Battery for electric start...

[Milton.Audas]

G'day guys. Has anyone any info on wiring in a battery for an electric start on my 9.9hp Mercury outboard ? During winter maintenance we just discovered that our motor has an electric starter, and we have a spare marine battery that will do the job. Yes, it's probably a luxury but we have it so why not use it (when the wind gods desert us)...

My questions are (2)...
1. How far from the gas tank should the battery be located ? Ideal loction is either a) in the portside locker, b) near the keel winch next to the existing battery, or c) in the starboard locker. My cable will easily accommodate 'a' & 'c', but 'b' will require a longer cable. Any issues/regs with locating near the gas tanks (shielded cable, battery in battery box) ?
2. Does the 2nd battery need to be hooked in to the control panel switch, or just stand alone for use by the motor starter ?
3. (bonus round question) If wired in to the control panel, parrallel or in series ?

Cheers,

 

[jrowan]

G'day guys. Has anyone any info on wiring in a battery for an electric start on my 9.9hp Mercury outboard ? During winter maintenance we just discovered that our motor has an electric starter, and we have a spare marine battery that will do the job. Yes, it's probably a luxury but we have it so why not use it (when the wind gods desert us)...

My questions are (2)...
1. How far from the gas tank should the battery be located ? Ideal loction is either a) in the portside locker, b) near the keel winch next to the existing battery, or c) in the starboard locker. My cable will easily accommodate 'a' & 'c', but 'b' will require a longer cable. Any issues/regs with locating near the gas tanks (shielded cable, battery in battery box) ?
2. Does the 2nd battery need to be hooked in to the control panel switch, or just stand alone for use by the motor starter ?
3. (bonus round question) If wired in to the control panel, parrallel or in series ?

Cheers,

I would contact Mercury for their recommendations. If they sold it, they should support it. But beware that just because its electric start doesn't mean that the engine has an alternator to charge it. That would be very rare for a small gas outboard engine to accomplish. So I would locate the battery in a sealed locker away from your gas tank, & wire a Zantrax or marine battery charger to it, or solar panel to charge it while being stored. If U rely on a starter battery, the I always like to have one dedicated starter battery & a seperate house battery for lights, etc. Group 24's should be enough for a C 22 load.

 

[CaptGregg]

My dad had a 16 ft Glaspar with an Evenrude 85 on the back of it, we had two 5 gallon gas tanks and the battery sat in a battery box in between the two gas tanks under the transom. It was a small boat with an open transom so it got plenty of air. The battery was enclosed in a battery box. My dad owned a service station all my life and never had a problem and is the smartest man I know. Based on this information, I would say it was all safe.

Anybody else feel free to chime in here... I am going on past experience but it was based on a man who knew batteries and gasoline very well!

 

[Milton.Audas]

Thanks guys. The motor doesn't have an alternator that I can see. The battery would be only to kick start the electric starter, not charge up the battery - that would be a luxury. We do have a solar panel that would do an adequate job of maintaining the charge on the starter battery, as it's totally useless at maintaining the main supply (that i will leave to shore power hook-up). I have a marine battery charger for shore power which does ok to replenish the juice after a weekend of sailing.

Based on your info, I feel OK with maintaining the two batteries as separate units, one for starter only, and the other for lights, nav, comms, satellite TV, etc (just joking on the latter !!). Will ensure that batteries are properly housed and separated from the fuel storage (I liked a previous posting that sealed in the gas tank with external venting. It was simple and appeared of sound design). Appreciate the help.

cheers,

 

[Clark]

I've never heard of an electric start outboard w/o an alternator. Keep in mind that alternator output ratings are at or near full throttle. A little math helps too - if you draw 40 amps to spin the motor for 10 seconds to start, you've consumed 40/360 AHr or .11 Ahr. A 6 amp alternator will put that back in a couple of minutes of full output. Don't expect it to recharge a 70 AHr battery any time soon though so your thoughts about a dedicated start battery are sound.

Edit: I HAVE seen several small outboards with an alternator but no starter. Make sure you've identified things accurately.

 

[Bilbo]

I've never heard of an electric start outboard w/o an alternator. Keep in mind that alternator output ratings are at or near full throttle. A little math helps too - if you draw 40 amps to spin the motor for 10 seconds to start, you've consumed 40/360 AHr or .11 Ahr. A 6 amp alternator will put that back in a couple of minutes of full output. Don't expect it to recharge a 70 AHr battery any time soon though so your thoughts about a dedicated start battery are sound.

Edit: I HAVE seen several small outboards with an alternator but no starter. Make sure you've identified things accurately.

I'd have to agree. There is a D.C. system that is necessary for providing spark for the ignition system. I"m curious as to what the model/year of this Mercury. Here is a link to parts for Mercury's in general. http://www.boats.net/parts/search/Merc2/Mercury/parts.html

Also, our elec. start Yamaha has provided enough power to maintain a good 12 V battery and starting system for the 6 years that we've owned it. It is true that Idling doesn't do much to charge the battery but the amount of charge to the battery is adequate at about 30-100% throttle.

 

[Milton.Audas]

Cheers guys. We have a 9.9hp Mercury 180cc Saildrive unit. Looks like 80's/early 90's vintage but hard to know for sure. Did my best to trace on Mercury's site by s/N but to no avail.

It is definitely an electric start. I'm not an EE or ME (better living through chemistry is more my mantra), so now not sure that we do not have an alternator. But I kick-started the motor on a stand it last weekend and the motor turned over at a light push of the button. Interesting location which also stumped our local Mercury dealer (given that they don't see many sailboats on this upper stretch of the Mighty Muddy River). His tech had to show him where it was. The button is recessed within the forward/reverse selector on the side of the housing. Neat system that doesn't need a separate switch to be mounted in the cockpit. Will take a couple of pics on the w/e when I head down to complete the pre-season checklist.

 

[Milton.Audas]

Hi guys. Took a few pics of the motor while down at the boat today. I appreciate the comments. If I do have the ability to charge the batteries while under power, can I rig a jump cable from the starter battery (its a dual battery) to the 'mains' battery and also charge that ? Suggestions or wiring diagrams most welcome...

 

[Chris Patterson]

Hey Milton, I've been watching this thread out of general interest, knowing little about an outboard engine, (mine's a steam engine, made by Fulton, with twin paddle wheels), but I can not imagine an engine, of any type, that has electric start, and no way for it to generate power for a battery, (alternator, generator, etc.). Even lawn mowers do that to some degree, although in the few autopsies that I have done on them, the charging apparatus seems to make little sense to me. For that matter, nothing makes sense to me too much...
But, if it were me, I would put a switching circuit on the batteries of some sort, you know, the one, two, both, off kind of switch.
And, upon cranking the engine, a simple volt meter will tell the tale of whether it's charging or not. And that being the case, I'd go ahead and put a volt meter on the panel, or elsewhere to monitor the rate.
Cool pictures though, I just wish I knew what all that stuff does..

 

[Bilbo]

Read the description on this video.
http://www.youtube.com/watch?v=AHyS5BODxNk

One thing that I can't see in any pics is the front of the head where the control things are located (Like the Choke and on/off) There may be a plug-in connection somewhere or maybe even a hole for a wire to pass through. OFr my outboard with Elec. start..(Yamaha) The wire from the battery that serves to start the outboard also serves to charge the battery.