I'm not trying to re-start the discussion on the merits of golf cart vrs. "regular" batteries. I made the decision to use golf cart batts. for my house bank, but today a friend of mine suggested I reconsider due to the weight difference. I presently have two group 27's. He claims there is a significant difference when compaired to four golf carts. So much so they created a list in his boat (O'day 27 or 30)and he has to keep his port water tank full to compensate. I never even thought about the weight difference. Should I? Thanks for your thoughts.
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It's like everything else,,,,It depends.
How's that Harry? Just what you wanted to hear, huh? Go back to the start of your decision making matrix and review why you wanted them. If the reasons are still valid, go for it. Otherwise you'll have to re-weigh your decision.
Sorry.
How's that Harry? Just what you wanted to hear, huh? Go back to the start of your decision making matrix and review why you wanted them. If the reasons are still valid, go for it. Otherwise you'll have to re-weigh your decision.
Sorry.How much is the Weight Difference?
Why is the weight difference a concern? Is it balance, ballast, structural or just the added weight? The weight difference probably is not that much different. Much of the weight of batteries is the lead which helps determine the number of amp hours. A six volt battery with 200 amp hours will weight about the same as a 12 volt battery at 100 amp hours. They have the same energy. My bet is that the weight difference is not that much.
Why is the weight difference a concern? Is it balance, ballast, structural or just the added weight? The weight difference probably is not that much different. Much of the weight of batteries is the lead which helps determine the number of amp hours. A six volt battery with 200 amp hours will weight about the same as a 12 volt battery at 100 amp hours. They have the same energy. My bet is that the weight difference is not that much.
Dollars per Amp Hour, Goft Cart wins
so if your cruising get 6v GC batteries. If your a racer get the 12 deep cycle jobs. Either way be sure to think about the best place to locate them cause that makes a difference
so if your cruising get 6v GC batteries. If your a racer get the 12 deep cycle jobs. Either way be sure to think about the best place to locate them cause that makes a difference
Harry, they average mid 60s each- wet
Go here. http://www.ibsa.com/www_2001/content/products/product_golfcar.asp These guys also make Trojans.
Go here. http://www.ibsa.com/www_2001/content/products/product_golfcar.asp These guys also make Trojans.
Watt Hours not Amp Hours
Watt hours is what counts not amp hours. You get roughly twice the amp hours for 6V batteries, but the watt hours are roughly equal to 12 volt batteries. For example if you want 400 amp hours at 12v. You can use four six volt 200 amp hour batteries with each pair wired in series or you can get four twelve volt 100 amp hour batteries with all four wired in parallel. In each case it is four batteries of roughly the same weight.
Watt hours is what counts not amp hours. You get roughly twice the amp hours for 6V batteries, but the watt hours are roughly equal to 12 volt batteries. For example if you want 400 amp hours at 12v. You can use four six volt 200 amp hour batteries with each pair wired in series or you can get four twelve volt 100 amp hour batteries with all four wired in parallel. In each case it is four batteries of roughly the same weight.
6v battery weight
Harry, 1. What counts is punds/amp 2 6Volt trojans equals 225 amp/h capacity. Weight divided capacity will define which weights more. 2. Indeed that each of the 4 golf batteries weights less than each of your 27. So when you need to remove them, is easier. They are even smaller. So depending on your boat, you might have several other options to locate them. That was my experience Regards.Fernando
Harry, 1. What counts is punds/amp 2 6Volt trojans equals 225 amp/h capacity. Weight divided capacity will define which weights more. 2. Indeed that each of the 4 golf batteries weights less than each of your 27. So when you need to remove them, is easier. They are even smaller. So depending on your boat, you might have several other options to locate them. That was my experience Regards.Fernando
Go back to Previous Post
Go back and read the previous post. What counts is watt hour capacity or the number of amp hours at the correct voltage. If I read what you are saying correctly, you are saying that 225 amp hours at six volts is the same as 225 amp hours at twelve volts and that is obviously not true. I may have misunderstood what you were saying. If so, disregard.
Go back and read the previous post. What counts is watt hour capacity or the number of amp hours at the correct voltage. If I read what you are saying correctly, you are saying that 225 amp hours at six volts is the same as 225 amp hours at twelve volts and that is obviously not true. I may have misunderstood what you were saying. If so, disregard.
Not much difference
As previously noted, there’s not a huge “Power to Weight” difference between differing Lead Acid (Flooded) Batteries . For Comparison: Batteries wired in series will double the voltage of each. Batteries wired in parallel will double the capacity (Amp-Hours or Watt/Hrs) of one. Hence: Two 6 Volt Traction Batteries will be wired in series to provide 12 Volt output at the same capacity (as one). Two 12V Group 27 Batteries will be wired in parallel to provide double the capacity at the same 12V (as one). So: Two 6 Volt “Traction” Batteries wired in series for 12V nominal: Trojan ‘T105' (6 V) - 225A/H each (20 Hr rate), 62 Lbs each = 225 A/H ÷ 124 Lbs 1.81 A/H per pound. or Two 12 Volt (Group 27) “SLI” Batteries wired in parallel: Trojan ‘27TMH’ (12V) - 105 A/H each (20 Hr rate), 58 Lbs each = 210 Ah ÷ 118 Lbs = 1.78 A/H per pound For those who prefer to compare Watt/Hours: 2 Six Volt Batteries (Series) @ (225 A/H x 6V) = Total 2,700 W/H or 21.8 Watt/Lb (2700W ÷ 124#) 2 Twelve Volt Batteries (Parallel) @ 105 A/H x 12V) = Total 2,520 W/H or 21.4 Watt/Lb (2520W ÷ 118#) Either way, the 6 Volt Traction Batteries are about 1% more Weight Efficient than the 12 Volt - hardly significant. HOWEVER: It all depends upon the Amp/Hour specifications and weights of the actual batteries you are comparing. If you were to compare a 90 A/H Group 27 battery, weighing 52 Lbs to the 6V Traction - the 6V Traction weight advantage increases to about 4 ½%. HTH, Gord
As previously noted, there’s not a huge “Power to Weight” difference between differing Lead Acid (Flooded) Batteries . For Comparison: Batteries wired in series will double the voltage of each. Batteries wired in parallel will double the capacity (Amp-Hours or Watt/Hrs) of one. Hence: Two 6 Volt Traction Batteries will be wired in series to provide 12 Volt output at the same capacity (as one). Two 12V Group 27 Batteries will be wired in parallel to provide double the capacity at the same 12V (as one). So: Two 6 Volt “Traction” Batteries wired in series for 12V nominal: Trojan ‘T105' (6 V) - 225A/H each (20 Hr rate), 62 Lbs each = 225 A/H ÷ 124 Lbs 1.81 A/H per pound. or Two 12 Volt (Group 27) “SLI” Batteries wired in parallel: Trojan ‘27TMH’ (12V) - 105 A/H each (20 Hr rate), 58 Lbs each = 210 Ah ÷ 118 Lbs = 1.78 A/H per pound For those who prefer to compare Watt/Hours: 2 Six Volt Batteries (Series) @ (225 A/H x 6V) = Total 2,700 W/H or 21.8 Watt/Lb (2700W ÷ 124#) 2 Twelve Volt Batteries (Parallel) @ 105 A/H x 12V) = Total 2,520 W/H or 21.4 Watt/Lb (2520W ÷ 118#) Either way, the 6 Volt Traction Batteries are about 1% more Weight Efficient than the 12 Volt - hardly significant. HOWEVER: It all depends upon the Amp/Hour specifications and weights of the actual batteries you are comparing. If you were to compare a 90 A/H Group 27 battery, weighing 52 Lbs to the 6V Traction - the 6V Traction weight advantage increases to about 4 ½%. HTH, Gord
My take on the advantages of golf carts
Weight is less a factor than other issues. Golf cart batteries are robust... the water tank capacity of a cell is much greater... to run one dry... it has to be neglected bad. It may also be that the larger the cell structure, that the less fragile the cell is. At any rate, six cells are simpler than twelve cells. Of course, it could be argued that if one of those cells goes out... then battery use is in jeopardy whereas with two 12v, one bank would still be capable of a full 12 volts. I guess I see the robust factor overshadowing that concern. Six cells in series are easier to charge and manage than two parallel groups of six series cells.
Weight is less a factor than other issues. Golf cart batteries are robust... the water tank capacity of a cell is much greater... to run one dry... it has to be neglected bad. It may also be that the larger the cell structure, that the less fragile the cell is. At any rate, six cells are simpler than twelve cells. Of course, it could be argued that if one of those cells goes out... then battery use is in jeopardy whereas with two 12v, one bank would still be capable of a full 12 volts. I guess I see the robust factor overshadowing that concern. Six cells in series are easier to charge and manage than two parallel groups of six series cells.
Fred, we only need three for our boat...
one starter and two house. Twelve seems like a lot of batteries unless you're using "D" type. Terry
one starter and two house. Twelve seems like a lot of batteries unless you're using "D" type.
Terry2 12 volt bats in parallel
Gord, a correction... Excellent workup, but a typo: 2 12 volt bats in parallel...105 AH each equals 210 AH, not 110 AH. You presented why I use 4 grp 27 105 AH bats. I can parallel them all (420 AH) or any combo. Here in Mexico, they are available easily. Not everybody can go to the nearest Costco or Sears (by the way the same manufacturer-Johnson Controls).
Gord, a correction... Excellent workup, but a typo: 2 12 volt bats in parallel...105 AH each equals 210 AH, not 110 AH. You presented why I use 4 grp 27 105 AH bats. I can parallel them all (420 AH) or any combo. Here in Mexico, they are available easily. Not everybody can go to the nearest Costco or Sears (by the way the same manufacturer-Johnson Controls).
Once again, a typo.
Every time I skip proof reading my stuff,,, I fixed it, too hard to look at otherwise,,,(is that a past partisomthing?) P.S. Terry as a Costco member, we have lots of D types too. P.S2. A reminder for the newbies, all this talk of amp hours has to be qualified. Cut it in half. Your batteries should never be drained below half charge. That's 12.2VDC. (I didn't leave it off, Terry) That's in the interest of battery life.
Every time I skip proof reading my stuff,,, I fixed it, too hard to look at otherwise,,,(is that a past partisomthing?) P.S. Terry as a Costco member, we have lots of D types too.
P.S2. A reminder for the newbies, all this talk of amp hours has to be qualified. Cut it in half. Your batteries should never be drained below half charge. That's 12.2VDC. (I didn't leave it off, Terry) That's in the interest of battery life.Fred, you mean 11.2 volts, right? I thought ...
wets that dropped to 11.1/11.2 volts were half discharged. That has always been my rule of thumb. Terry P.S. I just could not pass up your previous post. Of course I expect you to reciprocate...keeps us on our toes, you know. If I could figure out how to use red text I could error check your posts for you and really piss you off. Hey Phil, how can I select red text? Just kidding!
wets that dropped to 11.1/11.2 volts were half discharged. That has always been my rule of thumb. Terry P.S. I just could not pass up your previous post. Of course I expect you to reciprocate...keeps us on our toes, you know. If I could figure out how to use red text I could error check your posts for you and really piss you off.
Hey Phil, how can I select red text? Just kidding!Either Answer
Like many rules of thumb, whether you pick 11.2V or 12.2V is fairly arbitrary. A battery discharge voltage drops fairly quickly as the initial charge is bled off and then it runs flat until near the end of discharge when it again drops very quickly. The problem is the rate of discharge also affects the voltage. For example an open circuit battery voltage of 12.2V might indicate a half charge. However, if the rate of discharge is 30A, it could be 11.2V. 12.2V is the one I am accustomed to using, but it is an open circuit voltage. Regardless the voltage is not a very good indicator of battery capacity. It is better to calculate the remaining capacity using the discharge rates of the various electrical components. I recognize that in many and possibly most situations this is not practicle.
Like many rules of thumb, whether you pick 11.2V or 12.2V is fairly arbitrary. A battery discharge voltage drops fairly quickly as the initial charge is bled off and then it runs flat until near the end of discharge when it again drops very quickly. The problem is the rate of discharge also affects the voltage. For example an open circuit battery voltage of 12.2V might indicate a half charge. However, if the rate of discharge is 30A, it could be 11.2V. 12.2V is the one I am accustomed to using, but it is an open circuit voltage. Regardless the voltage is not a very good indicator of battery capacity. It is better to calculate the remaining capacity using the discharge rates of the various electrical components. I recognize that in many and possibly most situations this is not practicle.
Terry 11.2 is DEAD!! Stick a hydrometer in there
and see what you get. If you go that low, you will have to open the compression releases to start your Yanmar! Dan, yep, 12.2 is low drain voltage. The gurus/pundits even say to let the bank sit for two hours, disconnected, to get an accurate reading. Those guys need to sound important to justify getting paid for the dribble they write. Who does that? And Terry, I'll get ya.
and see what you get. If you go that low, you will have to open the compression releases to start your Yanmar!
Dan, yep, 12.2 is low drain voltage. The gurus/pundits even say to let the bank sit for two hours, disconnected, to get an accurate reading. Those guys need to sound important to justify getting paid for the dribble they write. Who does that? And Terry, I'll get ya. Fred, 11.2 is not dead. I've been on the hook...
for several days running my reefers and other stuff until the house system gets to 11 volts. That is my signal to fire up the genset and recharge the batteries. Even at 11 volts all the systems run just fine, maybe not as strong as at 12, but still running strong. However, it is a different story at 10 volts. Terry
for several days running my reefers and other stuff until the house system gets to 11 volts. That is my signal to fire up the genset and recharge the batteries. Even at 11 volts all the systems run just fine, maybe not as strong as at 12, but still running strong. However, it is a different story at 10 volts. Terry
11 OCV is
1.You are likely measuring (11.0V) "Operating Voltage" while under load. This loaded voltage is lower than Open Circuit Voltage (no-load). 2. Boat Voltmeters are notoriously inaccurate, and often low-impedance type. OCV must be measured with a low-impedance Voltmeter (or the meter affects the reading). A battery is effectively “dead’ at 11.5 Open Circuit Volts, and may not run your refrigeration nor start your generator at anything under 11.8 Volts. There’s a very brief essay on Open Circuit Voltage and Specific Gravity vs State of Charge - Depth of Discharge at: http://takehersailingboard.infopop.cc/eve Look for “Basic Battery Testing” Under the “Little Help..” topic Regards, Gord
1.You are likely measuring (11.0V) "Operating Voltage" while under load. This loaded voltage is lower than Open Circuit Voltage (no-load). 2. Boat Voltmeters are notoriously inaccurate, and often low-impedance type. OCV must be measured with a low-impedance Voltmeter (or the meter affects the reading). A battery is effectively “dead’ at 11.5 Open Circuit Volts, and may not run your refrigeration nor start your generator at anything under 11.8 Volts. There’s a very brief essay on Open Circuit Voltage and Specific Gravity vs State of Charge - Depth of Discharge at: http://takehersailingboard.infopop.cc/eve Look for “Basic Battery Testing” Under the “Little Help..” topic Regards, Gord
fred and gordo are right
to use voltage as a cdepth of discharge indicator the batteries need to sit a minimum of 2 hours before reading voltaage. 12.6-12.7, fully charged. 12.2-50% 11.8-25% 11.6 and lower is effectively dead. Having any load on a battery at less than 80% charge will effect the voltage reading dramatically. The best way to determine state of charge is with a battery status meter that measures what goes in and what comes out of your bank and gives you a cumulaive reading in % of full (like a Cruise Emeter, Bogart engineering tri-metric, etc.). If you run your batteries under 50% for any length of time you will be replacing them every 2 seasons instead of 5-7 seasons for golf cart batteries. Back to the original question of this thread, the weight to A/H ratio is determined by the thickness of the plates. A high quality deep cycle will have thicker plates than one of lesser quality, although they both are roughly the same A/H capacity. Check the weight of a Rolls battery, which will last over 20 years if properly cared for versus the weight of golf cart or L16 type batteries which will last 5-7 years of the same capacity, and you will see a substancial difference. Ross
to use voltage as a cdepth of discharge indicator the batteries need to sit a minimum of 2 hours before reading voltaage. 12.6-12.7, fully charged. 12.2-50% 11.8-25% 11.6 and lower is effectively dead. Having any load on a battery at less than 80% charge will effect the voltage reading dramatically. The best way to determine state of charge is with a battery status meter that measures what goes in and what comes out of your bank and gives you a cumulaive reading in % of full (like a Cruise Emeter, Bogart engineering tri-metric, etc.). If you run your batteries under 50% for any length of time you will be replacing them every 2 seasons instead of 5-7 seasons for golf cart batteries. Back to the original question of this thread, the weight to A/H ratio is determined by the thickness of the plates. A high quality deep cycle will have thicker plates than one of lesser quality, although they both are roughly the same A/H capacity. Check the weight of a Rolls battery, which will last over 20 years if properly cared for versus the weight of golf cart or L16 type batteries which will last 5-7 years of the same capacity, and you will see a substancial difference. Ross
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