Air Heaters draining battery on Yanmar 315?

[dowdster]

I have a 1999 Albin 28TE with a new 2008 Yanmar 6LPA 315hp. I've noticed that when I start up the engine cold, my voltmeter drops from 13+ to 12 and below. This persists for 5 minutes or so until the engine warms up, and the voltage abruptly jumps up into the healty range. I have read that this engine has 2 air heaters that draw 80-100amps to properly head incoming air for the cool engine to ensure properly combustion conditions and avoid white smoke etc. This is a major drain on the battery, especially considering that when you start the engine cold you're probably idling around the harbor away from the dock and the alternator has not hope of keeping up with the drain. I have also heard that some people disable this feature as it is not really necessary. Does anyone have any suggestions? What are the consequences of disabling this feature?

[Mariner]

A properly maintained diesel engine will last thousands of hours. An improperly maintained diesel engine can last less than one season, and can cost tens of thousands of dollars to replace.

A properly maintained battery will only last 5-7 years at best, and will cost several hundred dollars to replace. A battery experiencing greater than normal draw for short periods of time will only have its life shortened by a year or two.

Personally, I would leave it as-is. If the voltage drop is causing a problem with other devices or electronics, you may want to check the wiring and connectors for corrosion and proper sizing. If that is all good, you may want to consider a higher output alternator or larger battery.

[jleonard]

My Cummins would do the same thing. I disconnected the air heaters. We run the engines when it's warm so they are not needed to start the engine in our application. A good running diesel won't need the air heater to start until the air temp gets well below freezing.
Their second function is to keep the start up smoke to a minimum. Keep them in the circuit if you think you need that feature.

[Veebyes2]

VD (the voltage drop variety) is a bit of an issue with the Cummins as well. My first lesson was having the engine cut out while hoisting the anchor on one of our first trips. Now I know to run the throttle up just a little when applying a heavy 12V load. Same with a cold engine, 1200rpm is good enough to get the alternator to put out good amps.

I don't spend much time letting the engine warm up. It takes a few minutes from start to dropping the mooring, another 5 minutes to idle out of the no wake area. By that time temps are near enough to normal operating levels.

[jcollins]

Where do you boat? Are you in a cold climate?
I don't have that engine so my question may sound dumb. If you disconnect the heaters, is it as simple as unplugging a couple of wires? Or, can you add a switch so you can turn them back on when/if you need them?
Secondly, shouldn't the alternator provide the current you need if you bump the RPM up as Veebyes mentioned?

Just curious

[dowdster]

Thanks for all the helpful replies. A Yanmar specialist in my area states that the air heaters are mostly an emissions reduction (and white smoke prevention) device at startup (this engine is now rated EPA tier 2).

[jleonard]

Secondly, shouldn't the alternator provide the current you need if you bump the RPM up as Veebyes mentioned

The alternator can barely keep up when the heaters sre working. On a Cummins there are two smaller heaters and they alternate so that keeps the current draw down a bit. I think the Yanmar is one large heater but I'm not sure. Either way it's a huge draw.
I know in a Cummins if you throttle up to (I think it's) 1100 rpm the heater circuit cuts out by design. Not sure about Yanmar.
In a Cummins yes it's as simple as disconnecting a connector on top of the engine. And Yes you could switch it if you thought it was worth the effort. (I don't think it is).

Same in a truck as in a boat. I ran a Cummins in an old (91) pickup for many years in NW Connecticut. One winter I disconnected the heater circuit as an experiment (on my way to work as the heaters cycled my headlights would dim badly and if I had wipers on they would slow down and barely move). It started fine 1st or second compression stroke until the temp got into the single digits. After that it would start but took a few rounds of cranking the starter...then it coughed and sputtered a bit with "copious" amounts of white smoke. After 30 seconds or so it straightened out and ran fine.

edit: Boat or truck...I never,never warm up....start and go but take it easy until the engine temp comes up to 100 F or so.

[RobS]

Thanks for all the helpful replies. A Yanmar specialist in my area states that the air heaters are mostly an emissions reduction (and white smoke prevention) device at startup (this engine is now rated EPA tier 2).

The air heaters heat the intake air until the engine temp reaches 110 deg F, then they shut off. It is for reduction of cold start smoke. They were options on earlier 6LP's and standard on newer models. My 2000 does not have the heaters but mhanna's 2001 does...

[Donya]

Dowdster,
I have a 2003 6LPA and it is equiped with air intake heater but they are controled manually. The key switch has -off-on-glow, and push buttons for stop and start.
Just a thought.

Don

[RicM]

I only notice the effect of the heaters spring and fall, when the weather gets cooler on my 2003. Does it kick in at a certain air or motor temp?

[RobS]

I only notice the effect of the heaters spring and fall, when the weather gets cooler on my 2003. Does it kick in at a certain air or motor temp?

They come on automatically and shut off when engine temp reaches 110 deg F.

[mhanna]

I found that I have this heater on my 6LP.
There was a thread awhile back where I stated that while using my bow thruster my electronics would dim or shut off. Well this explains it, the problem usually only happened when leaving the slip to go out. If you start your boat (and even let it idle for a bit) it will not get to operating temp for the heaters to shut off for a bit, therefore when pulling away and using the bow thruster the draw from both of these devices was too much and would lower the voltage to everything else.
I Think I will be putting a switch in the engine box to prove this. Bottom line is if during the summer I do not see any smoke... well then it could stay off....

Matt