Charging house battery from Yamaha 150 when running

efx

efx

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I have two starting batteries and one house battery. I have two Yamaha 150 (2019). I have a three bank AC charger when boat is on the hard on a trailer. I want to make sure my house battery is charger when underway and running. I see there is an isolator port on the engine and cable available from Yamaha. So I just select one motor, plug it in and run the cable with fuse to the house battery and that’s it?
 
Simple as that! There is already a fuse in the charging circuit at the voltage regulator, at least there was on my 2011 F150. Shop around for the cable as it is simply a Yamaha plug and ring terminal end for the battery.
 
There may be another change...
Original grady setup had House breaker connected to Stbd motor ("Feed" terminal od Stbd battery switch)
The "House" was the Stbd bank(Batt1) of 2 parallel Start batteries. There was one Port start battery and two battery switches that let you choose various combinations.
Using switches, you would be able to run house (and start Stbd motor) off of the port battery (Batt2)

You say you have two starting batteries and one house battery so you may have changed things already.

If you have not already done so, you would want to move the feed of the House breaker to the House battery + terminal.
That would isolate it from the start batteries and the motor start cables. (You would be charging using Aux cable from one or both motors)
Isolating the House prevents the House voltage from dropping(sometimes electronics blink out) when you start a motor.
It also prevents you from running down start batteries

Ideally, you would add a switch that gives you the ability to run the house off of either start battery if needed in an emergency (or start a motor with the House bank..)
You would want that switch to allow you to turn OFF the House also.
 
Skunk boat has a good point. I was assuming you were going to run your charging lead directly to the battery and not through a switch. Always good to have the ability to back up your starting batteries. Most simple hook up is straight to the battery that you normally use as the house. Essentially, with two isolator cables, One for each motor, you have four charging sources for your batteries and you can hook them up anyway you want.
 
My 2007 F150's do not have a fuse block under the cowling. The Yamaha cable I installed is fused at the battery end with a fancy fuse holder you screw to an appropriate place in the battery compartment. $100+/-. Just buy the factory one - has the right engine end connector.

Mine is connected directly to the battery terminal same as my battery charger cables.
 
On my boat, the aux cables from both Yamaha F200's are feeding the house battery (via fuse blocks, etc). I figured that way I could get 90 amps to the house and keep up with a full electronics load. Anything wrong with using both that way?
 
Perfect guys. Thanks for all the info. I’ll check out the total wiring system so I can figure out the existing setup. I think it’s all factory wiring and switching back there so I have some flexibility. I’ll get the Yamaha cable to make it easy.
 
Rlloyd, so you have a feed from each motor to one battery via fuse blocks? I was thinking of that but I don’t want one motor to sense power from the other motors output. Does this make sense?
 
You can put both aux charging shunts (one from each motor) to a single battery. It will increase charging current but I wouldn't recommend it. The alternator produces 33 amps at 1,000 rpms. They are not "smart" in they they don't sense battery condition - they just output a voltage and charge. It also makes it harder to troubleshoot engine charging issues.

2002-F225-alternator-curve.png
 
Last edited:
Hookup1 said:
You can put both aux charging shunts (one from each motor) to a single battery. It will increase charging current but I wouldn't recommend it. The alternator produces 33 amps at 1,000 rpms. They are not "smart" in they they don't sense battery condition - they just output a voltage and charge. It also makes it harder to troubleshoot engine charging issues.

View attachment 21233
Click to expand...
Got it. Thanks. I only need one feeder from one motor for my application, so I’m going to go that route.
 
ya, its not going to sense anything...its an "isolator"

I have a double bank for my House with both Aux going to it. That way when I troll on either one engine its always charging.
I don't see any problem with using both. You are not going to overcharge the battery.

I imagine you original setup was like the 265. Here is what I did...

New Battery Config for 265
 
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