Early Motorola two wire alternator

Post by **waybomb** » July 29th, 2017, 6:59 pm

Anybody have any idea what the ignition wire is for on an alternator found on a 1987 mariner with crusader engines.
Only getting 13 volts output to batteries.
This is a Motorola 50 amp.
It appears to have a mounted external regulator on the back.

I'd like to see if I can fix it.

How do I test the alternators output, unregulated?

bud37 · Post by **bud37** » July 29th, 2017, 7:38 pm

If memory serves me I think that can be used to excite the field.........thats what comes to mind , been a while......need 1500 rpm,should see 14.5 volts at that.....at idle you may just see battery voltage.......... :beergood:

Post by **waybomb** » July 29th, 2017, 7:54 pm

That's what I thought it was for but not sure.
Only have 13vdc at all rpms.
Barely keeping it charged.

mjk1040 · Post by **mjk1040** » July 30th, 2017, 6:43 pm

Sounds like it needs to be pulled and replaced or rebuilt.

Post by **Viper** » July 31st, 2017, 7:08 am

Are you sure it's a regulator or is it a brush cover you're looking at?

Post by **waybomb** » July 31st, 2017, 10:26 am

Yes it's a regulator.
Motorola/prestolite 8mr2022k bi-directional alternator.
New number 8mr2048ka.
Sent a note to db electric for a price on a new one.

Early Motorola two wire alternator

Early Motorola two wire alternator

Re: Early Motorola two wire alternator

Re: Early Motorola two wire alternator

Re: Early Motorola two wire alternator

Re: Early Motorola two wire alternator

Re: Early Motorola two wire alternator