I purchased my Cd 28 from an estate. The original owner died and thus I have many unanswered questions so patients please. I was looking through the owners manual for my Universal 18 (I think 18)and read that I should not shut off the engine with the decompression lever. I have a plunger type knob on my gauge panel along with a tachometer, amp meter, glow plug button, start button, and keyed off/on switch. I have been pulling the plunger to shut down the engine. Is this the decompression lever (which will damage the exhaust valves according to the manual) or is this the correct procedure?? If this knob that I have been pulling is not the decompression lever, what is it?? Oh yeah, I have a single lever which controls the FWD/REV and throttle. All help appreciated!
MTaylor673@aol.com
proper method for engine shut down (Universal 18)
Moderator: Jim Walsh
-
tom b
Re: proper method for engine shut down (Universal 18)
I purchased my Cd 28 from an estate. The original owner died and thus I have many unanswered questions so patients please. I was looking through the owners manual for my Universal 18 (I think 18)and read that I should not shut off the engine with the decompression lever. I have a plunger type knob on my gauge panel along with a tachometer, amp meter, glow plug button, start button, and keyed off/on switch. I have been pulling the plunger to shut down the engine. Is this the decompression lever (which will damage the exhaust valves according to the manual) or is this the correct procedure?? If this knob that I have been pulling is not the decompression lever, what is it?? Oh yeah, I have a single lever which controls the FWD/REV and throttle. All help appreciated!Mac Taylor wrote: you are using the right item to shut off your engine . the decompression lever is on your engine ,it is located on top of the engine and is part of the valve cover .it looks like a little lever,you can lift it up when the engine is not running . it takes compression off the pistons/valves. have someone pull the engine shut off from cockpit while you look at engine to see where this cable connects on engine . if the cable breaks or jams or whatever you will know how to shut down the engine.
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D. Stump, Hanalei
Re: proper method for engine shut down (Universal 18)
Mac,
Yes, that is the proper way to shut her down. First idel down the engine for a couple minutes to let it cool off a little, pull the plunger on the instrument panel, and then, AND ONLY THEN, turn off the key! Never turn the key off when the engine is running, this will hurt the alternator.
Dave Stump
Captain Commanding
s/v Hanalei CD-30 (with Universal 18, 14 HP diesel)
Yes, that is the proper way to shut her down. First idel down the engine for a couple minutes to let it cool off a little, pull the plunger on the instrument panel, and then, AND ONLY THEN, turn off the key! Never turn the key off when the engine is running, this will hurt the alternator.
Dave Stump
Captain Commanding
s/v Hanalei CD-30 (with Universal 18, 14 HP diesel)
-
Larry DeMers
Re: proper method for engine shut down (Universal 18)
Mac,
Yup, as Dave Stump said..that is the correct way to shut down the engine. The key switch however, is simply a switch that connects power to the eng.temp sensor, dash board lights, engine run-time gage if so equipped. It *is not* a source of power to the alternator field winding, and therefore can be shut off with out fear of damaging anything. Dave has this mixed up with the Battery selector switch that selects Battery 1-2-both-off. This switch will damage the alternator diodes if it is switched to any other position while the engine is running. Leave it in one position while running.
The decompression lever should be on the engine top. I have the Volvo MD7B, and it is on the top front, but your Universal will be slightly different. The stop lever in the cockpit mounted panel cuts the flow of diesel to the injector rail.
Have fun with a great boat!
Larry DeMers
s/v DeLaMer
demes@sgi.com
Yup, as Dave Stump said..that is the correct way to shut down the engine. The key switch however, is simply a switch that connects power to the eng.temp sensor, dash board lights, engine run-time gage if so equipped. It *is not* a source of power to the alternator field winding, and therefore can be shut off with out fear of damaging anything. Dave has this mixed up with the Battery selector switch that selects Battery 1-2-both-off. This switch will damage the alternator diodes if it is switched to any other position while the engine is running. Leave it in one position while running.
The decompression lever should be on the engine top. I have the Volvo MD7B, and it is on the top front, but your Universal will be slightly different. The stop lever in the cockpit mounted panel cuts the flow of diesel to the injector rail.
Have fun with a great boat!
Larry DeMers
s/v DeLaMer
D. Stump, Hanalei wrote: Mac,
Yes, that is the proper way to shut her down. First idel down the engine for a couple minutes to let it cool off a little, pull the plunger on the instrument panel, and then, AND ONLY THEN, turn off the key! Never turn the key off when the engine is running, this will hurt the alternator.
Dave Stump
Captain Commanding
s/v Hanalei CD-30 (with Universal 18, 14 HP diesel)
demes@sgi.com
-
Don Sargeant
Re: proper method for engine shut down (Universal 18)
Larry,
How does one, then, charge both batteries? I use #1 for engine starting and #2 for house accessories. I switch to "both" after the engine has started. If this is incorrect, what is the right way? How long does it take to replenish the juice used by starting (assuming the egine kicks right on)?
Don Sargeant
~~COQUINA~~
CD25D #189
Greenwich Cove
don@cliggott.com
How does one, then, charge both batteries? I use #1 for engine starting and #2 for house accessories. I switch to "both" after the engine has started. If this is incorrect, what is the right way? How long does it take to replenish the juice used by starting (assuming the egine kicks right on)?
Don Sargeant
~~COQUINA~~
CD25D #189
Greenwich Cove
Larry DeMers wrote: Mac,
Yup, as Dave Stump said..that is the correct way to shut down the engine. The key switch however, is simply a switch that connects power to the eng.temp sensor, dash board lights, engine run-time gage if so equipped. It *is not* a source of power to the alternator field winding, and therefore can be shut off with out fear of damaging anything. Dave has this mixed up with the Battery selector switch that selects Battery 1-2-both-off. This switch will damage the alternator diodes if it is switched to any other position while the engine is running. Leave it in one position while running.
The decompression lever should be on the engine top. I have the Volvo MD7B, and it is on the top front, but your Universal will be slightly different. The stop lever in the cockpit mounted panel cuts the flow of diesel to the injector rail.
Have fun with a great boat!
Larry DeMers
s/v DeLaMer
D. Stump, Hanalei wrote: Mac,
Yes, that is the proper way to shut her down. First idel down the engine for a couple minutes to let it cool off a little, pull the plunger on the instrument panel, and then, AND ONLY THEN, turn off the key! Never turn the key off when the engine is running, this will hurt the alternator.
Dave Stump
Captain Commanding
s/v Hanalei CD-30 (with Universal 18, 14 HP diesel)
don@cliggott.com
-
Brewer Ezzell
Re: proper method for engine shut down (Universal 18)
Don,
Several options. From your slip or mooring, start the engine with your switch on "both", and then switch to "house" as soon as you are under sail and kill the engine. This way, you are not depleting your starting bank while you sail and have charged both banks while motoring. Better would be to add an isolator or battery combiner so that you get charging to both banks. Please note, however, that an isolator and a combiner perform different functions. West Marine's catalog can explain the difference to you.
Personally, I would go with an isolator and thus charge all banks whenever the engine is running. I also would have a second switch which allowed me to start the battery from the "start" bank and always have the boat on the house bank. You could still parallel the banks to provide emergency starting from the house bank. In addition, this provides you a way to "kill" power going to the starter. Last fall, my starter shorted out and tried a melt-down. I was able to cut off the electricity going to the starter, letting the engine continue to run. Without the second switch, my options would have been to cut the master switch to OFF, letting the engine continue to run to maintain steerage, and thereby ZAPPING the alternator, or cutting the engine off and then cutting the master switch to OFF to stop the electricity to the starter and preventing the melt-down. Of course, then, I'm faced with the decision of raising sails to sail out of my problem, or dropping anchor in a narrow channel. Also, if you should install a second switch, make sure that only individuals that understand the settings ever make adjustments to the switches. My actual bank configeration was House #1, House #2, and Start. The main switch went only to the two house banks (House #1,House #2, BOTH or OFF). The second switch, when set on "#1", went to the start battery, "#2" went to the house switch which allows starting from the house banks, "BOTH" paralleled the start battery with whichever bank was engaged on the house switch, and "OFF" killed all power going to the starter.
Brewer Ezzell
BLACKBERRY
a Chuck Paine Frances 26 by Morris
bezzell@murphyfarms.com
Several options. From your slip or mooring, start the engine with your switch on "both", and then switch to "house" as soon as you are under sail and kill the engine. This way, you are not depleting your starting bank while you sail and have charged both banks while motoring. Better would be to add an isolator or battery combiner so that you get charging to both banks. Please note, however, that an isolator and a combiner perform different functions. West Marine's catalog can explain the difference to you.
Personally, I would go with an isolator and thus charge all banks whenever the engine is running. I also would have a second switch which allowed me to start the battery from the "start" bank and always have the boat on the house bank. You could still parallel the banks to provide emergency starting from the house bank. In addition, this provides you a way to "kill" power going to the starter. Last fall, my starter shorted out and tried a melt-down. I was able to cut off the electricity going to the starter, letting the engine continue to run. Without the second switch, my options would have been to cut the master switch to OFF, letting the engine continue to run to maintain steerage, and thereby ZAPPING the alternator, or cutting the engine off and then cutting the master switch to OFF to stop the electricity to the starter and preventing the melt-down. Of course, then, I'm faced with the decision of raising sails to sail out of my problem, or dropping anchor in a narrow channel. Also, if you should install a second switch, make sure that only individuals that understand the settings ever make adjustments to the switches. My actual bank configeration was House #1, House #2, and Start. The main switch went only to the two house banks (House #1,House #2, BOTH or OFF). The second switch, when set on "#1", went to the start battery, "#2" went to the house switch which allows starting from the house banks, "BOTH" paralleled the start battery with whichever bank was engaged on the house switch, and "OFF" killed all power going to the starter.
Brewer Ezzell
BLACKBERRY
a Chuck Paine Frances 26 by Morris
bezzell@murphyfarms.com
-
Larry DeMers
Re:Starting Engine Procedure..answer to Don Sargent
Don,
To charge two batteries, put the battery selector on "both", and allow to recharge. Realize that the lower discharged battery will take the majority of the charge current. This means that the alternator sees the lowest charged battery only, and then charges to what it sees. The higher charged battery then will tend to be overcharged. A way around this is to leave the battery switch on "both" for an appropriate amount of time (for a starter battery that has just cranked an engine over to start it, the recharge for that could be put off for some time, or allow 10 minutes to do the charging, then stop the engine and switch over to only the battery that needs charging.
Another alternative is buying a new battery switch that includes a "field disconnect" wiper in it. The field of the alternator is attached to this wiper, which disconnectsd the field voltage before the switch changes loads. That is that the alternator is turned off with the field voltage going to zero while the battery switch is moving from position to position, then it is remade, reconnecting the field winding.. Now if you choose this route, you will be replacing the alternator with an external regulated alternator so that the field power is supplied from an external source. You may be farther ahead to just do the first suggested operation..charge both, then shut down and charge a single one. OR..use a battery combiner to direct the alternator charge to the battery needing it most. I do not have experience with these, and am frankly suspicious as to how effective they may be. All reviews I have read however are positive.
I would not recommend that you switch that battery switch at any time that the engine is running.
Nor would I recommend that you use Battery Isolators. Battery Isolators have an inherent problem in that they drop 7-800 mV while charging. This means that the battery will **never** reach full charge, as the voltage that it sees will always be 7-800 mV low when the alternator thinks that the battery is full. That means that the battery will always be recharged only to the 80-85% range. This shortens the battery life remarkably.
Regards,
Larry DeMers
s/v DeLaMer
Cape Dory 30 ~~~~~~~~~~Sailing Lake Superior~~~~~~~
demers@sgi.com
To charge two batteries, put the battery selector on "both", and allow to recharge. Realize that the lower discharged battery will take the majority of the charge current. This means that the alternator sees the lowest charged battery only, and then charges to what it sees. The higher charged battery then will tend to be overcharged. A way around this is to leave the battery switch on "both" for an appropriate amount of time (for a starter battery that has just cranked an engine over to start it, the recharge for that could be put off for some time, or allow 10 minutes to do the charging, then stop the engine and switch over to only the battery that needs charging.
Another alternative is buying a new battery switch that includes a "field disconnect" wiper in it. The field of the alternator is attached to this wiper, which disconnectsd the field voltage before the switch changes loads. That is that the alternator is turned off with the field voltage going to zero while the battery switch is moving from position to position, then it is remade, reconnecting the field winding.. Now if you choose this route, you will be replacing the alternator with an external regulated alternator so that the field power is supplied from an external source. You may be farther ahead to just do the first suggested operation..charge both, then shut down and charge a single one. OR..use a battery combiner to direct the alternator charge to the battery needing it most. I do not have experience with these, and am frankly suspicious as to how effective they may be. All reviews I have read however are positive.
I would not recommend that you switch that battery switch at any time that the engine is running.
Nor would I recommend that you use Battery Isolators. Battery Isolators have an inherent problem in that they drop 7-800 mV while charging. This means that the battery will **never** reach full charge, as the voltage that it sees will always be 7-800 mV low when the alternator thinks that the battery is full. That means that the battery will always be recharged only to the 80-85% range. This shortens the battery life remarkably.
Regards,
Larry DeMers
s/v DeLaMer
Cape Dory 30 ~~~~~~~~~~Sailing Lake Superior~~~~~~~
Don Sargeant wrote: Larry,
How does one, then, charge both batteries? I use #1 for engine starting and #2 for house accessories. I switch to "both" after the engine has started. If this is incorrect, what is the right way? How long does it take to replenish the juice used by starting (assuming the egine kicks right on)?
Don Sargeant
~~COQUINA~~
CD25D #189
Greenwich Cove
Larry DeMers wrote: Mac,
Yup, as Dave Stump said..that is the correct way to shut down the engine. The key switch however, is simply a switch that connects power to the eng.temp sensor, dash board lights, engine run-time gage if so equipped. It *is not* a source of power to the alternator field winding, and therefore can be shut off with out fear of damaging anything. Dave has this mixed up with the Battery selector switch that selects Battery 1-2-both-off. This switch will damage the alternator diodes if it is switched to any other position while the engine is running. Leave it in one position while running.
The decompression lever should be on the engine top. I have the Volvo MD7B, and it is on the top front, but your Universal will be slightly different. The stop lever in the cockpit mounted panel cuts the flow of diesel to the injector rail.
Have fun with a great boat!
Larry DeMers
s/v DeLaMer
D. Stump, Hanalei wrote: Mac,
Yes, that is the proper way to shut her down. First idel down the engine for a couple minutes to let it cool off a little, pull the plunger on the instrument panel, and then, AND ONLY THEN, turn off the key! Never turn the key off when the engine is running, this will hurt the alternator.
Dave Stump
Captain Commanding
s/v Hanalei CD-30 (with Universal 18, 14 HP diesel)
demers@sgi.com
-
Don Sargeant
Re:Starting Engine Procedure..answer to Don Sargent
Larry,
Thanks for the input. But as is usually the case your answer raises some more questions. I've been starting on #1, then switching to both. I not aware of any damage -- maybe I'm just being blind and it's too soon in the season to have run out of juice -- but it seems to me that CD wouldn't have installed a system where the alternator could be cooked so easily. Wouldn't shutting down and switching obviate the "one battery for starting and one for the house" approach that's touted by West and others? You'd be chasing your tail by constantly needing to replenish the starting battery. My old boat made life simpler -- one battery for all (but it was usually pretty flat).
Thanks for the dialog..
Don Sargeant
~~COQUINA~~
CD25D #189
Greenwich Cove
don@cliggott.com
Thanks for the input. But as is usually the case your answer raises some more questions. I've been starting on #1, then switching to both. I not aware of any damage -- maybe I'm just being blind and it's too soon in the season to have run out of juice -- but it seems to me that CD wouldn't have installed a system where the alternator could be cooked so easily. Wouldn't shutting down and switching obviate the "one battery for starting and one for the house" approach that's touted by West and others? You'd be chasing your tail by constantly needing to replenish the starting battery. My old boat made life simpler -- one battery for all (but it was usually pretty flat).
Thanks for the dialog..
Don Sargeant
~~COQUINA~~
CD25D #189
Greenwich Cove
Larry DeMers wrote: Don,
To charge two batteries, put the battery selector on "both", and allow to recharge. Realize that the lower discharged battery will take the majority of the charge current. This means that the alternator sees the lowest charged battery only, and then charges to what it sees. The higher charged battery then will tend to be overcharged. A way around this is to leave the battery switch on "both" for an appropriate amount of time (for a starter battery that has just cranked an engine over to start it, the recharge for that could be put off for some time, or allow 10 minutes to do the charging, then stop the engine and switch over to only the battery that needs charging.
Another alternative is buying a new battery switch that includes a "field disconnect" wiper in it. The field of the alternator is attached to this wiper, which disconnectsd the field voltage before the switch changes loads. That is that the alternator is turned off with the field voltage going to zero while the battery switch is moving from position to position, then it is remade, reconnecting the field winding.. Now if you choose this route, you will be replacing the alternator with an external regulated alternator so that the field power is supplied from an external source. You may be farther ahead to just do the first suggested operation..charge both, then shut down and charge a single one. OR..use a battery combiner to direct the alternator charge to the battery needing it most. I do not have experience with these, and am frankly suspicious as to how effective they may be. All reviews I have read however are positive.
I would not recommend that you switch that battery switch at any time that the engine is running.
Nor would I recommend that you use Battery Isolators. Battery Isolators have an inherent problem in that they drop 7-800 mV while charging. This means that the battery will **never** reach full charge, as the voltage that it sees will always be 7-800 mV low when the alternator thinks that the battery is full. That means that the battery will always be recharged only to the 80-85% range. This shortens the battery life remarkably.
Regards,
Larry DeMers
s/v DeLaMer
Cape Dory 30 ~~~~~~~~~~Sailing Lake Superior~~~~~~~
Don Sargeant wrote: Larry,
How does one, then, charge both batteries? I use #1 for engine starting and #2 for house accessories. I switch to "both" after the engine has started. If this is incorrect, what is the right way? How long does it take to replenish the juice used by starting (assuming the egine kicks right on)?
Don Sargeant
~~COQUINA~~
CD25D #189
Greenwich Cove
Don Sargeant wrote:Larry DeMers wrote: Mac,
Yup, as Dave Stump said..that is the correct way to shut down the engine. The key switch however, is simply a switch that connects power to the eng.temp sensor, dash board lights, engine run-time gage if so equipped. It *is not* a source of power to the alternator field winding, and therefore can be shut off with out fear of damaging anything. Dave has this mixed up with the Battery selector switch that selects Battery 1-2-both-off. This switch will damage the alternator diodes if it is switched to any other position while the engine is running. Leave it in one position while running.
The decompression lever should be on the engine top. I have the Volvo MD7B, and it is on the top front, but your Universal will be slightly different. The stop lever in the cockpit mounted panel cuts the flow of diesel to the injector rail.
Have fun with a great boat!
Larry DeMers
s/v DeLaMer
don@cliggott.com
-
Larry DeMers
Re:Starting Engine Procedure..answer to Don Sargent
Don,
It depends on which package the original owner ordered for the boat. If he opted for the more deluxe package, CD may have included a "Make_Before_Break" battery switch, which will make the next connection before breaking the previous connection. In your case, as you switch from batt. 1 to both, the battery switch contacts "both" before it breaks the #1 connection. This saves your alternator diodes from a 'no-load' condition (which if allowed to occur, will let the alternator output increase to 100-200vac, which is too much voltage for the diodes to handle, so they blow open..and it will take out light bulbs, leds etc that are connected and on at that time).
The thing that you most certainly DO NOT want to do is to turn the battery switch to off. Regardless of which switch you have, this will remove all loads from the alternator, and blow the diodes..*except* in the case of the battery switch that has a field disconnect contact wired to an after-market alternator. This scenario would disconnect the field voltage before the battery switch moves on to the next position. But you need to have an alternator that has been modified for external field control or an after-market alternator that has an external regulator.
Cape Dory provided a neat little warning plaque with our boat, written in two languages (Swedish and English -one on each side of the plaque)that says DO NOT MOVE BATTERY SWITCH WHILE ENGINE IS RUNNING. So they did provide a system that could destry the diodes if operated improperly..but so did everyone else. An upgrade of that system would replace that battery switch with a make-before-break switch.
Cheers!
Larry DeMers
s/v DeLaMer
Cape Dory 30
demers@sgi.com
It depends on which package the original owner ordered for the boat. If he opted for the more deluxe package, CD may have included a "Make_Before_Break" battery switch, which will make the next connection before breaking the previous connection. In your case, as you switch from batt. 1 to both, the battery switch contacts "both" before it breaks the #1 connection. This saves your alternator diodes from a 'no-load' condition (which if allowed to occur, will let the alternator output increase to 100-200vac, which is too much voltage for the diodes to handle, so they blow open..and it will take out light bulbs, leds etc that are connected and on at that time).
The thing that you most certainly DO NOT want to do is to turn the battery switch to off. Regardless of which switch you have, this will remove all loads from the alternator, and blow the diodes..*except* in the case of the battery switch that has a field disconnect contact wired to an after-market alternator. This scenario would disconnect the field voltage before the battery switch moves on to the next position. But you need to have an alternator that has been modified for external field control or an after-market alternator that has an external regulator.
Cape Dory provided a neat little warning plaque with our boat, written in two languages (Swedish and English -one on each side of the plaque)that says DO NOT MOVE BATTERY SWITCH WHILE ENGINE IS RUNNING. So they did provide a system that could destry the diodes if operated improperly..but so did everyone else. An upgrade of that system would replace that battery switch with a make-before-break switch.
Cheers!
Larry DeMers
s/v DeLaMer
Cape Dory 30
Don Sargeant wrote: Larry,
Thanks for the input. But as is usually the case your answer raises some more questions. I've been starting on #1, then switching to both. I not aware of any damage -- maybe I'm just being blind and it's too soon in the season to have run out of juice -- but it seems to me that CD wouldn't have installed a system where the alternator could be cooked so easily. Wouldn't shutting down and switching obviate the "one battery for starting and one for the house" approach that's touted by West and others? You'd be chasing your tail by constantly needing to replenish the starting battery. My old boat made life simpler -- one battery for all (but it was usually pretty flat).
Thanks for the dialog..
Don Sargeant
~~COQUINA~~
CD25D #189
Greenwich Cove
Larry DeMers wrote: Don,
To charge two batteries, put the battery selector on "both", and allow to recharge. Realize that the lower discharged battery will take the majority of the charge current. This means that the alternator sees the lowest charged battery only, and then charges to what it sees. The higher charged battery then will tend to be overcharged. A way around this is to leave the battery switch on "both" for an appropriate amount of time (for a starter battery that has just cranked an engine over to start it, the recharge for that could be put off for some time, or allow 10 minutes to do the charging, then stop the engine and switch over to only the battery that needs charging.
Another alternative is buying a new battery switch that includes a "field disconnect" wiper in it. The field of the alternator is attached to this wiper, which disconnectsd the field voltage before the switch changes loads. That is that the alternator is turned off with the field voltage going to zero while the battery switch is moving from position to position, then it is remade, reconnecting the field winding.. Now if you choose this route, you will be replacing the alternator with an external regulated alternator so that the field power is supplied from an external source. You may be farther ahead to just do the first suggested operation..charge both, then shut down and charge a single one. OR..use a battery combiner to direct the alternator charge to the battery needing it most. I do not have experience with these, and am frankly suspicious as to how effective they may be. All reviews I have read however are positive.
I would not recommend that you switch that battery switch at any time that the engine is running.
Nor would I recommend that you use Battery Isolators. Battery Isolators have an inherent problem in that they drop 7-800 mV while charging. This means that the battery will **never** reach full charge, as the voltage that it sees will always be 7-800 mV low when the alternator thinks that the battery is full. That means that the battery will always be recharged only to the 80-85% range. This shortens the battery life remarkably.
Regards,
Larry DeMers
s/v DeLaMer
Cape Dory 30 ~~~~~~~~~~Sailing Lake Superior~~~~~~~
Don Sargeant wrote: Larry,
How does one, then, charge both batteries? I use #1 for engine starting and #2 for house accessories. I switch to "both" after the engine has started. If this is incorrect, what is the right way? How long does it take to replenish the juice used by starting (assuming the egine kicks right on)?
Don Sargeant
~~COQUINA~~
CD25D #189
Greenwich Cove
Don Sargeant wrote:
demers@sgi.com
-
Don Sargeant
Re:Starting Engine Procedure..answer to Don Sargent
Thanks for the input, Larry. Our 25D has the Westerbeke option so I assume it has the better switch as well. There is a warning sign about not switching to "OFF" while the engine(s) are running.
Thanks again
Don Sargeant
~~COQUINA~~
don@cliggott.com
Thanks again
Don Sargeant
~~COQUINA~~
Larry DeMers wrote: Don,
It depends on which package the original owner ordered for the boat. If he opted for the more deluxe package, CD may have included a "Make_Before_Break" battery switch, which will make the next connection before breaking the previous connection. In your case, as you switch from batt. 1 to both, the battery switch contacts "both" before it breaks the #1 connection. This saves your alternator diodes from a 'no-load' condition (which if allowed to occur, will let the alternator output increase to 100-200vac, which is too much voltage for the diodes to handle, so they blow open..and it will take out light bulbs, leds etc that are connected and on at that time).
The thing that you most certainly DO NOT want to do is to turn the battery switch to off. Regardless of which switch you have, this will remove all loads from the alternator, and blow the diodes..*except* in the case of the battery switch that has a field disconnect contact wired to an after-market alternator. This scenario would disconnect the field voltage before the battery switch moves on to the next position. But you need to have an alternator that has been modified for external field control or an after-market alternator that has an external regulator.
Cape Dory provided a neat little warning plaque with our boat, written in two languages (Swedish and English -one on each side of the plaque)that says DO NOT MOVE BATTERY SWITCH WHILE ENGINE IS RUNNING. So they did provide a system that could destry the diodes if operated improperly..but so did everyone else. An upgrade of that system would replace that battery switch with a make-before-break switch.
Cheers!
Larry DeMers
s/v DeLaMer
Cape Dory 30
Don Sargeant wrote: Larry,
Thanks for the input. But as is usually the case your answer raises some more questions. I've been starting on #1, then switching to both. I not aware of any damage -- maybe I'm just being blind and it's too soon in the season to have run out of juice -- but it seems to me that CD wouldn't have installed a system where the alternator could be cooked so easily. Wouldn't shutting down and switching obviate the "one battery for starting and one for the house" approach that's touted by West and others? You'd be chasing your tail by constantly needing to replenish the starting battery. My old boat made life simpler -- one battery for all (but it was usually pretty flat).
Thanks for the dialog..
Don Sargeant
~~COQUINA~~
CD25D #189
Greenwich Cove
Don Sargeant wrote:Larry DeMers wrote: Don,
To charge two batteries, put the battery selector on "both", and allow to recharge. Realize that the lower discharged battery will take the majority of the charge current. This means that the alternator sees the lowest charged battery only, and then charges to what it sees. The higher charged battery then will tend to be overcharged. A way around this is to leave the battery switch on "both" for an appropriate amount of time (for a starter battery that has just cranked an engine over to start it, the recharge for that could be put off for some time, or allow 10 minutes to do the charging, then stop the engine and switch over to only the battery that needs charging.
Another alternative is buying a new battery switch that includes a "field disconnect" wiper in it. The field of the alternator is attached to this wiper, which disconnectsd the field voltage before the switch changes loads. That is that the alternator is turned off with the field voltage going to zero while the battery switch is moving from position to position, then it is remade, reconnecting the field winding.. Now if you choose this route, you will be replacing the alternator with an external regulated alternator so that the field power is supplied from an external source. You may be farther ahead to just do the first suggested operation..charge both, then shut down and charge a single one. OR..use a battery combiner to direct the alternator charge to the battery needing it most. I do not have experience with these, and am frankly suspicious as to how effective they may be. All reviews I have read however are positive.
I would not recommend that you switch that battery switch at any time that the engine is running.
Nor would I recommend that you use Battery Isolators. Battery Isolators have an inherent problem in that they drop 7-800 mV while charging. This means that the battery will **never** reach full charge, as the voltage that it sees will always be 7-800 mV low when the alternator thinks that the battery is full. That means that the battery will always be recharged only to the 80-85% range. This shortens the battery life remarkably.
Regards,
Larry DeMers
s/v DeLaMer
Cape Dory 30 ~~~~~~~~~~Sailing Lake Superior~~~~~~~
don@cliggott.com