Mercury 140 is overcharging

[Adamgoodell1]

My 1979 Merc 140 was overcharging at around 16.4 volt at WOT and 14.5 volts at idol. This must have burned out the rectifier, therefor it was'nt charging enough,(at about 12.2 volts, and ran bad). I replaced the rectifier again and now its back up to 14-16 volts. The stator, trigger, ign. coils, wire harnesses, and other electrics are all new. What could this be?

 

[bdean]

Re: Mercury 140 is overcharging

Just a thought have have you checked the battery with a volt meter. Or are you just going by the gauge?

 

[WillyBWright]

Re: Mercury 140 is overcharging

Dash voltmeters are notoriously innacurate.

So you replaced everything because you're getting too much voltage? Should've checked with us first. That's normal for the inlines. You would've just needed a regulator/rectifier in place of the rectifier. Those systems don't put out enough amps to cook the battery. That's why no regulator. If you're worried about electronics, then get a regulator. If you're worried about cooking the battery, it won't.

 

[emckelvy]

Re: Mercury 140 is overcharging

Try using your running lights all the time. This'll put a slight load on the system which will keep voltage down a bit.

Keep in mind that this type of charging system doesn't have a lot of output at idle speeds so if you're trolling for long periods of time you probably won't need to leave the lights on.

And as suggested in a previous post, if you're concerned about regulating voltage at the high end you can install a rectifier/regulator assy from a later model motor, such as a mid-90's 115, 125 etc. It won't increase output at idle, but it will limit the maximum voltage output of the charging system.

You'd have to come up with your own special mounting for the rectifier/regulator assy, which is quite a bit larger than the standard square rectifier.
And a lot more expensive!!!

I expect the Lo-Tech solution of running a load on the system will work as well for you, at extra cost.

HTH..........ed

 

[Adamgoodell1]

Re: Mercury 140 is overcharging

Thanks, I will check the battery with a volt meter. The fish finder is were Im getting the voltage info.

 

[Adamgoodell1]

Re: Mercury 140 is overcharging

The info inthis forum is awsome by the way, thank you all. Will the rise in voltage damage any thing on my motor other than the battery? Did the new rectifiier i put in only last a season because my voltage was too high.

 

[bdean]

Re: Mercury 140 is overcharging

Just a sugestion but when you check it with the volt meter you need to be running wot and then you will see for sure how much it is putting out. I would suggest hooking your volt meter up with some long leads so you can drive your boat and read the meter at different rpm's .

 

[rustyscrew]

Re: Mercury 140 is overcharging

I have a 1978 merc 1400. And I had the same exact problem. I checked everything starting from the stator. I considered running extra load to drop the voltage, but mine was even creeping up to 19 volts at WOT. So, based on recomendations from this site (thanks fellas) I replaced the rectifier with a rectifier/regulator. It bolts right in to the same holes even and for 100 bucks it has been fixed ever since. This is particularly good for me because I have a battery isolator for my auxillary battery that trips based on the voltage...now it works again.

I will try to dig up the model number of that rectifier/ regulator for you.

Good luck. 8)

 

[rustyscrew]

Re: Mercury 140 is overcharging

OK- got the part #. It is available from Iboats at:

http://www.iboats.com/194_5279_Volt...3370664--session_id.074284788--view_id.335920

CDI part # 194-5279

I am guessing this will work for you too....I imagine the Merc 140 is the same as the 1400....which is actually 115 hp.
good luck 8)