Alternator, Battery, What in the world is going on here?

[GraAlaMat77]

So I take my Ranger out this morning. Yamaha 200 Pro V on the back. I havent charged that battery in a while for the cranking battery because I figured the alternator was taking care of it. Well she starts up perfectly this morning and I fish for four hours with no problems. Then all of a sudden after a stop, she wont crank up, It was like I didnt have enough power to turn the fly wheel. Dead. So i troll back to the ramp and head back to the lakehouse. Me and my granddad check the water levels in the batteries, real low. I had not checked them previously since I just got the boat last month. After that we charge the battery for a whie. We then go down to the ramp and back the boat in and place a multimeter on the positive and negative terminals while the motor is running but the meter does not go up in voltage, which I would assume shows that the alternator is working. So we then charged it for a while and then backed it in again and cranked it up. This time we disconnected the positive terminal while it was running - It did not quit running. I'm not quite sure whats going on here, any suggestions?

 

[xtraham]

Re: Alternator, Battery, What in the world is going on here?

could be a bad battery, make sure all cables are like new clean, both ends, get rid of wing nuts on the battery if you have them and replace with stainless nuts and lock washers, check battery volts with the engine off then with it running it should increase...
I no nothing about yam,s but it's a no no to disconnect the battery on most outboards with the engine running..

Tom

 

[Paul Moir]

Re: Alternator, Battery, What in the world is going on here?

The ignition system on an outboard, unlike a car, is not dependant on the battery.

But if you disconnect an outboard from a battery while it's running, it'll fry it's rectifier/regulator (part of it's charging system) almost immediately. It was probably fried before since you weren't reading a voltage increase, but it's certainly fried now.

It's strongly recommended that you use battery nuts that require the use of a wrench. Since you can't tighten wing nuts down very well, they tend to vibrate loose and cause the rectifier to blow.

It's conceivable that the problem could be a blown fuse on the motor or the stator, which i s another part of the charging system. I don't know your outboard that well and you'll want to do a proper diagnosis before purchasing parts.

 

[GraAlaMat77]

Re: Alternator, Battery, What in the world is going on here?

could it be that the battery was just to low, and the alternator wasnt given enough time to charge it back up?

 

[Boatin Bob]

Re: Alternator, Battery, What in the world is going on here?

Don't think so, the clue was when you had the meter on it and it didn't change when the engine was running, a low battery would cause the alternator to put out a high voltage to charge the battery.

 

[Boatist]

Re: Alternator, Battery, What in the world is going on here?

I do not know your motor but all the I/O I know disconnecting the battery even for a part of a second will blow the output diodes and regulator. When you disconnect the load voltage will go to a very high voltage and blow the output diodes.

Never disconnect the battery with the motor running. That was ok with the old 1950 generators but not with an alternator.

With the motor connected to the battery and the motor running the battery should have between 13.8 and 14.4 volts if the alternator is working.

I think you would get a better responce if you posted in the proper Fourm. Yamaha Outboards

 

[Texasmark]

Re: Alternator, Battery, What in the world is going on here?

If your fluid in the batteries was below the top of the plates, you could have fried your battery.

In this condition, even after filling back up with water, the battery could have put a very high load on the alternator (acted like a short circuit) which may have exceeded it's amperage capacity and hence didn't give you the rise in voltage you normally get when charging.

The only way you can get high voltage (14.5v regulated) out of your alternator is with a good battery at a high level of static charge. Otherwise the load (discharged battery acting like a semi-short circuit) will pull down the voltage until the supply current eases off allowing it to rise. The mechanism causing this is the internal resistance of the alternator which is in series with the battery and drops a certain amount of the available voltage. As the current drops off the voltage drop across it (the internal resistance) decreases allowing more for the battery.

The reverse voltage of rectifiers used in battery charging circuits is usually only 50 volts. The ac output of the alternator, without a load could easily exceed that value and once there it would do as stated.....fry (short out) the diodes in your rectifier/regulator.

Mark

 

[GraAlaMat77]

Re: Alternator, Battery, What in the world is going on here?


went out today after charging the battery tonight, burned about 30 gallons of fuel, multiple stops (30+ crankups), lights, two grraphs, two livewells. At the end of the day the battery had a charge of 12.6 volts. I have an extra cranking battery, so I guess Im gonna just let it go and see how it turns out and do sumthin about it if a persistent problem arises.

 

[Texasmark]

Re: Alternator, Battery, What in the world is going on here?

If you ran/did all that stuff o/with one battery and wound up with 12.6 volts on it, there's nothing wrong with it nor your alternator.

My 2c

Mark

 

[GraAlaMat77]

Re: Alternator, Battery, What in the world is going on here?

i hope not, my granddad thinks the same as you, that the battery was so low that it would not charge because of lack of water and from not being charged so long. I dont know when the previous owner charged it and I havent charged it in the month I've had it, but im gonna watch it very closely

 

[Texasmark]

Re: Alternator, Battery, What in the world is going on here?

However, if that battery has been abused as mentioned with low water and sitting discharged for a long time, don't expect it to last you much longer.

My experience is that they can't take that and survive over the long haul.

Good luck,

Mark

 

[biggy boy]

Re: Alternator, Battery, What in the world is going on here?

I know with my suzuki DT 115 when i put a meter on the battery with the motor idling it does not charge the battery. the motor only puts out enough voltage to charge my battery when it is running at an RPM of over 2500. then it puts out about 13-14 volts.

Glen

 

[j_martin]

Re: Alternator, Battery, What in the world is going on here?

If your battery is using a lot of water, it is being overcharged. Many marine "systems" do not regulate the voltage, relying instead on the battery to limit the voltage. The battery just electrolyzes the water into hydrogen and oxygen with the energy, thus the loss of water. If the system only puts out a few amps, that's OK as long as you keep up on the water.

I'm amazed at how primitive the charging systems are on some very pricey motors.

John

 

[j_martin]

Re: Alternator, Battery, What in the world is going on here?

Just an afterthought, if all your batteries are using water, it might be your shore power charger that's overcharging them.

John