I have been battling a corrosion problem, had to have a new Mercathode, transom assembly, gimble ring and a brand new Bravo 1X installed.. $$$$$

Dealer doing the work said the battery installed from the factory did not meet Mercs. specifications found in the installation manual for a 496H.O. of 800 cold cranking amps, the battery Sunsation installed was only 690 cca. Had to pay 150.00 for the proper battery to be installed.

As soon as the dealer installed the proper battery the corrsion protection immediately jumped by 50 milli-amps to a more acceptable level..

This specification is minimum required by Merc. Sunsation is a Merc. certified installer so they should be responsible for supplying the correct battery.. I sent an e-mail to Joe but have not heard back...

For what it's worth, this is a heads up that the battery running your 496 may not be sufficient according to Merc. and could cause the mercathode to not function correctly...

If the problem is related to the factory installed battery why was the Mercathode replaced? What is the reading on the system as it is today with a new 800 CCA battery vs. a new (not your original) 690 CCA battery? Wouldn't the reduction in CCA only affect the battery's ability to turn the motor over in colder climates? BTW, Joe has been on the road delivering a boat to MO.

Here's some info from autobatteries.com...

CCA is critical for good cranking ability. It's the number of amps a battery can support for 30 seconds at a temperature of 0 degrees F until the battery voltage drops to unusable levels. A 12V battery with a rating of 600 CCA means the battery will provide 600 amps for 30 seconds at 0 degrees before the voltage falls to 7.20 V (six cells).
RC helps to power your vehicle's electrical system if the alternator fails. It indicates the battery's "staying power" -- how many minutes the battery can supply ample power without falling below the minimum voltage needed to run your vehicle.
In general for both CCA and RC, the higher the number the better. HOWEVER, if you live in a cold climate, the CCA rating should be an important consideration in choosing a battery. Conversely, if you live in a high heat climate, you don't need as much CCA.

Knot,, I obviously had other problems besides an in-addequate battery, wasn't blaming the problem directly on the battery, just giving a heads up about Mercs. minimum requirement for this engine, and the batteries Sunsation is installing from the factory do not meet these specifications.

In trying to diagnos my problem, this information came directly from a Merc. Technical consultant.

as far as the hull potential test, originally i was at 779 mA, with everything replaced I was at 850 mA w/ the stock battery, with the correct battery it jumped to 900 mA.. Ideal readings for fresh water are between 750 and I believe 1050 mA, Given I boat in a brackish river with strong currents a healthy reliable Mercathode is needed and the added 50 mA would have helped.. Merc. thinks I need to be up around 950 to be completely protected..

According to dealer's electrolysis meter the boat is still freely corroding, so they are still trying to find the answers..

Knot is right - not only was Joe on the road, he broke down this morning so he probably did not get back until later today, and at one point he had been on the road for 36 hours.

You may want to just give him a call at the office tomorrow morning. I have a friend with a fastek with 496HOs. This makes me interested in checking his batteries.

I had 454 mags in my dominator. Ran them for 6 years with absolutely no problems. Finally swapped them out last spring when the old ones gave out.

Chris, my Chaparral has a 496 and it too is not sporting 800 CCA batteries. So, manufactures in general must not pay much attention to Merc's recommendation. Sorry to hear about your problems and hopefully they can get your mA's up to where you are best protected. Is your original battery just weak? Like I said, I wonder if a new 690 CCA battery would have given you the same mA reading. If bumping up to an 800 really does boost the mA's, then this is good info to know for our boating brethren who leave their boats in the water.

Guys, this info came directly from a Merc. Tech. like I said, and I was told it's in the owner manual as well as the installation manual.. I am just relaying what the dealer doing the repair work found out. I am not blaming Sunsation, but feel they should supply a correct battery with the boat that meets Mercs. specs. I will give Joe a call and see what his feelings about this are... Thanks Chris

After reading the message this weekend i was of
course concerned and called Joe this morning.
Before we were a certifed builder Mercury sent us
no specs on what batteries were best suited for the 496.
We had used the other batteries for years with the 454 and
502 engines with no problems.
We are now using the correct batteries after we became
a certified builder and are using Mercurys guidelines.
This should no longer be an issue...

Thanks for the input Chris 288, and i am sorry for your
trouble.

Hey Chris, could the battery switch be the problem ( If you have 2 batteries and a switch of course), I know on mine I leave the Bat switches on "Both" when left in the slip, otherwise the mercat. system won't have any juice along with the auto bildge pump.

Claude, my understanding is the Merchathode is hard-wired to battery #1 so no matter what position the switch is in #1 #2 or off the Mercathode is always energized. Secondly, My thoughts on dual batts. and switch are this, if you leave the switch on both and something drains the battery down your still stuck, the idea is to leave it on #1 or #2 so that you always have a back-up, leaving the swith on both is kinda defeating the purpose...

P.S. I do believe the bilge pumps are hardwired also... thought I remember checking this but cant be positive...

I noticed on mine that with the switch off the bilge pumps did not work. And when I removed the bat covers there were no wires, (other than the ones going to the switch), that were connected. So this leads me to believe that the mercat system is not hot when the switches are off. ???