Armadillo - that could be my problem as well. I'll have to see what size my cranking batt is.

Kris - my engne is a 150hp Johnson OceanRunner

Have you tested (and cleaned) both the positive and ground cables, at the battery AND at the engine connection, and any intermediate connectors? A battery can show good voltage on a meter but then fail under a cranking load if there is corrosion on a terminal. These can fade in and out when not under heavy load, hence your FF coming back to life.

Well, it has happened again. After charging with onboard charger overnight, I took the boat out and everything worked fine (last weekend). I took it out today and everything worked fine. When I got home and went to go adjust the trim to reseat the trim saver bar, the cranking battery was dead. I put the volt meter on it and was only getting about 3.2.

To make matters worse, when I plugged the onboard charger in (Bass Pro xps), the Power light flashes rapidly and nothing is charging.

I'm ready to take this thing in and have it checked by a professional. Any recommendations for a good marine mechanic in the Grapevine/Colleyville area??

bp try this first, unhook just your engine and connect it to one of your trolling batteries, start and run the engine on the muffs then shut it off.

charge your normal start battery overnight on a manual charger, the one you use for your car/truck.
you will have to hit it with a high amp shot for a few mins to get the charger to recognize it and charge, below about 6 volts and most chargers will not even know it is there.

in the morning after it is charged unhook the charger check voltage (make sure your acc are all still attached and nuts are tight), leave it alone for the day. that night check voltage again and see if there is a difference, this will tell ya if one of your acc is running that you may not know about.

if it still shows full voltage then it is time to take it in

I charged it using a normal charger and was getting 13+ volts. So, I put it back in the boat and the onboard charger is now working. I'm letting the battery charge overnight. Then I'm going to check the voltage before starting and while the engine is running to see if it jumps up like it should.

But, I had another thought. I cleaned all of the connections today to make sure there wasn't any corrosion. When I reconnected all of the hook-ups (started with the main cranking cable) I got some sparking when I attached one of the positive cables (not sure what it went to or which Acc it was). And, i heard a small motor turn on and run for about 3 seconds. I'm wondering if I have a short in one of those lines. Because it shouldn't spark and nothing should run if none of the Acc are turned on. Correct???

BP,

After reading this thread and how you describe your problem it really sounds to me as though you have a load being drawn from your battery.

Assuming your battery has been properly load tested, then it most likely has close to the rated capacity. And after you charge the battery you are getting at least 12-13 volts after you take the battery of the charger and it will crank your motor at that point. The batteries capacity is probably not vanishing into thin air. But after being off of the charger for X amount of time the voltage reads <12 volts something must be drawing power.

So, If you have an Ammeter (Voltage Meter with an AMPS setting of at least 10 Amps) you should be able to isolate the amp draw by leaving everything in an off position (just don't try to start the motor or raise the trim as these take more than 10 amps) and taking a reading between the positive battery terminal and the positive battery cables. A reading of greater than .5 amp and you likely have found your problem.

This Meter Is similar to the one that I use and is relatively inexpensive.

yep if you have spark you have something running, not shorted unless the sparks are big, the small spark is an acc drawing on it. motor tells me you have a pump running and this will run down a battery overnight easy.

try taking out one fuse at a time (pump fuses) and touching the power wire to the battery again, find the one that does not spark and you have isolated your problem.

put fuses back when they test good (no spark).

Nic and Hopalong - I really appreciate the advice.

So, here is where I am this morning - The onboard charger ran overnight and the batteries are now full. Cranking batt is measuring 13.41 both with the charger on and off. I've unplugged the charger and will check the batt again in several hours to see if the voltage has dropped.

This afternoon, I'm going to run the engine on the muffs and check voltage before and after starting just to make sure my engine isn't causing this issue. Then, I'll go back to figuring out which one of those positive wires was sparking and causing that motor to temporarily run. I hate to admit it, but if I knew how to make my volt meter check current, I would. Here is a pic of the one I have. Can I use it to check current?

BP, Your Meter Apears To Only Be Able To Measure Amperage Up To 200 Milliamps. Do Not Try To UseIt As I Described Or You Will Most Likely Damage It or Blow The Internal Fuse.

I Wish You Were Closer, I Would Love To Help You With This In Person.

Good Idea To Check The Voltage With Engine Running. With Your Meter On It The Voltage Should Remain Steady With Engine Running And All Accesories On At about 12.6-12.8 Volts. If It Continues To Dtop With Engine Running, Your Alternator Is Likely The Culprit.

As Far As The Voltage Draw Goes I Would Highly Reccomend Using A Voltmeter With An Amp Rating Of At Least 10 Amps.The Spark Method That Was Mentioned Is Posible. HoweverEach Time You Do That The Pump Will Run And Shut Off And If That Is Not The Problem It May Make It Harder To Find The True Problem. And Arcing/Smoking Around Discharged Battery Can Be Very Dangerous!


Sorry for all Of The Capital Letters My Phone Does That On Here And It Is Annoying...

bp go to lowes and get this kit, also really handy around the house.

the meter is one of the best for those of us that ding around our boats.

http://www.lowes.com/pd_205783-72068-TK-30_0__?productId=1058561

The meter he has does everything that the greenlee one there will do. The greenlee only measures amps in milliamperes, so there would be no advantage over his current multimeter.

your right nic, didn't look at mine first, it has 3 amp readings but none that will go high enough.

Yessir,

I looked that meter up to see after you posted that. I use a multimeter all of the time in my business, and they are invaluable when used correctly.

Well after talking with 2 different Johnson marine mechanics today, we think we may have the problem identified!

Both mechanics said that my voltage regulator/rectifier is likely the problem. The fact that my Tach on the instrument panel is the only gauge that is not working is what sold both of them on this component.

I looked at the engine tonight and it looks like a fairly easy part to replace - 1 quik-connect cable, a couple of loose cables and a ground wire. But its a $200 gamble....

Any thoughts on this????

Nic - thanks a ton for your help this weekend!!!