Alternator upgrade

[rosatte]

Goodday lads just have a question we have purchased a new balmar 100amp alternator and need to know if we have to upgrade our wiring from it to the switch then upgrade to battery s current alternator is 50amp..cheers

[Stu Jackson]

Of course you do, there's more amperage flowing, so you NEED larger wire. Of course, you didn't bother to tell us what size wire you do have, did ya?

You should also get your AO off the switch and route it to the house bank. Like this:

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: Basic Battery Wiring Diagrams

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
1/BOTH/2/OFF Switches Thoughts & Musings | SailboatOwners.com Forums

The Short Version of the 1-2-B Switch Stuff: Electrical Systems 101 This is a link to the Electrical Systems 101 Topic, reply #2

What are ACRs, Combiners & Echo Chargers? (by Maine Sail)
Battery Switch Question ? | SailboatOwners.com Forums

[rosatte]

sorry wires apear to be 4gauge..motors a universal35

[rosatte]

thanks 4 the info stu.

[Stu Jackson]

Originally Posted by rosatte

thanks 4 the info stu.

You're welcome.

You might be interested in these, too, just posted on another thread today.

With your larger A alternator, are you getting an external regulator?

Alternator heat, Regulator Controls, Small Engine Mode

Alternator heat, Regulator Controls, Small Engine Mode

Small Engine Mode - discussion with link to the picture of the toggle switch: Alternator heat, Regulator Controls, Small Engine Mode

Small Engine Mode - the picture of the toggle switch Alternator Output Management with External Regulators [Small Engine Mode]

[fallingeggs]

The links Stu posted are a great source of knowledge. Following them will necessitate spending extra money in the short term, but the payoff is worth it. The regulator is almost required and the changing in how the switch is wired will keep you from frying your new purchase.

I'd guess you'd be better off with replacing/upgrading the wire. Maine Sail (who wrote/contributed much of the info in the links above) has said that the starter and charging circuits tended to be undersized 20+ years ago. You don't say what boat you have, but if it is from the 80's, you're likely undersized from what a manufacture would install today (being 0/2).

Assuming you don't have starting problems now, the real benefits of a large wire would be to allow that new, fancy alt to output as much as it can / wants to.

Plus, if you following the advice in the links above, you'll be replacing all the wiring, so why not do a quality job?

Enjoy!

-Stephen