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Is high charge voltage corrupting tach reading

G

gdog

New member
"Further to my problem with my

"Further to my problem with my "new" powerhead having a high indicated engine speed but the boat speed being lower that previous, the system voltage according to my fish finder volt meter is around 15.8 volts at 5000 rpm on the tach.

Is this too high and would it cause the tach to read higher than actual? The motor is a 1986 Johnson 140

Graeme"
 
"No. Voltage has nothing to do

"No. Voltage has nothing to do with tach reading. The only way to 'test' tach by using a multimeter, is You may use the Hz function, if You got one, and divide the reading by 6 measuring on the yellow/gray cable (tach cable) from stator to rectifier."
 
"A bit on the high side, but n

"A bit on the high side, but not abnormal for outboards. It might depend on battery type and condition. Some instruments might start to be 'unhappy' if it climbs past 16 Volts, fish finders normally have an automatic 'switch' 12-30 Volts to be able to be used on both 12 and 24 Volt systems. Main problem might be running life of light bulbs like navigation etc."
 
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