No maintenance free batteries with battery CD Ignition systems ???

[Moody Blue]

Have a 1971 Merc 800 with the battery CD ignition system.

Have read in a number of places NOT to use a maintenance free battery with that type of system because the switchbox can not tolerate overvoltage conditions. Since there is not a voltage regulator on the motor, the battery acts as the regulator.

Are not all marine batteries sold today considered maintenance free? Can't recall the last time I saw a battery where I could add water.

Why can't a maintenance free battery regulate voltage as well as a non-maintenance free type?

 

[Moody Blue]

Re: Battery compatibility with battery CD Ignition systems

Re: Battery compatibility with battery CD Ignition systems

Bump^^^

 

[76canaventure]

Re: No maintenance free batteries with battery CD Ignition systems ???

Hello!
I can't think of a single reason why not myself. Both styles work exactly the same way, the only difference would be how they manage gas venting and recovery. I have used both styles for years with no problems. My 75 rude and 76 Merc at WOT will throw out about 17- 18 volts, which can cause some vigorous (like 7-up) gassing. My understanding is that non sealed batteries have bigger vents in the caps that will reduce the bursting/ rupture/ mess risk. I would be scared to even try a gel or a spiral battery. I use Trojan Gp27 batteries now, they have a bigger vent in them, apparently, for just that. That having been said, I have also pried the caps off 'sealed' batteries to add water. I tend to keep an eye on the voltmeter and throw on some lights just to suck up some excess voltage when it starts to get up there. I have noticed that the maintenance free batteries don't seem to last as long as the older style, I don't think they like that over voltage too much.
Just some thoughts,
Steve

 

[Moody Blue]

Re: No maintenance free batteries with battery CD Ignition systems ???

Thanks for the info. Wonder if a voltage regulator can be added. How does everyone else deal with this issue? Can't see a battery lasting long if charged at 18v Also concerned about the ignition system components. They are too expensive to replace and the manuals warn against voltages greater than 16V.

 

[Moody Blue]

Re: No maintenance free batteries with battery CD Ignition systems ???

Any other thoughts on this ?

 

[76canaventure]

Re: No maintenance free batteries with battery CD Ignition systems ???

Sorry, been fishing all weekend!
I honestly haven't put too much thought into how much strain is put on the electronics at all. My fish finder shuts down automatically (supposedly, it never has,) at 20 volts. I toss my batteries every couple of years. The electronics on the motors I don't even think about, I figure the engineers that designed the things knew a lot more about them that I do. They've been running for 30+ years, so can't really complain. I've never had any issues with the potted components, other than the normal stuff. (Cleaning connections, etc.)
I suppose you could add a voltage regulator if you are that concerned, myself I just think it's easier to turn on the cabin lights.
Regards,
Steve

 

[Chris1956]

Re: No maintenance free batteries with battery CD Ignition systems ???

Nuts, That merc puts our 6-8Amps at high RPMS. Any decent battery will absorb that w/o an issue.

The maintenance free batteries are different from regular batteries because use so little water. After a long time the MF batteries could run dry, with an unregulated chargign system, however, if you look at the MF batteries, most have removeable caps, sometimes under a decal. if you find a MF battery you can refill there is no issue.

In addition, boat batteries only last a few years anyway. Most MF batteries wouldn't last long enough to run out of water, even if they were truely sealed.

 

[Moody Blue]

Re: No maintenance free batteries with battery CD Ignition systems ???

Soooo, what you are saying is quit worrying about nothing and enjoy the ride ?

I do tend to over analyze things. Thanks for getting me back on track.