I recently replaced my wimpy stock alternator with a more robust model. I elected (with the option to change my mind later) to keep internal regulation on the alternator. For the first couple of months the new alternator worked fine but on a cruise this weekend I started to see some problems and hoped that someone could shed some light on this. I was motoring for about 7 hours when I started smelling something. I traced the smell to the battery compartment where all batteries were very hot. My voltmeter was reading 14.1 volts. (I've really never seen anything other than 14.1 volts from the new alternator). Now I'm guessing that I've had some kind of failure on the alternator that is preventing the thing from reducing it's output current. Could this be due to a bad regulator? Or could something else be causing the problem? Is it normal to see a constant voltage from an alternator? The alternator is still under warranty so I'll be having it tested to make sure it's OK. If it checks out I'll probably convert it over to external regulation as soon as the budget allows. Thanks, Jim "Prospect"
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Bryan C.
Alternator problem
14.1 volts is too high for a "float charge" and you are boiling your batteries. It is not normal to see a constant voltage output -- the voltage output from the alternator should be reduced when your battery reaches a certain voltage level. The max float charge voltage for wet cell batteries would be about 13.4-13.6 volts. Sounds like a regulator problem. As I understand it, in a standard regulator, the regulator "trips" the voltage output down after the battery reaches a certain voltage to the" float charge" (With a "smart" multi-stage regulator, the higher output is maintained with the amps being reduced during the middle "absorption" phase before the float charge phase kicks in.) Have your regulator checked before you fry your batteries or worse. Probably worth the hundred bucks or so to get a smart regulator.
14.1 volts is too high for a "float charge" and you are boiling your batteries. It is not normal to see a constant voltage output -- the voltage output from the alternator should be reduced when your battery reaches a certain voltage level. The max float charge voltage for wet cell batteries would be about 13.4-13.6 volts. Sounds like a regulator problem. As I understand it, in a standard regulator, the regulator "trips" the voltage output down after the battery reaches a certain voltage to the" float charge" (With a "smart" multi-stage regulator, the higher output is maintained with the amps being reduced during the middle "absorption" phase before the float charge phase kicks in.) Have your regulator checked before you fry your batteries or worse. Probably worth the hundred bucks or so to get a smart regulator.
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Al
You haven't given us enough information
to help you with this problem. How old are your batteries? What was their state of charge before you started charging? Have you tried a new battery that is fully charged and measured the voltage output of the alternator regulator combination? What is the size of your new alternator(amp output)? What is the size of the battery bank you are charging? email me with this information and I'll try to help you with the problem. Al Budding
to help you with this problem. How old are your batteries? What was their state of charge before you started charging? Have you tried a new battery that is fully charged and measured the voltage output of the alternator regulator combination? What is the size of your new alternator(amp output)? What is the size of the battery bank you are charging? email me with this information and I'll try to help you with the problem. Al Budding
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Bryan C.
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Jim Ewing
More Info...
Here's the deal.. >How old are your batteries? About 20 months. >What was their state of charge before >you started charging? Full up. I keep them on a Statpower 40 amp smart charger. >Have you tried a new battery that is >fully charged and measured the voltage >output of the alternator regulator >combination? No. But existing batteries (Delco no maintenance deep cycle) have been showing green light. I can't test S.G. of electrolyte. >What is the size of your new alternator>(amp output)? 140 amp. >What is the size of the battery bank >you are charging? 525 AH +/-. 4 group 27 as house bank and 1 group 30 as starting battery. All same age. Thanks for the assistance. Jim "Prospect"
Here's the deal.. >How old are your batteries? About 20 months. >What was their state of charge before >you started charging? Full up. I keep them on a Statpower 40 amp smart charger. >Have you tried a new battery that is >fully charged and measured the voltage >output of the alternator regulator >combination? No. But existing batteries (Delco no maintenance deep cycle) have been showing green light. I can't test S.G. of electrolyte. >What is the size of your new alternator>(amp output)? 140 amp. >What is the size of the battery bank >you are charging? 525 AH +/-. 4 group 27 as house bank and 1 group 30 as starting battery. All same age. Thanks for the assistance. Jim "Prospect"
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Mike Kinney
So what should the volts be for wet cell?
So, for a smart regulator's bulk, absorption and float stages, what should the voltage tyically be for wet cell batteries. I haven't been able to find this information from other sources and am interested in others' input.
So, for a smart regulator's bulk, absorption and float stages, what should the voltage tyically be for wet cell batteries. I haven't been able to find this information from other sources and am interested in others' input.
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Bryan C.
Voltage
Jim -- what kind of alternator did you get, and what kind of engine do you have. (I'm thinking about upgrading too). I still think its a regulator problem. Perhaps you didn't hook it up correctly and just haven't motored long enough to cook your batteries prior to the 7 hour trip. Or perhaps the internal regulator isn't working. Most of my info comes from Nigel Calder's book "Boat Owners' Mechanical and Electrical Manual" found at WM and BoatUS which I highly recommend having. He provides a thorough yet understandable explanation of both DC and AC systems (as well as most of the other systems on boats). To the best of my recollection, the bulk charge voltage will normally be in the 14.2-14.4 range. Sounds like what Jim's regulator is doing. In the absorption phase with a multi-stage regulator, that voltage is maintained, but the amperage flow into the battery is slowly reduced while the charge is absorbed in the inner area of the battery plates. Finally, after a specific voltgage is reached (or after a period of time, can't remember which), the regulator trips the alternator to the float charge voltage which should be 13.4-13.6 which is low enough to keep the batteries from overheating. I'll try to check some sources to verify this tonight.
Jim -- what kind of alternator did you get, and what kind of engine do you have. (I'm thinking about upgrading too). I still think its a regulator problem. Perhaps you didn't hook it up correctly and just haven't motored long enough to cook your batteries prior to the 7 hour trip. Or perhaps the internal regulator isn't working. Most of my info comes from Nigel Calder's book "Boat Owners' Mechanical and Electrical Manual" found at WM and BoatUS which I highly recommend having. He provides a thorough yet understandable explanation of both DC and AC systems (as well as most of the other systems on boats). To the best of my recollection, the bulk charge voltage will normally be in the 14.2-14.4 range. Sounds like what Jim's regulator is doing. In the absorption phase with a multi-stage regulator, that voltage is maintained, but the amperage flow into the battery is slowly reduced while the charge is absorbed in the inner area of the battery plates. Finally, after a specific voltgage is reached (or after a period of time, can't remember which), the regulator trips the alternator to the float charge voltage which should be 13.4-13.6 which is low enough to keep the batteries from overheating. I'll try to check some sources to verify this tonight.
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Ernie Rodriguez
Alternator
You said you opted for an internal regualtor. I am not aware of an internal regulaor that has the "smart"regulator features that changes the regulating voltage once the batteries have reached full charge, typically an hour after being charged at the acceptance level of 14.2 volts. I suspect your internal regulator is set for around 14 volts and that will cook your batteries if they are fully charged as you said, and then continue to see 14 volts!You need an external "smart" regulator for proper charge control.
You said you opted for an internal regualtor. I am not aware of an internal regulaor that has the "smart"regulator features that changes the regulating voltage once the batteries have reached full charge, typically an hour after being charged at the acceptance level of 14.2 volts. I suspect your internal regulator is set for around 14 volts and that will cook your batteries if they are fully charged as you said, and then continue to see 14 volts!You need an external "smart" regulator for proper charge control.
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Bryan C.
Regulating Voltgages
I read up a little on this stuff last night. Ernie is right, with a simple regulator, like the one in cars and the one that is probably built into your alternator, Jim, the regulator acts as a simple on/off switch for the alternator current flow when the batter voltage reaches a certain level. As the battery gets charged, the regulator cycles the alternator on and off many times a second. The result is a decreasing current flow but at a steady voltage, which is usually set around 14.0. What I'm still not quite sure about is whether the regulator trip voltage would be set at 14.0, the voltage pumped into the battery. I have to believe it is supposed to be lower. At anything over 13.6 volts, a battery will overcharge (depending on the ambient temperature -- the warmer the temperature the lower the voltage that will cause a battery to boil). If the regulator maintained the battery charge at 14.0 volts, all our car batteries would be burning up whenever we went driving down the road. I have the standard Hitachi alternator with a built-in regulator, but it does not maintain a constant 14 volt charge to the batteries. The criticism with a standard regulator is not that it burns batteries up but that that it does not efficiently charge batteries, particularly deep discharge heavy cycle batteries. So I would still think there is a probablem with your regulator not charging properly. Multi-stage regulators have advantages. They are specifically designed for powerful alternators and deep discharge batteries. They provide a higher voltage charge to the batteries in the bulk/absorption phases (14.2-14.4 volts) (thus charging the batteries faster), and then trip down to to a maintenance level of about 13.2-13.6 volts when either a certain period of time has past or the battery has reached a certain absorption level. Good luck at let us know how it works out.
I read up a little on this stuff last night. Ernie is right, with a simple regulator, like the one in cars and the one that is probably built into your alternator, Jim, the regulator acts as a simple on/off switch for the alternator current flow when the batter voltage reaches a certain level. As the battery gets charged, the regulator cycles the alternator on and off many times a second. The result is a decreasing current flow but at a steady voltage, which is usually set around 14.0. What I'm still not quite sure about is whether the regulator trip voltage would be set at 14.0, the voltage pumped into the battery. I have to believe it is supposed to be lower. At anything over 13.6 volts, a battery will overcharge (depending on the ambient temperature -- the warmer the temperature the lower the voltage that will cause a battery to boil). If the regulator maintained the battery charge at 14.0 volts, all our car batteries would be burning up whenever we went driving down the road. I have the standard Hitachi alternator with a built-in regulator, but it does not maintain a constant 14 volt charge to the batteries. The criticism with a standard regulator is not that it burns batteries up but that that it does not efficiently charge batteries, particularly deep discharge heavy cycle batteries. So I would still think there is a probablem with your regulator not charging properly. Multi-stage regulators have advantages. They are specifically designed for powerful alternators and deep discharge batteries. They provide a higher voltage charge to the batteries in the bulk/absorption phases (14.2-14.4 volts) (thus charging the batteries faster), and then trip down to to a maintenance level of about 13.2-13.6 volts when either a certain period of time has past or the battery has reached a certain absorption level. Good luck at let us know how it works out.
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Jim Ewing
Right!
Well the consensus is a bad regulator which is what I thought going into this. And the comment is correct that the internal regulator does not have any "smart charge" features. I went with the internal regulation on the alternator on the recommendation of the marine electrical shop that sold me the alternator. The alternator itself is a no-brand model that the shop has made up. My engine is a Yanmar 3JH2E. I installed the alternator in March and went to the Bahamas for two weeks (motorsailed 10hrs in each direction without seeing the over charge problem). The reason behind the internal regulation choice was that the bulk stage is the critical one. Up to 80% charge the batteries are very easy to pump juice into. Once you're past that the law of diminishing returns kicks in and it just doesn't pay to run the engine for the small bit of extra charge you'll put into the batteries. The reason for the very big output (140 amp) was that in most anchor charging situations you'll run at a fast idle. This alternator puts out about 80 amps it that situation. I've got a Grunert reefer that sucks 36 amps when running, + a watermaker that draws 4 amps + recharging the house loads. So two hours a day gives me cold drinks, hot showers and bright lights. (The stock hitachi couldn't even keep up with the Grunert at fast idle). I've got a concern that the problem may be that the alternator puts out so much power (and heat) that it cooked the regulator. If this turns out to be the case I'll get and external regulator and mount it in a cooler location. I'll post the resolution when it comes. Thanks for all the feedback and insight. Jim "Prospect"
Well the consensus is a bad regulator which is what I thought going into this. And the comment is correct that the internal regulator does not have any "smart charge" features. I went with the internal regulation on the alternator on the recommendation of the marine electrical shop that sold me the alternator. The alternator itself is a no-brand model that the shop has made up. My engine is a Yanmar 3JH2E. I installed the alternator in March and went to the Bahamas for two weeks (motorsailed 10hrs in each direction without seeing the over charge problem). The reason behind the internal regulation choice was that the bulk stage is the critical one. Up to 80% charge the batteries are very easy to pump juice into. Once you're past that the law of diminishing returns kicks in and it just doesn't pay to run the engine for the small bit of extra charge you'll put into the batteries. The reason for the very big output (140 amp) was that in most anchor charging situations you'll run at a fast idle. This alternator puts out about 80 amps it that situation. I've got a Grunert reefer that sucks 36 amps when running, + a watermaker that draws 4 amps + recharging the house loads. So two hours a day gives me cold drinks, hot showers and bright lights. (The stock hitachi couldn't even keep up with the Grunert at fast idle). I've got a concern that the problem may be that the alternator puts out so much power (and heat) that it cooked the regulator. If this turns out to be the case I'll get and external regulator and mount it in a cooler location. I'll post the resolution when it comes. Thanks for all the feedback and insight. Jim "Prospect"
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