How much more load okay on the alternator? - PeachParts Mercedes-Benz Forum

DerBenz · #1 07-05-2003, 06:51 PM

I'm considering adding a fuel heater to my '85 300D for use with the waste vegetable oil I'm currently running in it.

The energy consumption specs. for the fuel heater are:
20-30 amps

Can someone please tell me if my alternator can handle this level of current draw using the stock alternator? What is the typical output of the alternator anyway, when you're going down the road?

Thanks

-Mike

ATLD · #2 07-05-2003, 07:28 PM

Stock alternator is 55 amps rated output.

This may not produce 30 amps unless the engine is revved, or at least at high idle.

I have an 80 amp alternator form a 560SEL in my 300d for my stereo, and I imagine youi could do the the same. Just requires a 4cm longer belt.

ATLD

javven · #3 07-06-2003, 02:41 AM

Check the rating, I highly doubt it draws that many AMPS. The unit that heats my whole house draws like 25 amps during start up. It's on a 30 Amp slow-blow fuze.

Make sure it says Amps not Watts. 24 watts would be 2 additional amps - which I could see being more logical.

But, if it's 20 amps it's 20 amps.

P.E.Haiges · #4 07-06-2003, 11:00 AM

DerBenz,

Why would you run an electric heater all the time when you have all the free heat from the engine once it warms up.

I could see running the electric heater when the engine is cold and until it warms up, but to run the electric heater is wasting a lot of energy and putting a strain on your alternator.

A little plumbing to your cooling system will heat your WVO fuel for free.

P E H

DerBenz · #5 07-07-2003, 11:09 AM

Thanks for the info. on the alternator's output. Double checked the rating of the heater and I read right: 20-30 amps. On using the cooling system to heat the WVO: I've been pondering which way to go (obviously) and may still decide on the cooling system route. Right now, my challenge is finding a decent diagram/
instructions on how to do this properly on my 617.952 engine. I've checked out Greasel and some other sites but I still don't have a solid understanding of what mods. I'd need to make to use the cooling sys. If anyone has any leads, I'll gratefully accept the help.

Thanks again

#6 07-08-2003, 10:15 AM

For the past 10 years I've used an electric heater running on house current to warm the car interior in the morning before driving. I truely do not understand why this, along with a trickle charger running on house current, is not provided in the modern car. Ice falls off the windows and the gap while the engine reaches heating temp is not noticed if the interior is preheated. Try it, you'll see what I mean.

coachgeo · #7 07-08-2003, 10:53 AM

Quote:

Originally posted by DerBenz
Thanks for the info. on the alternator's output. Double checked the rating of the heater and I read right: 20-30 amps. On using the cooling system to heat the WVO: I've been pondering which way to go (obviously) and may still decide on the cooling system route. Right now, my challenge is finding a decent diagram/
instructions on how to do this properly on my 617.952 engine. I've checked out Greasel and some other sites but I still don't have a solid understanding of what mods. I'd need to make to use the cooling sys. If anyone has any leads, I'll gratefully accept the help.

Thanks again

What is becoming the more common method is to use a Vege-therm for 12v heating when needed and coolant temp when it reaches normal opperating temprature. Also Dana has plans on how to build a warmer on the end of your fuel pick up tube in the tank so u dont have to have your WVO heated in it's tank to fuel burn temps. You just need WVO in the tank hot enough so it is able to flow at a viscosity the fuel pump likes. The 12v/coolant combination will heat the WVO to needed fuel burn temps just before the fuel filter if u install them correctly. Actually Dana has plans for a home built Vege-Therm also.

here is Dana's How To Plans ($5.00 per)

Here is where you can get the vege-therm I'm guessing this is the one you were planning on getting by your description.

hint... don't use a fuel heater rated for a standard diesel fuel. They do not get hot enough.

Maxwell · #8 07-08-2003, 11:57 AM

With a fuel heater is there any harm heating regular diesel. I'm planning on using liquid WVO at 50-80%, but some might be a little thicker than diesel, would a heated fuel line do any harm when running plain diesel?

coachgeo · #9 07-08-2003, 12:19 PM

From what I have read the issues seem to be two things; one, that manufacturers design in a cooling effect from diesel fuel for the injectors and/or IP to help cool them. Two, the effective firing of the fuels at too hot/cool temps.

There for I have wondered the same as you. Lately though, from what I have read, is that WVO helps pull heat out of the IP/Injector areas better than diesel there for a hotter solution of a WVO mix will cool as effectively as normal temp diesel fuel. Now with that said.... if your running a two tank system you can allways turn things off. Put the 12v fuel heater on a switch and relay. Maybe install some salvaged valves from a cars heating system to shut off flow to a coolant to fuel heat exchanger if you feel the need.

Some have experemented with their final fuel temps to find what makes their engine run best. I have only heard this a few times.