starter battery flat after couple of hours

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vasant

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Hi all,
Its quite a mystery to me what can be happening in this case that happenedalready now 2-3 times.
So first time 2 years ago we go sailing engine cranks normally after some hours of sailing battery is flat. Not even the lights of the panel light. After hand cranking the engine and going for half an hour battery is charged all is good. Then one day i come to boat battery is flat so it gets replaced.
Now after 1 year with NEW battery boat has cranked we go for training when trying to start engine again battery is flat.

Can there be something draining the battery? And randomly? Or am I just unlucky with batteries?
Service battery i always popped up, no issues.
 
Can a solenoid or something on the ignition system fail to disengage fully (key not turned back perhaps) & drain the battery? By hand cranking you are not using it so it does not engage electronically.
 
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Do you have a cold start mechanism that might be not disengaging?
half an hour doesn't seem long to fully charge from dead. Is it a v. small battery?
I wonder is the battery big enough, but if it works most of the time, only failing occasionally I suppose it might be.

Erratic faults like that can be a real pain, so unless you can trace it specifically I would consider having the starter/solenoid reconditioned, it may cure the problem, if not at least you can take it out of your diagnostics.
 
chewi said:
Do you have a cold start mechanism that might be not disengaging?
half an hour doesn't seem long to fully charge from dead. Is it a v. small battery?
I wonder is the battery big enough, but if it works most of the time, only failing occasionally I suppose it might be.

Erratic faults like that can be a real pain, so unless you can trace it specifically I would consider having the starter/solenoid reconditioned, it may cure the problem, if not at least you can take it out of your diagnostics.
Click to expand...
the solenoid would get very hot to drain a battery that fast
 
Old Harry said:
the solenoid would get very hot to drain a battery that fast
Click to expand...


I don't follow that Old Harry.
Would that be the starter solenoid or perhaps one on the cold start (if they use one at all)?
If a solenoid survives getting hot, it could be cold by the time the OP finds the battery flat, so he doesn't notice it being hot, yet it will still work next time, so he won't suspect it.

How fast is "that fast"?
I don't read any timings in the OP except the recharge in 30 mins?
 
Thanks all for your comments.
The battery is flat after some hours of sailing in one case it was 2hrs in another 5.

Something like a stuck solenoid is making sense however i wonder how to notice it. Of course a workaround could be to switch off engine main switch while sailing.
I was also aout to blame the old cabling, but this does not explain the randomness.....

The engine (old VP) has a coldstart plug, i never use it though. But i also dont think there is anything electrical connected to it.
thanks,
 
vasant said:
.....The battery is flat after some hours of sailing in one case it was 2hrs in another 5.Something like a stuck solenoid is making sense however i wonder how to notice it. Of course a workaround could be to switch off engine main switch while sailing. ....,
Click to expand...

2 hours of stuck solenoid would most likely be noticed by smell of overheating or burning and nasty noise from the starter motor when it starts to seize. Switching engine battery off when sailing is one option, assuming you also have a domestic battery for instruments and radio.
 
Sounds like your engine start battery is connected to the domestics. Highly unlikely anything on the engine is draining it. So, make sure it is completely isolated from anything else when not needed to start the engine.
 
Get a multimeter, on amps, connect it between the battery+ and the +tive lead. Don't try a start. Is there a drain showing? If so start disconnecting things including the starter and panel if necessary or removing fuses until it stops.
 
fisherman said:
Get a multimeter, on amps, connect it between the battery+ and the +tive lead. Don't try a start. Is there a drain showing? If so start disconnecting things including the starter and panel if necessary or removing fuses until it stops.
Click to expand...

Be simpler if the multimeter he gets has a DC clamp.
 
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