24v Eberspacher in 12v boat

[Modulation]

You know the scene. £180 all in for a 24v system from a lorry (incl that weird skin fitting) but my boat is all wired for 12v.
Question is , as I have 3 batteries, would it make sense to hook 2 of them together to give me 24v for the Eb?
Pros? Cons?
Thanks

Brendan

 

[ChrisP]

Having just recovered fron the trauma of a phone call where the prime subject was the fire on the boat next to mine in the marina caused bay an electrical fault. My advise is to ditch any ideas of lashing up the electrical system and buy the correct kit. I maybe more expensive but have you counted the cost of the alternative which sod's law says will occour when you are least in a position to do anything about it?

 

[Strathglass]

I have often thought about that. If you have used a boat with an elderly eberspacher you will find that the heating goes off a short time after the engine is stopped. I think the only practical way would be to get a 12 volt to 24 volt invertor then you would have no problems. It would overcomplicate things by trying to charge two batteries from a single alternator then connecting them in series to give 24 volts.
In my case I bit the bullet and fabricated a skin fitting myself using 1" and 1.5" stainless tubing and some plates welded together for the eberspacher I purchased secondhand.
Iain

 

[bedouin]

Sorry - I don't think that there is an easy answer. Yes you can wire 2 12Vs in series to give 24V - but how would you charge them?

You could fit a second alternator (24V) but that would be a LOT of effort. You could also try some form of switching arrangement to put the batteries in parallel when charging and series when powering the heater; but that would be quite complex and anyway to keep a 24V system purely for running the heater seems a bit extravagent!

 

[HaraldS]

Not that easy.
Setting up your batteries in series, is essentially going towards a 24V system, which would be fine, but is a very expensive step to take as your would need a separate alternator for the 24V domestic, you will need a shore power charger for 24V and so on.
And then an inverter to run the 12V equipment. And that wouldn't work for power hungry stuff like an anchor windlass (which could theoretically be laft on the engine battery).
So once a boat is set up for 12V it probably is so forever.

I think the only practical way to run your Ebersbacher would be through an inverter. A good switch mode inverter would only 'loose' less then 10% of the power it converts. The problem will be finding one.

There are plenty on the market that step down from 24V to 12V, but I haven't seen many for stepping up. Since they are rare, they'll probably want it's weight in gold for it when you find one.

There are modest priced inverters on the market, to run laptops on airplanes and cars, supplied with 12V. They come with cables for a specific laptop, but the units are the same. The desired output voltage is coded in the plug of the special cable. Some of these can do up to 24V and 2A. (Older Apple Powerbooks were 24V).

An D3LC, draws 1.5A at 24V in boost mode, and less in the others. So normally such an adapter would do. The big problem is that it draws 10A during start-up, powering the glow plug. And 10A inverters will be quite expensiv, as I pointed out.

To overcome that problem, you could consider a 12V glow plug.

Eberspacher models differ in the way they drive the glow plug and the newer the model the harder it will be to convince it to work with a modification. That is because they sense for open or shorted glow plugs.

If you are lucky, you got an old model that pulses the glow plug negative. I think it would have a model number like 25 1907 05 if it is a D3LC. In that case your glow plug would be connected between pin 6 and pin 9 of the control board. Assuming you connected your -12V with the -24V output of the inverter, on some it already is, then you could just take the pin 6 glow plug wire and run off the control bord plug and connect it to +12V.

Some models have an external solid state switch for the glow plug, that also acts as a current regulator, it looks like a relais with a heat sink. If you have that, it would need to be replaced too because it would limit the current to early for the 24V plug.

 

[Guest]

What about investing in a nice 12V DC - 230V AC inverter (for all your mains gadgets) and then using a 230 - 24 volt transformer for the heater. Modern stuff may well be that efficient that the power losses from the double transformation are acceptable. Speak to Mastervolt or Victron for proper advice.

 

[pvb]

Yes, there\'s a relatively cheap solution

Although you can buy a 12volt to 24volt DC converter which will supply enough current for starting the Eberspacher, it would cost you about £500. A much cheaper solution would be to add a dedicated 12v battery and use a simple changeover switch to control it. It's safe, and won't affect your charging arrangements.

As the dedicated Eberspacher battery will only have a drain of around 1.5amps (you can effectively ignore the short-term higher current of the glow plug), something like a 60Ah battery would give you 15-20 hours of heating before it needed recharging. With the heater switched off, the dedicated battery would recharge whenever your engine is on or your charger is on. You don't really need a heavy-duty battery - you can use an ordinary cheap automotive battery. So total cost would be around £100 including the switch (which needs to be able to handle about 30amps for when the dedicated battery is on charge).

If you're interested, email me at pvb@btinternet.com and I'll scribble down a circuit diagram and send it to you.

 

[ean_p]

Hello Harald
Can you tell me if the majority of parts from a D7L and compatable with the parts from aD3L as I have a 12v D7L that I would like to convert to a 24v set up and between us Brenden and I may be able to help each other....

 

[ean_p]

Hello Harald
Can you tell me if the majority of parts from a D7L and compatable with the parts from aD3L as I have a 12v D7L that I would like to convert to a 24v set up and between us Brenden and I may be able to help each other....

thanks Ian P.

 

[paulrossall]

Re: What sealant did you use?

Just fitting a 2nd hand 12volt Eberspacher and with a 2 metre felible exhaust I am using a standard bronze-type skin fitting. Boat has reverse slope (ie. like bow) so getting angle for goose neck is no problem. Question is what sealant do I use on the skin fitting? I do not think it will be very hot after exhaust gases have gone through 2 metres of exhaust but dont think sikaflex will cope with any warmth at all. Did wonder about using Gum-Gum which is car exhaust sealer and I happen to have some in my garage! Any suggestions? Can you use normal plastic tube for the combustion air intake? Thanks for anticipated responce.

 

[HaraldS]

Hi Ian,

I don't know. My wisdom is from the two units on my boat which are both24V a D3LC and a D5LC. I did study the service manuals when I originally had the problem that the larger one was shutting down when it was operating at the lowest stage. Moving the metering pump solved my problem and since I didn't have to look after the units. So I'm not an Eberspaecher expert, just digged into it deep enought to understand how they work and that I can help myself in case they cause trouble.

The two service manuals I have are on my boat and I'm flying there this weekend to do zinks and some other stuff, so I will have a chance to compare the two, which might give us a smart guess at the D7L.

I couldn't find an online manual (PDF) for the D7 or the D5, but found the D3 and some others at the US site of Eberspaecher, called www.espar.com.

From that you can see that the voltage dependant parts are: metering-pump, thermostat, glow plug, main control board and blower motor.

I'm sure the blower motor will be different for differnt size models, but the control boards I'd expect to be largely the same, but maybe with differnt software in the ROM. For example they do measure blower RPM and comapre it against the expeted value for the stage it is running at, and shut if there is more than 10% deviation for over 30 seconds. Would not be surprised if differnt size units expect differnt blower RPM.

I'll check on the difference between the D3L and the D5L and let you know.

Cheers,
Harald

 

[Strathglass]

Re: What sealant did you use?

The fitting I made is very similar to the normal ones which cost many gold coins. It has two concentric tubes, thus there is a longer path between the inner tube carrying the hot exhaust gases and the mounting flange which is bolted to the hull. You will have a much higher temperature against the hull using a skin fitting.
To answer your original question. The sealant I used was a +600 deg F. High Temperature Silicone Adhesive Sealant.

Send me a PM if you want more details. Also if you send your direct email address I could send a photo of the fitting I made.
Iain

 

[paulrossall]

ReM sent NM

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