Voltage error webasto diesel heater

[Jewellbags]

Just a glitch but our diesel heater has errored twice (voltage error - 3 flashes ) when off grid - got two batteries and the cab battery was pretty full and the leisure battery about 50% . I even started the heater first time with the engine running - but only for a few minutes .

Now running the engine again and trying a third attempt but any other suggestions if it occurs again - btw fans and heat is coming out .

 

[tonka]

I know those diesel heaters have a big draw as they start up and get to temperature, something like 10 amps.
Also when they cool down for turn off there is a big draw.
Once at temperature and ticking over they use a lot less.
Sounds like not enough battery power to me, if leisure batteries were 50% and lead acid they are on the edge of becoming damaged.

 

[Jewellbags]

Thanks for that - working at the moment with the engine running . But it’s a foggy day so far and the solar won’t be doing anything . Might have to try and grab a EHU for the rest of the trip

 

[DBK]

My guess is your leisure batteries are on the way out. The state of the cab battery doesn't count unless you have an odd wiring setup.

You need to know what voltage they are at when the heater starts up. 50% charge will show about 12 volts when the batteries are rested and not being used. If on start up it is dropping to 11 or less volts I suspect the Webasto will complain. There will be a low voltage limit but I haven't looked up what it is. There is certainly a high voltage limit which causes it to shut down.

 

[rod_vw]

Similar problem with an Eberspacher yesterday in this thread.

Check the voltage at the heater not forgetting to measure between +ve & -ve connections at the heater not just +ve to chassis.

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[Jewellbags]

My guess is your leisure batteries are on the way out. The state of the cab battery doesn't count unless you have an odd wiring setup.

You need to know what voltage they are at when the heater starts up. 50% charge will show about 12 volts when the batteries are rested and not being used. If on start up it is dropping to 11 or less volts I suspect the Webasto will complain. There will be a low voltage limit but I haven't looked up what it is. There is certainly a high voltage limit which causes it to shut down.

Forgive my ignorance as I’m not technically minded however the battery is about 6 months old and the 12 v socket indicates about 11.8 at the moment . It’s not a disaster as we can get to a ehu . We also have a B2B setup but I think that just shares the solar charge between the batteries - not the draw from devices ?

 

[mitzimad]

b2b is only on when engine is running you havent said what batteries you have if you have lead acids and youve regularly gone down below 12v they could well be damaged even in six months

 

[Jewellbags]

Lead acid yes but “apparently” tolerate a deep drain ? Webasto still running btw

 

[TheBig1]

Seen this several times with the supply wires to the heater being undersized and causing a voltage drop over their length. As the battery ages and especially when cold the voltage is then too low to start the heater. Run an oversized supply cable to the heater will resolve it

 

[DBK]

Forgive my ignorance as I’m not technically minded however the battery is about 6 months old and the 12 v socket indicates about 11.8 at the moment . It’s not a disaster as we can get to a ehu . We also have a B2B setup but I think that just shares the solar charge between the batteries - not the draw from devices ?

A bit of a search suggests the default low voltage alert on a Webasto is probably 11.4 volts.

As has been suggested, if you have been discharging the batteries too far too often they may have been damaged. For example, 11.8 volts when not under load indicates only 30% state of charge. You shouldn't normally run them below 50% if you want them to last.

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[gus-lopez]

As TheBig1 undersized wiring from new is also a problem. My mate had that.

12 v socket indicates about 11.8 at the moment

That is nearly dead.