OK, one more Baja trip story.... I got a chance to try out the fire extinguisher supplied with my 2004 Sportsmobile. Actually, I'd never used any fire extinguisher before this. In any case, it works!
I was happily bouncing along on a dirt track, when all of a sudden I felt a loss of power. Glancing, down I saw all my gauges go haywire -- with the speedometer doing its full-sweep test mode. And, I smelled smoke. Eek!
I immediately pulled over, stopped the engine, and gave everything a thorough looking over. I couldn't find anything amiss, so I gingerly started the engine, and started driving onwards. One minute later, it happened again. Engine completely died. More smoke. Now pouring out from under the hood!
Key off. Brake hard. I yanked hard on the fire extinguisher from behind the passenger seat, pulling it out. (Luckily that's all there is to removing it.) I popped the hood (perhaps a mistake) run outside, and see flames
coming out from the battery area on the passenger side of the engine!
I realized I'd never used one of these things before, but here goes... A few squirts with the fire extinguisher, and the fire is ... out! Phew!
OK, what the #### happened?!?
I quickly removed the battery. Then I blew out much the accumulated fire extinguisher dust and took a look around the engine compartment.
I notice a sooty broken braid wire next to the battery:
And another next to the ExtremeAire circuit breaker. I vaguely remember that braided copper wires like these are some kind of grounding strap. And perhaps they are meant to melt when overloaded by a short?
The braided strap next to the ExtremeAire looks suspicious. Had it been touching that bolt next to it? Sure enough, that bolt is live +12v.
I check the battery cables (now disconnected from the battery) with my multimeter. Yes, something was still causing a short! What was shorting? Something major!
In any case, I knew I had to repair the grounding straps. I found three melted grounding straps, and hacked up some fixes:
At this point, it was getting dark, so I camped right there on the road. After lots of sleep, in the morning I got back to tracking down that short. Luckily all the house battery appliances still work with the engine battery disconnected.
I noticed that three red cables had been bolted to the battery. I assumed one was the stock Ford cable, and two more were added by Sportsmobile. Checking with my meter, I found that only one of these three cables was shorting to ground. A thick one. Now I was getting somewhere.
I followed this red cable back, as it left the rear of the engine compartment, and followed the passenger side of the frame back to the house battery. Hmmm, the house battery didn't look right:
The red shorting cable followed the frame of the van up to the house battery, then passing alongside it and out the other side. I pulled this cable out and found the short. The house battery had rotated out of its pan, and was pinching the red power cable against the van, causing this:
Sure enough, pulling the cable away from the van body fixed the short. I wrapped this cable with lots of tape and conduit.
Righting the heavy house battery wasn't trivial. I finally managed to get it to budge by using the van's bottle jack, and wriggled it back into its tray. I then used thick garden wire to strap the house battery down, positively attaching it to its tray.
If you like to drive bouncy roads, you might want to check your house battery too -- it might be worth your time to tie it down like I did.
I don't know what I would do if that extinguisher hadn't worked! Next time I'm buying two!!
[edit: Here is the full story of my Baja adventure: Baja 2014