Webasto diesel heater

[curlytim]

Hello everyone.

I have a fairly new looking webasto waterheater that came with the boat.

I have 3 new 110ah batteries. 

At the moment the heater will start fine with engine on (can turn engine off as soon as heater in run mode )

It's also fine when batteries are fully charged.

Problem is in the morning when the batteries are not 100%...it goes through the start up cycle fine till the last bit where you can hear the combustion fan kick in.

Presumably the volts drop at this point at the unit enough to cause it to lock out on undervoltage.

Has anyone bought the pc webasto diagnostic lead kit..I've seen them starting around £50 on ebay?

I thought I'd post this before starting to test voltages etc...I know it's very easy to lose a volt or 2 especially when a heavy load is suddenly introduced to the system. 

Appreciate any thoughts and suggestions please.

Thanks. Tim.

 

[Jen-in-Wellies]

Welcome to the forum. Some questions:

How do you know the batteries are fully charged in the evening? What are you using to charge them and how often? Do you know what your daily amp.hour consumption is? Are you living on the boat?

How far is the webasto from the battery? What size wire is used (mm2 cross sectional area)? This can be used to calculate the likely volt drop.

Do you have a multimeter and if so, can you measure the voltage at the Webasto when it gets to the combustion part of the start cycle?

 

[David Mack]

Is the webasto a proper marine unit or one designed for vehicles? The latter are said to be less tolerant of low voltage.

[curlytim]

Thanks for the replies..only at early stages of looking into it at this point so thanks for the questions 

We've been cruising every day so engine running for approx 5 hours so I'm only assuming batteries are good after this. 

Feed cable looks like 2.5mm

Not far from batts.

Initial iooks like 2 fuses/ cables feed the heater...I haven't done any tracing/testing yet.

Heater running fine now for over an hour right now in morning after I ran engine for 10 mins during start up cycle.

Also runs right down to low and can hear it speeding up again. 

I'm going to look into it further in next few days when I get a min.

Was just wondering if anyone had had similar probs and what solutions/ outcomes were.

Thanks.

Ps..it looks like new unit was fitted same time as new vetus engine so assuming they knew to fit marine version...how can I check for this?

 

[Jen-in-Wellies]

Just now, curlytim said:

Feed cable looks like 2.5mm

Is that diameter (mm), or cross sectional area of all the copper conductors inside (mm2). The cross sectional area is usually marked on the insulation at regular intervals.

1 minute ago, curlytim said:

Not far from batts.

How far is not far?

2 minutes ago, curlytim said:

Was just wondering if anyone had had similar probs and what solutions/ outcomes were.

It is a common problem. Causes are usually duff, or discharged batteries, too long, or too small wires. All more likely to have issues when using a Webasto with vehicle firmware, rather than marine, as @David Mack mentioned.

[curlytim]

Ok thanks.thought it might be...I'll look into that...test the voltages etc..and check for bad connections etc...I'll post what I find and any solutions. 

[Brian422]

Be careful when buying ebay £50 diagnostic Kit.

I purchased a kit only to find out they're only suitable for Webasto with digital control board.

My Webasto was installed in 2009 and has analogue control board board.

Hopefully, if your Webasto is relatively new you shouldn't have a problem.

 

Regards

Brian.

[Tracy D'arth]

The usual causes have been quoted, low battery, thin wires, long runs.  

The main difference in performance with the vehicle units is that they shut down at a higher voltage than the marine ones. This is to stop them flattening the vehicle battery too much for it to start the engine.

Starting up should be the same.

Accurate voltage readings at the heater will show whether its volts drop.

 

[MtB]

Also bear in mind that:

 

1) Wires are usually thinner than you think they are

2) Wires are usually longer than you think they are

3) Batteries are usually more knackered than you expect

 

 

 

[Onewheeler]

It's most likely due to it being an automotive model. We have one, it starts unaided down to battery voltages of about 12.4 V but needs the engine to run for a minute or two to get it going for lower terminal voltages. It's difficult or impossible to convert the automotive version to a marine version according to a Webasto servicing centre.

[PeterF]

Our diesel heater started doing this, investigation found that the fuses had surface corrosion from dampness in the engine hole. Cleaned up the contacts with some wet and dry and replaced the fuses. All was well after that. Something worth checking but may not be your issue.

[curlytim]

So far...

Voltage at the main fusebank is around 12.4volts tonight...heater started ok without engine.

However   it looks like the heater has its own feed from the leasure isolator. 

Looks like the main feed for heater is 2.5  sq.mm.

Feed cable is from battery compartment in one side of engine bay to the other side. So prob about 2.5m ...3m max.

The batteries are good 110amp hour. New spring this year..

Haven't worked out our power usage yet.

Fridge is heaviest user.

Questions...

Is there any way of telling whether the unit is marine or vehicle?

I'm presuming the vehicle ones are hot air and marine are water...someone mentioned the firmware so we're saying the control gear/hardware inside could be vehicle/set for vehicle. 

Someone said its near impossible to change yet someone else said its relatively easy to adjust the low volt cutout level if you have the kit?

I've put a connector in so I can test the voltage at the unit and compare it to battery terminal voltage..then it got dark!

Thanks for all the interest and help.

Tim.

 

[Sea Dog]

22 minutes ago, curlytim said:

However   it looks like the heater has its own feed from the leasure isolator. 

My Eberspacher is fed directly from the batteries (through an inline fuse). Pretty sure this is in the installation instructions (along with minimising the cable length) and is based on removing any additional resistance being imposed by having any switches, fuse panels, isolators in the circuit. Even the marine versions are voltage sensitive, so if yours is also an automotive version you're really up against it!

[Tracy D'arth]

39 minutes ago, curlytim said:

So far...

Voltage at the main fusebank is around 12.4volts tonight...heater started ok without engine.

However   it looks like the heater has its own feed from the leasure isolator. 

Looks like the main feed for heater is 2.5  sq.mm.

Feed cable is from battery compartment in one side of engine bay to the other side. So prob about 2.5m ...3m max.

The batteries are good 110amp hour. New spring this year..

Haven't worked out our power usage yet.

Fridge is heaviest user.

Questions...

Is there any way of telling whether the unit is marine or vehicle?

I'm presuming the vehicle ones are hot air and marine are water...someone mentioned the firmware so we're saying the control gear/hardware inside could be vehicle/set for vehicle. 

Someone said its near impossible to change yet someone else said its relatively easy to adjust the low volt cutout level if you have the kit?

I've put a connector in so I can test the voltage at the unit and compare it to battery terminal voltage..then it got dark!

Thanks for all the interest and help.

Tim.

 

I would say that 2.5mm2 of copper cross sectional area is too small for a 3m run, its 6m total out and back. Try with 6mm2 copper....  But you need to check the voltage at the heater, not the supply.

Clean and refit every connection even though they may look OK.

The vehicle and marine units are both water heaters and look identical.

I was told that they can be reprogrammed but have never done it, you need the lead and a computer + software and it only applies to the digital controlled ones.

Edited October 3, 2023 by Tracy D'arth

[curlytim]

I'm hoping it's a marine unit. Why would anyone fit a vehicle one...are they cheaper?

We bought the boat last spring...the new vetus engine only had 130 hour on it..maybe the heater was fitted at same time as it looks pretty clean...I'm trying to resize a pic I took of the model no etc in hope of someone identifying it as marine or vehicle. 

Yes Tracy. Rewire in 6mm sounds best longterm plan. We're not living on the boat through winter so not a major prob. I've got some work to do on her before next spring so I'll include that...and continue the research..I'll post back here any solutions I find.

Many thanks. Tim.

[Sea Dog]

9 minutes ago, curlytim said:

I'm hoping it's a marine unit. Why would anyone fit a vehicle one...are they cheaper?

They are on the second hand market. Sounds like yours was done at original fit out though, doesn't it? In which case, it really ought to be a marine unit. 🤞

[curlytim]

Here's a pic of the plate...looks like a 2010/12 model...so should be digital firmware?

Even if rewiring solves the problem for now  so long as safety isn't compromised, I think trying to reprogram the low volt cut out could prevent future probs because the batteries aren't always 100% especially on cold mornings in a cold engine compartment. 

[Jen-in-Wellies]

Searching on various numbers on that plate, the only one giving results when used with Webasto is 00 0002  03 1232. This is coming up with listing for second hand vehicle heaters, not marine.

For example, https://www.ebay.co.uk/itm/115915742964 and https://www.ebay.ca/itm/363127169089

That isn't conclusive, but there is very little else on any of the other numbers there.

 

[David Mack]

3 hours ago, curlytim said:

The batteries are good 110amp hour. New spring this year..

New batteries can be wrecked within a few weeks if you don't look after them. Not saying that's the case here, but newness is no guarantee of condition.

[curlytim]

11 hours ago, Jen-in-Wellies said:

Searching on various numbers on that plate, the only one giving results when used with Webasto is 00 0002  03 1232. This is coming up with listing for second hand vehicle heaters, not marine.

For example, https://www.ebay.co.uk/itm/115915742964 and https://www.ebay.ca/itm/363127169089

That isn't conclusive, but there is very little else on any of the other numbers there.

 

Thanks for that Jen. That would explain the high setting for the low volt cut out. 

Maybe the plate is referring to some kind of refirb...unit looks very clean. It seems older than the engine at 2010/12

Next is to find out if it can be altered as batteries will always be tired in the cold mornings. 

I have a spare leasure battery I may use as a dedicated start up...rewire in 6mm 1st though. I'll talk to an engineer too.

All the best and thanks again Jen.

 

 

[Tonka]

2 minutes ago, curlytim said:

Thanks for that Jen. That would explain the high setting for the low volt cut out. 

Maybe the plate is referring to some kind of refirb...unit looks very clean. It seems older than the engine at 2010/12

Next is to find out if it can be altered as batteries will always be tired in the cold mornings. 

I have a spare leasure battery I may use as a dedicated start up...rewire in 6mm 1st though. I'll talk to an engineer too.

All the best and thanks again Jen.

 

 

Surely running in a new bigger cable for the heater is easier then running in a new much bigger cable to charge the leisure battery

[curlytim]

9 hours ago, David Mack said:

New batteries can be wrecked within a few weeks if you don't look after them. Not saying that's the case here, but newness is no guarantee of condition.

Yeah I know...new to boats but I've had campers for years...I am looking after them..eg. not letting the fridge drain them and keeping an eye on the charge % and voltage on the solar unit. I will check them before mooring the boat up for the winter.

Thanks David.

2 minutes ago, Tonka said:

Surely running in a new bigger cable for the heater is easier then running in a new much bigger cable to charge the leisure battery

Yes...if that's necessary...1st things first...