troubleshooting a potential charging issue

Capt Ahab · Jun 6, 2014

Hi Guy's,
Looking for some opionions.
91 225 Yamaha
I was out last Sat and noticed that the first few times I started up to make a move, the fathometer would reset and twice my chart Plotter powered off. Looked at the Voltage guage and noticed that with the ignition off, I was reading 11.5V and when ideling it wasn't any better. At around 3500-4000RPM it did read higher but still just under 12V. I did notice why my electronics had a hemorage. When I cranked the engine, the voltage dropped wayyyy down. The batteries are three years old. I pull them every year and stow them in the garage. I also fully charge them before I put them up and at the begining of each season. I pulled them today and had 10.5V on one and just under 11.5V on the other. My starting point is going to be to put a full charge on both then have a load test done. If bad I'll replace and hope that resolves the problem. My primary question is if my charging system is fully oporational, would the regulator not be putting out something like 13+V? and would I not be seeing that at the Voltage guage?

I appreciate any feedback.

C.A
21 CC Parker
Absecon

DaleH · Jun 6, 2014

I was out last Sat and noticed that the first few times I started up to make a move, the fathometer would reset and twice my chart Plotter powered off.

That is a sure sign of the starting circuit pulling power from wherever it can ...

Looked at the Voltage guage and noticed that with the ignition off, I was reading 11.5V and when ideling it wasn't any better.

You should read over 12VDC and up to 12.6 VDC, if you have a good battery and an accurate analog voltmeter, as 12.6 VDC is the max you will ever see using a DVM on a 12V battery. Given voltage drop for the length of the run and that's why one may read as low as 12V at the helm.

At around 3500-4000RPM it did read higher but still just under 12V.

Once above 2000 RPMs or so the alternator should be kicked in full and you should be reading 13.8 volts from the volt meter on the dash.

I pulled them today and had 10.5V on one and just under 11.5V on the other.

They're dead. Watch that low one, if it sulfated - it can never be recovered.

My primary question is if my charging system is fully oporational, would the regulator not be putting out something like 13+V? and would I not be seeing that at the Voltage guage?

Yes, you should see 13.8 or thereabouts.

1) Check your Battery Connections:
Take off any ‘wing nuts’ if used on the battery and do us all a favor … THROW them overboard! They can loosen up and by doing so can cause starting problems and even blow out and damage OB electrical components like the voltage rectifier or the stator.

2) Check under your flywheel for any 'black goop' dripping down from the stator windings. The flywheel has magnets in it that revolve around the fixed stator (stationary - get it?) creating a high voltage electrical output. This is fed into 2 circuits, 1 powering the plugs and coils to keep her running, while the other gets fed into the voltage rectifier that converts the AC power in useable DC voltage. That circuit is then stabilized to 12-14 volts (RPM dependent) to run accessories.

3) On some Yam motors, the rectifier and regulator is a combination part, where one or the other can go bad. Note - if you ever see voltage pegging over 14-volts then the regulator is shot, but to the high side ... I saw a boat putting out 18+ VDC!

So, with what you stated, either there's a problem in the stator windings or the regulator went south ...

Brent · Jun 6, 2014

m2cw
pull batteries, charge then load test
clean all connections and reinstall
discard wing nuts, replace with hex nuts or nylon lock nuts, add flat and lock washers
On the OB side, clean + and neg cables
and tighten

check resting voltage and write it down
start OB in water, not on muffs or take it for a ride
measuring voltage, write it out. at idle you should 12.1 - 12. 7

As you increase the engine rpms, the voltage should rise. At 1500 or higher rpm, the voltage should read up to about 14.5 VDC. If you have increased the rpms, up to 2000 or higher rpm, and the voltage is lower than 12.5 VDC or higher than 14.8 VDC, the regulator is faulty.

there are other methods to test

Capt Ahab · Jun 7, 2014

Dale,
Thanks for the detailed feedback. Roger all.
Brent,
Thanks also for your feedback.

I'll start with a load test on charged batt's and follow Dales down stream checks from there.
I'll let you know.
V/R
C.A.

jeffnick · Jun 7, 2014

Don't be fooled by the tiny load testers used at some auto parts stores (and Walmart). I was told at three of these places that my battery was good but when tested with a high amp load tester it failed miserably.