Alternator on Crusader engines

[juryduty]

Hi folks,
I have a pair of Crusader 220's in my boat, each with the original Motorola alternators. This alternator has a 3-wire connection to an external regulator. The single output wire of the regulator goes to the coil.

Question is, can I simply replace the alternator and regulator with a 1-wire unit with a built-in regulator? I have my eyes set on a Motorola-replacement marine alternator with identical mounting bracket, but I can't find one that has a 3-wire connection. Thanks for any help!

juryduty

[bobconnie]

Just an Idea, but try looking at the larger GM alts. They internaly regulated, and if ya can find ones off of ambulances, or off the diesel pick ups, they are at least 100 amps, and I pick them up all the time for 100 bucks or less that work just fine! any good shade tree mechanic can fix ya a mount. Ive just changed the alt on my 4-71 Detroit, used the ambulance mount and the front pully and went to a flat belt from the same ambulance! took 1 day and no machine work needed !(did take about 20 minutes of welding time) just a thought

[westwinds]

Originally Posted by juryduty

Hi folks,
I have a pair of Crusader 220's in my boat, each with the original Motorola alternators. This alternator has a 3-wire connection to an external regulator. The single output wire of the regulator goes to the coil.

Question is, can I simply replace the alternator and regulator with a 1-wire unit with a built-in regulator? I have my eyes set on a Motorola-replacement marine alternator with identical mounting bracket, but I can't find one that has a 3-wire connection. Thanks for any help!

juryduty

Yes, but you need about a 4 gauge wire from alternator to battery because of the voltage drop to the battery at high current flow. The one wire alternator gets its sense voltage right at the alternator, not the battery.


With two engines, you have enough amps considering both alternators. The amount of current acceptance to charge a battery is about a tenth of the amp-hour rating so unless you have a huge house battery bank or AGM batteries that can take very high charging current, you should be ok with the Motorola.

[Redcoat]

You need to buy marine altenators with gas operation. Its different with diesel but you don't want any enclosed surprises.

[juryduty]

Originally Posted by westwinds

Yes, but you need about a 4 gauge wire from alternator to battery because of the voltage drop to the battery at high current flow. The one wire alternator gets its sense voltage right at the alternator, not the battery.


With two engines, you have enough amps considering both alternators. The amount of current acceptance to charge a battery is about a tenth of the amp-hour rating so unless you have a huge house battery bank or AGM batteries that can take very high charging current, you should be ok with the Motorola.

Problem is, I think the port side alternator is not charging. It was seized up and I had a guy replace the bearing in it, but when I rev the engine I don't get up to 14V, voltage at the battery just stays the same. I do get a ramp up on the starboard side. Maybe I should try replacing the regulator first?

[westwinds]

Originally Posted by juryduty

Problem is, I think the port side alternator is not charging. It was seized up and I had a guy replace the bearing in it, but when I rev the engine I don't get up to 14V, voltage at the battery just stays the same. I do get a ramp up on the starboard side. Maybe I should try replacing the regulator first?

No, do some testing first. Check all of the connections and if still a problem, pull the alternator and have it tested. If it is OK, then replace the regulator.

[donradcliffe]

Take the regulator wire from the alternator and hold it on the +12 volt output terminal when the engine is running. If the voltage ramps up the regulator is not working, if it doesn't, the alternator is not working.