I installed a battery charger and a second battery for the bilge pump. My boat always goes home to the dock for now. When charger is plugged in I only keep the battery switch to #1 house bank and the bilge pump on auto thru the panel. now the alternator is getting warm almost hot all the time is this normal. This is an older boat new to me, only my second sailboat and sailing for about 2.5 years, first post but I read thru the forum almost daily and cant find this one,you all have been very very helpful. thanks Cliff
warm alternator
- Thread starter Cliff E
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Ahoy Cliff,
It could be you have the wrong wire hooked to the rotor. To make an alternator work, 12 volts has to be applied to the alternator.
This 12 volt supply should come on when the key is turned on. Seems to me you have power going the rotor all the time.
Fair Winds
Dave
It could be you have the wrong wire hooked to the rotor. To make an alternator work, 12 volts has to be applied to the alternator.
This 12 volt supply should come on when the key is turned on. Seems to me you have power going the rotor all the time.
Fair Winds
Dave
Are you saying that the alternator is hot while sitting at the dock and the engine is NOT running? Guess I do not understand the question.
At any rate your battery switch and panel switch should not need to be on if the bilge pump is wired correctly. The bilge pump should be wired directly to 12v through a fuse. On my boat that "always on" 12 volts goes to the back of the big battery switch common. Then you never have to worry about switch positions. The float switch will always turn on the pump.
At any rate your battery switch and panel switch should not need to be on if the bilge pump is wired correctly. The bilge pump should be wired directly to 12v through a fuse. On my boat that "always on" 12 volts goes to the back of the big battery switch common. Then you never have to worry about switch positions. The float switch will always turn on the pump.
Check to ensure that your ignition switch is "OFF". On most boats there is a "hot" wire from the ignition switch to the alternator. If you accidently leave the ignition switch "ON" without the engine running, there is still current going thru the field of the alternator, thus the hot case.
Both Dave and Hutch are suggesting that the alternator exciter voltage is on fulltime. I guess that is possible although it would have to be a serious wiring error. And on my boat the exciter voltage is only there when START is engaged, not when the key is turned to ON. An older alternator or one that is 35amps or less would not have an exciter wired. If you can tell us make and model we can tell you which wire to unplug from the alternator. Then you can put a meter on it.
Alternator wiring
The ignition switch does not go to the alternator. It goes to the regulator (may be inside the alternator) which then controls the rotor field current. in either case the resistance of the field rotor winding is high enough to only allow 6ish amps max. This would not cause the alternator to get "hot" No current would flow if the ignition switch is off in any case.
The field windings however are directly connected to the batteries through the diodes. If the right two diodes in the pack go it will allow current to go from bat to ground through an unknown resistance. The diode could have a high or low resistance when it is blown. Course if you have some start/house isolation diodes then it gets more complicated.
The ignition switch does not go to the alternator. It goes to the regulator (may be inside the alternator) which then controls the rotor field current. in either case the resistance of the field rotor winding is high enough to only allow 6ish amps max. This would not cause the alternator to get "hot" No current would flow if the ignition switch is off in any case.
The field windings however are directly connected to the batteries through the diodes. If the right two diodes in the pack go it will allow current to go from bat to ground through an unknown resistance. The diode could have a high or low resistance when it is blown. Course if you have some start/house isolation diodes then it gets more complicated.
Thanks for the reply. everytime I go to fix something I find a few more problems but I'm having fun. sounds like all of the comments could be the problem. Had a great sail sunday with a dolfin surfing my boat wake, sorry to our snowed in freinds. forgot what that is like. the way I remember I did hook the bilge pump to a switch at the panel, on/auto, that is powered thru a breaker so my board has to be on thats why I kept the house bank on. I should move that to the battery or the common on my switch[didnt think that was powered unless the switch was on 1 or 2] the alternator I did not know needed power supplied to it to work and I think one wire is to the common on the switch to charge batteries the other I will have to check to see if it goes to the key, could the po have them backwards It charges the batteries. I do have to try this again not totally sure I tuned the key off. I will get the make of my alternater, need a backup anyway. could this have hurt the alternator I said it was hot but should have said very warm it was cold that day 50. thank you all I will let you know what I find today I have to check the boat left pump and charger off last night, Had to much fun.
What should happen altenator wise
If the ignition is off or on you alternator should not get hot while the engine is not running. While it is running it gets pretty dang hot and that is normal (engine heat and power production) With the ignition off the alternator should be at what ever the engine temp is, hot after shutdown and cooling till it is at ambient temp. It should not be anything else with the ignition off. With the ignition on and the engine stopped the alternator can get warm from the regulator turning it on full field to get it to produce max output. The regulator can't tell the engine is not turning so it tries its best to get the alternator to put out. This full fielding of the rotor (6ish amps) will warm the alternator and on a 50 degree day it would be more noticeable than in the summer.
I'd check the ignition switch first and make sure it is off. If it is on the most likly you don't have a (engine/alternator) problem. Just need to develop a habit.
Then check the alternator to get a sense of if it is warm or not so you can come back in a few hours and check again.
If the ignition was off and the alternator was warm the you have something wrong and need to start the standard (lots of books cover this) diagnosis of an alternator problem. email me if you need some specifice guidance. william-roosa@us.army.mil
If the ignition is off or on you alternator should not get hot while the engine is not running. While it is running it gets pretty dang hot and that is normal (engine heat and power production) With the ignition off the alternator should be at what ever the engine temp is, hot after shutdown and cooling till it is at ambient temp. It should not be anything else with the ignition off. With the ignition on and the engine stopped the alternator can get warm from the regulator turning it on full field to get it to produce max output. The regulator can't tell the engine is not turning so it tries its best to get the alternator to put out. This full fielding of the rotor (6ish amps) will warm the alternator and on a 50 degree day it would be more noticeable than in the summer.
I'd check the ignition switch first and make sure it is off. If it is on the most likly you don't have a (engine/alternator) problem. Just need to develop a habit.
Then check the alternator to get a sense of if it is warm or not so you can come back in a few hours and check again.
If the ignition was off and the alternator was warm the you have something wrong and need to start the standard (lots of books cover this) diagnosis of an alternator problem. email me if you need some specifice guidance. william-roosa@us.army.mil
Re: What should happen altenator wise
I got back to the boat, weather today was bad but I did wire my bilge pump to the battery[need to install a fuse] made sure the ignition was off left the battery switch to #1 for one hour came back to a warm aternator, did not start engine today. my alterator is a delco and I think it said remy after hard to see and was painted by po. started to trace wires from alt. but rain ran me off I did see 6 ga maybe 8 wire to common on battery switch, other wires run to the start button and or gauges in cockpit then I guess down to ignition switch inside on panel. When I go sailing I turn on the ignition switch and leave it on all day and the battery switch to bank#1 I think this is normal and start engine with button when needed. so is aternator draining my battery when the enigine is not running, is it time for a new alt. I do have boatowners illustrated electical handbook and will try the troubleshooting. not a great mechanic or sailor but getting better. thanks again Cliff
I got back to the boat, weather today was bad but I did wire my bilge pump to the battery[need to install a fuse] made sure the ignition was off left the battery switch to #1 for one hour came back to a warm aternator, did not start engine today. my alterator is a delco and I think it said remy after hard to see and was painted by po. started to trace wires from alt. but rain ran me off I did see 6 ga maybe 8 wire to common on battery switch, other wires run to the start button and or gauges in cockpit then I guess down to ignition switch inside on panel. When I go sailing I turn on the ignition switch and leave it on all day and the battery switch to bank#1 I think this is normal and start engine with button when needed. so is aternator draining my battery when the enigine is not running, is it time for a new alt. I do have boatowners illustrated electical handbook and will try the troubleshooting. not a great mechanic or sailor but getting better. thanks again Cliff
Considered normal
Well, I would have to disagree that leaving the ignition ON while sailing is normal. That is like leaving your car ignition ON when you park the car and go into walmart. You want to leave the ignition OFF when the engine is not running. Your Delco-remy alternator has an internal regulator. The ignition switch supplies power to the smaller wires going to the alternator.
Try this:
pull off the smaller wires. They should have a plug. If the alternator cools down you have a bad regulator. If not reconnect and then pull the large wire going to the 3-way. if that lets the alternator cool then you most likely have a bad diode. In either case the replacement parts are easy to replace and much cheaper than a new unit.
Well, I would have to disagree that leaving the ignition ON while sailing is normal. That is like leaving your car ignition ON when you park the car and go into walmart. You want to leave the ignition OFF when the engine is not running. Your Delco-remy alternator has an internal regulator. The ignition switch supplies power to the smaller wires going to the alternator.
Try this:
pull off the smaller wires. They should have a plug. If the alternator cools down you have a bad regulator. If not reconnect and then pull the large wire going to the 3-way. if that lets the alternator cool then you most likely have a bad diode. In either case the replacement parts are easy to replace and much cheaper than a new unit.
Leaving the ignition on when the motor is not running should activate the alarm, if this is not sounding you may have other problems as well. The loss of oil pressure should be activating the alarm in most configurations. The alarm is also meant to let the captain know his motor has died at the worst possible time.
on my Oday I had only ignition switch out in cockpit, It made it easy to stay out of trouble. With the key down below this is not so easy. could I move the key to the button location. I also dont have any alarms on the boat it is part of my long and getting longer list of things to do. I will try to pull wires off today and see what stops heating. Never taken an alternator apart before but not scared should I change the diode and the regulator while its apart any way and is there any kind of worn out parts I should look for. are diodes and regulator on the list off parts to carry when I go to the bahamas if I make it. Sorry for all questions but this is better for me than going thru the books and doing alot of reading and running around. thanks.
What kind of boat is this
A 37' boat with the ignition key down below and no alarms???? Pretty screwy, no offense but somebody should be keel-hauled for designing it that way.
Alternator repair is pretty simple. Crack the cases, pull the rotor and watch the brushes fly out of their holders. Note the small hole on the brush holder and a corresponding hole in the back of the case. The diode pack and regulator are mounted on the back case behind the stator (bunch of coiled wire attached to the case) coils. Check the two slip rings that the brushes ride on and clean as needed. Make sure the cleaning does not leave grit on the rings. This destroys brushes in short order. If you have determined which unit is malfunctioning then just replace that. They may both be part of a single unit though. They usually just unbolt from the stator and case with no problem. When putting it back together grab a paperclip, straighten it and push it through the case (little hole I mentioned before) from the back into the brush holder while pushing each brush into its holder. This keeps the brushes locked in their holders so you can put the rotor on. Once the case is back together pull the paperclip and the brushes pop out and contact the slip rings as normal.
Yes a diode pack and regulator would be a good thing to have on an extended trip. A new set of brushes is a good idea too.
A 37' boat with the ignition key down below and no alarms???? Pretty screwy, no offense but somebody should be keel-hauled for designing it that way.
Alternator repair is pretty simple. Crack the cases, pull the rotor and watch the brushes fly out of their holders. Note the small hole on the brush holder and a corresponding hole in the back of the case. The diode pack and regulator are mounted on the back case behind the stator (bunch of coiled wire attached to the case) coils. Check the two slip rings that the brushes ride on and clean as needed. Make sure the cleaning does not leave grit on the rings. This destroys brushes in short order. If you have determined which unit is malfunctioning then just replace that. They may both be part of a single unit though. They usually just unbolt from the stator and case with no problem. When putting it back together grab a paperclip, straighten it and push it through the case (little hole I mentioned before) from the back into the brush holder while pushing each brush into its holder. This keeps the brushes locked in their holders so you can put the rotor on. Once the case is back together pull the paperclip and the brushes pop out and contact the slip rings as normal.
Yes a diode pack and regulator would be a good thing to have on an extended trip. A new set of brushes is a good idea too.
Cliff,
Odd set up and wiring that's for sure. On many Delco alts the voltage sense is through a terminal usually referred to as #2. Depending upon how it is wired this terminal may or may not remain connected to the battery at all times. The draw would be low even if always connected and should not develop any noticeable "heat". I don't personally like the #2 always connected and prefer it switched with ignition.
In my opinion the easiest thing to do is to remove the alt and have it tested after you have traced your wiring. Many autoparts stores, like Autozone for example, will test your alt for nothing.
If you've never rebuilt, tested or done any sort of alternator work I would suggest finding a small mom and pop auto electric shop and having them fix it and test it. They are usually very reasonable price wise. I've rebuilt many alternators but rarely do anymore because I have a local guy who does it for so little money it's just not worth my time. They will also know where and how to source the right internal parts. Delco's are easy parts wise but also easy to get the wrong part for because many of them look alike and often the internal parts are not well marked. Someone who does this everyday will know all those little nuances and differences.
Personally I would much rather carry a complete spare alternator rather than the parts. Murphy always tends to make sure it's the part you don't have that will fail rather than the ones you do have. Delco alts are so popular you can probably find the exact replacement for not much more than just the spare parts. I have seen 10SI's etc. on Craig's list or eBay for $20.00...
Once you know which model you have a quick internet search may reveal some very good deals on a complete unit.
Odd set up and wiring that's for sure. On many Delco alts the voltage sense is through a terminal usually referred to as #2. Depending upon how it is wired this terminal may or may not remain connected to the battery at all times. The draw would be low even if always connected and should not develop any noticeable "heat". I don't personally like the #2 always connected and prefer it switched with ignition.
In my opinion the easiest thing to do is to remove the alt and have it tested after you have traced your wiring. Many autoparts stores, like Autozone for example, will test your alt for nothing.
If you've never rebuilt, tested or done any sort of alternator work I would suggest finding a small mom and pop auto electric shop and having them fix it and test it. They are usually very reasonable price wise. I've rebuilt many alternators but rarely do anymore because I have a local guy who does it for so little money it's just not worth my time. They will also know where and how to source the right internal parts. Delco's are easy parts wise but also easy to get the wrong part for because many of them look alike and often the internal parts are not well marked. Someone who does this everyday will know all those little nuances and differences.
Personally I would much rather carry a complete spare alternator rather than the parts. Murphy always tends to make sure it's the part you don't have that will fail rather than the ones you do have. Delco alts are so popular you can probably find the exact replacement for not much more than just the spare parts. I have seen 10SI's etc. on Craig's list or eBay for $20.00...
Once you know which model you have a quick internet search may reveal some very good deals on a complete unit.
thanks again, done with work for now and will head to the boat. it is a 79 gulfstar 37 that I will be fixing until it sinks or I trade up, I just added a battery and charger new wires and new switch with the help of this forum, messed up on the bilge pump but its fine now. I did have my alt. from the Oday 28 rebuilt from a good mom and pop shop here so I will take it and see what he says then I will get a used one and rebuild for a spare. next I will move the new ignition to button area do I need that button, will look into alarms and the set up in this forum. you all have posted many helpful articals in the past, great stuff
got the alt. tested and it was fine well kinda he told me it was illegal (auto alt) and someone rigged a wire for rpms thru the back of the case, said it could be a 10,000.00 dollar fine but coast guard would probably never check it, it has a constant blue spark ? so that will be the new spare and he is selling me a perkins that I wont have to run thru the ignition. now to search the forum on setting up a new ignition.
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