Hi folks, just bought an old (1985) 9.9HP Evinrude outboard to put on the Oday 22. It has as I understand it a 6 amp charging system and is not regulated, again as I understand it. What I don't want to do is get in a situation where I am running wide open or thereabouts, (Is that a word?) and overcharging the battery. I have read that you can sometimes boil the water right out of the battery doing that with those type charging systems. Has anyone out here run into that situation and how did you deal with it? I have a couple of books on 12 volt electrical systems, however I thought I would throw that out here for you experts! Thanks in advance to all. Jack Hart SEA-YA!
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The key is matching battery size.
The regulation is done by the battery itself. If the charging system is rated 6 amps @ 12 volts, it is only 72 watts. At 10 volts it can put out 7.2 amps. At 14 volts it can only manage 5.14 amps. This is not enough power to damage a decent sized battery. A group 24 battery is about 75 AH (IIRC) and the full 6 amp output is less than 1/10 of capacity. In general a battery won't be harmed when charged at a rate of amps equal to 1/10 of the AH rating. If you have a 6 AH motorcycle battery, you could probably fry it.
The regulation is done by the battery itself. If the charging system is rated 6 amps @ 12 volts, it is only 72 watts. At 10 volts it can put out 7.2 amps. At 14 volts it can only manage 5.14 amps. This is not enough power to damage a decent sized battery. A group 24 battery is about 75 AH (IIRC) and the full 6 amp output is less than 1/10 of capacity. In general a battery won't be harmed when charged at a rate of amps equal to 1/10 of the AH rating. If you have a 6 AH motorcycle battery, you could probably fry it.
Other are correct
You won't have a problem. If you use any electronics on the boat or run the lights pretty often, you will need another way to charge the battery as the motor, while it will help, will not keep the battery fully charged unless you run it an awful lot.
You won't have a problem. If you use any electronics on the boat or run the lights pretty often, you will need another way to charge the battery as the motor, while it will help, will not keep the battery fully charged unless you run it an awful lot.
I was Once Told...
...by a o/b dealer that if I suspected that a battery was overcharging (especially on a long run) then just to turn on a light that was connected to the overcharged battery. It would burn off any excess energy that was generated. FWIW
...by a o/b dealer that if I suspected that a battery was overcharging (especially on a long run) then just to turn on a light that was connected to the overcharged battery. It would burn off any excess energy that was generated. FWIW
Boil the Water
It isn't usually boiling it is electrolysis..splitting the water into hydrogen and oxygen. If you add some more distilled water there should be little if any damage. But as the others have said...unless you motor a whole lot overcharging shouldn't be a problem.
It isn't usually boiling it is electrolysis..splitting the water into hydrogen and oxygen. If you add some more distilled water there should be little if any damage. But as the others have said...unless you motor a whole lot overcharging shouldn't be a problem.
Overcharging
I have personally run my Johnson 15, which is the same motor as yours, as much as 22 hours straight at full throttle (it was a long trip). Although the voltmeter was reading as high as 15.5 at times, the amperage was not high enough to cause any damage or electrolyte loss. You don't really have anything to worry about.
I have personally run my Johnson 15, which is the same motor as yours, as much as 22 hours straight at full throttle (it was a long trip). Although the voltmeter was reading as high as 15.5 at times, the amperage was not high enough to cause any damage or electrolyte loss. You don't really have anything to worry about.
Thanks a ton folks!
Thanks a lot folks, soory it took a while to reply, was traveling last couple of days. I really appreciate the information from all.
Thanks a lot folks, soory it took a while to reply, was traveling last couple of days. I really appreciate the information from all.
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