REPAIR: OB Not Charging

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adudinsk
Engineer
Posts: 190
Joined: Tue Aug 27, 2019 12:53 pm
Sailboat: MacGregor 26M

REPAIR: OB Not Charging

Post by adudinsk » Mon Jun 29, 2020 8:14 am

Ok.. not a huge issue, but my boat would be charged up from A/C charger. Took it out. GPS started showing LOW VOLTAGE

How to test charging system
In my Merc (a Yamaha replant) and most other OBs that are not high HP the charging is done with a Stator and a Voltage Regulator.
Stator replacement .. not hard.. but a pain.
Voltage Regulator is only 2 bolts (if you can get at them easy)
Only 1 or the other (or both ) can go bad
Usually NOT the stator


Stator Test
On the Regulator there is a large round connector with 3 connections in it.
Take a Ohm meter, measure EVERY combination of the 3 connectors, they should all be the same, all about 0.6-0.9 OHMS depending on your unit
THen test if shorted to Ground. Put one end of meter to ground.. the other to the 3 pins ONE at a Time.
They should read OL or No connection (not shorted to ground)
If this all is as above.. its the Voltage Regulator


Some motors have a Regulator, some have just a rectifier.. If the stator is good, and your not charging replace the Regulator/Rectifier

You can tell from the photo, my Regulator was clearly blown.
The original one has a Green/White wire for a tach connection and its HARD to find one that has this output even from Mercury (and I was not buying a used unit).

The hardest part was one bolt was hidden behind some plastic covering for the carbs.. would have beena NIGHTMARE to remove.
SOlution: offset brake bleeder wrench (10mm in my case)
The NEW units do not have 2 bolt holes.. but rather one, and a slot.. so you can start the hidden bolt,.. and slide the part in and tighten.

Easy Fix.. cursing about who designed the placement of this part.
(You can see the back is blown off the unit.. it was a 2005 original part (as it had the burnt up tach connection) so it owed me nothing.
Generic part...$75cnd .. time to change 5 min.. plus 1 hr cursing at the hidden bolt..
Works perfect now.

Also if in doubt if your battery is up to snuff , consider an AUTOOL ST-460 meter (about $50 cnd). It will test capacity, charging, starting..etc.. fantastic for the price.. (now everyone at the club has me checking their batteries) It works for 12 and 24v systems. Does not work for lithium Ion batteries only AGM and WET CELL. (doubt if many Macs have LI batteries..)
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Jimmyt
Admiral
Posts: 1156
Joined: Sat Jul 18, 2015 9:52 am
Sailboat: MacGregor 26M
Location: Mobile AL 2013 26M, 60 Etec

Re: REPAIR: OB Not Charging

Post by Jimmyt » Mon Jun 29, 2020 9:05 am

Very informative. Thanks for posting!
Jimmyt
P-Cub-Boo
26M, Etec 60, roller Genoa, roller main
Cruising Waters: Mobile Bay, Western Shore, Fowl River

adudinsk
Engineer
Posts: 190
Joined: Tue Aug 27, 2019 12:53 pm
Sailboat: MacGregor 26M

Re: REPAIR: OB Not Charging

Post by adudinsk » Mon Jun 29, 2020 10:50 am

I have lots of little things to do.. thought posting would be helpful.
Hate going to a mechanic..

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