Low Voltage - Raymarine Autopilot SG3

[mikedefieslife]

Originally Posted by geoffr

Wondering if anyone has a solution to this problem:

Our Raymarine Autopilot SG3 // ST6002 is giving us "Low Voltage" alarms when I know the voltage to it isn't low as our batteries are being charged. Does anyone know if it gives the same error for higher voltages?

The problem seems to go away in the afternoon after motoring all morning...

I had this same issue on my Snowgoose (not that the boat has anything to do with it) with the EV1.

Voltages measured were good. What it turned out to be was a rotten cable from the main bank to the main switch panel where it passed through a bulkhead. Must have been that way for years. It was a 16mm2 cable that just fell apart in my hands when I pulled it. As the damaged part was hidden by the bulkhead it wasn't possible to see.

Voltages all looked good, when measured, but I'm guessing when the AP had to struggle the voltage dropped low enough to trip the alarm.

[Snore]

Originally Posted by geoffr

I would normally agree with you, however I only see this problem at the start of the day when the voltage is higher.. which is what is confusing me so much!

The wire is AWG8 which is oversized according to the documentation for the SG3 and Type 2 pump. The run between the breaker and SG3 is perhaps 8 feet. There is no corrosion at all on the wires.

IMHO, the fact that it gets worse when the engine compartment gets hot (where the pimp and ram are?) seems to confirm a wiring or connector issue - in the engine compartment. I would gently pull the wire where it goes through the engine compartment bulkhead to check for abrasion. Then run my hand along the wires. If there is a fuse at the pump open the fuse holder and check it out. Finally I would check the connections where the boat wiring connects to the pump. If all is good then go to next paragraph.

While doing a cat delivery we had an intermittent AP failure. I decided to wait until it failed and enter the compartment where the pump was. Everything looked good so I did what any good mechanic would do— I gave the pump a gentle whack. It started working. The point is, if there is no fuse on the power supply to the pump, an issue with the pump, could cause the controller to see it as simply a voltage drop. How yes I ended up installing a new pump that was flown in.



Checking the simple issues first is easier.

[geoffr]

So after chasing this problem for a long time I finally figured it out. It is indeed a high voltage problem!

In the mornings the alternator would charge the house battery bank back up. While it was doing that things are good initially as the voltage isn't "too high". Once the battery bank was high enough the voltage being put out form the solar controller was higher than the alternator which the autopilot didn't like.

Once I figured it out I could "turn on and off" the "Low Voltage" alarm in the afternoon by putting a towel over our largest solar panel - towel off... alarm, towel on.. no alarm.

[DeepFrz]

Thanks for posting the solution.

[geoffr]

Yes.. it's always frustrating when you find the same problem.. but no solution

[svmobert]

What is the model of the solar controller you have? And what type of batteries?

[geoffr]

House Bank is 6 Trojan T105s
Solar Controller is Blue Sky 2512 : https://sunforgellc.com/solar-boost-2512i-hv/
Alternator Regulator is Balmar MC614

[svmobert]

Trojan specifies 14.8V for the absorb voltage but your MC614 and sounds like your Bluesky is also running high.. My suggestion would be to reconfigure the MC614 AND the BlueSky for no higher than 14.8V bulk/absorb and 13.2V float. Don't want to cook the batteries, and it may reduce the S3 alarms also.

[Snore]

Originally Posted by geoffr

Yes.. it's always frustrating when you find the same problem.. but no solution

Thanks for the update. Who would have thought of over voltage??? Well done!!

[Dsanduril]

The S3 (not the S1 or S2) can use either 12V or 24V. I suspect the "low voltage" alarm at absorption voltage is because the S3 has decided it is on a 24V system. I've had a number of other pieces of dual voltage equipment with the same problem - they think normal battery charging voltages on a 12V system are low voltage on the next higher voltage system. This is just poor programming on Raymarine's part, the unit shouldn't think it is on a 24V system until it sees something like 16V, but instead it decides at something like 14.5V.

[Paul L]

Originally Posted by Dsanduril

The S3 (not the S1 or S2) can use either 12V or 24V. I suspect the "low voltage" alarm at absorption voltage is because the S3 has decided it is on a 24V system. I've had a number of other pieces of dual voltage equipment with the same problem - they think normal battery charging voltages on a 12V system are low voltage on the next higher voltage system. This is just poor programming on Raymarine's part, the unit shouldn't think it is on a 24V system until it sees something like 16V, but instead it decides at something like 14.5V.

Good explanation. I was baffled at why a low voltage alarm would come on at high voltage. But then it is Raymarine.