|
|
05-01-2014, 06:57
|
#1
|
Registered User
Join Date: Feb 2013
Location: Santa Monica, CA
Boat: Club Sailor; various
Posts: 922
|
Turning off Ignition?
One of the things I was taught early and continue to tell people who have less experience than I do is never turn off the ignition key while the engine is running but not being a mechanic I'm not sure why.
What damage does it cause? Alternator, regulator, batteries; what?
|
|
|
05-01-2014, 07:11
|
#2
|
Registered User
Join Date: Jun 2012
Location: england east coast
Posts: 65
|
Re: Turning off ignition?
Alternator becomes unregulated by loosing ignition feed
Sent from my HTC One S using Cruisers Sailing Forum mobile app
|
|
|
05-01-2014, 08:27
|
#3
|
Registered User
Join Date: Feb 2013
Location: Santa Monica, CA
Boat: Club Sailor; various
Posts: 922
|
Re: Turning off ignition?
Quote:
Originally Posted by wmcruiser
Alternator becomes unregulated by loosing ignition feed
|
And then what happens?
|
|
|
05-01-2014, 08:32
|
#4
|
Registered User
Join Date: Dec 2008
Location: Oriental, NC
Boat: Mainship Pilot 34
Posts: 1,461
|
Re: Turning off ignition?
Nothing happens. When you turn off the ignition the regulator stops sending current to the field winding and the alternator stops putting out current. No damage though.
You are probably thinking about another alternator no no: never turn the 1,2,all,off switch to off while the engine is running. That leaves the alternator with suddenly no where to put its juice and the voltage spikes and blows the alternator diodes. A Zap Stop diode will usually protect from that happening however.
David
|
|
|
05-01-2014, 08:45
|
#5
|
Registered User
Join Date: Feb 2013
Location: Santa Monica, CA
Boat: Club Sailor; various
Posts: 922
|
Re: Turning off ignition?
Quote:
Originally Posted by djmarchand
Nothing happens. When you turn off the ignition the regulator stops sending current to the field winding and the alternator stops putting out current. No damage though.
David
|
The school/charter company made a big deal about it when I was starting out I assumed it burns something up otherwise why emphasize it?
Better safe than sorry I guess.
|
|
|
05-01-2014, 08:56
|
#6
|
Registered User
Join Date: Dec 2009
Boat: JBW club 420, MFG Bandit, Snark
Posts: 871
|
I imagine, on most boats, oil pressure alarms and such would cease to function as well.
__________________
I love big boats and I can not lie.
|
|
|
05-01-2014, 09:02
|
#7
|
Registered User
Join Date: Sep 2009
Location: Houston
Boat: ‘01 Catana 401
Posts: 9,626
|
Re: Turning off ignition?
This all depends on how the alternator is wired. On our boat, all that happens is the power to the alt regulator is cut, rendering no output. On some small OEM installations (not too common) the alternator output ran through the ignition switch, turning off this switch would then cause the alternator to see an open in the path to the batteries, and as a result the rectifier diodes would burn out. IMHO this was a really dumb way to wire the output anyway......
|
|
|
05-01-2014, 09:02
|
#8
|
Registered User
Join Date: Mar 2012
Location: On board in Leros, Greece
Boat: Hunter Legend 420 Passage
Posts: 863
|
Re: Turning off ignition?
Not a problem.
This is one very good way to force the external regulator back into Boost mode when it has prematurely dropped down to Float mode. Try this as soon as the regulator has fallen to Float and see the difference in charging current when the voltage goes from 13.2v to 14.4v.
|
|
|
05-01-2014, 09:21
|
#9
|
Registered User
Join Date: Feb 2013
Location: Santa Monica, CA
Boat: Club Sailor; various
Posts: 922
|
Re: Turning off ignition?
Is it possible turning off the ignition and motoring for an extended period of time can burn up the alternator (bad) or burn up the regulator which then results in overcharging and damaging the batteries and then burning up the alternator as well (worse)?
|
|
|
05-01-2014, 09:26
|
#10
|
Registered User
Join Date: Sep 2009
Location: Houston
Boat: ‘01 Catana 401
Posts: 9,626
|
Quote:
Originally Posted by OldFrog75
Is it possible turning off the ignition and motoring for an extended period of time can burn up the alternator (bad) or burn up the regulator which then results in overcharging and damaging the batteries and then burning up the alternator as well (worse)?
|
Again depends on how the boat is wired, but normally all that happens to the alt is that it is turned off. I could motor for days with the ignition switch off and suffer no ill effects.
|
|
|
05-01-2014, 09:41
|
#11
|
Registered User
Join Date: Mar 2011
Posts: 88
|
Re: Turning off ignition?
On most boats when you turn off the ignition you also turn off the oil pressure sender and the temperature sender too. Not a big deal for a short while and if you are careful but under some conditions could ruin the engine.
|
|
|
05-01-2014, 09:54
|
#12
|
Registered User
Join Date: Mar 2007
Location: Santa Cruz
Boat: SAnta Cruz 27
Posts: 6,711
|
Re: Turning off ignition?
On some boats, the stop solenoid is energized by the ignition switch, so it won't work if you turn off the ignition. Otherwise its no big deal.
|
|
|
05-01-2014, 11:06
|
#13
|
Registered User
Join Date: Jul 2010
Location: Southern California...s/v Feral Cat Catalina 38' S&S design
Boat: Catalina 38' S&S design
Posts: 66
|
Re: Turning off ignition?
Guess i am just curious, why would you WANT to shut off the key only? What would be the benefit to this? Sounds and seems like way too many risks associated...
__________________
Wayne
= =
|
|
|
05-01-2014, 11:25
|
#14
|
Registered User
Join Date: Mar 2012
Location: On board in Leros, Greece
Boat: Hunter Legend 420 Passage
Posts: 863
|
Re: Turning off ignition?
Quote:
Originally Posted by Feral Cat
Guess i am just curious, why would you WANT to shut off the key only? What would be the benefit to this? Sounds and seems like way too many risks associated...
|
Read my post #8.
|
|
|
05-01-2014, 11:33
|
#15
|
Registered User
Join Date: Oct 2005
Location: Presently on US East Coast
Boat: Manta 40 "Reach"
Posts: 10,108
|
Re: Turning off ignition?
Quote:
Originally Posted by sailinglegend
Not a problem.
This is one very good way to force the external regulator back into Boost mode when it has prematurely dropped down to Float mode. Try this as soon as the regulator has fallen to Float and see the difference in charging current when the voltage goes from 13.2v to 14.4v.
|
This is probably regulator brand/model dependent. On our two different brand/model regulators, if the batteries were in float and the regulators turned on and off, both go to 14.8V, but drop back down into float within a minute or two, and put in almost no current in that short time before float.
What would make a regulator prematurely drop into float? Another current source at a higher set voltage than the regulator?
Mark
__________________
www.svreach.com
You do not need a parachute to skydive. You only need a parachute to skydive twice.
|
|
|
|
|
Thread Tools |
Search this Thread |
|
|
Display Modes |
Rate This Thread |
Linear Mode
|
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|
Advertise Here
Recent Discussions |
|
|
|
|
|
|
|
|
|
|
|
|
Vendor Spotlight |
|
|
|
|