Low Battery

[jc27]

Please Help I Replaced All 4 Of My Batterys And Took Ride Yesterday My Battery Guage Was 11 And Falling Got Down Under 10 Depth Finder Stoped Working And Other Issue That Are From Low Battery This Is Why I Replaced Them To Begin The Year, At One Point I Was Cruising Around 17knts And Guage Went Up Around 12 But Came Back Down Minutes Later The Port Battery Seemed Lower Than Normal I Have 1batt For Port 2batt For Starbord Connected With Factory Jumper Wires And 1 Batt For Generator

 

[Morpheus]

Did you check your alternator?

 

[gerryb]

+1 on your alternator as a likely culprit. Do this. Charge your batteries fully. Then check your depth gauge and other electronics when at the dock with engines off as they will only be running by the battery. If all seems OK, then your bats are fine.

Doesn't it take you longer to type in mixed case?

 

[fc3]

First things first. Ensure the battery switches are on. Since you have twins you might have the cross-over charging option. That consists of a rectifier mounted on the bulkhead. Usually has a huge heat sink and four large gauge red or orange wires attached to it. Check that the battery connections, they're marked as such, have full same voltage as measured at the batteries. If not, you have a wiring problem. Now disconnect the battery wires after turning off the battery switches. Perform a diode test ensuring that current flows from the alternator 1 terminal to both the battery 1 and battery 2 terminals. (One way only! It's a diode test!) Then test ensuring that current flows from the alternator 2 terminal to both the battery 1 and battery 2 terminals. (One way only! It's a diode test!)

If the diode test fails, replace the isolator. Reconnect the battery wires to the isolator and turn on the battery switches.

Check that there is little or no resistance between the alternator terminal and the orange wire on the back of the alternator. Don't know if the port or starboard engine is alternator 1 and which is 2. One of them should conduct to one of the alternators and the other terminal to the other engine's alternators. If you have no reading, look for a wiring problem.

If you don't have an isolator, you should see battery voltage on the alternator terminal with the orange wire attached. If not, you have a wiring problem.

If you've found nothing this far, you have an alternator problem.

Stick a metal tab into the full field regulator bypass. Start the engine and measure the voltage at the orange wire's terminal on the alternator. If the voltage goes over 14 then the regulator is bad. Replace the regulator.

If you're not reading over 14, the rectifiers are bad or the brushes are bad. It's possible, but unlikely that the windings are bad. Some brushes and regulators can be replaced without opening the case. Pull the regulator assembly and check the brushes. If they're worn, replace them. Brushes are cheap, about $5. You'll get intermittent charging as the brushes fail.

To replace the rectifier bridge, you have to open the alternator case. The rectifiers are mounted as a set and screw to the case. Three wires from the stator attach to the diode assembly. Do a diode test again to verify that the diode assembly is bad. Test from each stator terminal to ground and from each stator terminal to the output stud. Open or shorted diodes indicate that the assembly needs replacement.

Best regards,
Frank C

 

[rondds]

jc27:
that's gotta be hard to type the first letter of every word in caps! i'm so friggin lazy i dont bother with caps at all!

uh, what was the question?