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2003 40hp merc

Discussion in 'Boats and Motors' started by shaprap RS, Jun 28, 2004.

  1. does anyone know what kinda voltage i should be getting to my starting battery from the motor while its running........1 year old battery went bad, im curious if its not being charged
  2. Use a voltmeter to check your battery with the engine not running. A fully charged battery should read at least 12.6 volts. Check the battery voltage again with the engine running at about mid throttle. The voltage should read higher than your original reading. My older Mercs put out as much as 16 volts depending on engine speed. Newer motors, such as yours, may be regulated better and not produce as much voltage but it should be at least 13 volts.

  3. My 02 merc 50 charges @ 14.1 volt at mid range. Needs to be over 13v to maintain a battery. Top end of 14.8v -15v or you will over charge your battery. Gel cells are even lower, 14.2 max.

  4. thanks for the input guys, checked it lastnight with the engine running, was getting 14.3 volts, eveything seems to be ok