Webasto airtop 5500D - Low Voltage 12.3v

[zuzullo]

My webasto works for 5min and then shuts down with error code F03 (Voltage too low or too high).
I monitored the battery voltage which starts at approx. 12.9v and during the webasto 5min operation, it drops to 12.2v or 12.3v and then it shuts down.
Is this voltage really too low for the webasto to continue to operate? I would hope to get a couple of hours our of one battery (80Ah). Any suggestions?

 

[PaulRainbow]

The low voltage shut down of the Webasto is 10.5v. How and when are you measuring the voltage ? You need to measure it at the heater, whilst it is running. If you measure it at the battery (or from a battery monitor) and you get 12.2/12.3v but a lower voltage at the heater you need to check all of the power supply connections and make sure that the wiring is rated high enough to allow for voltage drop.

 

[pcatterall]

All As per PaulRainbow.
The voltage drop is what you would expect in the first 5 minutes when the glow pin is doing its stuff.
Those voltages should be OK but only if measured at the heater not the battery.
Your battery should be ok for 20 hours assuming that you want to limit discharge to 50%

 

[matthewriches]

See this regularly, ended up with a load of crisis calls around November when heaters weren’t firing up... at least 4 were due to bad connections that had gone unnoticed in the main feed i.e. the fuse holder. 1 wire pulled right out! Another was a loose terminal that was touching enough to pass voltage but when any amperage was applied, it failed and dropped right down.

Start from one end and work backwards.

 

[zuzullo]

Thank you for the input. I found out that the Webasto had a 4meter, 13ft (2.5mm2, AWG 13) wire from factory that was just rolled up laying next to it. So I unrolled it and it almost reached the battery. Only 1.5meter (5ft) missing.
For this last piece of wire I am using the standard in this boat (6mm2, AWG 10) fused at 16Amp.
Does it look ok?

 

[PaulRainbow]

Thank you for the input. I found out that the Webasto had a 4meter, 13ft (2.5mm2, AWG 13) wire from factory that was just rolled up laying next to it. So I unrolled it and it almost reached the battery. Only 1.5meter (5ft) missing.
For this last piece of wire I am using the standard in this boat (6mm2, AWG 10) fused at 16Amp.
Does it look ok?

Fit the correct fuse for the heater, up to the max rating for the 2.5mm cable, which is 30a.