Yamaha F75 charging prblem

[triumph3]

2004 F75 4 stroke-300hrs.-/while running I noted low voltage (12.2) on dash volt display. Checked generator input to Batt. at about 7amps.Realizing generator rated at 25 amp output and usually kicks volts up to 13v plus, Increasing rpms decreased voltage to 12, then at lower rpm increased to 12.4. Cleaned all batt. connections and batt. all seemed good. In checking posts I note that diodes and regulator mentioned as cause for low output. Any advice of process (manuals,testing etc) would be greatly appreciated. Thanks, Vern

 

[Lone Duck]

Re: Yamaha F75 charging prblem

Send for a manufactures manuel . They will tell you the correct testing meters and values. And how to test.

 

[Silvertip]

Re: Yamaha F75 charging prblem

7 amps being fed TO the battery means the battery is charging. However, where you measured this 7A means the battery may actually have been DISCHARGING at 7A rather than charging. It is the voltage regulator that determines how much is being fed to the battery so it may rarely charge at the full 25 amp rate. So lets have a look at how you did this 7A check. The fact is however, if the VOLTMETER (not AMMETER) you are using is measuring less than 13 - 13.5 volts at moderate RPM then the battery is definitely not being charged. To measure amperage you need to break the connection from the charging system (not at the battery because that big cable is a two-way street). You insert the ammeter leads between the where the voltage regulator output lead was connected and the lead itself. Now run the engine and make your measurement.

 

[99yam40]

Re: Yamaha F75 charging prblem

Or use a clamp on DC amp meter to put around the cable/wire to read it, but need to make sure how you put it around it so you can see which direction the current is flowing

 

[triumph3]

Re: Yamaha F75 charging prblem

Or use a clamp on DC amp meter to put around the cable/wire to read it, but need to make sure how you put it around it so you can see which direction the current is flowing

Thanks for feedback. I will complete all testing again now that you explained it so this dummy can understand. I thought single small red wire (with fuse) attached to positive post on batt. was from charger instead of leading to bilge pump.

 

[triumph3]

Re: Yamaha F75 charging prblem

I checked volts/amps again. Battery at rest-12.4 volts @700 -1200rpm-12.4 volts on dash volt gauge with no change with engine running/ 1 amp measured on red battery line from engine while running. It seemed to have decreased from 7 amps. yesterday. I think I'll break down and order the $70 Yamaha repair manual. If there is something easy that I'm missing , I'd appreciate a note. Thanks again