Charging System Is It Working Battery of Rectifier/Regulator?

[Knottymate]

The Tach is working. 99 Merc XR6 2 year old starting Battery went dead after briefly visiting several fishing spots having to keep Nav lights on due to fog. Trolling motor on separate batteries. Curious why charging system did not charge battery after running several minutes between spots

Charge battery up but only a few times with volt meter saw variance readings from 12.4 to 14.2. Battery reading just weeks after charger would show discharge. But now, volt meter just stays on 12.2 with no volt variance. Thinking maybe if battery defective will not see voltage variation if battery only reads 12.2

Bought new battery with 12,7 on the get go but, still no variance on meter. Does the new battery need a drain so charging can take place or should I see at least some variation up/down form 12.7 to 14.2 if voltage/regulator system is OK

 

[alldodge]

No, new bat will read above 12.2 an should be at least 12.6

Charge the bat disconnected from the boat. Then let it sit for an hour and check voltage. Then connect to boat and see if it drops, if it does you have a current draw.

My guess is there is a motor charge circuit problem

 

[Knottymate]

Any idea what the labor and parts would be for the Merc XR6 if rectifier/regulator?

 

[alldodge]

If we had a serial number it could be looked up. I'm finding around 200 or so. Have a look here to find the part number, then search the net to see if you can find the best price

http://www.mercruiserparts.com/xr-6

 

[sam am I]

With the tach still working, it COULD imply the rec/reg is okay as it is then receiving a complete AC voltage path from the stator (tach sig is derived internally from the AC sig, that part of the rec/reg must be good), perhaps it a problem at the rec/reg's red power output wires? Those stock bullet connectors are flaky and crap over time (c/t = f).

Check ALL those bullet connections (bet they're all melty black and show evidence of heat) into and out of the rec/reg, if still not charging........

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Same ^^^ part others are selling for 100's, Have been running these exact rec/reg's for 4/5 years now, no probs BUT, cut off the bullets and hard wire them!!

Fusing those output's is a good idea (if none exist) too! I use a re-settable type fuse inline...........If that rec/reg EVER shorts internally to ground (its happened), that output wire that ties directly to the battery can cause "Smoke on the Water"

 

[lmuss53]

I'll do a plus one to the Amazon off brand model of this reg/rectifier. This part goes on a LOT of Merc motors and these aftermarket ones work just fine. I have probably installed 6 or so and none has come back.

This is also a very sensitive charging system on these motors. It is the one system where I will insist on a marine specific battery only, and all wing nuts should be removed and replaced with nylok nuts, A loose wire can and often does result in the loss of the reg/rec in a cloud of smoke and sometimes fire.

These will often not show an increase in output voltage until the RPM's get up in the 1800 range, so bump it up a little with everything tight as described and it should come up to the 14+ range.

If it doesn't the troubleshooting process starts with DVA measurements of the stator output.

I would figure on an hour to troubleshoot this and another hour if it is the reg/rec. 3 to 4 hours if it is the stator.

More than once I have seen a loose nut be the only problem here.

 

[Knottymate]

Thanks to all for great inputs. The motor serial number is OG826606. I had taken the motor up 3000 RPM with no voltage variation. Will change the wing nuts to nylok nuts and steel wool all the connectors. The bullets will all be checked. The motor of course is nearly 19 years old. The connections make a lot sense since I was getting voltage variations intermittently the last few months.

 

[Knottymate]

To Sam Am I and others. Having trouble confirming if new rectifier is needed is the one referenced in the Amazon link
LActrical 815279 the correct one for serial number OG826606? Thanks again

 

[alldodge]

The one in post 5 is not yours from what I'm finding. You need part number 8M0084173 (item 7)
http://www.mercruiserparts.com/bam/subassembly/28698/3998/30

If you search for the part number it does show amazon and others which have it
https://www.amazon.com/Genuine-Mercury-Voltage-Regulator-8M0084173/dp/B00J5QESR6
https://www.ebay.com/itm/Mercury-Ma...Regulator-Kit-8M0084173-883072T-/191204875127

 

[sam am I]

It's all the same part cept the newer one adds the fuse in the output wire. That's why I suggested adding a fuse to the less expensive ones I linked too. If you look at your old one, I'd guess it DOESN'T have the fuse since its a 19 yr old motor

I think after a few rec/reg outputs had shorted to ground internally over the years which literally fried the entire output wire(including the wiring loom it may have ran in) all the way from the reg to the battery (starter solenoid post) , someone took notice and started adding fuses (see "new" below) in the output, thus the new merc numbers. Again, It's just the old part with a fuse....Internally the rec/reg is the same/Identical.


OLD






NEW

 

[lmuss53]

Sam is right on the rectifier. The fuse is actually a very good idea, these guys like to melt down everything and that would stop that process as soon as it starts. I think I'm going to add that fuse from here on out.

Knottymate, you can troubleshoot this yourself if you have just a little electrical know how and a DVA capable meter or a decent VOM meter with a DVA adapter. If you don't know what that is, you should start by reading that portion of the troubleshooting guide provided by CDI electronics at their website. Once you have a decent grasp of DVA readings, look your stator up on the CDI website and click on the PDF file that has the installation instructions. The beginning of that file will have troubleshooting procedures for the stator and rec/reg.

You can also just buy a regulator/rectifier and try it, but that can get real costly, that parts swapping procedure. If that regulator/rectifier is shot you also need to look for those loose connection, bad battery issues I mentioned or you might just burn another one up right away.

 

[Knottymate]

Thanks for all the info, you guys are good. Had to take it to a mechanic as the shift cable or the Merc Quicksilver 3000 control box was getting dangerous as it started hanging up in reverse (could not literally shift it out - stuck) and had to really
ram forward to get the dog clutch engaged vs letting it grind when forward shifting.

Going to let him diagnose the rec/reg/charging system so will let you know what he finds.

 

[Knottymate]

One rectifier was melted on the back side and some of the bullets melted also, Replaced both with a Sierra brand and shop
says now 14 volts which I will confirm in a few days.