Hi all, Trying to sort out what kinds of limitations, if any, I should put on the use of electric lights on our O'Day 30. We have two "large" (sorry I don't have specifics at the moment) batteries on board which are charged solely by the alternator on our 16 HP diesel. We don't have dock power as yet. My bias is to use these lights very sparingly and rely primarily on candles or our oil lamp in the evenings rather than risk running either battery down such that we can't start the engine. I use a separate battery operated anchor light rather than might mast head light for anchoring for the same reason. Is this too conservative, over the top, reasonable? My sense is without having some kind of an ongoing load test available to you while you're out there, you really can't know with great accuracy how much stored power you have...loose belts, alternators or batteries potentially on the decline, etc., all can contribute to battery drainage beyond the lowest threshhold needed to start the engines. Overly cautious here? What do most folks do? Inputs most welcome.. Thanks, Jim
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Justin - O'day Owner's Web
Electric thoughts
Jim, My boat sites on a mooring with only the alternator on a small outboard for charging purposes, so I am also very conservative in my use of power. I would consider a couple of things: First, isolate the batteries into a dedicated house and a dedicated starting battery. using a three way switch, or better, three one way switches. Second, consider a battery combiner to deliver the output from the alternator to both batteries. Also, I would at least install a voltimeter so that you know how much power is in the battery. Consider a Link 10 if you want to really know how much juice you have. Unless you have an engine that can be reliably hand cranked, I would not want to guess how much power you have remaining. If you are on a dock without shore power on the boat, but with power available on the dock, you could always use a charger with a standard extension cord. If you choose to do that, make sure it is fuse or circuit breaker protected, and include a GFI. I would also only use it sparingly and remove it when not in use to protect against electrolisis. Justin - O'day Owners' Web
Jim, My boat sites on a mooring with only the alternator on a small outboard for charging purposes, so I am also very conservative in my use of power. I would consider a couple of things: First, isolate the batteries into a dedicated house and a dedicated starting battery. using a three way switch, or better, three one way switches. Second, consider a battery combiner to deliver the output from the alternator to both batteries. Also, I would at least install a voltimeter so that you know how much power is in the battery. Consider a Link 10 if you want to really know how much juice you have. Unless you have an engine that can be reliably hand cranked, I would not want to guess how much power you have remaining. If you are on a dock without shore power on the boat, but with power available on the dock, you could always use a charger with a standard extension cord. If you choose to do that, make sure it is fuse or circuit breaker protected, and include a GFI. I would also only use it sparingly and remove it when not in use to protect against electrolisis. Justin - O'day Owners' Web
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Don
Take the time to know your electrical demands
Educate yourself on your electrical systems and you will feel much better about your own situation with regards to present power consumption and future expansion. I would second Justins' advice with regards to the Link 10, or perhaps an E-meter. These are like gas guages for your electrical consumption, indicating "fuel" remaining until you need to recharge. Nothing wrong with kerosene or candle lighting. Invest in a good "marine" book on configuring and sizing your 12V systems. You may also want to consider adding in alternate power source, such as wind or solar. Perform an energy audit, determine amp hours used, size your batteries accordingly and factor in charging capabilities. I think you may be a bit cautious, but once you know your systems you will be more confident. Don
Educate yourself on your electrical systems and you will feel much better about your own situation with regards to present power consumption and future expansion. I would second Justins' advice with regards to the Link 10, or perhaps an E-meter. These are like gas guages for your electrical consumption, indicating "fuel" remaining until you need to recharge. Nothing wrong with kerosene or candle lighting. Invest in a good "marine" book on configuring and sizing your 12V systems. You may also want to consider adding in alternate power source, such as wind or solar. Perform an energy audit, determine amp hours used, size your batteries accordingly and factor in charging capabilities. I think you may be a bit cautious, but once you know your systems you will be more confident. Don
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Jim
Power Limits
Thanks for the input Justin... I do have two batteries rigged in parallel, a three way switch and a voltmeter for readings on each battery. However, it is my understanding that even a solid reading on the voltmeter is not necessarily assurance that either batter, or both combined, will necessarily have enough depth of charge to turn the engine over. Hence my concern that use of lights or other battery operted electrics, other than say a radio or CD player which draw very little, should be held to a minimum. Further feedback welcome here given the additional info provided here regarding what my rig is equipped with... Thanks, Jim
Thanks for the input Justin... I do have two batteries rigged in parallel, a three way switch and a voltmeter for readings on each battery. However, it is my understanding that even a solid reading on the voltmeter is not necessarily assurance that either batter, or both combined, will necessarily have enough depth of charge to turn the engine over. Hence my concern that use of lights or other battery operted electrics, other than say a radio or CD player which draw very little, should be held to a minimum. Further feedback welcome here given the additional info provided here regarding what my rig is equipped with... Thanks, Jim
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Philippe Rouleau
You Should Get a Portable Battery
With a portable battery you will always have a backup to start your engine. Boat US Sells one 12v with 18amps which is plenty to start your engine. It sells for $99.00. You can carry the battery with you and recharge it at home. I would also follow the others recommendation.... volt meter, create two banks... Look at your total amps in your battery and divide it by two, this will tel you how many amps you can use before your battery will become unusable. However you have to be able to put back wath you took out. Thath depends on your alternator and how long your are willing to run your engine. Say if your alternator gives you 25amps/hours, and run your engine one hour at 5 pm, you should have plenty (25 amps) to run your lights. One thing is certain if you have two big battery (100 to 150 amps total usable 50 to 75) you should be able to use that 25 amps. go see the following site it will give you a chart of what you consume with different type of equipment : http://www.jackrabbitmarine.com/reference/diagram_3.html This site also have a lot of info and do not be affraid to call them... Jack Rabbit is very friendly and cooperative.
With a portable battery you will always have a backup to start your engine. Boat US Sells one 12v with 18amps which is plenty to start your engine. It sells for $99.00. You can carry the battery with you and recharge it at home. I would also follow the others recommendation.... volt meter, create two banks... Look at your total amps in your battery and divide it by two, this will tel you how many amps you can use before your battery will become unusable. However you have to be able to put back wath you took out. Thath depends on your alternator and how long your are willing to run your engine. Say if your alternator gives you 25amps/hours, and run your engine one hour at 5 pm, you should have plenty (25 amps) to run your lights. One thing is certain if you have two big battery (100 to 150 amps total usable 50 to 75) you should be able to use that 25 amps. go see the following site it will give you a chart of what you consume with different type of equipment : http://www.jackrabbitmarine.com/reference/diagram_3.html This site also have a lot of info and do not be affraid to call them... Jack Rabbit is very friendly and cooperative.
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Ned Young
Electric Management
I have a O'day 28 with two 115 AH Trolling Motor Batteries that I bought at Wal Mart for $65. My boat has all the normal equipment i.e. pressure water etc plus a refrigrator and DC TV and Tape player. I can go one night without recharging. I use only one Battery at night and keep the other for starting the engine. I try to rotate the use of the batteries Don't be afraid to use your batteries that what they are there for. Ned Young
I have a O'day 28 with two 115 AH Trolling Motor Batteries that I bought at Wal Mart for $65. My boat has all the normal equipment i.e. pressure water etc plus a refrigrator and DC TV and Tape player. I can go one night without recharging. I use only one Battery at night and keep the other for starting the engine. I try to rotate the use of the batteries Don't be afraid to use your batteries that what they are there for. Ned Young
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Justin - O'day Owner's Web
More
Jim, A few more thoughts on the battery situation - You are absolutely correct that the voltimeter will not give you a true sense of how much power you have less, unless you know the condition of the batteries. What happens as batteries age they is that effective capacity decreases. As a consequence a 100 AH battery may become a 20AH battery. The issue is that even at its reduced capacity it will read fully charged; it will simply discharge faster. Once you know the condition of your battery however, you are in better shape. At that point you can determine how long it takes your specific battery to lose power, and the voltimeter becomes a useful tool. On my boat, I currently have one 100AH battery. (I am comfortable with one battery because my engine is pull start only; I don't have to rely on electrics to go home). There is no way it is still holding 100AH. I would guess that 75 is more realistic. Nevertheless, I know when you find a dock to charge at when my gauge gets low. I charge when the battery is half-discharged to reduce sulfation. As far as your current lay out, here's what I think I would do. Put both batteries in the circuit and run the engine for a couple of hours or until the voltimeter reads 14+. Switch each on independently and check for voltage. Then shunt one out and run the other normally and see how long it takes to get to half charge. That will give you your effective useable power for that battery. From then on it doesn't matter how much actually power you have because you know what it translates to in terms of use. When you get a chance, I would still install a Link or similar, and I would personally remove the BOTH feature from your distribution setup, but I have been told I am into massive overkill. I just think I hate hearing the click of the solenoid when I should be hearing the engine turn over. YMMV, Justin - O'day Owners' Web
Jim, A few more thoughts on the battery situation - You are absolutely correct that the voltimeter will not give you a true sense of how much power you have less, unless you know the condition of the batteries. What happens as batteries age they is that effective capacity decreases. As a consequence a 100 AH battery may become a 20AH battery. The issue is that even at its reduced capacity it will read fully charged; it will simply discharge faster. Once you know the condition of your battery however, you are in better shape. At that point you can determine how long it takes your specific battery to lose power, and the voltimeter becomes a useful tool. On my boat, I currently have one 100AH battery. (I am comfortable with one battery because my engine is pull start only; I don't have to rely on electrics to go home). There is no way it is still holding 100AH. I would guess that 75 is more realistic. Nevertheless, I know when you find a dock to charge at when my gauge gets low. I charge when the battery is half-discharged to reduce sulfation. As far as your current lay out, here's what I think I would do. Put both batteries in the circuit and run the engine for a couple of hours or until the voltimeter reads 14+. Switch each on independently and check for voltage. Then shunt one out and run the other normally and see how long it takes to get to half charge. That will give you your effective useable power for that battery. From then on it doesn't matter how much actually power you have because you know what it translates to in terms of use. When you get a chance, I would still install a Link or similar, and I would personally remove the BOTH feature from your distribution setup, but I have been told I am into massive overkill. I just think I hate hearing the click of the solenoid when I should be hearing the engine turn over. YMMV, Justin - O'day Owners' Web
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Ron Doescher
Power Consumption
First, I'd be more paranoid about the use of open flame/heat producing devices (candles, lanterns) on board. The risk of fire is far more serious than running down a battery. Second, if you have two batteries you probably have a switch to select A, B, Both, or Off. Most folks I know charge while on the "both" position. They reserve one battery "B" for starting use, and run their nav/comfort stuff from "A". The previous comment with Jackrabbit's chart was a good way to plan for power management. Remember, plan your consumption to run no more than a 50% capacity discharge before going into a recharging cycle. Otherwise the battery life starts to deteriorate faster. The central idea here is that you are managing energy consumption. Energy(joules) is proportional to Power(watts) x Time(hours); Power is proportional to Electrical Pressure(volts) x Current(amps). So the Ampere-Hour rating is a rough approximation of the battery's energy capacity, and of consumption by the various "appliances". Rough in the sense that a battery's voltage does not remain constant, varying over its range of charge state and load (due to internal resistance, which in turn is a function of the battery design and aging history).
First, I'd be more paranoid about the use of open flame/heat producing devices (candles, lanterns) on board. The risk of fire is far more serious than running down a battery. Second, if you have two batteries you probably have a switch to select A, B, Both, or Off. Most folks I know charge while on the "both" position. They reserve one battery "B" for starting use, and run their nav/comfort stuff from "A". The previous comment with Jackrabbit's chart was a good way to plan for power management. Remember, plan your consumption to run no more than a 50% capacity discharge before going into a recharging cycle. Otherwise the battery life starts to deteriorate faster. The central idea here is that you are managing energy consumption. Energy(joules) is proportional to Power(watts) x Time(hours); Power is proportional to Electrical Pressure(volts) x Current(amps). So the Ampere-Hour rating is a rough approximation of the battery's energy capacity, and of consumption by the various "appliances". Rough in the sense that a battery's voltage does not remain constant, varying over its range of charge state and load (due to internal resistance, which in turn is a function of the battery design and aging history).
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