Webasto not working properly.

[Soupdragon]

Hello gents, my webasto has flummoxed me and a few others.  Over the past 6 weeks when i switch the webasto on it goes through its pre start checks and then switches it's self off.  However if I switch the engine on it fires up no problem.  If I switch the engine off the webasto follows about 10mins after.

Now I can hear its a power problem, but I have changed the batterys because after scratching of heads the opinion was the batterys were flat at 12.4v insufficient to start it, but it still happens, swaped the heater for one that was working still happened. So I put my hand in the pocket for a new loom, still happened. The experts say that if it works with the engine on it is unlikely to be the heater, and since I have tried another unit that worked before and after that is probably true.

So new batterys, new loom what else do I try?  The heater is a marine thermo top c. 

Over to you ladies and gents.

[Alan de Enfield]

It is almost guaranteed to be a power problem.

If the batteries have not been FULLY charged in that 6 weeks they could be 'sub-optimal'.

 

How many leisure batteries do you have ?

How do you charge them ?

How long do you charge them ?

How do you know when to charge them ?

How do you know when to stop charging them ?

 

What voltage is your battery(s) showing when the heater is trying to start ?

Edited October 26, 2020 by Alan de Enfield

[Tonka]

What about the cable from the loom to the battery

[TheBiscuits]

Is it flashing an error code?

 

As you have swapped batteries, loom and the unit itself it's removed most of the usual issues.

 

Is the metering pump or it's loom faulty?  I'm assuming you didn't swap the fuel pump when you tried another unit.

 

Is it connected directly to the batteries, or via an isolator switch?  There may be a bad contact in the switch if it's connected like this.

 

Alan's questions about battery voltage are very relevant too.

[Tonka]

What type of fuse does the unit connect through. I have had a dirty contact on the old  car type ones which played havoc with the shower pump

[Rob-M]

We had a fuse issue with our eberspacher which would start firing up and then shut down until the fuse was replaced.

[Onewheeler]

I've had this with an iffy connection in the power feed. The heater pulls about 20 A at startup so a poor connection will pull the voltage down. Never traced in unequivocally but wiggling and tightening everything sorted it.

[Soupdragon]

Batteries are connected to the victron 702 and I charge them when the victron reads over 150 amps used then I use the engine to charge them back up again usually till I have a tail reading between 4-6 amps. But this was suggested as the problem and 6 X 110ahc were purchased on friday and the problem still persists.the new loom hsd all the connections from the battery to the unit fuel pump and timer. I have not yet changed the fuel pump as this is working when working with the engine, fuses will be checked as soon as i come back from work tomorrow.

[rustynewbery]

Possibly a high resistance on the fuse/fuseholder.  Was the cause of my Eber problems some  years back

[Tracy D'arth]

There is no certainty that the new batteries are fully charged when bought.   4 to 6 amps tail current does not suggest that they are fully charged either. 

 

It will be a high resistance connection or cable or fuse etc. Even 1 ohm is too much resistance.

[Sea Dog]

10 minutes ago, Tracy D'arth said:

There is no certainty that the new batteries are fully charged when bought.   4 to 6 amps tail current does not suggest that they are fully charged either. 

 

This ^^^^

1 hour ago, Soupdragon said:

Batteries are connected to the victron 702 and I charge them when the victron reads over 150 amps 

But this ^^^^ makes no sense to me.  Are you saying after your gauge tells you that 150 Amp Hours have been used, or something else? If so, how often is that?

[Soupdragon]

We use 150 ahc in 24 hrs the meter will zero after an hour or so but the amps will still be high so when this gets down to less than 8 i  stop the engine. Then once a fortnight I put the bank on the battery charger through the generator for about 6 hours.

Yes its dark now so i will check all the suggestions tomorrow. 

[Tracy D'arth]

2 minutes ago, Soupdragon said:

We use 150 ahc in 24 hrs the meter will zero after an hour or so but the amps will still be high so when this gets down to less than 8 i  stop the engine. Then once a fortnight I put the bank on the battery charger through the generator for about 6 hours.

Yes its dark now so i will check all the suggestions tomorrow. 

You are killing the batteries with your poor charging regime.

[noone]

I once fixed one for a friend without knowing it!..He had lived aboard for about 3 years,and the webasto had never worked.

Fitted him some new batteries and noticed that one of the battery connection cables had corrosion on the crimp.Took it apart and cleaned it up.Connected the batteries,switched the isolation switch....We both got the fright of our lives as his webasto kicked in!!. ?

[Mad Harold]

3 hours ago, Soupdragon said:

Hello gents, my webasto has flummoxed me and a few others.  Over the past 6 weeks when i switch the webasto on it goes through its pre start checks and then switches it's self off.  However if I switch the engine on it fires up no problem.  If I switch the engine off the webasto follows about 10mins after.

Now I can hear its a power problem, but I have changed the batterys because after scratching of heads the opinion was the batterys were flat at 12.4v insufficient to start it, but it still happens, swaped the heater for one that was working still happened. So I put my hand in the pocket for a new loom, still happened. The experts say that if it works with the engine on it is unlikely to be the heater, and since I have tried another unit that worked before and after that is probably true.

So new batterys, new loom what else do I try?  The heater is a marine thermo top c. 

Over to you ladies and gents.

Sounds like voltage drop due to wiring to the unit being too thin.

There is a ready reckoner on here somewhere (that I can't find) for calculating the thickness of wire for minimum voltage drop,posted (I think) by Jen In Wellies or Alan De Enfield.

 

[mrsmelly]

3 hours ago, Soupdragon said:

Hello gents, my webasto has flummoxed me and a few others.  Over the past 6 weeks when i switch the webasto on it goes through its pre start checks and then switches it's self off.  However if I switch the engine on it fires up no problem.  If I switch the engine off the webasto follows about 10mins after.

Now I can hear its a power problem, but I have changed the batterys because after scratching of heads the opinion was the batterys were flat at 12.4v insufficient to start it, but it still happens, swaped the heater for one that was working still happened. So I put my hand in the pocket for a new loom, still happened. The experts say that if it works with the engine on it is unlikely to be the heater, and since I have tried another unit that worked before and after that is probably true.

So new batterys, new loom what else do I try?  The heater is a marine thermo top c. 

Over to you ladies and gents.

Sounds as others have said entirely like lectric problems. If I were you to remove any doubt I would remove the unit ( twenty minutes job easy ) if you can get at it and take it to someone with a test rig, many hire boat yards have one. If it runs there then it has to be yer wiring/power supply.

[TheBiscuits]

2 hours ago, Tracy D'arth said:

4 to 6 amps tail current does not suggest that they are fully charged either. 

 

 

It's not far off on a bank of 6 X 110Ah new batteries.

 

What would you suggest charging to?

[Col_T]

Doesn't that depend on the voltage?

 

FWIW - the MV on our boat is especially sensitive to input voltage: if that's down at 12.6v, the little darling doesn't start at all. In our case, the answer is to run the engine above tickover for a couple of minutes and then try to start it, or just make sure that the batteries are fully charged, which I gauge as tail-current of 1% of battery capacity with alternator output voltage above 14.4v.

[p6rob]

If the batteries are fully charged, it sounds like voltage drop through too thin cables, or a high resistance connection. As a test, try running an extra pair of positive and negative cables from the battery to the heater. If it then runs, either make the new cables part of the install, with an inline fuse, or replace the existing ones with thicker cables.

 

Rob

[Flyboy]

15 hours ago, Mad Harold said:

Sounds like voltage drop due to wiring to the unit being too thin.

There is a ready reckoner on here somewhere (that I can't find) for calculating the thickness of wire for minimum voltage drop,posted (I think) by Jen In Wellies or Alan De Enfield.

 

https://www.calculator.net/voltage-drop-calculator.html

[Tony Brooks]

8 minutes ago, Flyboy said:

https://www.calculator.net/voltage-drop-calculator.html

 

Not very easy to use for the normal UK cable designations like 28x0.30 or 2 mm sq CCSA but better than nothing/

[Alan de Enfield]

I use the one here (about half way down the page)

 

 

https://www.12voltplanet.co.uk/cable-sizing-selection.html

[Soupdragon]

Thank you all, i have changed the loom, fuel pump and am charging the batteries for 5 hours a day, I really don't know what it was but its started to work normally again.  Adding up the bills it would have been better to buy a brand new set up, but that is knowledge for the future.

Thanks again.

[boots]

Long shot, but had a power issue on our webasto - turned out to be dirty terminal on one of the blade fuses

[Flyboy]

49 minutes ago, Soupdragon said:

Thank you all, i have changed the loom, fuel pump and am charging the batteries for 5 hours a day, I really don't know what it was but its started to work normally again.  Adding up the bills it would have been better to buy a brand new set up, but that is knowledge for the future.

Thanks again.

If you had bought a new one I think you would have had the same problem as it appears to have been a voltage/connection problem.