The Balmar Centerfielder provides a centralized source of charging control for twin engine applications where two alternators and two regulators are used to charge a single battery bank. The Centerfield senses when only one engine is running. When the second engine is started, the Centerfielder determines which regulator's field current is dominant, and directs that field current to both alternators . This even distribution of field current ensures that both alternators deliver comparable percentages of their available capacities. Outputs may vary based on engine rpm' s, comparative alternator size, and distances from dominant regulator to alternators. For best performance, regulators used should be identical. In addition to its ability to equalize regulation to both alternators , the Centerfielder provides the assurance that both alternators will continue to supply your batteries with charging amperage, should either starboard or port side regulators fail.
The Centerfielder is designed for use ONLY with Balmar MC-612 or MC624 regulators ..."

[allene222]

You made a good decision not to bond. I think I got flamed some for this article I am posting below but you might find it interesting and it talks about wood boats as well. I have a wood boat that is 55 years in salt water unbonded with no damage to the through hulls. The basic idea is only bond for safety or mechanical necessity (a prop and its shaft are inherently bonded). If you bond you have to protect things with zinc or equivalent (there may be something else than zinc for fresh water). You will want to bond the big metal things like the engine but again this is a safety thing. The little things that are not going to get near a wire do not need to be and should not be bonded. You see, the zinc-metal reaction includes a reaction that eats the wood. It happened to my boat. The article is from both experience and reading everything I could find on the subject.
Bonding and Corrosion

[bill good]

It seemed to me a problem of connecting the wrong pole to earth. I remember a very long way back in the past where this "problem" on a wooden boat would not destroy wood if the positive was bonded as earth. (Them were the days when it was easy to reverse charge by flashing the field.)

ps it has been a mistake for a long while that the wrong pole was made ground & I wish it was corrected soon!!!

pps the devil made me post this reply

[allene222]

Originally Posted by bill good

It seemed to me a problem of connecting the wrong pole to earth. I remember a very long way back in the past where this "problem" on a wooden boat would not destroy wood if the positive was bonded as earth. (Them were the days when it was easy to reverse charge by flashing the field.)

Very interesting point. Looking up the reactions I find this:
Cathode (reduction): 2 H2O(l) + 2e− → H2(g) + 2 OH-(aq)
Anode (oxidation): 4 OH- (aq) → O2(g) + 2 H2O(l) + 4 e

The OH eats the wood so you want to be the Anode, or positive electrode as you point out. But in the case of grounding a battery, you are talking about a reaction with another boat and if you are properly isolated from dock ground, there will be no reaction and it won't matter.

However, the wood around any bonded bronze also gets eaten by the reaction with the zinc. In that case, which battery pole is grounded won't help.



Allen

[Ike]

Just a link for some info

USCG NVIC on Guidance On Inspection Repair and Maintenance of Wooden Boats
http://www.uscg.mil/hq/cg5/nvic/pdf/1995/n7-95.pdf

Section 4 has some info on corrosion of fasteners in particular pages 4-10 and 4-11, but you should read the entire section on corrosion. But it all makes interesting reading.

[allene222]

Ike, Wonderful link and very interesting article. I will have to add a section on internal stray currents to my article.