Dan Baker via EV wrote:
I'm not sure how many of us use Alltrax controllers in their EVs but I wanted to share a learning experience I had with one. I purchased an AXE-7245 3 years ago and last summer it started acting up where it would not boot in my boat (http://www.evalbum.com/4767). It appeared something was amiss in the logic of the unit- green light would not come on. If I waited a few hours, tried it again it would come on and stay on with no issue. However every few days this issue would creep back. Being that the controller was installed in a boat and always just a few feet from lake water, I called Alltrax support and inquired whether moisture could be the culprit. They advised me that the boards are 100% sealed and that as long as water wasn't being splashed and arcing out the connections this wasn't the cause. Well I dug some more and found in one of their documents that a diode should be installed on the power pin as well as the contactor. I installed one and the issue appeared to go away. Fast forward a few months and I swapped this controller into my snowpig (http://www.evalbum.com/4544) for winter duty. It worked great up until last week and the no LED gremlim re-appeared. After checking everything 10 times and another winter storm bearing down on us I was a little worried to say the least! Just as I was about to do a hard day of shovelling/ snowblowing with an old ICE snowblower, I took the chance and focused a hair dryer on the serial port opening. Within 2 minutes the controller booted up! I think where the weather had warmed up a bit and my garage had gathered some moisture something inside the controller got damp and crossed something out. I guess the learning part of the story here is that despite what support tells you or what the advertisements say, sealed controllers can be prone to moisture over time. I suspect some of the epoxy has cracked or developed openings around the board with it heating up and cooling up with service. I have since ordered another controller and I'm also building a Cougar controller, be good to be able to service/see the controller board to be able to service it.
Sounds like you got it resolved; but here is a little background that might help.
How did you connect the diode on the power supply? Was it in series with the power input? Such a diode is added because the 12v system can experience sudden voltage drops, such as from some big load being turned on.
Or did the diode go from power to ground (cathode +, anode -), like a zener diode or transient absorber? A diode in this position is used to suppress positive voltage spikes, usually from some inductive load being turned off. It also protects against polarity reversal, such as from connecting the 12v battery backwards (it blows the fuse instead of blowing up the controller).
Note that manufacturers should know that both events are likely to occur in 12v vehicles. They usually include such protection diodes in their design. Automakers have a special "load dump" test to make sure a device is protected from such events.
On water: Electronic devices hate water. Manufacturers try to seal it out, but moisture is really good at creeping into things. Especially in an outdoor environment, temperature, humidity, age, and Murphy's law will inevitably defeat all their attempts to keep water out.
It is hard (expensive) to literally make something waterproof. No matter what the manufacturer says, most devices are really only partially sealed. They work fine indoors, where they never get exposed to rain, mud puddle splashes, snow, fog, 100% humidity, or condensation due to temperature changes. But put them outdoors, and water gets in!
Even if the manufacturer says it's sealed, I still put electronic devices in a separate box to keep out moisture. As long as either the manufacturer's package or my package works, the water stays out. You can buy waterproof electrical boxes that have gasketed lids, and use water-tight strain reliefs to bring wires through. For small gadgets where heat is not an issue, one useful trick is to put the electronic device in a plastic bag, drop in a little packet of dessicant, and then heat seal it shut.
-- Knowledge is better than belief. Belief is when someone else does your thinking. -- anonymous -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
