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battery not charging

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Sandman26

Contributing Member
followed the instructions on troubleshooting ,the stator tests good 0.16 ohms and the voltage reg. looks a little burned up ;no way to test it.could i assume this is the problem ? Engine is a 2 stroke 4 cyl. 100 hp. Merc. Mariner.
 
one batt. is 2 wks. old the other is almost 3 yrs. old.the bilge pump was comin on too much and really weakened the old batt.I now take the fuse out at the end of the day.after buying a new batt.the switch makes it come on but then it comes on anyway once in awhile.like I said I take the fuse out at night and I'm guaranteed a strong batt. in the morn.
 
Take a reading with a volt meter at the batteries WITHOUT the motor running. You normally get between 12.0 - 12.8 volts depending on the condition of the battery.

Start the engine (on a flusher or in a tank if on land, of course) and take another reading.

If it's below 13.5 volts, replace your rectifier/regulator.
 
I have a related question.... my fish finder has a voltage readout. While fishing my battery voltage says 12.55 volts, I stated the motor probably 20+ times yesterday while on a 10 hour fishing trip. I noticed that the battery voltage would creap up to 12.66 volts while the motor was running and then would settle back to the 12.55 again while at rest. Obvioulsy it is charging or I probably would have killed my battery yesterday. I plan to put the charger on my batteries today and see how long it takes to top them off.

Do you think that my fish finder hould have shown 13V or more while running?
 
The charging system on outboards can work in one of a few different ways, but the power going to the assessories will always remain in a (regulated) range (usually not exceeding 12.8 volts).

The charge portion of the stator on most outboards produces AC that varies between 12 and 16'ish volts. The power is fed to either a regulator or rectifier. Most "regulators" will convert the power to DC and keep in a range generally not exceeding about 14 volts (mid 13's is common) and sends it to the battery. A "rectifier" simply converts the AC to DC and feeds that on to the battery, so you can get voltages as high as about 16 volts.

The "battery" acts as the capacitor in the outboard power system. So while it will be accepting between 13.5 and maybe 16 volts, it is still only going to puke out voltages into the high 12 volt range.

That's why it's important, particularly with "rectified" systems, that you use a "Marine" battery (or a tractor battery). They are designed to handle the unregulated power without doing damage to the battery, and ultimately, anything that is being powered by that battery.

If you have a regulated system and you hooked your fishfinder directly to the leads (without a battery in place) you would see voltages above 13. However, you could cause damage to the system because the power being produced must go to a battery (or it will feed back and fry components). Starting a rectifier system motor without a battery connected will immediately kill the rectifier.

Clear as mud? :)
 
I know that I have a 1" square rectifier on the side of my motor. I do have a "marine" starting battery and my accessories run directly off of additional terminals right on the battery post.

Clear as mud.....LOL With the termonals removed, the voltage will be higher. In order to charge the battery, the voltage need only to be higher than that of the battery. The battery will act as a load on the charging system and therefore the voltage read on my screen will remain lower than the advertised "charging" voltage. The 13+ volts would only be VOC .... voltage open circuit. By the fact that my voltage reads higher after the motor ran should be an indication of a charging system that is working.

I only ask these question sice I, like an idiot, connected the wires on the battery backwards for a mere 2 seconds and got a spark. I looked at my regulator and the potting in the center has a small crack. The potting is some sort of rubber or silicone that could have just dried out over the last 33 years, or could have been comprimised to let the smoke out. As we all know all electrical/electronics work on smoke, if you let it out, it quits working...LOL
 
ok.,I did take a reading with a voltmeter at the batts.and it was within 12.0-12.8 then and only when i went fwrd. did the voltmetr and instrument panel voltmetr rise up to 13.5 somethings not right on the way back in from the ocean instrument panel voltmeter was in the white ,never getting to the "green charging" zone.but with a voltmeter on the battery being used it read 13.5 volts. by the way ,I installed the new voltage reg. yesterday. i think maybe i have an intermittent problem ?
 
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