OX66 battery voltage problem

[maestro]

Have a single 1999 Yamaha 225 on a 24 Grady White. Set up with dual batteries via a Perko switch. Battery 1 reads 13.4 volts when under way. Switch to battery 2 and only reads 12.2 volts. Replaced battery 2 last week and still have the same problem. (The original battery 2 tested OK on the computerized load tester)

I searched and found a lot of issues like this on Yamahas but no real solution. Has anyone fixed a similar problem? I would think if it was the charging system it would affect both batteries.

Thanks, Don

[FishEye]

Are the wires clean at the battery switch?

[finadict]

There may be a couple of issues here, the most logical would be a bad connection on the second bat. either at the switch, cables or at the terminals. The second may be the charge state of the second bat, if the battery is discharged the charging voltage (what appears on the meter)will be below 13 volts, for the simple reason that the output of the alternator is not sufficent to put enough current into the battery and keep the the voltage in the 13 to 14 volt range that you would expect. Its a voltage drop, and is normal, but the indicated voltage should increase over time as the battery is charged.

[Gil Morgan]

Check the wire that connects the negative (-) or ground posts of the 2 batteries. That wire should be at least #2 wire. If the engine ground wire terminates on Bat #1 and the wire running between the 2 Bats is not large enough, there will be a voltage drop in that wire probably sufficient to account for the voltage difference at the meter. How does Bat 2 start the engine when connected?? If the wire is in fact too small, you will also notice a slugish cranking of the engine if it cranks at all.

[Harpoon]

Besides bad connections, your probably due for new batteries ....1999 ??

[Harpoon]

Sorry didn't read.

Did you check the water level in the new batteries ?

I got a crappy one from Boat US last year. When I topped it off with DI water it began charging fine.