Apparently idling with high alternator load is bad

I just lost another alternator and it was in a similar situation as last time. I left the car idling with a heavy load on it - the marine batteries I have in the back of my camper van were running low so I left the engine running while I cooked my breakfast in a 350 watt cooker. The combo of pulling max amps from the alt while the van is stationary seems to be the killer.

Luckily I have an extra alt with me now, but I'd like to fix the one I'm taking out. What goes bad under these conditions, anyway? I don't have a power steering leak - the alt is dry, shiny, and only a few weeks old. The weather here has been cool and dry.

Wish I could help you Reducto. I'm also looking at making mine a camper mobile. I haven't tackled as much as you have, I don't think, but I'm always curious to what others are doing. I also got a fairly large capacity marine battery in mine. I just have one, but would eventually move it to supporting the stuff happening in the back. I was thinking of putting in a solar panel for most of the charging on that one.

Sorry I couldn't be of more help.

Solar is definitely worth it. I had no problems when I was driving 50+ miles per day every day, but staying in one place for a while kills the battery. A 200 watt panel should help quite a bit. I'd still like to not have to worry about killing the alt, though! They simply shouldn't be dying this easily.

IMO pulling a heavy battery load at idle shouldn't stress the alternator too much. This is because our alternators don't have much output at idle. If you were pulling a heavy load, most of it would be coming from your batteries. Of course once you start driving the alternator has to charge the batteries & that will stress it. If you have more than 1 low battery that can easily cause the alternator to overheat in just a few minutes. I'm guessing anything over 15 minutes at max output would be enough to kill it. If you're alternator is a cheap rebuild, then it's even more likely to fail.

I repair alternators and I've found the cheap rebuilds don't hold up well in the van. Some other brands with pressed in diodes aren't so bad, but the Denso alternators for our vans have the diodes soldered in. If the rebuilder didn't use a high temp solder, then running the alternator hot will melt the solder and kill it fast (I've actually pulled these apart with loose diodes laying inside the case). Factory Denso alternators and the ones rebuilt by Denso hold up much better due to the high temp solder and the rubber-like coating they put over them. Here's a thread where alternators are discussed in detail:

http://www.toyotavantech.com/forum/s...lternator-woes

Another possibility is you may have a bad or damaged alternator wire harness. It's not unusual for the little wires to break off inside the insulation at the small round plug. Here's a thread that deals with that issue:

http://www.toyotavantech.com/forum/s...rnator-harness

I recently came up with a permanent fix for our alternator problems by installing a Delco-Remy CS-144 in my van. It required fabricating a new mount and some wiring mods. I'll probably never need to deal with alternator problems again, but it takes a bit of time and effort to make the conversion. I plan on posting details of this mod after I finish about 100 other things I need to do. In the meantime here's a few teaser pics:

http://i8.photobucket.com/albums/a23...lternator1.jpg

http://i8.photobucket.com/albums/a23...lternator2.jpg

http://i8.photobucket.com/albums/a23...lternator3.jpg

http://i8.photobucket.com/albums/a23...l/IMG_2201.jpg

http://i8.photobucket.com/albums/a23...l/IMG_2202.jpg

http://i8.photobucket.com/albums/a23...l/IMG_2203.jpg

Ok, maybe it isn't the idling, but the fact that I'm draining the 200AH of batteries. It's bad for the batteries anyway, so I guess I'll just watch my usage more carefully until I install some solar.

Many of us are very anxious to hear about your swap! That big alt should solve a lot of problems.