(Potentially) Catastrophic Electrical Shut-down
After the haul-out, the boat spent yesterday at at the visitors' dock, so I
decided to put the batteries - probably about 5 years old - on the
"Equalize" cycle. When I went back 8 hours later the boat was full of acrid
fumes from off-gassing. Since this was the first time I had done this
procedure, I wasn't aware of what the fumes implied. I aired the boat out,
and set the inverter to the normal charge cycle. When I went back this
morning to take the boat on the 3 hour trip back to its home dock, both the
house and start batteries were completely flat. I used the generator to
start the engine, and set out with the generator turned off. A couple of
hours later, I checked the panel again and everything was normal with the
batteries showing absolutely full charge.
Illusory happiness.
Just as I started to turn into my slip, everything on the boat just shut
down, including the engine and thruster. I was extraordinarily lucky in that
I was in a very difficult situation, drifting out of control with a lot of
expensive fiberglass very close at hand. Had the shut-down occurred a few
seconds earlier, there would have been some serious insurance claims. My
first instinct was to drop the anchor, it was held fast by the immobile
winch - no power - and I couldn't move it. The boat was pushed past the slip
by the light breeze, but breasted into an inflatable dinghy long enough for
me to jump to the dock with a line, and hold on until someone came to help.
Only because the slip with which mine shares was empty, between us, we were
able to manouver the boat into place and tie it up with absolutely no damage
to anything. This was little short of miraculous.
Then I went aboard and looked at the panel again. The "AC IN" LED showing
"Fault" and was solid red, as were the lower battery charge LED's. The best
explanation I've found so far is that the batteries were so close to the end
of their lives that equalizing simply killed them off. The fumes were
evidence of the degradation of the plates. The inverter sensed the absence
of charge in the battery banks, and went 'balls to the wall' as long as it
could to restore capacity. That caused it to overheat, so it shut itself
down. However, why there wasn't enough juice from the alternator with the
engine running at idle, I don't know, but the only way I can explain the
simultaneous engine shut-down is that the fuel pump cut out.
An electrician is coming to sort things out tomorrow and I'll report back.
Cheers, Garrett
Did you check your electrolyte level. Equalization on modern 3 stage
chargers is time and should be temperature limited. You must remove the caps
from lead acid batteries to permit the hydrogen to escape - the boat should
be open.
After equalization, it is often necessary to top-off the batteries with
distilled water. In fact, with hindsight, it would be wise to top them off
prior to equalization.
Ron Rogers
With all due respect I would not put batteries on equalize and leave the
boat for any lenght of time - especially the first time - I just don't
trust electronics that much.
Why did the engine quit ?? Good question. I would check the wiring from
the batteries. The alternator requires a battery to "excite" it.
I am contemplating buying an EZ-Puller anchor winch (drum type) however it
does not free-fall. I have been told free-fall is not required it powers
down very quickly!!
John
After the haul-out, the boat spent yesterday at at the visitors' dock, so
I
decided to put the batteries - probably about 5 years old - on the
"Equalize" cycle. When I went back 8 hours later the boat was full of
acrid
fumes from off-gassing. Since this was the first time I had done this
procedure, I wasn't aware of what the fumes implied. I aired the boat out,
The best
explanation I've found so far is that the batteries were so close to the
end
of their lives that equalizing simply killed them off. The fumes were
evidence of the degradation of the plates. The inverter sensed the absence
of charge in the battery banks, and went 'balls to the wall' as long as it
could to restore capacity.
Amazing that you did not get the hint from the 'acrid air'. The instructions
for equalize in all manuals I have seen say 'do not leave the batteries
unattended during equalize', and most require that batteries be at normal
fluid levels before equalize. The fumes had little or nothing to do with
degradation of the plates, everthing to do with too little care and
attention to the process. Once batteries go into thermal runaway, which is a
small possiblity here, the only thing to do is complete disconnect, that is
no charge, no load. This is also not a time to attempt adding water.
It is also possible (but unlikely) that the odor came from a source other
than the batteries.
Many inverters have a time component in the charge cycle that will limit the
period of time bulk charge was on. (also true for equalize). Check to see
that the standard times have not been tampered with. The situation you
describe was much more common with ferroresonant chargers that typically did
not have time control on the charge cycle.
Aside from the electric fuel pump possibility, if the engine has a very
large alternator and is a moderate size engine, it is possible the engine at
idle was stalled by the alternator load if the alternator was fully loaded
serving all the electric demands. I would go over every connection in your
high amp circuitry and check for 'clean and tight' after an event like this.
Also check on wire sizes and breaker functioning. Look for signs of burned
wire ends especially under connectors or other areas where wires are
'packed'.
Consider a breaker on your charge line from the alternator sized to protect
the wire.
Richard