About a month ago, sometime after I left Yuma, AZ on my way to Pecos, TX, noticed that the voltage needle was fully pegged to the right side instead of staying steady'ish in the middle.. Knew this wasn't good so I immediately turned on everything I could, just to draw more power to reduce the voltage. Pulled into the first place I could find (a Love's truck stop), and looked at the battery. It boiled over. They were able to test voltage and the younger person there said the battery was bad.. I was like, yup, kinda new that.. He also measured the alternator voltage, and while don't know the readings, he said it was "charging fine", even though volt meter on the dash showed it over charging.
So, went off to find a Walmart and replace the battery, this was a fairly easy process and didn't upload a picture of that. They had almost the same battery, a 12 Volt RV/Marine Deep Cycle battery. Almost even the same CCA (Cold Cranking Amps).
After a new battery it still didn't fix the issue, so spent night in the general area and continue trip to Pecos, then to San Marcos, Austin, and back to San Marcos, TX. In the meantime fried another battery and just replaced it.
There's a remote sense terminal on the alternator. What this does is make sure that there's about fourteen (14) volts sent to the battery, so the auto sense wire goes to the battery to measure the voltage. Am assuming this allows the voltage regulator to adjust voltage appropriately. This document describes process of testing, and bypassing, this function.
What I did was take off the wire, check it's serviceability, cleaned it little with WD-40 (not that that cleans things, but what had on hand), and put the wire back on.
|Ground wire on left, power on bottom|
I also asked around at the RV.net forum. There's a thread there where all sorts of great people came together to help me answer my question.
Another person came up with this alternator diagram that shows all the parts which make up the alternator. If the voltage regulator was bad (and think it was in the beginning), looks like it would've been fairly easy to replace that one piece.
Since I ran the alternator so long in it's overcharging state, truly think that this caused the whole alternator to go bad. As can be seen in the thread, the alternator stopped charging totally and was warm to the touch (with engine off all day). So pretty sure that there is a short in there someplace.
Testing "spare" alternator
When I bought the RV it came with a bunch of spare parts, and one of those was a spare alternator. When first noticed it I looked at it and said "really"... turns out it was there for a reason.. Now I hope don't need all the other spare things.
The testing piece was interesting too. Brought it to the local AutoZone, and to their credit, they went above and beyond to get this tested. Took them about an hour to do, in between other things, but they never gave up!
The main problem they had in testing is their testing rig is from a different manufacturer, and so requires the manufacturers part number. Things is, for this alternator, the manufacturer didn't have anything comparable.
After quite some time they found something that worked, though the amp rating was lower (100 amps instead of 160), but they got it to work.
Turns out the alternator is perfectly fine. Spoke with someone from the RV.net forum (owns a repair shop) and he said that sometimes alternators that have sat around for awhile are flaky and might work for a week, month, year, or a lifetime, and there is no rhyme or reason to how long they last, and he wasn't sure why. So for now am living in the lap of luxury!
Lamp/Diode Trio PASSED
Regulator Test PASSED
Rectifier Test PASSED
Rated Amps: 100
Battery volts 14.20 14.44 16.00
Ripple volts 0.00 0.40 2.00
Lamp On volts 0.00 1.97 9.00
Lamp Off volts 11.00 14.52 0.00
Rated Amps: 100
Unsure what the three sets of numbers mean, but this is what it was rated at. Looks OK to me.
Replacement of Alternator
|Engine, under bed|
This part was a little easier than I thought. Went to a Vocational - Technical high school, which allowed us to learn a trade for half of the school year, and took normal high school classes the other half (in three week blocks). As a freshman, we went through one week of each of the nine different shops, and one of them was Diesel shop. Forget what we actually did, but we worked on engines, got greasy and smelly, and it was actually somewhat fun.
|"front" of the engine|
If look closely at what I call the tensioner can see there's a square "hole" in there. This is where something like a breaker bar goes, to lift it up and out of the way. According to the youtube video I watched, believe he said it was 1/2 inch. Turns out that in this instance it was 3/8 inch, so used my ratchet (better to use a breaker bar or something without fine gears). It worked fine, though was a little rough as couldn't really brace it all that much while removing belt from the alternator (another pair of hands would've been great). Just push the ratchet (or breaker bar), it will move the whole thing just enough to remove tension on the belt, then slide belt off of alternator. I found it best to not move it too far off the alternator, basically slide it off and down a little. This is to help avoid having to reroute the whole belt through all the wheels... That would've been not so fun.
Here can see where I start to remove the wires. Hard part here was getting a wrench down there to loosen the bolts, especially for the ground wire. Can see, at top of the picture, the ground wire is removed. Also, mostly removed is the two "live" wires, the ones which carry the "juice". Not sure why there's two, but there is.
Of course, the next part is to actually remove the alternator. At this point, have done the following: Removed serpentine belt, removed the two wires at bottom of the alternator, removed the ground wire, and removed the power wire.
|Top mounting bolt|
Removing alternator is a fairly simple process. With this one, there are two nuts and bolts to remove. A long one on the top, as seen here, and then a smaller one at the bottom, which is just out of the picture. On the top it's a longer one to presumably help with stress of the serpentine belt (only a guess).
|Alternator at the bottom|
|It's out, and made in USA!!!|
|Couldn't get it on|
To correct this tried using breaker bars, wrenches, etc, and none of them seemed to work. Would always lift it up a little, not enough, and then go back down. Suddenly had a spark of consciousness.. Used an allen wrench that I had, a bigger one, that slid into the hole and was able to move it around enough to allow the bolt to slide in. This picture, only for illustrative purposes, shows the allen wrench on one side, bolt on the other.
|Bolt on left, allen wrench on right|
It was then a simple matter matter of tightening up the bolts, lifting up the tensioner and sliding the belt on (make sure it's FULLY seated, another important thing). Double check everything again and then fire up the engine.
Engine running, have only done for a minute so far. The voltage meter showed right around 13.5 - 14.0 volts, which is right where it should be. Revved engine a little and no problems. Will be updating this as appropriate.
Alternatives to fixing
While this would have to be fixed for the long run, the owner of repair shop mentioned something and thought worth noting here, as never know if it'll help someone.
RV's have two sets of batteries, a pair for the house to provide electricity to lights, fans, refrigerator, etc., and one for the starter engine. These are typically seperated and the house (lights, fans) battery is not charged when engine is running. The reverse is also true in that if plugged into the power grid (120V), the engine batteries are not charged.
So, what could have done, is started the generator. This would have the effect of charging the house batteries (as well as providing 120V power). Since the house batteries are charging, could run a wire (jumper wires in a pinch) between the house batteries and the engine batteries. This would keep the engine battery charged.
Couple caveats can think of is that this would use more fuel (engine and generator). It could also wear down the house batteries a little (in terms of longevity) as they're meant to draw down slow. If have headlights on this would tend to draw battery down faster.
However, it would get me down the road with minimum of fuss. The repair shop owner said someone went 500+ miles like this, just enough to get where he was going before getting it properly fixed.
If I was to do this with my overcharging problem, think it would have been best if removed the positive battery from the alternator, and wrapping the end in electrical tape, then hooking up the jumper cables to the two batteries and go down the road.
This would only be a last ditch effort and not something want to do as a common practice.