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#1
posted to rec.boats.cruising




Electrical, battery, question
I get so confused when it comes to electric power, especially battery
output. How many AMPs can a battery put out before the battery is dead? Say, a 12 volt battery. Could you put this as .. "if you have on a light for xxx hours the battery is gone". I know AMPs are the flow of power and volts is the possible amount .. measure of flow and time . and light bulb. Why am I asking? I was looking at this boat on a web site and the owner had added a bank of small batteries. About half the size of the marine ones I'm use to. The batteries were tied together so they became on big battery in power possibility. Now,, if he had 6 batteries and each one is an 8 volt .. does this mean he has 8x6 = 48 volts of possible power? And how does this work out to amps. ? batteries are heavy. how many do you carry. wouldn't a bunch be bad for the boat?? also.. solar power.. how much power does one of those things give you? thanks, 
#2
posted to rec.boats.cruising




Electrical, battery, question
Thomas Wentworth wrote:
I get so confused when it comes to electric power, especially battery output. How many AMPs can a battery put out before the battery is dead? Say, a 12 volt battery. Could you put this as .. "if you have on a light for xxx hours the battery is gone". I know AMPs are the flow of power and volts is the possible amount .. measure of flow and time . and light bulb. Why am I asking? I was looking at this boat on a web site and the owner had added a bank of small batteries. About half the size of the marine ones I'm use to. The batteries were tied together so they became on big battery in power possibility. Now,, if he had 6 batteries and each one is an 8 volt .. does this mean he has 8x6 = 48 volts of possible power? And how does this work out to amps. ? batteries are heavy. how many do you carry. wouldn't a bunch be bad for the boat?? also.. solar power.. how much power does one of those things give you? thanks, The voltage has absolutely nothing to do with it. A 12volt battery has a stated capacity in amp/hours, and will last until exhausted when a 12volt load is applied. How big a load? You tell us! If a battery's stated capacity is say, 100A/H, then a 5amp bulb would in theory burn for 100/5=20 hours, but in practice this is simply a guide, since the bulb would go dim once the battery's voltage dropped below the 12volts output, and in fact the bulb might still be showing some faint light after 30 hours or more. For the six batteries you mention to give 48 volts they would have to be wired in series, i.e. each one positive to negative, whereas in parallel (positive to positive and negative to negative) they would give you 12 volts, but the capacity would be the sum of the six batterys' capacities. Space and layout permitting, It is better to have as big a battery as the boat will permit for house use, and a starter battery appropriate to the size of the engine installed, banks of batteries are fine until one packs in, then you have to find the culprit and remove it from the bank. Auto batteries are often used as the starter battery, whereas a slow discharge battery is better for the house requirements. The 2 batteries can be wired for charging purposes by a splitting diode or similar arrangement which allows them both to be charged together, but discharged separately. Amps = volume and volts = pressure, think of a hosepipe. 
#3
posted to rec.boats.cruising




Electrical, battery, question
On Sun, 29 Jan 2006 19:34:10 GMT, "Dennis Pogson"
wrote: Thomas Wentworth wrote: Now,, if he had 6 batteries and each one is an 8 volt .. does this mean he has 8x6 = 48 volts of possible power? And how does this work out to amps. ? For the six batteries you mention to give 48 volts they would have to be wired in series, i.e. each one positive to negative, whereas in parallel (positive to positive and negative to negative) they would give you 12 volts, but the capacity would be the sum of the six batterys' capacities. The OP's suggested 8 volt batteries  if he connects them in parallel, they'll still give him 8 volts.  Peter Bennett, VE7CEI peterbb4 (at) interchange.ubc.ca new newsgroup users info : http://vancouverwebpages.com/nnq GPS and NMEA info: http://vancouverwebpages.com/peter Vancouver Power Squadron: http://vancouver.powersquadron.ca 
#4
posted to rec.boats.cruising




Electrical, battery, question
Well, if the six batteries are wired in series to get 48 volts, the
capacity of the six is essentially the capacity of the smallestcapacity battery of the lot. As the smallestcapacity battery discharges, its internal resistance increases, which prevents the discharge through it of the batteries with greater capacity. If the six are identical, however, then the capacity in amphours of the six in series is the same as the capacity of any one of them alone. Only the voltage changes. Or is that more confusing? Chuck Peter Bennett wrote: On Sun, 29 Jan 2006 19:34:10 GMT, "Dennis Pogson" wrote: Thomas Wentworth wrote: Now,, if he had 6 batteries and each one is an 8 volt .. does this mean he has 8x6 = 48 volts of possible power? And how does this work out to amps. ? For the six batteries you mention to give 48 volts they would have to be wired in series, i.e. each one positive to negative, whereas in parallel (positive to positive and negative to negative) they would give you 12 volts, but the capacity would be the sum of the six batterys' capacities. The OP's suggested 8 volt batteries  if he connects them in parallel, they'll still give him 8 volts. 
#5
posted to rec.boats.cruising




Electrical, battery, question
On Mon, 30 Jan 2006 00:56:53 GMT, chuck wrote:
Well, if the six batteries are wired in series to get 48 volts, 8 volt batteries are not that common except on boats with 32 volt electrical system like the older Hatteras motor yachts. Much more common on sailboats are banks of 6 volt batteries wired in seriesparallel to yield high capacity 12 volt battery banks. Four 6 volt golf cart batteries in series parallel will give you about 440 amphours of capacity but in actual practice it is a bad idea to discharge below the 50% level since that will greatly shorten batter life. You can get a rough idea of discharge level by looking at a digital voltmeter when the batteries are under load. 12.6 volts is fully charged, 11.6 volts is about 50%, and 10.5 is fully discharged. 
#6
posted to rec.boats.cruising




Electrical, battery, question
Yeah. Should've mentioned that. I was trying to respond to the original
question as posed. He seemed to be asking about the capacity of seriesconnected batteries. Chuck Wayne.B wrote: On Mon, 30 Jan 2006 00:56:53 GMT, chuck wrote: Well, if the six batteries are wired in series to get 48 volts, 8 volt batteries are not that common except on boats with 32 volt electrical system like the older Hatteras motor yachts. 
#7
posted to rec.boats.cruising




Electrical, battery, question
chuck wrote:
Yeah. Should've mentioned that. I was trying to respond to the original question as posed. He seemed to be asking about the capacity of seriesconnected batteries. Chuck He would be better reading a copy of "The 12volt Doctor's Practical Handbook", a must for all who find boat electrical technology difficult. Sadly, any .pdf copies seem to have disappeared from the Web, and you have to pay around $30 for a hard copy. Dennis. 
#8
posted to rec.boats.cruising




Electrical, battery, question
"Thomas Wentworth" wrote in message news:dz7Df.1473$UY3.1361@trndny05... I get so confused when it comes to electric power, especially battery output. How many AMPs can a battery put out before the battery is dead? Say, a 12 volt battery. Could you put this as .. "if you have on a light for xxx hours the battery is gone". I know AMPs are the flow of power and volts is the possible amount .. measure of flow and time . and light bulb. Why am I asking? I was looking at this boat on a web site and the owner had added a bank of small batteries. About half the size of the marine ones I'm use to. The batteries were tied together so they became on big battery in power possibility. Now,, if he had 6 batteries and each one is an 8 volt .. does this mean he has 8x6 = 48 volts of possible power? And how does this work out to amps. ? 1. Volts = pressure. Add batteries nose to tail (+ to , or in series) and you add up their voltage. The most common sipboard voltage for yachts 20ft to 40ft is 12v (actually, 10.5v to 12.7v, depending on their charge state). 2. Battery capacity is shown in ampere x hours (AH). Very approximately, divide the AH by the number of amps you're using, and that's how many hours you'll get out of the battery if it's fully charged. 3. If you join similar voltage batteries nose to nose, and tail to tail (in parallel), the voltage will stay the same, but the capacity will multiply by the number of batteries. 4. If you recharge your discharged 12v battery using a 48watt (power: watts = volts x amps) solar panel, you should get 4 amps out of it (48/12), and if it keeps up its 4a (which it won't) you'll get 4 x (the number of hours) of AH back into the battery. Those are the basic rules. They get screwed up by efficiency (or lack of it), but they're a good start. Have fun doing the sums. JimB http://www.jimbaerselman.f2s.com/sw_peloponese.htm 
#9
posted to rec.boats.cruising




Electrical, battery, question
News f2s wrote:
"Thomas Wentworth" wrote in message news:dz7Df.1473$UY3.1361@trndny05... I get so confused when it comes to electric power, especially battery output. How many AMPs can a battery put out before the battery is dead? Say, a 12 volt battery. Could you put this as .. "if you have on a light for xxx hours the battery is gone". I know AMPs are the flow of power and volts is the possible amount .. measure of flow and time . and light bulb. Why am I asking? I was looking at this boat on a web site and the owner had added a bank of small batteries. About half the size of the marine ones I'm use to. The batteries were tied together so they became on big battery in power possibility. Now,, if he had 6 batteries and each one is an 8 volt .. does this mean he has 8x6 = 48 volts of possible power? And how does this work out to amps. ? 1. Volts = pressure. Add batteries nose to tail (+ to , or in series) and you add up their voltage. The most common sipboard voltage for yachts 20ft to 40ft is 12v (actually, 10.5v to 12.7v, depending on their charge state). 2. Battery capacity is shown in ampere x hours (AH). Very approximately, divide the AH by the number of amps you're using, and that's how many hours you'll get out of the battery if it's fully charged. 3. If you join similar voltage batteries nose to nose, and tail to tail (in parallel), the voltage will stay the same, but the capacity will multiply by the number of batteries. 4. If you recharge your discharged 12v battery using a 48watt (power: watts = volts x amps) solar panel, you should get 4 amps out of it (48/12), and if it keeps up its 4a (which it won't) you'll get 4 x (the number of hours) of AH back into the battery. A 100 amp hour battery. 100/5amps = 20 hours. Yes. 100/50 = 2 hours. NO! Maybe 20 minutes. Those are the basic rules. They get screwed up by efficiency (or lack of it), but they're a good start. Have fun doing the sums. JimB http://www.jimbaerselman.f2s.com/sw_peloponese.htm 
#10
posted to rec.boats.cruising




Electrical, battery, question
Peter Bennett wrote:
On Sun, 29 Jan 2006 19:34:10 GMT, "Dennis Pogson" wrote: Thomas Wentworth wrote: Now,, if he had 6 batteries and each one is an 8 volt .. does this mean he has 8x6 = 48 volts of possible power? And how does this work out to amps. ? For the six batteries you mention to give 48 volts they would have to be wired in series, i.e. each one positive to negative, whereas in parallel (positive to positive and negative to negative) they would give you 12 volts, but the capacity would be the sum of the six batterys' capacities. The OP's suggested 8 volt batteries  if he connects them in parallel, they'll still give him 8 volts. Perhaps 3 x 8V = 24V? Evan Gatehouse 
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