12v DC should be easy right?
having an issue with the battery charge dropping to where I am getting failure to crank after a few hours of switch is left on.
Getting a static 1.5A draw with battery switch on and all systems off. Pulled EVERY fuse and connection I can find and cannot get a drop. Main cable wire will spark when connected too so definitely a draw.
Checked resistance in battery cables, all between 0.2-0.5ohms
Checked diodes on regulator, all good
Replaced battery
What am I missing?
Corrosion on battery terminals or wiring can cause a slow drain.
Do you have a float switch connected directly to the battery?
Battery is left on a charger at night so it goes from “full” to failure in a few hours
Terminals are fairly clean but I’m not naive to think there isn’t some corrosion somewhere.
Float switch as in bilge? Float circuit fuse has been pulled to eliminate that as well as pump replaced (full auto)
Hard to tell without looking it over. You have a massive draw/short somewhere though. If you can’t find it pulling fuses, that leads me to believe it might be the motor. Fuel pump or something stuck on.
I’ve seen this on customer boats and the battery cable ends looked great until I cut the heat shrink, stripped the insulation and found corrosion inside.
I’ve cut back over a foot of wire and still find corrosion on some boats. Marine grade heat shrink is cheap, don’t be a cheap azz.
Easiest way to tell, if the wire is stiff, it’s corroded.
I’ve pulled all the fuses as well as leads to the motor and draw doesn’t drop
Am I going to loose cranking power that quick over it? Leads ohm-d out Ok but not against just throwing new ones on.
I’f you can pull the wires off and add one at a time looking for a draw.
Do you have a main disconnect?
What kind of battery? Could have a cell going out in the battery. Could connect the battery wires, leaving all other electrical loads disconnected, and put a voltmeter across the terminals, then turn over the engine to see if the voltage pulls way down. If the voltage pulls way down, could be the battery is on its way out. If there is a master disconnect switch, put the voltmeter across the pos and neg terminals with the master “on”, should read over 12 VDC, turn the master switch off, voltage should stay the same. If not, there may be a parasitic drain on some device. Then could duplicate that procedure with master on, lifting one fuse at a time to try to find the offending device or circuit. Electrical problems can be fun. Corrosion can lead to some weird stuff happening.
Two items to check in addition.. If that cranking battery is at or nearing the three year mark - suspect it… and remember that if you have one of those “automatic bilge pumps” they work by periodically turning on no matter what you’re doing or where you are… they turn on, sound then turn off if no water is found - that might be the source of your drain - if it’s not turning off… Hope this helps