To many VOLTS! 84 merc 150

[jman72637]

I had just got the engine serviced and the mecanic had told me that the motor was not charging the battery.... he had said to replace the rectifier, so I ordered one and did so.
Last year I was running the boat in a passage outside Whittier Alaska and being from around this area, I knew it would rain eventually, and when it did I had noticed that I had left the battery exposed. When I flipped the gauge on I was reading 16 volts. Now, I don't know if this had happened before I had just noticed that when I was running at above 3000rpms, soaking wet, I was frying the battery out. Present day- I took the boat out this weekend with a fresh new battery started the boat and at idle I'm putting 14.4 volts back into the battery, but when I excelerate that gauge creeps up pretty fast.... until BAM! on step and then in the red on the gauge(16volts) Please dont tell me its my stator... but if it is I would like to know... Thanks so much in advance.

 

[j_martin]

Re: To many VOLTS! 84 merc 150

Actually, for that motor, it's normal. It'll read higher if the battery connections are weak. Before you get too excited, check the battery voltage with a real, reasonably precision meter. The dash gauges are just a reference tool, usually not very accurate.

There should be a shunt regulator, which may have been removed. No matter, it's basically a fire starter anyway. That's why it's listed NLA. If you maintain your battery, it won't hurt it. If you are concerned, you can get a mercury 20 amp regulator and wire it in and have regulated 12V like the modern stuff.

hope it helps
John

 

[Silvertip]

Re: To many VOLTS! 84 merc 150

Or just flip on a few accessories to pull the voltage down.

 

[PHE]

Re: To many VOLTS! 84 merc 150

Mine also does not have the regulator. I always turn on my VHF radio and fish finder, and sometimes the stereo or lights to keep the voltage low enough not to damage any electronics.

Make sure you check the water level in the battery often. It boils it off pretty fast if you run around a lot. Put a couple hundred miles on my boat last week and added nearly pint of water when I got back. Doesn't seem to hurt the batteries as long as you add water and keep the plates covered. I only buy deep cycles. New one is for trolling and backup. Old one is for starting. My old one is at least 6 or 7 years old now and still holds a charge and spins the starter. Its been used for starting for three years. I thought about putting a regulator on, but if it ain't broke, why fix it.