higher output alternator

[jdgrnt66]

Hello, I am adding a new alternator to my boat. My current alt output is 80 amps and the new alt puts out 100 amps and the current wiring sizing is 6 awg. Is this sufficient or do I need to upgrade the wiring to larger size/

Thanks for the help.

Jeff grant

 

[Ross]

How long is the wiring run?

Check a current capacity table.

 

[Landsend]

You will need larger diameter wire...and more...

most 100 amp alternators need twin belts, not to mention a heavy ground wire also. Going from 80 amps to 100 amps isn't going to give you much of a difference in charging rate.

 

[Nice N Easy]

Not worth the money

IMHO going from 80 to 100 amps isn't worth the money and effort. You will only gain any out put when the batteries are very low. Once the regulator cuts back a little the regulator is the limiting factor. And Landsend is correct about the belts. It is pretty difficult to drive a 100 amp with a single belt. You would be better served by going to a three stage regulator if you don't have one.

 

[Don S/V ILLusion]

Charging curves

You might want to review the charging curves in the link attached which will show you that, as other have said, you gain essentially nothing by going from an 80 - 100 amp rated alternator. It's ALL about the regulator as N&E said.

You didn't mention the size of your house bank which should dictate charging component sizing.

 

[jdgrnt66]

voltage regulator

can i use a 3 stage regulator with my stock hitachi alternator on my yanmare 4JH2E?

jeff

 

[yachtwork.com]

Second alternator idea

Greetings-If you’re trying to up the amperage of the engine alternator system you might consider a second alternator. This is the fast and simple method of increasing the output of any charge system. You can run a search for Yachtwork or Yanmar Second Alternator to find the kits. I’m guessing A JH2 kit cost about 400 plus a Delco alternator for another 200. So for 600 bucks you can charge at about 200 amps. I’ll try and load a JH2 photo.
Cheers
Scott

 

[Stu Jackson]

Jeff, you first need to define

what it is you want to do, what's called a "design criteria." As mentioned, you need to share what your goals are (i.e., marina hopping, anchoring out, long range cruising, use of shorepower or alternator only dependency) and then indicate what house bank size you have.

If you want more out of your alternator, going from an internally regulated 80 to an internally regulated 100A won't make much difference. The acceptance of the battery bank will control your charging ability. While Maine Sail and I disagree a bit about this, an externally regulated alternator will give you (somewhat) greater initial input compared to an internally regulated tapering regulator charge. You can't necessarily just slap an external regulator on your existing alternator because usually OEM alternators will end up getting burnt out from external regulation. OEM alternators with internal regulators are just like car alternators, and don't do as much charging for a depleted house bank as is required.

We need more info to begin to be able to help you address your question meaningfully. What are you trying do is clear, we need to know why, other than "more charge", as far as your boat operation. You may be just fine as you are.

 

[larryw]

Consider this; take your alternator to a shop (preferably a truck electric shop or an RV shop) and ask them if they can rebuild your current alt. to about 115 amps and remove the internal regulator. Then get an external from Jack Rabbit Marine or someone similar. You can still run one belt with that set-up. It'll be a lot cheaper than an additional alternator with all its brackets and idler pulleys or even buying a new alternator.

 

[Ross]

Much of the success of that plan would depend on the size of the "vee" belt. The load would exceed 2 horse power when you consider the internal fan.

 

[Bill Roosa]

Battery bank issues

This is all moot until we know the size of your battery bank and how deeply you intend to discharge it on average. The latter is determined by the battery bank size, loads, and how often you will attempt to recharge and for how long you can leave it on recharge.
What you are giving us amounts to "build me a bridge" but not saying how long to make it or where or what kinds of vehicles will be crossing it. You will no doubt get a bridge that is massively over designed, in the wrong place and does not even connect what you want it to.

 

[larryw]

That sounds like a Bridge to Nowhere