F300 Alternator Question

[HMBJack]

Sorry for a silly question but here goes:

On the F300, by attaching an auxilary charging lead, will the engine produce any more net amps to the battery?

For example:

There are two boats. Boat "A" and "B". Each boat has ONE F300 attached to a SINGLE battery. Assume no House battery.

Boat "A" has no auxilary charging lead installed. Just the Factory connection to the single battery.

Boat "B" however has an auxilary charging lead installed to the single battery along with the normal Factory connection.

Does the SINGLE battery on Boat "B" get any more charge or amps than Boat "A"?

I think not. Correct?

[boscoe99]

First, it is known by Yamaha as an isolator lead. Best that we all speak the same language. Makes life less confusing.

The answer to your question is, it depends.

The current flow to a battery is based on a number of variables. Type of the battery. Size of the battery. State of charge of the battery. Output of current available from the alternator. Etc.

The output of the F300 Offshore model is stated as 70 amps. With 55 amps being available to charge a battery. If and when both alternator output leads (main battery cable and the isolator lead) are being used. Use just one and the output available is approx 27.5 amps.

If the situation is that the current flow to a battery can be say 35 amps, and just the main battery cable is used, the current flow will be limited to more or less 27.5 amps. If the isolator lead is also connected to the battery then the current flow will be more or less 35 amps.

Conclusion, if the conditions are right then using both leads to one battery will result in more current flow than if just one lead is used.

[HMBJack]

"The output of the F300 Offshore model is stated as 70 amps. With 55 amps being available to charge a battery. If and when both alternator output leads (main battery cable and the isolator lead) are being used. Use just one and the output available is approx 27.5 amps."

Oh Okay then.

So it seems in my example above, the single battery on Boat "B" would be charged better and faster than Boat "A".

[boscoe99]

It depends. It might or might not.

If there is only one battery in the boat, then I would connect the isolator output leads to it.

[boscoe99]

Particularly if the one battery is powering lots of equipment in the boat. More power is available if and as needed.

[boscoe99]

[99yam40]

seems to me a house battery for things other than the motor would be the best way to go.
and always make sure you have fully charged batterys before leaving the dock.
draining your starting battery with other things is not a very good idea.
but each person has their own way to do things

[HMBJack]

I ask this question because I commercial fish and want to maximize my Yamaha's charging capability.
I run no less than ten 12V "consumers" on my boat while fishing.

I believed the alternator had limited output - like 55 amps at WOT.
What I didn't know is I would likely only get a maximum of 27.5 amps on the Factory installed lead (at WOT).

Adding an isolator lead would, in theory double my charging capability.

This is exactly what I'm after. More juice from the same alternator.

My example above is overly simplified so as to understand if an isolator lead would be helpful or not.

Sounds like it would be helpful in all applications to connect the isolator lead to a battery, any battery!

It also seems Yamaha should asterisk their spec. for a 70 amp Alternator to say "when the isolator lead is connected to a battery"

[99yam40]

it would be interesting to actually measure amps from the 2 leads to the same battery.
If one was putting out enough voltage would it limit the current out of the other?
would the current be equal out of both leads?

[HMBJack]

This exactly my question...

Is one lead 50%?
Are two leads 100%?

Before I posted this topic, my thinking was One lead was 100% of available amps and two leads would be 50% each.
Why? because you can only get 55 amps from one alternator no matter how many leads you connect to it.

Boscoe however suggests one lead delivers 50% or about 27amps.

Add a isolator lead and together you get 100% or about 55 amps total.

If true, everyone on the planet should connect their isolator lead to a battery. Any battery...
If nothing else, just to "get" that extra 50% that would otherwise be wasted.

[boscoe99]

it would be interesting to actually measure amps from the 2 leads to the same battery.
If one was putting out enough voltage would it limit the current out of the other?
would the current be equal out of both leads?

My testing of two different regulators providing current to one battery indicates that the current from each regulator may/will be slightly different, but one regulator does not prevent the other regulator from providing current to the battery.

Because of manufacturing tolerances no two regulators will hardly ever have the same output voltage. The regulator with the higher voltage will be supplying a tad more current than will the regulator with the lesser voltage.

My digital ammeters were not high precision. Due to their tolerances, it was difficult to get them to all read the same current when they were measuring the exact same wire.

[boscoe99]

This exactly my question...

Is one lead 50%?
Are two leads 100%?

Before I posted this topic, my thinking was One lead was 100% of available amps and two leads would be 50% each.
Why? because you can only get 55 amps from one alternator no matter how many leads you connect to it.

Boscoe however suggests one lead delivers 50% or about 27amps.

Add a isolator lead and together you get 100% or about 55 amps total.

If true, everyone on the planet should connect their isolator lead to a battery. Any battery...
If nothing else, just to "get" that extra 50% that would otherwise be wasted.

Many get all of the current needed via the battery cable. No need for them to spend money on the isolator lead if they will not receive any benefit from it being used.

[boscoe99]

From the 2012 Yamaha Outboard Rigging Guide.

[boscoe99]

A Mercury Marine way of using to two stators and two regulators to either double the current to one battery or halve the current to two batteries.

[boscoe99]

Some Yamaha electrical generation systems have two stators that are feeding current into two regulators that are integrated into one assembly.