Tachometer not Reading While Charging

[Wainui]

I have a Motorola 105 amp internally regulated alternator on my 4108 Perkins charging 4 x 6 volt golf cart batts. I have 2 problems:

1, When the batts are down about 60 amp hours and the alternator is charging at about 30 amps the Tachometer does not register above 800 rpm until the batteries have been charged for about 20 mins.

2, If the batteries are down about 120 amps and the alternator is charging at around 65/70 amps, the belt will slip unless I increase speed very slowly and let the Batteries charge a little. The belt is not loose and I do not want to over tighten and stress the water pump bearings.

Would a externall regulator fix these problems?

Many thanks
Mark

[donradcliffe]

Your alternator-based tach is telling you your belt is slipping at 30 amps--and its probably screeching at 65 amps. Time for a newer and tighter belt.

All belts are not created equal. Buy a good belt like a Gates Tri-power or Dayco Topco. If the tension is correct, you should be able to to twist the belt 90 degrees halfway between the pulleys with your fingers.

If you are still having trouble with slippage, you can go to a larger diameter alternator pully--It should be at least 2.6 inches in diameter, and for 100 amps it should be sized for a half-inch wide belt.

[Wainui]

I did manage to get the belt tightened a little bit more and that seems to have cured the problem. I tried it at 85 amps and the tach and the belt was working fine. It was not loose but I did get a bit more tension.
Many thanks
Mark

[bill good]

I saw a spray can to prevent belt slip. Might help. Fixed my problem by not trying to charge a 400a bank from 30 alternator designed to charge much smaller batteries!! You may need to look at the pulley/belt size for what you are asking them to do.
Bill

[speciald@ocens.]

NAPA sells "Belt Conditioner" which might help as well.

[perchance]

Belt sprays are at best a stop gap measure. Check your pulley for wear and that you are using a belt of the proper width. A worn pulley or too narrow a belt will cause the belt to drive off the bottom surface instead of the sides.