Running Ignition from battery, how long?

[Sleepy850]

I have a 1974 mercury 850 (85 HP) serial # 4100979<br />I was wondering how long the ignition system on this motor could run from the battery?

 

[Joe Reeves]

Re: Running Ignition from battery, how long?

Sleepy.... Mercurys are not my line of expertise, but your question would pertain to any outboard, and there is no standard answer. If your engine does indeed have the battery type ignition, I would suggest that you carry a fully charged "spare" battery with you to use when the original battery gives out, and judge the time for yourself.

 

[Sleepy850]

Re: Running Ignition from battery, how long?

The reason I ask is because the stator ( and a few other things) on my motor is bad and needs replacing, and i just wanna run the thing a bit to decide if I want to keep it or move on to bigger and better things, plus it's good to know these sorts of things.

 

[hondon]

Re: Running Ignition from battery, how long?

That will depend, for the most part on the condition of your battery, but I would'nt run it out too far.Heres the rub.That battery cdi unit is full of little electronic solenoids called scrs.Anyone here that knows beans about solenoids and such can tell that a low voltage situation can take them out.That means by ignoring your charging system, you not only risk getting stranded out there ,but also taking out that switchbox.Not cheap.

 

[clanton]

Re: Running Ignition from battery, how long?

The cdi needs a min of 9 1/2 volts from battery to make a spark. If the battery is a group 27 in good condition, and you dont use the tilt/trim or radio, it should last about 2 hours. Just a guess. Take a paddle along.

 

[rickdb1boat]

Re: Running Ignition from battery, how long?

Take a cheap Voltmeter with you to check it or install a Voltmeter in the Dash(Always handy anyway). Of course if you decide to keep the Motor, fix it asap.

 

[Sleepy850]

Re: Running Ignition from battery, how long?

Thanks everyone,<br />I feel assured now tbat I could loaf along for about 10 minutes just to see how it does...<br /><br />PS. Whats an "scr" what does it do? and what's inside of a switchbox?

 

[dkondelik]

Re: Running Ignition from battery, how long?

SCR= Silicon Controled Rectifier<br />Somthin' like a transistor. Bias voltage on gate lead effects/sets conductivity.

 

[Sleepy850]

Re: Running Ignition from battery, how long?

Like an Amplifier?<br />I'm picturing a high current amplifier or something similar, can I put one of these together?

 

[mellowyellow]

Re: Running Ignition from battery, how long?

you can get a new rectifier for $30 bucks or so.<br />this should charge the battery for you. it runs<br />off the stator. the manual will give you specs<br />to test it out. if you have the origional, they<br />will try to zap you another $15 for a little<br />bracket, the new ones are a different shape.<br />good luck,<br />M.Y.