DF 140 Alternator Voltage High

[jdensler]

I have two new (2010) Suzuki 140's. After running a while the battery voltage goes up to 14.8 volts. The suzuki manual allows up to 15.2 volts. Battery manufacturers indicate that 14.4 volts is a upper limit. (2.4 volts per cell.) I have just replaced the batteries earlier in the season and had the same problem with the old batteries. The old batteries test ok.

The dealer indicates that the local rep will not even look at the problem, as it is within manual specs. It looks as this is either a design or manufacturing problem as both engines exhibit the same voltage after the batteries are fully charged. This applies when either battery is connected or both batteries are connected to the engines.

An not quite fully charged battery showed 14.8 volts and 20 amperes charging current. For further details on lead acid wet cell batteries see Charging Information For Lead Acid Batteries ? Battery University

How do I get Suzuki to resolve this problem as this high voltage will cook the new batteries?

[courtenay7500]

go to a repable battery shop and talk to them.

[jdensler]

Hi Tim,

I am an EE with experience in the design of power supplies. The Suzuki designer did not consult with battery manufacturers on the alternator specifications. I spoke to the Excide folks and they referred me to the "Battery University" article referenced in my updated posting. Today, I was running 14.84 volts and 12 amps into one battery when both engines were turning about 1000 rpm, clearly too high! If I ran the engines very long, the batteries would bubble electrolyte and overflow! This would substantially cut down battery life.

John