Hi, My boat is a 1995 and all the summer I had troubles with the charge system. My boat is on mooring.My alternator (85A) is insufficient for charging my house batteries (3x250A). All the time my house batteries are low and my motor battery is very high. There are an isolator and the cie advice me to bypass it, I did it but it's not enough. Many "specialists" told me many things like: add an external regulator or change the alternator for a better one with a new regulator. I want to add solar panel but before I want to maximise the work of the alternator. Somebody can help me?
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Shawn Severn
AMP Meter?
I recently took our P450 down the West Coast and had a similar problem. However, the problem was not the charging. It turned out that a 50 AMP meter that all of my house bateries feed into was causing a voltage drop that made it look like the bateries were not charging properly. I took the AMP meter out of the system and everything started to work fine.
I recently took our P450 down the West Coast and had a similar problem. However, the problem was not the charging. It turned out that a 50 AMP meter that all of my house bateries feed into was causing a voltage drop that made it look like the bateries were not charging properly. I took the AMP meter out of the system and everything started to work fine.
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Rich Stidger
Do an Electrical analysis
I would suggest performing a comphrensive analysis of what your total electrical system is drawing. Get another person to help you and then place a ampmeter in the circuit for one of your batteries. Disconnect the other two batteries so that you can be sure that you are measuring all of the current. Turn on each light and appliance in turn and record how much current is drawn. Record the battery voltage at the start and recheck it at the end of the session. It should be within 0.1 volts between start and end. VERY IMPORTANT: With everything turned off, do you measure any current? Use a low current scale, 100 mA. The LEDs on your power panel will draw 5-10 mA each, the panel label lights will draw another 10-20 mA each. If these are left on all week, you could have a draw of 1/4A all of the time. Over 5 days (Monday-Friday) this is 30AH. That's a lot of power to light lamps that nobody is looking at. If you have current draw that you can't explain, you need to find out what is the cause. This could involve actually disconnecting appliances that are "turned off". Estimate how many hours each day you use each appliance. Time them if you have to. My refridgerator is my biggest user and it runs about 15-20 minutes/hour *after* it is down to temperature. It runs nearly 100% for 4-5 hours getting down to temp. Multiply the hours/day times the current of each apliance to get your total daily amp-hour requirements. You said that your house batteries were 750 AH total (3x250). According to recommended practices, that means that if you begin recharging when your batteries are discharged 50%, you have used 375 AH. The 85A alternator will probably put out a maximum of 57A of DC current. Most alternators are rated at *peak* currents, not average currents. The DC average of full-wave AC rectified power is about 2/3 of the peak, thus the 57A estimate. I suppose it is possible that your alternator is actually rated at the full DC average vs. peak, but I would be surprised. The math: 375AH / 57A = 6.6 hours of engine running to generate the replacement power. This calculation ignores the taper of the regulator (which is very significent) and the efficency of recharging which is typically 85-90%. The efficiency means that to replace 90AH drawn out of a battery, you must charge 100AH. The taper of the regulator is most apparent after the battery reaches 80% of full charge. Thus you should be able to charge your batteries from 50-80% (30% of capacity) at your near maximum rate. That would be: 750AH x 30% = 225AH / 57A =3.95 hours + 10% more time to allow for the charging efficiency or about 4.4 hours. Not that this is *not* to fully charge, but only to 80% of full. Depending upon your total usage, you may discover that for the hours that you are running your engine, you are not keeping up with your total draw. You may need to modify your usage: Conserve where possible, run your engine longer, or put in a larger alternator. Be aware that a larger alternator will only help to shorten the "bulk" charging time, and not the time to "top-off" the last 20% of the battery capacity. Before I would buy a larger alternator, I would install a good 4-stage regulator on the present alternator. That will give you the best performance and minimize the total time to fully recharge. Also note that it may not be practical to recharge to the 100% level all of the time. You may want to achieve 85-90% weekly and then each month bring the batteries up to 100% and then run an equalizing cycle to maintain the health of your batteries. Two information sources that you may wish to check out are: http://www.yachtsurvey.com http://www.4unique.com/battery The above sites have great info (IMO) and links to other informative sites. One last opinion. If your 85A alternator isn't keeping your batteries charged, forget solar panels. You would need to cover your boat and the cost per AH of solar power is very high. These are not a good choice to supply large amounts of power. They are good to keep batteries topped-off, and could be considered effective in high sun areas of the world to supply power for a specific requirement. Good Luck.
I would suggest performing a comphrensive analysis of what your total electrical system is drawing. Get another person to help you and then place a ampmeter in the circuit for one of your batteries. Disconnect the other two batteries so that you can be sure that you are measuring all of the current. Turn on each light and appliance in turn and record how much current is drawn. Record the battery voltage at the start and recheck it at the end of the session. It should be within 0.1 volts between start and end. VERY IMPORTANT: With everything turned off, do you measure any current? Use a low current scale, 100 mA. The LEDs on your power panel will draw 5-10 mA each, the panel label lights will draw another 10-20 mA each. If these are left on all week, you could have a draw of 1/4A all of the time. Over 5 days (Monday-Friday) this is 30AH. That's a lot of power to light lamps that nobody is looking at. If you have current draw that you can't explain, you need to find out what is the cause. This could involve actually disconnecting appliances that are "turned off". Estimate how many hours each day you use each appliance. Time them if you have to. My refridgerator is my biggest user and it runs about 15-20 minutes/hour *after* it is down to temperature. It runs nearly 100% for 4-5 hours getting down to temp. Multiply the hours/day times the current of each apliance to get your total daily amp-hour requirements. You said that your house batteries were 750 AH total (3x250). According to recommended practices, that means that if you begin recharging when your batteries are discharged 50%, you have used 375 AH. The 85A alternator will probably put out a maximum of 57A of DC current. Most alternators are rated at *peak* currents, not average currents. The DC average of full-wave AC rectified power is about 2/3 of the peak, thus the 57A estimate. I suppose it is possible that your alternator is actually rated at the full DC average vs. peak, but I would be surprised. The math: 375AH / 57A = 6.6 hours of engine running to generate the replacement power. This calculation ignores the taper of the regulator (which is very significent) and the efficency of recharging which is typically 85-90%. The efficiency means that to replace 90AH drawn out of a battery, you must charge 100AH. The taper of the regulator is most apparent after the battery reaches 80% of full charge. Thus you should be able to charge your batteries from 50-80% (30% of capacity) at your near maximum rate. That would be: 750AH x 30% = 225AH / 57A =3.95 hours + 10% more time to allow for the charging efficiency or about 4.4 hours. Not that this is *not* to fully charge, but only to 80% of full. Depending upon your total usage, you may discover that for the hours that you are running your engine, you are not keeping up with your total draw. You may need to modify your usage: Conserve where possible, run your engine longer, or put in a larger alternator. Be aware that a larger alternator will only help to shorten the "bulk" charging time, and not the time to "top-off" the last 20% of the battery capacity. Before I would buy a larger alternator, I would install a good 4-stage regulator on the present alternator. That will give you the best performance and minimize the total time to fully recharge. Also note that it may not be practical to recharge to the 100% level all of the time. You may want to achieve 85-90% weekly and then each month bring the batteries up to 100% and then run an equalizing cycle to maintain the health of your batteries. Two information sources that you may wish to check out are: http://www.yachtsurvey.com http://www.4unique.com/battery The above sites have great info (IMO) and links to other informative sites. One last opinion. If your 85A alternator isn't keeping your batteries charged, forget solar panels. You would need to cover your boat and the cost per AH of solar power is very high. These are not a good choice to supply large amounts of power. They are good to keep batteries topped-off, and could be considered effective in high sun areas of the world to supply power for a specific requirement. Good Luck.
B
Bryan
Charging it.
With your huge 750 Amp hours of batteries to charge, it is going to take all day for an 85 amp alternator to charge them. If your batters are more than 50% discharged, and figuring a warm 85 rated alternator will probably only be putting in about 75% of its rating into the batteries, its going to take at least 6-8+ hours of alternator charging to bring that bank up. Your options: (1) get a bigger alternator (like the biggest you can find); (2) use smaller batteries (i.e. less amp-hours); (3) plan on motoring a lot, (4) find alternative charging sources, i.e solar panels (which I doubt will in one day significantly charge a bank that size), or a inverter/battery charger. Also, you should be able to just charge the house bank if your start battery is isolated off at the battery switch. If the problem you have is that the charging current is not isolated into the house bank, you need to rewire your switch to be able to do that. If you charge your smaller starter battery simultaneously with your house bank (i.e. in parallel), you will have a chronically undercharged house bank, because the starter battery will register fully charged quickly, causing the voltage regulator to reduce the charge flow into the house bank before they are fully charged.
With your huge 750 Amp hours of batteries to charge, it is going to take all day for an 85 amp alternator to charge them. If your batters are more than 50% discharged, and figuring a warm 85 rated alternator will probably only be putting in about 75% of its rating into the batteries, its going to take at least 6-8+ hours of alternator charging to bring that bank up. Your options: (1) get a bigger alternator (like the biggest you can find); (2) use smaller batteries (i.e. less amp-hours); (3) plan on motoring a lot, (4) find alternative charging sources, i.e solar panels (which I doubt will in one day significantly charge a bank that size), or a inverter/battery charger. Also, you should be able to just charge the house bank if your start battery is isolated off at the battery switch. If the problem you have is that the charging current is not isolated into the house bank, you need to rewire your switch to be able to do that. If you charge your smaller starter battery simultaneously with your house bank (i.e. in parallel), you will have a chronically undercharged house bank, because the starter battery will register fully charged quickly, causing the voltage regulator to reduce the charge flow into the house bank before they are fully charged.
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