Rectifier: How often to replace?

[DJ_Allatoona]

('86 Mariner 75 hp 4-cyl.)

Few days ago, my battery died during cold starting. No sweat, I had a charged one, threw it in, away I went. Yesterday, THAT battery was weak on starting, and I noticed that the VOLTAGE METER on my Garmin fishfinder was showing the 12v at 11.8 or 11.7 and then back to 12.0, but never above. I shut it down, worked the tilt/trim a bit to test the battery strength, and the battery died.

I think it's the rectifier, I'll put a new one in tomorrow and hope that fixes it. I was just wondering how often rectifiers go bad? I had to replace one in my older inline last year, and that fixed the problem. Also, how well can I trust the volt meter on my fishfinder? Is that more or less accurate?

Thanks for all input.
DJ

 

[Barnacle_Bill]

Re: Rectifier: How often to replace?

A rectifier can last a very long time if you are careful. If you ever create any sparks there is a good chance you blow it. If you every hook the battery up backwards, even for a second, its toast. I would think the readings on your Garmin should be fairly accurate. Check it by comparing the readings at the battery with it.

 

[j_martin]

Re: Rectifier: How often to replace?

The stock mercury rectifier is marginal at best. Sometimes they last a long time. They can't take any abuse at all, ie a loose connection.

Aftermarket replacements are better, or you can buy a 25 amp, 200 volt or better bridge rectifier, cobble it in, and never have another problem with it.

hope it helps
John

 

[JB]

Re: Rectifier: How often to replace?

The rectifier is an electronic part. It never wears out but can be zapped by a number of events.

Change it when it is broke. Not needed any other time.

 

[j_martin]

Re: Rectifier: How often to replace?

The rectifier is an electronic part. It never wears out but can be zapped by a number of events.

Change it when it is broke. Not needed any other time.

Contrary to popular opinion, semiconductors do age. If the design is good and the junctions operate well within their intendended range, they age very slowly, and are usually obsolete by the time they fail. Heat and overload accelerate the ageing. Thus is the case with the Mercury (Mexican) rectifier.

I've been in electronics since before the ck722 germanium transistor. (prox. 1960)

hope it helps
John

 

[DJ_Allatoona]

Re: Rectifier: How often to replace?

Thanks to all who responded...new rectifier tomorrow. I'm thinking (based on replies above) that with all the jerking around with dead/fresh batteries, I may have sparked the rectifier dead. Possible?

Also, from my initial message, what is consensus on the voltage indicator on the FishFinder? Should I trust the readout? On my other boat, often the readout on the fishfinder would be 15v or even higher, like 17v! Any thoughts there? Thanks.

 

[Yepblaze]

Re: Rectifier: How often to replace?

Regulate does not a rectifier do.

Thus, on some motors you will find a reglating rectifier.

Which under some conditions can be retrofitted.

 

[j_martin]

Re: Rectifier: How often to replace?

On some low amperage systems, the battery is the voltage regulator. When they wear out, the voltage will go high.

On the meter in the fish finder. It said your battery was dead. It was dead. How's that for accurate?

hope it helps
John

 

[Yepblaze]

Re: Rectifier: How often to replace?

17-18 volts on an unregulated system is not unusual.







(rapair aftermarket ignitions do not run long on 18 volts, I know)

 

[DJ_Allatoona]

Re: Rectifier: How often to replace?

UPDATE: I replaced the rectifier today (new part: $42) and the volt meter on the fishfinder now reads between 14v-15v while running. That's different. OK, we'll see now how the battery behaves. Stay tuned.