Webasto heater under/over voltage issue

[Vance1965]

Does anyone have experience with a webasto heater throwing an error code of under/over voltage? I have a battery monitor(Victron-712) that's saying I have 12.5v at the house batteries but it will not fire off. Is it normal to have the voltage drop to 12.0v at start up ?

When I switch batteries to supply 12.7v it works fine . It seems odd the the small difference causes an error. I remember having lower batteries in the past and the heater worked .

Webasto's site suggested batteries failing, bad fuseholder or loose electrical connectors. I am going thru the wiring now to look for obvious faults. I wonder if the heater itself could have a bad component that would cause this issue?

Any ideas or suggestions would be greatly appreciated.

 

[glider4]

Battery voltages should be measured under load. If your battery under load is only showing 12.0 volts that’s about 45 percent SOC which is pretty low. If switching to a different battery solves the issue then my bet is on a failing battery, not the Webasco.

 

[Vance1965]

Thank you for the information. I'll give it a try with the other batteries on line and monitor the voltage. I may just need to replace my house batteries.

Another question would be am I making a mistake by keeping my batteries on the charger 24/7 when the boat is on the trailer in the off season?

 

[Submariner]

Does anyone have experience with a webasto heater throwing an error code of under/over voltage? I have a battery monitor(Victron-712) that's saying I have 12.5v at the house batteries but it will not fire off. Is it normal to have the voltage drop to 12.0v at start up ?

When I switch batteries to supply 12.7v it works fine . It seems odd the the small difference causes an error. I remember having lower batteries in the past and the heater worked .

Webasto's site suggested batteries failing, bad fuseholder or loose electrical connectors. I am going thru the wiring now to look for obvious faults. I wonder if the heater itself could have a bad component that would cause this issue?

Any ideas or suggestions would be greatly appreciated.

There's a setting in the Webasto controller (assuming you have the SmarTemp 2.0 or 3.0 controller) to set a low voltage cutout. (Low Voltage disconnect).

Upon initial startup of the Webasto heater it'll pull a fair amount of amps. I forget the number as it's only for a short time needed to fire the glow plug to start the combustion. This higher current draw will result in a voltage drop on AGM or FLA batteries, especially from aging or otherwise unhealthy batteries.

For healthy batteries I'd think the LVD should be around 11.8 volts or 12.0 volts to be conservative.

Once the heater is running, it's usually about 20 watts (2amps), which is for the fan to blow the hot air around.

 

[glider4]

Vance, we keep our boat on “shore power” on the trailer in the driveway during the off season. Water heater off, engine and thruster banks off. In a few weeks when I’ve winterized it, I’ll also put in a big automatic bilge heater, one automatic cabin heater and two cabin always on Calframo dehumidifier fans. Those are all A/C users and need the shore power.
There’s some always on DC systems (CO monitor & bilge pumps among others) that draw from the house bank and I want the house batteries fully charged all winter so the battery charger is left ON.

 

[Vance1965]

Martin,
We have a 2015 R27 with an EVO-M basic controller. Looks to have an RJ-11 cable from the unit and a set of NO, NC contacts for accessories. No settings that I can see. Possibly down on the unit? It's an adventure to get to the heater I know as I had to remove it to clean out the soot last year.

Glider4,
It sounds like leaving the house batteries on the charger all winter is the right thing to do. Just can't imagine that the AGM batteries are getting weak after only 1.5 years of light use and being never discharged farther than 80%. Is there something I'm missing here on battery care?

 

[Hamster]

Under Options in your controller, you can change the low voltage setting for the heater.

LVD “Low Voltage Disconnect” allows the user to set the battery
voltage level at which the Webasto SmarTemp Control 2.0 will shut
down the heater. A warning (LED and message) will appear after 8
minutes of low voltage. The warning will remain on for 2 minutes
before the heater is shut off.
If battery voltage is equal to or less than the threshold selected
+0.1v, the heater will not start. I.e. if an 11.5v threshold is selected
the heater cannot be started until B+ has reached 11.7v.
12 volt - Range between 11v – 12.5v
24 volt - Range between 21v – 25.5v

 

[Toucan]

Our heater coked up because we tried to start it up on lower batter voltages multiple times. Cleaning it out is a job I would not want to ever repeat. We were told by Sure Marine to be on shore power or have the engine on to provide 14 volts when the start cycle begins. After the heater gets going and is putting out a lot of hot air (the combustion chamber is hot), you can turn the engine off and let the heater run off the battery.

Barry Thompson
TOUCAN, R-27 Classic

 

[Vance1965]

Barry, I too had the pleasure of cleaning out all the buildup of soot in the combustion chamber on ours. We were in a marina and it was an adventure getting it out of the boat as well! Thank you for the info on the startup. We have never had an issue in the past with startup on the hook (somewhere in the 12.6v range ). It seems weird that all of a sudden now it's acting up. I took both my batteries in to interstate tonight to have a diagnostic test done and they are in great shape. Now I wonder if there is something in the Webasto that is failing that is drawing excessive power.