Mercury 6.2 ECT DTS Axius Voltage Issue

[dubs283]

I'll have to see where the port engine clean power cable is located.

You must

This is a part of fundamental electrical troubleshooting isolation

View entire vessel electric systems independently. Key to figuring out your specific issue

 

[muc]

You must

This is a part of fundamental electrical troubleshooting isolation

View entire vessel electric systems independently. Key to figuring out your specific issue

Yes

I hadn't posted about this earlier because I couldn't remember what product this advice applied to. Finally found it in an Axius manual. I had this in the back of my mind as something that might help troubleshoot the relay buzzing.
When you shut down the engines,
turn the key off
move both remote control handles to WOT reverse
now turn the battery switch's off.
The reason I'm asking you to try this is I remember in one of the classes they told us the various module's remain powered up for a set amount of time (can't remember the exact amount, maybe 10-15 minutes) So if we wanted to work on the system, we would need to shift to full reverse and the program in the PCM would recognize this command and shut down power. Might prove helpful with your issue.

Be careful with clean power. Please read this and pay attention to the last couple of sentences I highlighted in red.

Diagnostic Basics There are many steps to diagnosis listed in this manual that may or may not take into account the basics. Here are the steps that should be covered prior to any other deeper investigations into what may be causing the fault or complaint.
• Battery ground pathways: All electronic systems must have unobstructed, clean, uncorroded pathways for the current to return to the negative side of the battery. If the ground path is partially interrupted, the current will seek an alternative path back to ground. If a sensor is part of the path it uses, this will fail the sensor in a very short amount of time.
• Battery state and correct rating: Batteries can display a seemingly correct amount of voltage while static, but can appear as failed if a load tester is applied. The load test simulates exactly what happens to a marginal or bad battery when a significant load is applied such as cranking the engine. The result is low‑voltage faults to the system as well as communication faults as the modules are powered down due to low voltage. Even if the engines complete the start up, the faults can remain even after voltage recovers from alternator output.
• Battery positive pathways: Modules in the Axius system all get their operating power from the clean power harnesses attached to each engine. These harnesses should connect to an unswitched power source such as the cranking battery or a power junction immediately off of the cranking battery. Power should not be removed from the clean power harness with the key switches in the on position. Always ensure remote control levers are pulled back to reverse wide‑open throttle after turning the keys off and before disconnecting clean power.

 

[tpenfield]

Thanks @muc. Good to know about the reverse thrusters. I will try this after any testing of the ignition. FWIW - I have not interrupted power with the ignition switches on . . . figuring something bad could happen.

I won't be back at the boat until Monday (traveling this weekend). Testing should resume then.

 

[tpenfield]

Monday morning update . . .

I am definitely getting 'crosstalk' from the port battery to the starboard battery/engine. I took the 2 alt/3 batt (only 2 batts are connected) out of the equation and the crosstalk went away.

Thinking over the weekend, I had a hunch that the problem would be somewhere the batteries/engine power join. So those are the 2/3 isolator and the parallel solenoid. Still working on a few more things.

The stbd alternator issue is still there (9.2 volts on the purple wire). The port alt is fine (11.5 volts) . . . both ignition on, not running.

I did get to apply the reverse thrusters after doing the ignition test.

 

[Scott Danforth]

Ted, most battery isolators are just big shottky diodes. should be a 0.7 volt drop across them. the 2 alternator, 3 battery may have additional diodes so the batteries may see 1.4 volt drop (I would have to dig up the specs)

are you running an Acro or Shur Power?

I remember there being issues on emergency vehicles with them because of the voltage drop and electronics and we had to switch to a zero voltage drop isolator (really expensive ACR)

some battery isolators have a custom sense wire running back to the alternators.

just a thoughts

 

[tpenfield]

Ted, most battery isolators are just big shottky diodes. should be a 0.7 volt drop across them. the 2 alternator, 3 battery may have additional diodes so the batteries may see 1.4 volt drop (I would have to dig up the specs)

are you running an Acro or Shur Power?

I remember there being issues on emergency vehicles with them because of the voltage drop and electronics and we had to switch to a zero voltage drop isolator (really expensive ACR)

some battery isolators have a custom sense wire running back to the alternators.

just a thoughts

It is a ProMariner Model 2-70-3
.

.
I believe it is a simple diode-based isolator, there was not a ground connection.

The engines are happy now. Clean power is clean. and other power seems to be where and when it is supposed to be. Still getting the 9.2 volts on the ignition feed, but with the engine running, it is up to about 14 volts.

Maybe I can test the current on the purple wire, just to be sure. Could be just a voltage drop from a bad connection.

I even tested the outdrives to make sure I got those back together OK.

Now I am considering if I should replace the isolator. The advantage would be the ability to have alternator redundancy in charging the batteries. Probably helpful with the LiFePO4 charging from the engines and if I loose an alternator while out in the boat.

 

[tpenfield]

As for the alternator(s) . . .

On the starboard engine (new alt) the current down the purple wire is 3.5 amps @ 9.3 volts with the ignition ON.

On the port engine (existing good alternator) the current down the purple wire is 0.12 amps @ 11.5 volts with the ignition ON.

Doing the math . . .

Stbd Alt: The resistance through the exciter circuitry is 2.65 ohms

Port Alt: The resistance through the exciter circuitry is 95 ohms

 

[tpenfield]

I have ordered a new battery isolator, along with a new alternator (Arco Marine brand this time).

I'm returning the DB Electrical branded (actually came in a J&N Electric box). I've had good luck with DB Electrical stuff in the past, not this time . . .

Hopefully the electrical system woes will be behind me . . . got to make room for the next boat-buck issue to come along.

 

[tpenfield]

Thanks everyone for your help and guidance with this issue.

In working through this issue, one of my great mysteries of VesselView / SmarftCraft has been solved. The Battery voltage displayed on the VV screen and the Diacom readout appears to be the voltage on the purple wire (Ignition).

It seems odd, since much of the voltage to the system comes from Clean power (Red/Black), the 50 amp CB (Red/Purple), and the MPR (Red/White) wires. All those wires tend to run about 1 volt higher than the purple wire.

 

[tpenfield]

The new 2 alt/2 batt isolator arrived today (that was fast). I think the alternator will arrive tomorrow or Friday. (The defective one is on its way back)

But . . . I am traveling for the next 5-6 days, so I won't be installing things until next week.

 

[Lou C]

I think you’ll have good luck with ARCO I have their starter & alternator on mine

 

[Lou C]

Plus they have tech support if you call a guy actually picks up the phone!

 

[bruceb58]

Finally got to my boat to scan it. Not sure if you still need it. Here is running and not running.

 

[bruceb58]

If and when my alternator fails I will buy an OEM Mercruiser one.

 

[tpenfield]

Thanks. Yes, we have the same engines . . . and the 'system' voltage and 'battery' voltage have the same issue (if you want to call it that). Your readings are a bit closer (Within 0.5 volts) than mine, which are typically about 1.0 - 1.5 volts apart.

I have found that what is titled "battery voltage" is the ignition (purple) wire voltage, and what is titled "system voltage" is the voltage on red/black (clean power) or perhaps the other power circuits . . . (Red/purple, Red/Pink, etc).

Not sure the titling matters much, but it is interesting that the readout is implying that the 'system' is making voltage .

 

[tpenfield]

I got all my parts . . .
.

.
Alternator, Isolator, Rubber bands.

Ready to have a go at it tomorrow.

 

[tpenfield]

All set . . .

The new alternator is working as expected, voltages are all good. I replaced the isolator. The engines are happy.
.

.
The pulley on this alternator was a wee bit bigger than the original. So, I had to go up a notch on the serpentine belt size.

For those following along, the Acro Marine Part# for the identical alternator is '20815', (50mm pulley).
.
Here is the new isolator . . .

.
A make-over of the electrical box is on the docket for this fall/winter.

Launch day is next week . . .

 

[tpenfield]

Quick Update . . .

The boat is launched, engines seem good, and I saw 74 watts of power from the solar panel out at the mooring . . . which I think is a world's record for this solar panel.

In other news, the truck broke down on the way back from the ramp . . . transmission cooling line started leaking. I made an appointment with a local shop for next week.