So I lost my battery on July 5th (at least it worked on the 4th!) and it was only 3-1/2 years old. I tried to charge it overnight on the deep cycle charger but it was dead with around 10.5 volts. I picked up a new DC battery and put it in the boat only to notice the voltmeter was showing around 12.5 while running. Earlier in the year it would go up to 14 volts when first started and then drop back to 12.5 to 13 volts the rest of the day. I figured it was the voltage regulator/rectifier and got a cheap new one but the stupid wire bullet connectors were slightly smaller and I had to pry them open to try to get it to connect tight enough. I put the boat back in the water and it slowly worked it's way back up to 13.9 volts while running. The next time out it was running around 13.2 volts on the trip upstream. When I started it back up to come back to the dock, it was around 12.6 volts (battery power). I went out the next day and it was around 12.5 volts for the 5 minute trip upstream. I'm not sure if the regulator wires came loose so I need to pull the boat back out of the water to dig into it. The motor is a 1994 Mercury 60/45 jet and runs great other than this charging issue. I don't want to kill a new battery and I need the battery to run the bilge pump when it's sitting at the dock. The Seloc manual doesn't show the best way to verify if it's the stator/charging coil or regulator/rectifier so I was wondering if anyone else has run into a similar issue and what the solution was. I'm not convinced my old regulator is bad either. The only real history I know on the motor before I got it was that a large tree branch came down during Sandy and the motor took a direct hit. It has a cracked hood, needed new linkage and starter, so anything is possible. I did remove the oil injection since it was leaking and I'm used to doing premix anyway. The overheat indicator also went bad a couple of years ago so I disconnected that as well. I only run for 5-10 minutes and watch the telltale for water flow so I'm not worried about overheating.
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So I picked up a used Mercury voltage regulator/rectifier and the diode test readings were different from my old one. So I put it in the boat and ran the motor on the hose and it puts out in the low/mid 13 volt range at idle so I think I'm good. My old regulator went bad, then the cheap chinese replacement one went bad in 2 days so don't waste your money on those. I picked up a used CDI regulator as well and I'll check the readings when it gets here. Guys keep saying the CDI is better quality than the Mercury so I'll have that as a backup. I only run for 5 to 10 minutes so there isn't much charging going on but it should keep the battery from running the engine. With the hurricane rain heading up the coast, I pulled the boat out of the water to work on it and not worry about the bilge pump draining the new battery. It's cleaned up and in the garage for now.
Update: I took the boat out yesterday and at normal speed it was around 14.3 to 14.4 volts and at idle around 13.8 so it looks like the voltage regulator/rectifier was the problem. Hopefully, the used Mercury one will give me a few seasons at least.
Update: I took the boat out yesterday and at normal speed it was around 14.3 to 14.4 volts and at idle around 13.8 so it looks like the voltage regulator/rectifier was the problem. Hopefully, the used Mercury one will give me a few seasons at least.
I figured I would update this. I took the boat out for the first time this year a couple of days ago and it was running in low 14 volt range going upstream for a 10 minute run. When I fired it back up to pull away from the shoreline it was running around 12.5 volts again so I think the used regulator/rectifier got fried. I had picked up a used CDI reg/rect last year as a backup so I put that on and it's running over 13 volts again. CDI does recommend some heat sink compound on the back of it and I didn't have any so I ordered it to see if that helps. I'm not convinced the reg/rect is my main problem at this time, it could the stator overcharging.
MrGiggles
Well-known member
JL8Jeff said:
I had one of those CDI regulators, even though it was recommended for my engine, it was totally different than the factory one. I was never able to get it to work right on the engine, I ended up moving it out of the cowl and into the bilge area on it's own heatsink, worked well after that.
You can check the battery charging coil output with a multimeter, however it can not over charge. Usually when those regulators burn up, it is because of a bad battery, or a poor connection to a good battery.
InSaneFisherMan
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Are you using a deep cycle battery for your starting battery?
InSaneFisherMan said:
Yes, I only have 1 battery and it has always been a deep cycle. This battery was new from July of last year. The CDI regulator I put in has the same wires/connections as the oem regulator so it was a straight swap. My volt meter in the boat doesn't show real accurate numbers, just the gauge sweep so it's a bit of a guess what the real number is. I'll start taking my multimeter out with me to get some real numbers when it's running. It will be a couple of weeks before I get out again.
onthewater102
Well-known member
Try the heat sink compound, it's cheap, plus it is possible you're not getting sufficient contact between the backside of the rectifier and the block to dissipate the heat, but I think you're more likely seeing an intermittent issue with the stator taking out the rectifier(s) as you've suspected.
There is an updated rectifier that costs 3x-4x what the OEM replacement one for that motor costs, but it's got a voltage regulator built in to protect digital devices you may have in the boat (such as a fishfinder or digital controlled trolling motor.)
There is an updated rectifier that costs 3x-4x what the OEM replacement one for that motor costs, but it's got a voltage regulator built in to protect digital devices you may have in the boat (such as a fishfinder or digital controlled trolling motor.)
I put the boat in the water for the season yesterday and it's still running around 14.4 volts so the CDI regulator looks pretty good so far.
I don't have any electronics other than the bilge pump so fortunately, that's not an issue.
I don't have any electronics other than the bilge pump so fortunately, that's not an issue.
