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#1
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Battery question
Hi , i was wondering if there is any danger to fry the magneto of an
outboard 40hp Suzuki engine if install 2 12 volts battery in parallel . I do use lots of 12 volt equipments on the pontoon, so i figured that 2 batteries would be better and last longer .Last year a battery died on me in the midle of the lake. I just bought 2 brand new marine ones . would that be too much strain on the magneto ? thanks for your help ! |
#2
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Battery question
Lead acid batteries in parallel are hard to manage for charge. A better
solution is a starter battery for the engine and a deep cycle (house) battery for everything else. Switch between the two for charging. Just remember that most outboards that size usually put out only 10 amps or less which is fine for topping off the starter battery but you are not going to be able to charge the house battery at much of a rate once it is down. You will have to shed load down to what the OB charging circuit will support in order to maintain voltage. Best to charge the house battery to full charge with shore power to before you go out. If you need more, add another fully charge house battery. I have 3 batteries on my toon boat. Ron |
#3
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Battery question
Not familiar with this particular engine. If it has a
generator/alternator like the comparable Evinrude - this only puts out a few amps - six tops, if I recall. So if you feed two batteries in parallel instead of one, what's the effect? I don't think it alters the 'strain' or load on the generator. You won't be able to take more amps out of TWO batteries than you can out of ONE if you rely purely on the OBs generator to charge them. So the real benefit of having two batteries is this: If you charge them at home - you have twice the ampere hours for use afloat, with the discharge rate slowed down a little by the OBs generator. That's probably a safe way not to get stranded without electric power.... Some users with troll motors use seperate batteries for trolling - so they retain electric start when the troll motor flattens its battery - as it will just at the most awkward moment. Brian Whatcott Altus OK On Thu, 17 Jul 2003 16:19:10 -0400, "Belgian" wrote: Hi , i was wondering if there is any danger to fry the magneto of an outboard 40hp Suzuki engine if install 2 12 volts battery in parallel . I do use lots of 12 volt equipments on the pontoon, so i figured that 2 batteries would be better and last longer .Last year a battery died on me in the midle of the lake. I just bought 2 brand new marine ones . would that be too much strain on the magneto ? thanks for your help ! |
#4
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Battery question
Belgian wrote:
Hi , i was wondering if there is any danger to fry the magneto of an outboard 40hp Suzuki engine if install 2 12 volts battery in parallel . I do use lots of 12 volt equipments on the pontoon, so i figured that 2 batteries would be better and last longer .Last year a battery died on me in the midle of the lake. I just bought 2 brand new marine ones . would that be too much strain on the magneto ? thanks for your help ! Typically, outboard alternators are pretty weak. Yours probably isn't giving much of a boost while running. Our 55 amp alternator can hardly give us a night's usage in an hour because of it's (basically) automotive regulator. You (and we) might do better by mounting a small solar panel to charge the batteries during the week. A half-amp for 70 hours or so a week will probably be more than you get from the engine. You *probably* won't cook the alternator with the extra battery. -- Jere Lull Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD) Xan's Pages: http://members.dca.net/jerelull/X-Main.html Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/ |
#5
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Battery question
I'm a degreed electrical engineer, which means my answer will work on
paper but may not in your boat. Go easy the first couple times and see. That's the engineer's final test! I'll give a little intuition on how it will work and then give you the tools to crunch the numbers. Think of electricity as a big water tank. The water in the tank is the electric current, or load. The water pressure is the voltage. Your magneto is a special device that has unlimited water to pump into the tank, but has a fixed rate pump that shuts off at a given pressure. Thus it fills your water tank when the pressure drops until the pressure is restored. Now if you have two water tanks, you've got twice the water but the same amount of pressure. So if you run both tanks dry, it will take twice as long, relative to a single tank, to fill the tanks back up. But the pressure has not changed so the strain (pressure) on the magneto is no different. Anyway, it's fairly simple but a little tedious to calculate how multiple batteries are going to change your situation. I'm only going to cover batteries in parallel. There are a few numbers you should find for your batteries. The first, you've already got, is the rated voltage. The second, is the number of amp-hours the battery is rated for. Third, either assume or find out, how the manufacturer of your battery measures amp-hours. A brief digression on amp-hours. The standard is to measure amp-hours for a twenty (20) hour period. Amp-hours are calculated as an average load. This average load is 5% of the rated capacity. So for a battery rated at 7Ah (Amp-hours), the manufacturer made the amp-hour rating assuming a constant load of 0.350 amps. If your load exceeds this, the performance of the battery will not match manufacturer's specifications and will discharge faster than expected. Two batteries in parallel means double the amp-hour capacity (two water tanks). So if you have two 7Ah batteries in parallel, you effectively have 14Ah of capacity. Which, as your gut intuition told you, means longer lasting. Is this better? Well it probably is for what you're doing. But notice, that you still shouldn't exceed the 0.350 Amps of draw if you want to meet manufacturer's specifications. The following equation will let you do a "back-of-the napkin" calculation. It errors on giving you a liberal answer, meaning you probably won't get the complete expected life. In my line of engineering we use a 50% rule meaning that we engineer to 1/2 of manufacturer's specifications. Expensive? Yes. Reliable? Yes. So if you're willing to handle the expense, halve the answer you get below. I also realize you probably don't know the current draw so the equation is probably useless. (Expected life) = (Amp-Hour Rating) * (Number of Batteries) * (20) / (Current Draw) On Thu, 17 Jul 2003 16:19:10 -0400, "Belgian" wrote: Hi , i was wondering if there is any danger to fry the magneto of an outboard 40hp Suzuki engine if install 2 12 volts battery in parallel . I do use lots of 12 volt equipments on the pontoon, so i figured that 2 batteries would be better and last longer .Last year a battery died on me in the midle of the lake. I just bought 2 brand new marine ones . would that be too much strain on the magneto ? thanks for your help ! |
#6
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Battery question
I'm a degreed electrical engineer, which means my answer will work on
paper but may not in your boat. Go easy the first couple times and see. That's the engineer's final test! I'll give a little intuition on how it will work and then give you the tools to crunch the numbers. Think of electricity as a big water tank. The water in the tank is the electric current, or load. The water pressure is the voltage. Your magneto is a special device that has unlimited water to pump into the tank, but has a fixed rate pump that shuts off at a given pressure. Thus it fills your water tank when the pressure drops until the pressure is restored. Now if you have two water tanks, you've got twice the water but the same amount of pressure. So if you run both tanks dry, it will take twice as long, relative to a single tank, to fill the tanks back up. But the pressure has not changed so the strain (pressure) on the magneto is no different. Anyway, it's fairly simple but a little tedious to calculate how multiple batteries are going to change your situation. I'm only going to cover batteries in parallel. There are a few numbers you should find for your batteries. The first, you've already got, is the rated voltage. The second, is the number of amp-hours the battery is rated for. Third, either assume or find out, how the manufacturer of your battery measures amp-hours. A brief digression on amp-hours. The standard is to measure amp-hours for a twenty (20) hour period. Amp-hours are calculated as an average load. This average load is 5% of the rated capacity. So for a battery rated at 7Ah (Amp-hours), the manufacturer made the amp-hour rating assuming a constant load of 0.350 amps. If your load exceeds this, the performance of the battery will not match manufacturer's specifications and will discharge faster than expected. Two batteries in parallel means double the amp-hour capacity (two water tanks). So if you have two 7Ah batteries in parallel, you effectively have 14Ah of capacity. Which, as your gut intuition told you, means longer lasting. Is this better? Well it probably is for what you're doing. But notice, that you still shouldn't exceed the 0.350 Amps of draw if you want to meet manufacturer's specifications. The following equation will let you do a "back-of-the napkin" calculation. It errors on giving you a liberal answer, meaning you probably won't get the complete expected life. In my line of engineering we use a 50% rule meaning that we engineer to 1/2 of manufacturer's specifications. Expensive? Yes. Reliable? Yes. So if you're willing to handle the expense, halve the answer you get below. I also realize you probably don't know the current draw so the equation is probably useless. (Expected life) = (Amp-Hour Rating) * (Number of Batteries) * (20) / (Current Draw) On Thu, 17 Jul 2003 16:19:10 -0400, "Belgian" wrote: Hi , i was wondering if there is any danger to fry the magneto of an outboard 40hp Suzuki engine if install 2 12 volts battery in parallel . I do use lots of 12 volt equipments on the pontoon, so i figured that 2 batteries would be better and last longer .Last year a battery died on me in the midle of the lake. I just bought 2 brand new marine ones . would that be too much strain on the magneto ? thanks for your help ! |
#7
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Battery question
Well, that's all very wonderful ... the part about water tanks and all ...
but does not answer the question. The question pbosez asked is ... can my outboard (I assume with alternator) maintain a charge on 2 batteries in parallel without burning up. The answer is ... yes. From previous posts though, my understanding is, don't stress the alternator by letting the batteries go too low, else the alternator will be putting out maximum current meaning it will get hot meaning that's not good to do too often. "edg" wrote in message ... I'm a degreed electrical engineer, which means my answer will work on paper but may not in your boat. Go easy the first couple times and see. That's the engineer's final test! I'll give a little intuition on how it will work and then give you the tools to crunch the numbers. Think of electricity as a big water tank. The water in the tank is the electric current, or load. The water pressure is the voltage. Your magneto is a special device that has unlimited water to pump into the tank, but has a fixed rate pump that shuts off at a given pressure. Thus it fills your water tank when the pressure drops until the pressure is restored. Now if you have two water tanks, you've got twice the water but the same amount of pressure. So if you run both tanks dry, it will take twice as long, relative to a single tank, to fill the tanks back up. But the pressure has not changed so the strain (pressure) on the magneto is no different. Anyway, it's fairly simple but a little tedious to calculate how multiple batteries are going to change your situation. I'm only going to cover batteries in parallel. There are a few numbers you should find for your batteries. The first, you've already got, is the rated voltage. The second, is the number of amp-hours the battery is rated for. Third, either assume or find out, how the manufacturer of your battery measures amp-hours. A brief digression on amp-hours. The standard is to measure amp-hours for a twenty (20) hour period. Amp-hours are calculated as an average load. This average load is 5% of the rated capacity. So for a battery rated at 7Ah (Amp-hours), the manufacturer made the amp-hour rating assuming a constant load of 0.350 amps. If your load exceeds this, the performance of the battery will not match manufacturer's specifications and will discharge faster than expected. Two batteries in parallel means double the amp-hour capacity (two water tanks). So if you have two 7Ah batteries in parallel, you effectively have 14Ah of capacity. Which, as your gut intuition told you, means longer lasting. Is this better? Well it probably is for what you're doing. But notice, that you still shouldn't exceed the 0.350 Amps of draw if you want to meet manufacturer's specifications. The following equation will let you do a "back-of-the napkin" calculation. It errors on giving you a liberal answer, meaning you probably won't get the complete expected life. In my line of engineering we use a 50% rule meaning that we engineer to 1/2 of manufacturer's specifications. Expensive? Yes. Reliable? Yes. So if you're willing to handle the expense, halve the answer you get below. I also realize you probably don't know the current draw so the equation is probably useless. (Expected life) = (Amp-Hour Rating) * (Number of Batteries) * (20) / (Current Draw) On Thu, 17 Jul 2003 16:19:10 -0400, "Belgian" wrote: Hi , i was wondering if there is any danger to fry the magneto of an outboard 40hp Suzuki engine if install 2 12 volts battery in parallel . I do use lots of 12 volt equipments on the pontoon, so i figured that 2 batteries would be better and last longer .Last year a battery died on me in the midle of the lake. I just bought 2 brand new marine ones . would that be too much strain on the magneto ? thanks for your help ! |
#8
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Battery question
Well, that's all very wonderful ... the part about water tanks and all ...
but does not answer the question. The question pbosez asked is ... can my outboard (I assume with alternator) maintain a charge on 2 batteries in parallel without burning up. The answer is ... yes. From previous posts though, my understanding is, don't stress the alternator by letting the batteries go too low, else the alternator will be putting out maximum current meaning it will get hot meaning that's not good to do too often. "edg" wrote in message ... I'm a degreed electrical engineer, which means my answer will work on paper but may not in your boat. Go easy the first couple times and see. That's the engineer's final test! I'll give a little intuition on how it will work and then give you the tools to crunch the numbers. Think of electricity as a big water tank. The water in the tank is the electric current, or load. The water pressure is the voltage. Your magneto is a special device that has unlimited water to pump into the tank, but has a fixed rate pump that shuts off at a given pressure. Thus it fills your water tank when the pressure drops until the pressure is restored. Now if you have two water tanks, you've got twice the water but the same amount of pressure. So if you run both tanks dry, it will take twice as long, relative to a single tank, to fill the tanks back up. But the pressure has not changed so the strain (pressure) on the magneto is no different. Anyway, it's fairly simple but a little tedious to calculate how multiple batteries are going to change your situation. I'm only going to cover batteries in parallel. There are a few numbers you should find for your batteries. The first, you've already got, is the rated voltage. The second, is the number of amp-hours the battery is rated for. Third, either assume or find out, how the manufacturer of your battery measures amp-hours. A brief digression on amp-hours. The standard is to measure amp-hours for a twenty (20) hour period. Amp-hours are calculated as an average load. This average load is 5% of the rated capacity. So for a battery rated at 7Ah (Amp-hours), the manufacturer made the amp-hour rating assuming a constant load of 0.350 amps. If your load exceeds this, the performance of the battery will not match manufacturer's specifications and will discharge faster than expected. Two batteries in parallel means double the amp-hour capacity (two water tanks). So if you have two 7Ah batteries in parallel, you effectively have 14Ah of capacity. Which, as your gut intuition told you, means longer lasting. Is this better? Well it probably is for what you're doing. But notice, that you still shouldn't exceed the 0.350 Amps of draw if you want to meet manufacturer's specifications. The following equation will let you do a "back-of-the napkin" calculation. It errors on giving you a liberal answer, meaning you probably won't get the complete expected life. In my line of engineering we use a 50% rule meaning that we engineer to 1/2 of manufacturer's specifications. Expensive? Yes. Reliable? Yes. So if you're willing to handle the expense, halve the answer you get below. I also realize you probably don't know the current draw so the equation is probably useless. (Expected life) = (Amp-Hour Rating) * (Number of Batteries) * (20) / (Current Draw) On Thu, 17 Jul 2003 16:19:10 -0400, "Belgian" wrote: Hi , i was wondering if there is any danger to fry the magneto of an outboard 40hp Suzuki engine if install 2 12 volts battery in parallel . I do use lots of 12 volt equipments on the pontoon, so i figured that 2 batteries would be better and last longer .Last year a battery died on me in the midle of the lake. I just bought 2 brand new marine ones . would that be too much strain on the magneto ? thanks for your help ! |
#9
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Battery question
You should have no problem using 2 batteries.
One other item...I did not see if this was in a previous post BUT... Buy a switch made for 2 batteries. Always start from one battery or the other (This is a good test to see if one is not as healthy as the other). You can charge in parallel if you want. When you are at anchor or dockside with the engine off turn the battery switch back to 1 OR 2 (not BOTH). This will assure that you have plenty of power to start the engine. ALSO... NEVER put the switch in the OFF position with the engine running (that WILL kill your alt) most (probably all) of the batt switches made for this task will be MAKE-BEFORE-BREAK switches so you can switch from 1 to both to 2 without hurting the alt. bowgus wrote: Well, that's all very wonderful ... the part about water tanks and all ... but does not answer the question. The question pbosez asked is ... can my outboard (I assume with alternator) maintain a charge on 2 batteries in parallel without burning up. The answer is ... yes. From previous posts though, my understanding is, don't stress the alternator by letting the batteries go too low, else the alternator will be putting out maximum current meaning it will get hot meaning that's not good to do too often. "edg" wrote in message ... I'm a degreed electrical engineer, which means my answer will work on paper but may not in your boat. Go easy the first couple times and see. That's the engineer's final test! I'll give a little intuition on how it will work and then give you the tools to crunch the numbers. Think of electricity as a big water tank. The water in the tank is the electric current, or load. The water pressure is the voltage. Your magneto is a special device that has unlimited water to pump into the tank, but has a fixed rate pump that shuts off at a given pressure. Thus it fills your water tank when the pressure drops until the pressure is restored. Now if you have two water tanks, you've got twice the water but the same amount of pressure. So if you run both tanks dry, it will take twice as long, relative to a single tank, to fill the tanks back up. But the pressure has not changed so the strain (pressure) on the magneto is no different. Anyway, it's fairly simple but a little tedious to calculate how multiple batteries are going to change your situation. I'm only going to cover batteries in parallel. There are a few numbers you should find for your batteries. The first, you've already got, is the rated voltage. The second, is the number of amp-hours the battery is rated for. Third, either assume or find out, how the manufacturer of your battery measures amp-hours. A brief digression on amp-hours. The standard is to measure amp-hours for a twenty (20) hour period. Amp-hours are calculated as an average load. This average load is 5% of the rated capacity. So for a battery rated at 7Ah (Amp-hours), the manufacturer made the amp-hour rating assuming a constant load of 0.350 amps. If your load exceeds this, the performance of the battery will not match manufacturer's specifications and will discharge faster than expected. Two batteries in parallel means double the amp-hour capacity (two water tanks). So if you have two 7Ah batteries in parallel, you effectively have 14Ah of capacity. Which, as your gut intuition told you, means longer lasting. Is this better? Well it probably is for what you're doing. But notice, that you still shouldn't exceed the 0.350 Amps of draw if you want to meet manufacturer's specifications. The following equation will let you do a "back-of-the napkin" calculation. It errors on giving you a liberal answer, meaning you probably won't get the complete expected life. In my line of engineering we use a 50% rule meaning that we engineer to 1/2 of manufacturer's specifications. Expensive? Yes. Reliable? Yes. So if you're willing to handle the expense, halve the answer you get below. I also realize you probably don't know the current draw so the equation is probably useless. (Expected life) = (Amp-Hour Rating) * (Number of Batteries) * (20) / (Current Draw) On Thu, 17 Jul 2003 16:19:10 -0400, "Belgian" wrote: Hi , i was wondering if there is any danger to fry the magneto of an outboard 40hp Suzuki engine if install 2 12 volts battery in parallel . I do use lots of 12 volt equipments on the pontoon, so i figured that 2 batteries would be better and last longer .Last year a battery died on me in the midle of the lake. I just bought 2 brand new marine ones . would that be too much strain on the magneto ? thanks for your help ! |
#10
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Battery question
You should have no problem using 2 batteries.
One other item...I did not see if this was in a previous post BUT... Buy a switch made for 2 batteries. Always start from one battery or the other (This is a good test to see if one is not as healthy as the other). You can charge in parallel if you want. When you are at anchor or dockside with the engine off turn the battery switch back to 1 OR 2 (not BOTH). This will assure that you have plenty of power to start the engine. ALSO... NEVER put the switch in the OFF position with the engine running (that WILL kill your alt) most (probably all) of the batt switches made for this task will be MAKE-BEFORE-BREAK switches so you can switch from 1 to both to 2 without hurting the alt. bowgus wrote: Well, that's all very wonderful ... the part about water tanks and all ... but does not answer the question. The question pbosez asked is ... can my outboard (I assume with alternator) maintain a charge on 2 batteries in parallel without burning up. The answer is ... yes. From previous posts though, my understanding is, don't stress the alternator by letting the batteries go too low, else the alternator will be putting out maximum current meaning it will get hot meaning that's not good to do too often. "edg" wrote in message ... I'm a degreed electrical engineer, which means my answer will work on paper but may not in your boat. Go easy the first couple times and see. That's the engineer's final test! I'll give a little intuition on how it will work and then give you the tools to crunch the numbers. Think of electricity as a big water tank. The water in the tank is the electric current, or load. The water pressure is the voltage. Your magneto is a special device that has unlimited water to pump into the tank, but has a fixed rate pump that shuts off at a given pressure. Thus it fills your water tank when the pressure drops until the pressure is restored. Now if you have two water tanks, you've got twice the water but the same amount of pressure. So if you run both tanks dry, it will take twice as long, relative to a single tank, to fill the tanks back up. But the pressure has not changed so the strain (pressure) on the magneto is no different. Anyway, it's fairly simple but a little tedious to calculate how multiple batteries are going to change your situation. I'm only going to cover batteries in parallel. There are a few numbers you should find for your batteries. The first, you've already got, is the rated voltage. The second, is the number of amp-hours the battery is rated for. Third, either assume or find out, how the manufacturer of your battery measures amp-hours. A brief digression on amp-hours. The standard is to measure amp-hours for a twenty (20) hour period. Amp-hours are calculated as an average load. This average load is 5% of the rated capacity. So for a battery rated at 7Ah (Amp-hours), the manufacturer made the amp-hour rating assuming a constant load of 0.350 amps. If your load exceeds this, the performance of the battery will not match manufacturer's specifications and will discharge faster than expected. Two batteries in parallel means double the amp-hour capacity (two water tanks). So if you have two 7Ah batteries in parallel, you effectively have 14Ah of capacity. Which, as your gut intuition told you, means longer lasting. Is this better? Well it probably is for what you're doing. But notice, that you still shouldn't exceed the 0.350 Amps of draw if you want to meet manufacturer's specifications. The following equation will let you do a "back-of-the napkin" calculation. It errors on giving you a liberal answer, meaning you probably won't get the complete expected life. In my line of engineering we use a 50% rule meaning that we engineer to 1/2 of manufacturer's specifications. Expensive? Yes. Reliable? Yes. So if you're willing to handle the expense, halve the answer you get below. I also realize you probably don't know the current draw so the equation is probably useless. (Expected life) = (Amp-Hour Rating) * (Number of Batteries) * (20) / (Current Draw) On Thu, 17 Jul 2003 16:19:10 -0400, "Belgian" wrote: Hi , i was wondering if there is any danger to fry the magneto of an outboard 40hp Suzuki engine if install 2 12 volts battery in parallel . I do use lots of 12 volt equipments on the pontoon, so i figured that 2 batteries would be better and last longer .Last year a battery died on me in the midle of the lake. I just bought 2 brand new marine ones . would that be too much strain on the magneto ? thanks for your help ! |
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