Boat Electrical Problems. Low Voltage.

[La Buena Vida]

Thanks for any help with my boats electrical problems.

Boat 07' Key West Bay Reef w/ Yammy F150. No prior electrical issues.
Perko Switch.


Issue: I had been driving at planning speed when I hit the motors trim button briefly and the motor stumbled and almost died. I tried it again and the motor stumbled again. Throughout the day I learned that my Battery Meter on the dash said that my batteries were around 13.4V's most of the day and the motor/trim ran fine. Strangely sometimes the meter would say that my batteries were around the low 12V's and if I pushed the trim at this time, the motor would stumble or even die. The meter would read both 13.4 and low 12's off and on throughout the day. At one point I stopped the motor to fish and it would not start. The meter showed the battery at 12V and would go down to 9V or so under the load of the starter. Because of the fact that the meter would show the battery go from the mid 13's to the low 12's while running, back and forth made me rule out bad batteries. I have in fact replaced the engines batteries and the problem still exists, so bad batteries can be ruled out. Just now checking the boat while I hit the motors tilt switch, it hardly moves. It goes so slooow and makes a sad sound. Ok so where do I start. Seems like a bad connection somewhere. I have a voltmeter and I want to figure this out.

Other little facts about the set up. These batteries are used on the motor and all (?) electronics. There's a separate set for the Trolling Motor.

There's a Perko Switch and a fuse (?) see pic.

Thanks, Jared

 

[NYBo]

Re: Boat Electrical Problems. Low Voltage.

Welcome to iboats!

Sounds like a bad connection to me also. The wingnuts on the batteries can be problematic, especially when there are multiple connectors attached to the post. They can work loose easily. Remove all the cables from the battery terminals (one at a time so you don't mix up the wiring!) and clean up the connectors with emery cloth. Even connectors that look clean can have a thin coating of corrosion. Then replace the wingnut with a stainless steel locknut.

 

[wire2]

Re: Boat Electrical Problems. Low Voltage.

A resistive connection will generate heat. Next time you see those symptoms, stop the boat, feel the connections at the batteries & alternator.

 

[La Buena Vida]

Re: Boat Electrical Problems. Low Voltage.

NYBo, I have removed the wingnuts and cleaned the connectors...maybe too well (200grit sandpaper!). Anyway I'm confident that the problem lies elsewhere. Bad connection likely but I don't believe it's at the battery.

Wire2. The motor will not start any longer as the bad connection is no longer intermittent.

If I go checking wires looking for a bad connection, anyone have a "best" place to start. Can someone explain the basics of the engine to battery relationship. I know the engine charges the battery but also pulls electricity from the battery when running. Does/can it do this through the same set of wires? Can a voltage go both ways through the wire at once. Does this even matter? Maybe I ought to just go looking for a bad connection and not worry about how the whole thing works.

thanks for your replies.

jared

 

[wire2]

Re: Boat Electrical Problems. Low Voltage.

....

Wire2. The motor will not start any longer as the bad connection is no longer intermittent. ...

...[/QUOTE]

That's a good thing. Now you can put a voltmeter on the + battery post, the other on the starter stud, key to crank and watch the meter. If you see 1 volt or more, there's resistance somewhere in the + line. If it shows only a small fraction of a volt, do the same with the neg cable. Voltmeter to batt post, other lead to block. Since it won't start, you'll probably see 6 volts or more across connections that should be near zero. (assuming your battery has 12+ volts)

.... I know the engine charges the battery but also pulls electricity from the battery when running. Does/can it do this through the same set of wires? Can a voltage go both ways through the wire at once. Does this even matter? ...

Electricity flows in conductors like water in a pipe. It goes from greater pressure to lesser pressure, not both ways at once. When the engine runs, the alternator makes enough power to run the electrics and charge the battery at the same time, so there's some flow to each.

 

[Silvertip]

Re: Boat Electrical Problems. Low Voltage.

All electrical circuits have more than one connection. In the case of battery to engine connections, both the positive and negative battery cables have connections at both ends. Checking/cleaning one end looks at only half the potential problem. The engine end of the cables must be checked also. Ground cables are just as much to blame for electrical issues as the positive. If you have a dual battery switch all terminations on all of the large cables need to be checked at all points between the batteries and the engine.

 

[La Buena Vida]

Re: Boat Electrical Problems. Low Voltage.

Thanks for the info. I'm excited to try these things out tonight. I'll report on my findings.

Jared

 

[La Buena Vida]

Re: Boat Electrical Problems. Low Voltage.

Ok just had about 15 min to look things over and sadly my problem became intermittent again. I checked the voltage on the engine and it showed 12.6. Hmm tried cranking engine for a sec and it seemed fine. (i didn't really want to start it because it's out of the water).

I then started digging around in the battery box and noticed what I think is a thermal fuse (looked it up). It has at least one severely corroded terminal. I think this might be the problem and even if it's not, I should replace the nut on it.

thanks again for all the advice.

 

[NYBo]

Re: Boat Electrical Problems. Low Voltage.

That could certainly be the problem!

 

[fish_on_the_deck]

Re: Boat Electrical Problems. Low Voltage.

It has at least one severely corroded terminal. I think this might be the problem and even if it's not, I should replace the nut on it.

I dont think thats your problem, as that breaker is not feeding your engine right? that must be to your console for your house loads. The cable seem way too small, plus thats only a 30A breaker... that F150 pulls way more than that while starting I believe.

I dont think thats your problem (with engine starting anyway... I'd clean and replace nut anyway).

If I was a betting man, I'd say you've got a severly corroded terminal (similar to the breaker), but its behind that damn Perko switch! Those things have hidden terminals back there, and I've seen a couple that were just covered in rust and corrosion.

Take that switch off and inspect and let us know! If I'm wrong there, try measuring the resistance from batt to starter and see if you can narrow it down to + or - side.

 

[Boatist]

Re: Boat Electrical Problems. Low Voltage.

What you have done is very good but I question if you even have a problem.
Both your batteries could be fully discharged and to charge both with your motor would take at least 12 hour running above 1000 RPMS,

I would start by charging both batteries with a good automatic or smart charger of 10 amps or more until it shuts off or tapers to 0 amps.

Then with you perko switch off I would measure and record the voltage on each battery.
At that point I would switch to the battery with the highest voltage and with water to the engine would start up and run at 1000 RPMS
I would again measure and record the voltage on the battery. It should be 13.8 to 14.8 volts with out any heavy load.
Now slow to idle and run you trim or other heavy load items. Shut down and switch to the other battery.

Note on you switch it says do not turn off with the engine running. If turn off with the engine running can blow your charging system or alternator.

Do the same test with the other battery.
Last turn the motor off and the switch off and every thing on the boat off.
Let it sit with no load on the batteries and check again at the end of the day or next day.

If you do not have a good automatic charger then still select the battery with the highest voltage and start with water and run 1000 RPMS.
Connect the meter and look for at least 13.8 volts. If lower then it should at least be charging and the voltage climbing

 

[La Buena Vida]

Re: Boat Electrical Problems. Low Voltage.

Worked on (but didn't fix) the problem yesterday.
"fish_on_the_deck" you are right about that circuit. Further exploring found that it went to the electronics. I replaced it anyway as the nut fell apart as I tried to remove it. I pulled off the Perko and everything was really clean and tight. I cleaned it all and re tightened anyway.

"Boatist" My batteries are ok. They test around 12.48 and 12.50 individually. The voltage tests at 12.5 on the engine studs when the Perko is set to ALL and about the same at "1" and "2". The motor is now not starting with the 12.5V. The starter clicks, the voltage drops but the motor doesn't turn over.

I'm starting to wonder if there's a problem somewhere in the engine itself...something to do with the starter or alternator? I really have no idea as I'm even less knowledgeable about a complicated engine like this.

Two clues that are bugging me.
1. It won't start with 12.5v at the motor. (Starter problem?)

2. When it would run, the battery power would drop and when it was at this "dropped" state, running the Tilt/Trim would kill the motor. (alternator problem?)

Any correlation between the two?

Thanks again for any help. I believe the engine is still under (extended) warranty so I'll likely take it in but I would have rather fixed it with the help of the you guys and learned a lesson for the inevitable "next time".

jared

 

[Silvertip]

Re: Boat Electrical Problems. Low Voltage.

While you may be measuring 12 volts static (no load) take those measurements while actually trying to start the engine. Bet it drops like a rock. If so, you do not have good batteries. Have them load tested for free at most auto stores.

 

[Denniskorch]

La Buena Vida

I have EXACTLY the same problem/set of symptoms as you had in this old thread, on my 2008 Yamaha f225.

I would be so grateful if you could let me know what the problem turned out to be and how it was resolved.
If anyone else has insight into this issue, I welcome your input.

thanks in advance for all the great information and helpful people on this site.
Dennis