Well, I guess I lied when I said on a previous post that I had enough information about this subject. And; I will admit here and now that my original post on this subject was misleading, and I apologise for that; but, the actual experience with that combination was as reported.

I couldn't let it go. So; I contacted a well known and well respected battery dealer who has been in that business for over 26 years in the Dallas area.

He informed me that I could be having a problem with vocabulary when I asked him about Mercury and Bombardier recommending lead, acid batteries only for starting purposes. He said. as has been expressed in some of the responses to the prior posts, that AGMs are lead-acid batteries with the acid in fiberglass envelopes around the plates, and that they have the same basic performance as a wet cell battery, which is the correct way to refer to the differences in construction of the two batteries.

There are, according to this expert, a couple of differences:

One - The AGM and gell cell carries a higher average voltage: 12.88 for AGM; and 12.65 for wet cell.

Two - AGM is harder to charge when fully discharged, as opposed to a gel cell or wet cell.

Three - AGM transmits more power when cycling and gel can be cycled more times before failure.

Then he offered his OPINION reference the possible relationship between the AGM and my stator when all of the motor electronics crashed. Because my AGM battery was fully discharged during the long period of non use, my charging and relying on the charger meter to show '100 percent charged' may not have resulted in the battery being actually charged to full capacity. If this were true, and I expect that it is, the battery was unable to fully charge the stator enough for starting; AND LOW VOLTAGE - NOT A SPIKE to the stator could have damaged the other parts. This opinion and explaination makes more sense to me than the other opinions I have received.

The battery dealer did not have a recommendation as to which type of battery to use for an outboard - especially one of 200hp, as high battery output is required for the first start of the day.

Also, I believe the terminology used by the two motor mfg.s when they only recommend lead-acid for start batteries is some sort of PYA to avoid any liability in the case of some idiot (like me) not properly checking the battery with a hydrometer before use after an extended idle period. My OPINION ONLY. The different terminology should have been wet cell vs. AGM or gel cell.

I sure hope no one rushed out and bought a un-needed start battery based on my very un-professional opinion posts. This discussion has helped me to better understand the differences in some of the battery types.

Another apology for my prior mis-leading comments.

"the battery was unable to fully charge the stator enough for starting"

I don't want to be overly picky........long as we're just having a theoretical discussion....I wouldn't think of disputing the advice you got from your various sources....but, theoretically speaking, as I understand it, the battery doesn't charge the stator for starting....the battery only supplies power for the starter motor. The stator generates the electricity that makes the spark for combustion. If the battery doesn't supply enough power for the starter, the starter won't spin the flywheel fast enough for the stator to generate enough electricity, and your motor won't start. The stator also generates electricity for charging the battery, but since it's generating AC, it has to be "rectified" into DC by the "rectifier", and "regulated" by the "regulator" (but not all motors have regulators).

There's no "black box" circuitry for detecting when the battery is fully charged...it's just a characteristic of batteries that their "internal resistance" increases as state of charge goes up...and whenever resistance increases current decreases (its the law). A battery with lower internal resistance might demand more current from the stator...but the stator can only put out what it can put out, all it is is just magnets and copper windings. A failed voltage regulator can ruin a battery, a failed rectifier prevents it from charging. In the charging circuit, the battery is just a passive component, like a big capacitor.

btw, you can't check an AGM or gel cell battery with a hydrometer.

Thanks again, jtexas,

I do appreciate the very polite manner of reply to a poster who doesn't even have a clue what he is talking about (that would be me) from you, who does know what he is talking about. And; for the detailed insight into the what, how and why of the electric thing.

I am going to say this in my attempt at some sort of defense. I thought I had contacted as many of the knowledgeable sources as was reasonable to try to determine some facts concerning the perceived conflict between my old battery and the motor electronics failures. Actually, what I received from these sources was opinions, not facts. I mistakenly accepted the opinions from the ones I considered to be the best sources.

My only purpose in posting on this subject was to attempt to alert the average boat owner about a possible, not widely known conflict between components. I really hope that this discussion has helped someone through yours, and other responders trying to keep the subject on an even keel. Thanks again.

Because I normally do not make public statements or base my decisions on inadequate information, I am embarrassed and shamed for deviating from my usual norm, and I do offer my sincere apologies to this excellent forum.

Now to list the facts:

The motor broke. It was fixed. I am a happy camper.

well said cajunride.