Outboard 12v output

A

Aurelia

New member
So we have this new Victron monitor installed and it is interesting to see the amps going in and out of the house bank as we use power or charge them back up. I finally had the chance to start the outboard (on land) with the monitor running and at Idle it was only pushing .96 Amps into the house bank through the combiner. Now I know the output at idle would be quite low so this was not a surprise to me.

But, as I revved it briefly up to 2k and 3k the charging actually went down to about .5 amps from the outboard. Shouldn't I see an INCREASE in power with an increase in RPM? This is not normal is it? Would it charge more if in the water under a load? That doesn't seem possible.

I think we have a problem with our 2003 Honda 75.

Greg
 
More likely that you have your Victron installed incorrectly. I'd start with the install manual and think it through very carefully and make sure you have done the right install.
 
Forgot to say that the current into the battery will go down the higher the charge already on the battery. You could conceivably have zero amps going into a well charged battery. The key for knowing the 75 is okay is that the VOLTAGE goes up some as you rev up the RPMs. You should be seeing something around 14 volts with those revs. If you are, then it is possible you have a well charged battery.

Just some thoughts.
 
Did you turn off the battery charger? If it has the battery voltage up at 13.6, the Honda isn't going to pump any current into the batteries.

Boris
 
Most of my outboards charge at 14.4 to 14.8 (even at an idle)--I have a voltmeter on the GPS, which may not be as accurate as some other. I agree that if the house bank is fully charged--as it should be when the boat had been on a battery charger, then you would push very little amperage into the battery.

Better to test the entire unit, by leaving lights on and seeing what the draw (as per the Victron monitor). Get a draw of about 10 amps, and leave it on for 3 hours--that means that you should have pulled out 30 amp hours. Then start the motor, and see what the output of the alternator is. The Honda does require a certain amount of power just to run the motor, what is left over, is available to charge the batteries. Also you were running thru a combiner--which gives the starting battery priority--and does not open until the starting battery comes up to about 13.7 volts. (Most cases).

I know that the more recent Honda 75's have a 44 amp alternator--but the 2003, may only have a 16 amp alternator. That is what my B (Not BF) 90 has, and the 75 should be the same.
 
The house bank was fully charged and I was just a little rushed and watching the amps too hard. I think I also figured the outboard would push push push not thinking about the jar with a lid on. I will discharge the house bank some and try again and good point on the volts, I will watch the volts as well as amps next time.

Greg
 
The ameter on my old truck always reads in the middle (0) when all is well. If there is a big draw it goes into the (+) and then back to the middle. If the key is on and the motor not running but the fan/lights are on, it reads on the negative side. What you describe does not indicate a problem.
 
Journey On has a Honda 150 engine, which has a 12 V(nominal), 40 amp alternator. And I believe it's unregulated, since on a long trip, say 5 hrs, the battery voltage will approach 15 V.

So, yes, not only keep track of the amps, but the voltage. And the batteries haven't yet been hurt by the charge voltage of the Honda, just check your water often.

Boris
 
We were out for a few days recently and anchored with the heater and other accessories plus charging the Torqeedo battery back from about 50%. That brought us down a total of over 29AH the next morning. We started up and putted out of the bay at 1500 rpm and I was surprised to see over 10amps coming out of the motor to replenish the system. I tried coming up to 4500rpm and the amps barely changed. I was surprised and happy to see such significant (16amp max rated honda 75 carbed model) power coming back in and we were up to 100% well before reaching our next destination.

Greg
 
The 90 HP carburetor Honda also has 16 amp output. The injected 75/90 which came out in late 2006 is 35 amps. This gives considerably more power to battery charging (more than double)

I was surprised and happy to see such significant (16amp max rated honda 75 carbed model) power coming back in and we were up to 100% well before reaching our next destination.
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This may not apply to Greg's situation and it does show the importance of the monitoring systems. If Greg used 29 amp hours and put back in about 30+ Amp hours, then the battery may be charged up. But, there are many times that an outboard does not charge the battery fully. You may read a voltage of 12.7 volts, but that will be a surface charge, and not reflect the total amount of power used., and what is necessary to fully charge the battery. The remainder of the charge is during the Absorption and floatation phases, when the last 20% of the battery charging occurs.

Once the battery has reached about 80% state of charge, the charger will enter the absorption stage. At this point most chargers will maintain a steady voltage, while the amperage declines. The lower current going into the battery safely brings up the charge on the battery without overheating it. This is important, because out outboards are not smart chargers.

The remaining 20% of the battery takes much longer when compared to the The current continuously declines until the battery almost reaches full capacity. Next is the float phase, which can be at 85% charge, up to 95% of full charge. The float stage brings the battery up to full charge and the state of charge involves the full thickness of the plate, not just the surface.
 
I am getting my info from the Victron monitor I installed a few months ago. I love all the stats that unit keeps and its ability to show me a fuel gauge related to capacity and power flow instead of just voltage as Bob is talking about.

knowing your battery voltage plus having some knowledge about how to use that simple number effectively is great and worked well enough for me in the past but for the relatively few dollars and simple installation of the monitor, I really like the added precision and plus the ability to see how much any power consuming device on board really consumes.

Greg
 
Aurelia":29doragh said:
... but for the relatively few dollars and simple installation of the monitor, I really like the added precision and plus the ability to see how much any power consuming device on board really consumes.
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They are fun (in a useful way), aren't they? It's like when I finally got my first hand-held IR thermometer and just had to measure everything :D just so darned handy (and nifty).
 
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