How do you see if alternator is charging?

I have a 1996 Johnson 225 HP 2 stroke Outboard, Is there a easy way to check and see if the alternator is working Thanks Bill

 

Alternators charge at a higher voltage than your battery will store.
Put a voltmeter across your battery terminals while your motor is running and if it is a 12V charging circuit it should read between 13.6---> to 14.6 volts.
Below 13.6 volts, I would recheck with a known good battery and if the same would look at rebuilding the alternator.
What other symptoms does your electrics exhibit? Just flattening batteries?

 

Thanks for the reply. I think its working but today while running the live well the low battery alarm came on the gps. I know the alt gauge works and it was showing around 12 volts, and when I was under way it didn't seem to go up, but never above 12 1/2? I am going to make sure all of the terminals are clean as they are both brand new batteries.

 

Did the GPS low voltage alarm go off while the motor was running?
If so, either the alternator is sad or you have a fault.

"Two batteries" I guess in parallel? Or do you have a dual 24v/12v
for different loads?

If neither the GPS or the live well are new devices and there is nothing else new on that circuit to create a volt drop, there could be a med. resistance fault somewhere creating the volt drop.
The GPS voltage monitor could be affected also by a "spike" from high current draw from starting an electric motor.( e.g. the live bait recirculator) Especially
if the pump bearings are sticky.
It may pay also to check the alarm trigger voltage setting in the GPS's settings menu.
A few things to consider.

 

Okay thanks again for the help, yes the batteries are in parallel. Nothing is new as far as the gps or pumps. The alarm went off while I had been fishing for quite a while. The motor was off but the GPS was on. Then when I did start up to leave I noticed the gauge was down around 12 and didn't seem to go up as I made the seven mile run back home. This happen one other time and as I recall I cleaned up the battery terminals and then at one point I noticed that it was charging on the gauge above 14. I took off the leads and cleaned them while fishing (fast) and it didn't seem to help so I thought maybe there was something wrong with the charging system. Thanks Bill

 

Okay I worked on it this morning. I cleaned all the terminals etc. Then I started it up the volt meter was still reading around 12 volts, however when I started the engine I could tell that it was charging but not a lot. I then checked the battery switch and discovered that there was a white resister or fuse ???? All it did was go from the positive to the negative inside the switch and had a small fuse or resister (white) in line. One of these wires had corroded off was broke. Not sure if this could be the cause it doesn't seem like it would but I will be replacing that as soon as I can find one.

 

Thanks Roly for all your input, got it working apparently the terminals where just dirty even though they didnt look it because I took them all off both batteries put it back and went out and now the gauge was showing it charging above 14 volts. By the way that fuse or whatever I was talking about turned out to be a small light (Ha-ha) Thanks again tight lines and safe boating.....

 

Good! Always pays to do the basics first. Something I am guilty of not doing
if I suspect something else.
I have cleaned terminals thoroughly and still had the volt drop, only to find a high resistance junction buried in a lug. (crimp). A megger can be helpful.(careful tho' of electronics)