Saved by small engine mode

[joe_db]

On the way home from Rock Hall the engine started to produce a horrible squealing noise
I quick disconnect of the field wire showed why, it was the alternator belt slipping.
I didn't want to have no charging, so I dove into the Balmar manual and it turns out if you short the alternator temp sensor terminals together the regulator limits the field to 50% power. They call this "small engine mode". It worked a treat to keep the belt from slipping the rest of the way home. I still got about 12 amps charging and the voltage gradually crept up to over 14.
Now to check the belt - I swear it doesn't have 40 hours on it I also like this field limit mode enough to put in a switch for it.

[hanleyclifford]

You didn't say what size Balmar you have. The larger ones ( have a 110 amp) like a dual belt system.

[joe_db]

I have the 65 amp small Balmar.

[hanleyclifford]

I remember reading something by Don Moyer to the effect that 55 amps is about all you can get from the accessory drive arrangement without getting problems like you experienced. You could mitigate the problem by charging at a lower voltage, say 13.7 or so. I wanted to run a big inverter so I changed to a front crankshaft syle dual belt drive. There is a thread here showing some pictures.

[joe_db]

Originally Posted by hanleyclifford

I remember reading something by Don Moyer to the effect that 55 amps is about all you can get from the accessory drive arrangement without getting problems like you experienced. You could mitigate the problem by charging at a lower voltage, say 13.7 or so. I wanted to run a big inverter so I changed to a front crankshaft syle dual belt drive. There is a thread here showing some pictures.

Better is to turn down the max field strength I think from full to maybe 70%. That way I still get to the charge voltage I need eventually. My batteries would die quickly if charged to 13.7 volts.

[hanleyclifford]

Originally Posted by joe_db

Better is to turn down the max field strength I think from full to maybe 70%. That way I still get to the charge voltage I need eventually. My batteries would die quickly if charged to 13.7 volts.

How would you go about turning down the max field strength?

[joe_db]

Originally Posted by hanleyclifford

How would you go about turning down the max field strength?

It is one of the regulator settings. It works in reduction, so 30% reduction would be 70% of max field and so on. I might start with 10% and see if that does it and work my way down.

[joe_db]

The Small Engine Mode:
Additional Regulator Features
Small Engine Mode
In situations where additional power is needed for propulsion, the ARS-5 provides the option to manually
reduce regulator field output by approximately one half. This option, called Small Engine Mode, can be
accessed by creating a direct pathway between the positive and negative Alternator Temperature Sensor
terminals. This can be done by splicing into the positive and negative wires of the Alternator Temperature
Sensor cable (MC-TS-A) with a switched wire. With the switch in the OFF position, the Alternator #1
Temperature Sensor will work normally. With the switch in the ON position, the regulator will reduce field
output by approximately 50%.
To enable the Small Engine Mode:
1. If the Alternator Temperature Sensor cable is being used, replace the female terminal connectors on the
cable with Multi-Stack Connectors (Ancor Part # 230612).
2. Install a standard ON/OFF switch in a location that’s easily reached from the helm.
3. Run wires from the switch back to the positive and negative terminals of the Alternator Temperature Sensor terminals.
4. Add appropriate connectors to the switched wires and connect to the positive and negative terminal connections

[hanleyclifford]

What sort of regulator do you have?

[joe_db]

It is a Balmar ARS-5. It has alternator and battery temperature sensors.
https://balmar.net/product/ars-5/

[joe_db]

I found out why the belt slips, it is wet! The water pump is leaking and spraying water around

[sastanley]

Gosh darnitt, Joe! stupid water pump.