Deschanel Posted February 10, 2008 Share Posted February 10, 2008 Just wondering if anyone knows what the charging voltage of a battery should be when the motor is going at high revs. The motor is a 1997 Johnson 30HP and we were getting around 12.3 volts across the terminals underway. Is this normal? How can it be fixed. No other instruments were being used at the time? Link to comment Share on other sites More sharing options...
tuffy Posted February 11, 2008 Share Posted February 11, 2008 That voltage is about right. Any more than that and you will stuff( blow up) the battery and all your electronics etc. Just make sure you have a voltage regulator fitted. If the engine doesn't have one internally then get one from someone like J**car or another electronics retailer. They should only cost about $10 with instructions on how to wire up into your wiring loom.Some of the older smaller motors have them and some don't. My old motor was a 25hp Jonno, 2000 model pull start and did not have one - cost me $100 worth of battery - cooked it big time. Link to comment Share on other sites More sharing options...
Hooky. Posted February 11, 2008 Share Posted February 11, 2008 Underway you should be getting about 13.5 and maybe 14 volts. Link to comment Share on other sites More sharing options...
impulse Posted February 14, 2008 Share Posted February 14, 2008 Just wondering if anyone knows what the charging voltage of a battery should be when the motor is going at high revs. The motor is a 1997 Johnson 30HP and we were getting around 12.3 volts across the terminals underway. Is this normal? How can it be fixed. No other instruments were being used at the time? Thats way to low, your battery should be about 12.6V standing voltage (battery fully charged with nothing connected). If it's at 12.2V while running you are not getting any charge at all and will die quickly because of the current used to start the motor. I think you need to check the charing circuit on the motor, it might be as simply as a fuse, loose connecting, or it maybe the magneto coil/s are dead. As stated earlier it should charge at full rev arround 13.5 to 14V's. I would charge the battery from a wall charger until the work out whats wrong, also buy a battery hydrometer (under $20) to see if any of the cells are the battery are dead (battery needs to be lead acid (car type), you cant use a hydrometer on a gel type battery). Link to comment Share on other sites More sharing options...
Deschanel Posted February 21, 2008 Author Share Posted February 21, 2008 Thanks for that guys will definitely have to get it checked out Link to comment Share on other sites More sharing options...
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