Voltage drop test

[wayneo99]

2003 f225
motor has run great all summer, last week it started missing when the trim switch was activated even stalled at low RPM, also acted like I had a low/dead battery then it was fine.

watching the digital volt meter 13.6 to 14.2 while running, 12-12.6 with key on, hit the trim switch and it drops in the 11ish area sometimes it cuts out for a sec but not always.


I have three batteries and switched between each one and then combinations and finally all paralled with the same results, but not consistantly.

I pulled the terminals on the batts and the battery switches and cleaned them and made sure they were tight, took a look at the engine terminal block posts near the oil filter and they are tight. maybe there are other connections on the block I need to look at?

I did some searching on the forum and found a few threads with the same symptoms but no results.

I suspect I need to do a voltage drop test but CAN'T find the procedure.

The main engine battery is 3 years old, other 2 new this year, using the battery switch to swap in/out all the different combination leads me to think its engine cables or under the cover

thanks

 

[yamamarinetech40]

Re: Voltage drop test

OK, although you've changed switch positions to different batteries, when batts. are in parallel connection, the ground for ALL the batts. is still just the one ground on main batt., the other grounds are just connecting the batts. together, so only one ground path for ALL the batts...right? You could swap the old batt. to last place with one of the 'new' ones....also the batt. connections are easy to get to on motor, one is 12mm bolt, other is a 10mm bolt, think ground is the bigger, can't be sure....check both even if tight. Voltage drop is generic, just google VOLTAGE DROP TEST. Also could be your key switch, but my bet is grounds on motor(Yamaha uses grounds to complete circuits, not juice).