Battery warning

[Karen Ann IV]

I was out fishing when I used the bow thruster to turn my 33 ft grady. A warning showed up on the screen "battery 11.5" what does that mean? should I be concerned? I had no problems starting the engines.

 

[Hookup1]

Low voltage warning. How old are your batteries? How is the bow thruster hooked up (which battery)?

Thrusters are hard on batteries. 5 years it typical and thruster battery less.

 

[seasick]

In summary, your thruster battery is discharged.
If installed correctly your thruster battery should not have anything to s do with motor operations.
Your thruster battery may be charged by one of the motors or perhaps by a charger connected to shore power.
What is wired to what and where the charging current comes from will help with the diagnostic steps.

 

[SkunkBoat]

Which screen? Your MFD?

Is your thruster using the House batteries or does it have its own dedicated batteries?

If your thruster runs on the House then it would not be unusual to get a low volt alarm on an MFD when using the thruster.
Garmin can adjust the alarm cutout down to 11v to get f`ewer` alarms.

Ideally, you would have a completely separate battery system for your thruster.

 

[Karen Ann IV]

Thank you The thruster is on a house battery . out today w/o any issues

 

[seasick]

Probably the house battery was a bit drained before the last trip.

 

[Fishtales]

^^^ This. Watch the level, it may be time for a new one in the near term.

 

[dogdoc]

After a somewhat similar situation with auto pilot pump draining house bank secondary to aux wires on OX66 not charging. I put a dedicated voltmeter on each start batt and house bank. This lets you know where you are more reliably and tells you if you are charging while running.

 

[DennisG01]

Thank you The thruster is on a house battery . out today w/o any issues

An assumption is that you had the battery on a charger and you left the dock with it fully charged. The assumption is that you ALSO did that last time and the battery eventually started to fail due to either not being properly charged by the engines or it's just past its due date.

There is no good reason for a battery being so low as 11.5V. Something caused that... and it generally doesn't fix itself

 

[seasick]

An assumption is that you had the battery on a charger and you left the dock with it fully charged. The assumption is that you ALSO did that last time and the battery eventually started to fail due to either not being properly charged by the engines or it's just past its due date.

There is no good reason for a battery being so low as 11.5V. Something caused that... and it generally doesn't fix itself

I believe that the 11.5 volts was a low voltage alarm from an electronic device like a multi-function plotter. When the thruster is activated, it draws significant current that will result in a voltage drop at the battery which shows up at the accessory (house) bus and eventually at the electronics. I've had situations where I had to turn off the low voltage alarm in the plotter settings to get rid of the annoying alarms

 

[Hookup1]

Charging at the dock and engine charging should be checked. Is this a 3-bank battery setup? I'll assume 3. Make sure second engine has charging shunt installed and is working.

Probably a bad battery or all of the above.

Newer generation of chart plotters "make" their own power internally. They can run on 10.5 volt up to 35 volts. But I'll bet that 11.5 volts is a lot lower when the thruster is run. It's also not good for the thruster - they draw more current.

 

[SkunkBoat]

Charging at the dock and engine charging should be checked. Is this a 3-bank battery setup? I'll assume 3. Make sure second engine has charging shunt installed and is working.

Probably a bad battery or all of the above.

Newer generation of chart plotters "make" their own power internally. They can run on 10.5 volt up to 35 volts. But I'll bet that 11.5 volts is a lot lower when the thruster is run. It's also not good for the thruster - they draw more current.

They don’t “make “ power. They have a regulated power supply. They can run with a wide range of input power. They still have an alarm to warn you that input power is below expected.

it is possible that the battery is weak but it is also possible that the thruster is fed with the same wire as the House from battery to panel. The high current draw of the thruster causes a voltage drop on the House

the OP said the 11.5 was when running th thruster. They did not say it is always 11.5

 

[dogdoc]

Back when it was a starting battery and a Humingbird flasher who cared. If need be you could start with the pull rope and get home. Today with auto pilot pumps, windlass, bow thrusters, etc... if I see 11.5v I am looking for a problem before it gets out of hand.

 

[Hookup1]

They don’t “make “ power. They have a regulated power supply. They can run with a wide range of input power.

Yes - When I said they "make power" I meant that they take unregulated, noisy power the boat provides, clean it up and run sensitive electronics with it. To me that is "making power" - no flux capacitor required.

 

[SkunkBoat]

An assumption is that you had the battery on a charger and you left the dock with it fully charged. The assumption is that you ALSO did that last time and the battery eventually started to fail due to either not being properly charged by the engines or it's just past its due date.

There is no good reason for a battery being so low as 11.5V. Something caused that... and it generally doesn't fix itself

The battery was not "being so low" as 11.5V The voltage at the MFD did for some instant during the time the thruster was running. That triggered an alarm on the mfd.

Assuming standard Grady setup, the Stbd starting batteries are also running house. There has been no problem starting or raising/lowering motor.


I think you guys are barreling down the battery path and charger path too fast.

 

[SkunkBoat]

Were the motors running when you ran the thruster?

 

[DennisG01]

The battery was not "being so low" as 11.5V The voltage at the MFD did for some instant during the time the thruster was running. That triggered an alarm on the mfd

If it was showing 11.5 DURING USE of the thruster - I completely agree.