Problem with belt

[marioxp]

I noticed black dust around the belt.  The belt is properly tensioned.  The alternator is new.  The water pump is new.  How can I check if all three pulleys are aligned.

[Yngmar]

Straight edge, string, laser, or special mounts+sticks kit.

But also check for rust on the pulleys, which can eat belts, and if you have an upgraded alternator it can be simply overload.

[marioxp]

what do you mean overload?  the new alternator is 100Ah, the old one was 65Ah.  What are the possible consequences?  Can I just change the belt more often?

[Yngmar]

Yes, probably belt overload then. The belt has a maximum of power it can transmit. A bigger alternator (under load) is drawing more power from the belt, meaning it is harder to turn, causing the belt to slip. So normally, with a bigger alternator you should also fit a bigger/better belt, meaning either a multi-v belt or twin single belts. Either solution requires changing the pulleys, which are super expensive. We had the same problem with our Balmar 100A alternator.

You can replace belts as they get chewed up, but if it's constantly slipping it will get destroyed pretty fast and leave a lot of dust (not great for the alternator). There's industrial belts that perform slightly better (Gates ESC and XZ). With our Balmar regulator it was also possible to reduce the maximum output of the alternator to match what the belt can handle, somewhere around 80% was fine with the improved belts.

[marioxp]

Yngmar, thanks for the help.

I used the old trick, I smeared the belt with honey, now it's better, it will probably need to be repeated.

But when I slow down the gas my battery alarm goes on.  I went to investigate and found that the alternator does not charge below 1000 rpm.  So it's logical for me that the alarm goes off, but it's annoying.  I believe it's nothing dangerous, but is there anything I can do?

I really appreciate your opinion, it was often more accurate than the marine technician.