At mile marker 529 I approach Watts Bar Lock & Dam and the cooling towers of the nearby nuclear power plant loom on the port shoreline. The lock has the same size chamber and configuration as Chickamauga and the lift here is normally about 59'. I again have to wait for the chamber to be lowered before I enter. No problem though. These 15 to 20 minute delays are much better than the 2 to 3 hours I often encountered on the lower Tennessee. (For size reference note semi truck on bridge over lock)
While waiting for the gates to open I am sitting with the engine idling I decide to mess with the battery. On all my river trips in the back of my mind there has always been one small gnawing concern. At night I run the lights in the cabin and berth, sometimes a 12v fan and always the anchor light. I know these don't pull many amps but still I am concerned about getting up in the morning and finding I have a dead battery. The Honda has provisions to pull start it but I honestly have my doubts about trying to start a cold engine this way.
Because of this I installed a device called "PriorityStart". The idea is if a load pulls the battery down to 11.9v it will cut off the load and save enough battery power for the starter. Shortly after installing it I noted that if Therapy sat for more than a week without running the device would be activated. Was the battery getting weak or did I have a drain? This question arose right before I left so I decided to take an extra battery along. When I built Therapy I had installed a battery switch so I just plugged the extra one in and left the switch to the main figuring if I needed the other one I would just throw the switch.
So now I am waiting for the lock with the engine idling and for some reason I decide to unplug the extra battery and move it forward. Just as I do the gates open and I idle in, tie up and shut down. While waiting I look up and notice both the depth sounder and GPS are shut off. Strange - that shouldn't have happen. I press the buttons and neither will respond. I hit the engine switch and nothing. Suddenly I get a sick feeling and realize what I have done!
I "thought" I had the battery switch on the main but all the time it was on the spare. When I pulled the plug on the spare I then in effect had NO battery in the system. This is bad news! I have read the running the engine without a battery connected can have dire effects on the charging system and possibly any electronics connected. Great!!!
I go back and reach under the splashwell and throw the switch. First I try the key switch and all the instruments come to life (part of them are digital and more subject to surge damage). That's good! I them try the sounder and it comes on as usual. Next I switch on the mapping GPS and it too seems OK. But just about five miles before the lock I drug out my old Eagle Explorer GPS and had it plugged in. I was just playing around wanting to see how closely the two performed. I tried it and it was dead! Nothing I did would revive it. I didn't make me happy but things could have been worse - as I was about to find out.
The gates opened to let me out and I started the engine with no problem. I idled out and everything seemed just fine so I advanced the throttle and continued making my way upstream. Exiting the lock places me on Watts Bar Lake which is a little larger Chickamauga with about the same amount of shoreline.
As I cruise along I scan the gauges and all look fine except the voltmeter. It is reading about 13 volts. This is not normal. Usually at cruise speed it always shows almost 16 volts (this is an analog gauge so it is hard to get a precise reading). This could be bad! Have I blown out the charging system and am now running on battery power alone?
I pull back the throttle to idle and the voltage drops to a little over 12 volts. This tells me that the engine is outputting "some" voltage but is it damaged and not working full output? I decide to shutdown and switch to the other battery and see what I have. I hook it up and turn on the key. It indicates about 14 volts. Starting the engine and bringing it up to about 5000 rpm shows the roughly the 16 volts I normally see. But as I think about it this really doesn't help. This is the battery I was running in the system before I screwed up and it would be fully charged. So its readings should be higher. The system again showed a voltage increase at rpm but still I wonder if it is it putting out the full amount needed to charge the battery? Plus how accurate is the gauge? Both 14 volts at rest and 16 volts running sound a little high to me so is that the true reading?
So now what do I do? With the two batteries onboard I feel confident I can get back to Chattanooga running on just them if need be. If I turn off everything else the outboard won't draw much power. But I hate to turn around and head back and later find out I don't have a problem. Yet, if I continue on I am moving even farther from the trailer if there is a problem.
Well here I go again! I was hoping my reoccurring "first day out glaring problem" scenario had passed but obviously it is still enjoying watching me squirm a little. After some thought I decide to take may chance and continue on using the main battery. I will watch the voltage gauge and if after a half hour I see no improvement I will reverse course and head for the trailer.
Between the 536 and 566 mm there are three cutoffs that can shorten the trip by about 8 miles. I was busy watching the voltage meter and taking in the scenery when I realized I had past the first one. I decided to watch the chart closer and did catch the next two. There are a good number of marinas on Watts Bar but many of off channel and not readily visible from the main lake.
A half hour seems to pass very slowly mostly because every 15 seconds I am looking at the gauge hoping to see the needle creep up a bit. At the end of the 30 minutes it appears it has indeed moved upward a little - not much but maybe just a bit. I decide to press on but make the decision I am going to buy one of the inexpensive digital voltmeters that plug into the cigarette lighter and throw it into my box of stuff I take along on the long trips. This would have given me a much clearer picture of what the charging system was doing.
Feeling slightly better about the situation I start to enjoy more of the view offered by the lake. It seems to have an unlimited supply coves and islands. The wind had died down somewhat so the ride is quite comfortable. I convince myself not to look at the gauge for a while - you know - the old "a watched pot never boils" thing. I allow the sound of the water sizzling off the chines and watching the Great Blue Herons working the shorelines in search of today's catch to occupy my mind. I just needed to enjoy the morning on the water and let things work their way out. They usualy do........
Finally, about 10 or 15 minutes later I do decide to take a look. The river gods have decided once again that I have passed their little test and will allow my continued passage. The meter read 16 volts...........
So I guess this is normal operation for the charging system. I am surprised in the 400 hours I have run the boat I never managed to notice it before. But perhaps I have never really had the battery low enough to yield these readings. At any rate everything now looks fine and I can lean back and relax again. But you know, it is interesting how much location has to do with the severity of a problem. If I were running local I probably would not have given the low reading much thought. Just watched it but not really worried about it. But when you find yourself 500 miles away from home and miles from the trailer even small glitches seem to be magnified about 10 times