www.iFourWinns.com

So my marina shop and I are stumped... My 2007 Vista 357 has the twin 5.7 VP OSXi engines. Starting late last season I started noticing symptoms of a low house battery after a relatively (2 hours or less) short time on the hook. My chart plotter would blank out when I tried raising the anchor. I always start my engines before retrieving the hook. All three batteries are new Interstate ones as of that time.

So, fast forward to this spring. I dewinterized the boat and happily headed out, only to find my Teleflex engine synchronizer not working on the starboard engine, then next my chart plotter went dead followed by my stereo. When I turned off the synchronizer my engines ran perfectly. Perplexed I headed back to the slip. My batteries all tested good but I noticed my starboard voltmeter reading less than 11. I reported this to the marina shop who tested the starboard alternator and declared it dead. So new alternator, problem solved!

Except it wasn’t. Same durn thing next trip out, turns out both engine voltmeters are reading below 11 and by the time I’m passing the fuel dock my chart plotter says goodbye!!!

I check the batteries and look at the water level in them. All three are low. Nearly half a gallon of distilled water to refill them to normal. Never seen such a quick drop in just one season.

After filling up with water I go from dead battery in 5 minutes to now 21 minutes.

So, are the batteries fried? Is my charger defective? My marina shop is pretty expert on Mercruiser but not so much on VP. They have a call in suspecting something engine related, but the alternators both test full output. All three batteries bad, or just the house? I’m asking them to go ahead and replace the house battery and to test the charger.

Any other thoughts? Here on the Tennessee marine experts are far and few between and getting them to where your boat is can be challenging, so we tend to stick with our local guys who this time seem stumped.

A Sea Ray on the dock was having similar issues for the last couple months, his main ground on one of the engine blocks was loose, tightened it, all is well, 2weekends in a row

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Current:
2000 Sea Ray 380 Sundancer "still Livin the Dream"

Past
2002 268 Vista 5.7 GXI "Livin' the Dream"
1996 Rinker 192 Captiva. "The Simple Life"
1999 Yamaha XLL 1200 Waverunner.
1976 Mercury Marquis tri hull 120 hp

I’ll pass that tip on to the shop! Thanks!

If its the original on board charger(probably guest) it most likely toasted the batteries. I had an issue on the 258. Went to start the boat one day and battery 1 was dead, the batteries were only 2 years old and were always on the charger. I switched to parallel both batteries and next thing I knew battery 1 exploded, what a mess and VERY loud. Be very careful with those batteries. I installed a pro mariner charger, new wiring, and new batteries and all was good again.
Those are the bad wiring years and my opinion they used too small a gauge wire so the charger probably got false readings on voltage.

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--2002 3880 Regal Flybridge | Twin Merc 8.1HO **Seven**
--2003 AB 13 VST Console Inflatable | Tohatsu 40hp TLDI **Phish'n ski**
--310 Mercury Inflatable | 1982 9.9 Johnson

there is a good chance your charger is done, and your batteries also. I am on my second Vista and both needed new chargers. I’m not a battery expert, however, I’m pretty sure overcharging would be a possible reason the water evaporated. You want to make sure the charger shuts off when the battery is fully charged. The charger manual will tell you when it is set to shut off.

On my boat, the port and starboard alternators charge separate battery banks. One charges starting batteries and one charges the house batteries. If you suspect a bad alternator you will have to figure out which charges your house bank. This way you can test for proper voltage, and to ensure to voltage regulator is working properly.

Each positive wire from each alternator goes to a separate post on the battery isolator. There is a second set of posts and wires connected to the isolator, one for house batteries and one for starting batteries. 2 small wirees from my onboard charger connect to the battery side of the isolator, 1 wire per post. You might want to check the voltage across your isolator to make sure there is not too much of a voltage loss. You will see a small loss on a properly functioning isolator.

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2004 - 288 Vista
Twin - 5.0 Volvo Penta GXi DP

Well, the shop gave the batteries a more intensive test and found the house battery had an internal short with no reserve capacity. So a new battery was installed. The charger was tested and found to be in working order. Problem solved!!!

NOT

Taking the boat out this afternoon the voltage gauges still read VERY low voltage, around 11. The DC panel showed exactly 12.6 with the charger on and 12 with it off. Weirdly, with the generator running it showed 13.

Anyway, once I activated the Teleflex synchronizer the starboard engine started surging like before. With the sync off the engines behave normally and the throttles work smoothly. With greater reserve capacity the battery seemed to hold up well, but then I turned on the generator to see if the additional power helped the sync to work. It did not help. Plenty of power going into the batteries, but seemingly not making it from the alternator to where it is needed.

So, after a new battery, and even with the generator running the panel voltmeters still read very low voltage. Supposedly both alternators are testing as normal output. The engine grounds were checked and were as they were supposed to be. My shop is stumped.

That stinks that its still not working. I am wondering if there is short somewhere that's discharging the battery at a faster rate. I would think the mechanic could track it down. Can you tell if anything electrical is running that shouldn't? For a battery to discharge that fast it must be something big. I don't think even the engines with a bad alternator would discharge that fast.

_________________
--2002 3880 Regal Flybridge | Twin Merc 8.1HO **Seven**
--2003 AB 13 VST Console Inflatable | Tohatsu 40hp TLDI **Phish'n ski**
--310 Mercury Inflatable | 1982 9.9 Johnson

An update. The shop finally figured it out. It was a badly corroded bus bar behind the dash. What helped narrow it down was one evening while cruising slowly up the river I turned on the nav lights and every gauge on the dash went stone cold dead. Turned the nav lights off and they came to life, albeit with the wonky readings.

So a $22 part later and $170 total labor everything works fine. Even the radar which had never worked right functions perfectly now. The boat is a from salt to fresh conversion and that exposure caused the corrosion.

Like getting a new boat. Many of the niggling issues from last season have just disappeared!