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Battery switch
I'm about to wire up a battery switch so that I can switch between two
batteries. (one or the other or both) Just wondering if I should put the switch on the positive or negative?? Or doesn't it matter? Also, do both the batteries have to be the same age/rating??? I was hoping to use my old battery for powering accessories when I'm stopped, but charge it when the engine is running with the other battery. Thanks in advance! :) |
"bowgus" blathered....
in Message-id: ... "GC" wrote in message ... I'm about to wire up a battery switch so that I can switch between two batteries. (one or the other or both) Don't use the "both" setting ... read on Just wondering if I should put the switch on the positive or negative?? Or doesn't it matter? Positive is the norm around here (geez ... hurts the head to even think about switching the negative since that's normally the electrical reference) Also, do both the batteries have to be the same age/rating??? I was hoping to use my old battery for powering accessories when I'm stopped, but charge it when the engine is running with the other battery. In your situation, I would ... (get myself a deep cycle for the accessories ... e.g. my accesory is my electric trolling motor) a) make sure the switch is a make before break type which they normally are so that the alternator is never without a load if switched while running; b) when stopped select the old battery (if it's a regular starting type battery it won't tolerate many cycles of being discharged), before starting, switch to the new battery; c) while running charge batteries by switching between the two (hmmm ... when are they charged ... well, maybe your batteries have indicators of the green it's charged variety?); d) never connect the batteries ... it's my understanding that the charged one could pump a lot of current into the discharged (my theory ... a battery (let's just say for the sake of argument rated 800 cold cranking amps) has no current limiting feature like a battery charger does) which could result in 800 amps going through wiring/switch resulting in fire, exploding battery, ... Thanks in advance! :) My 2 cents worth ... And worth slightly less than 2 cents. Where do you people get your information? Disneyworld? A typical engine start battery would be 600 to 650 CCA As you have quoted 800 CCA we shall use that as the example. A brand new 800 CCA engine start battery will have an internal resistance of around 0.004 ohms and an _open circuit_ voltage of around 12.7 volts (you can calculate the fully charged internal resistance of an engine start battery using the given CCA and the _definition_ of what CCA means - but of course you didn't know that). A flat deep cycle battery will have an _open circuit_ voltage of around 11.9 volts and an internal resistance of around 0.06 ohms. The voltage _difference_ between the 2 batteries is therefore 0.8 volts dropped across the two internal resistances of 0.004 + 0.06 = 0.064 ohms = 12.5 amps. And that is making the simple assumption that the voltage of the fully charged engine battery does not fall under load (in addition to the voltage drop caused by the internal resistance) which in practice it will, by about 0.2 volts at this sort of loading. So the _real_ current draw will be approximately 9.4 amps. Further, there is a dead band between the open circuit voltage and the voltage at which charging will commence. This dead band varies quite dramatically depending upon the state of charge of the battery in question. A typical figure for a flat deep cycle battery would be about 0.2 volts. So an even closer figure for the current draw (that you assert is 800 amps) would be (12.5V - 12.1V) 0.4V/(total internal resistance) 0.064R = 6.25 amps. And of course you won't believe me. So instead of using half a theory that you don't understand anyway, either go learn the rest of the theory or try it and take some measurements. Connectng the batteries in parallel is perfectly safe, quite normal, will achieve what is desired and is used in millions of installations the world over. Idiot Folklore Killer. |
"GC" wrote in message ... I'm about to wire up a battery switch so that I can switch between two batteries. (one or the other or both) Don't use the "both" setting ... read on Just wondering if I should put the switch on the positive or negative?? Or doesn't it matter? Positive is the norm around here (geez ... hurts the head to even think about switching the negative since that's normally the electrical reference) Also, do both the batteries have to be the same age/rating??? I was hoping to use my old battery for powering accessories when I'm stopped, but charge it when the engine is running with the other battery. In your situation, I would ... (get myself a deep cycle for the accessories .... e.g. my accesory is my electric trolling motor) a) make sure the switch is a make before break type which they normally are so that the alternator is never without a load if switched while running; b) when stopped select the old battery (if it's a regular starting type battery it won't tolerate many cycles of being discharged), before starting, switch to the new battery; c) while running charge batteries by switching between the two (hmmm ... when are they charged ... well, maybe your batteries have indicators of the green it's charged variety?); d) never connect the batteries ... it's my understanding that the charged one could pump a lot of current into the discharged (my theory ... a battery (let's just say for the sake of argument rated 800 cold cranking amps) has no current limiting feature like a battery charger does) which could result in 800 amps going through wiring/switch resulting in fire, exploding battery, ... Thanks in advance! :) My 2 cents worth ... mainly because I'm up at 5:00 in the morning mulling over a work related situation ... er ... challenge :-) |
On 06 Nov 2004 11:10:38 GMT, Folklore killer wrote:
....snip Connectng the batteries in parallel is perfectly safe, quite normal, will achieve what is desired and is used in millions of installations the world over. If one connects a battery near the end of it's life in parallel with a relatively new, fully-charged battery, are you saying that the old battery will not discharge the new one? By your own calculations, it appears that it will. If that's the case, then shouldn't one be careful paralleling two batteries of different age and condition? Of course one could prevent this by the use of high current diodes, but that lowers voltage by about 0.7 volts per diode. I think that's the reason the practice tends to be discouraged, but I'm not an expert. -- Larry email is rapp at lmr dot com 11/06/04 9:38:03 AM |
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"bowgus" miserably failed in attempting to insult his superior.....
in Message-id: .... By blathering..... So what you're saying is no need to turn in those old batteries, just hook up a new one in parallel ... Which is not what I wrote so you clearly need to go back to "baby school" to learn how to read. and oh yeah, no problem running a starting battery (my understanding that's what GC has) for accessories until it's dead ... That is because either A) You misunderstood what OP wrote or more likely B) You did not read it (or perhaps _couldn't_ read it). or even more likely C) were so busy trying to prove your superior knowledge (and failing quite dramatically) that you forgot to read the entire thread before collapsing your lower jawbone muscles. they can be recharged over and over and over? Now please quote where that was stated by anyone. Geez ... even a deep cycle's life is shortened by doing that. You don't say! I do agree that a healthy lead acid fully discharged has a very high internal resistance ... as a matter of fact, so high that it cannot be charged using the alternator ... my jeeping buddy found that out. Well you've improved your standing because now you have actually posted something that is correct. Well done. Have a banana. As they say... "there's a first time for everything".... Now the whole of usenet knows that you know _one_ thing, whereas before they all thought you knew _nothing_. Well done. But about that old starting battery (that GC has) that's maybe dry to the plates or maybe bridged or ... my quick and dirty risk assessment So you forgot the read the sentence that said... "unless the battery is U/S" U/S being "un-servicable". As in broken, faulty, kapputt. Can you actually read? Or perhaps that sentence did not fit in with your plans of trying to attack a superior knowledge? ... adios old batteries ... I for one would do not connect an old battery in parallel with my only way back to shore. Again you show your inability to read. I did not tell OP to do that. Learn to read. Apparently, even in your hick ridden town, there are some people who read. Even better there are some people who can _teach_ you to read. So post us a picture of your batteries configuration ... I'm always up for a good laugh ... adios ... "killer" :-) You can laugh at your own inability to read. That is assuming you didn't actually post using your own name. You didn't did you? Post using your own name I mean. Not really? Well now you must feel really stupid. Don't worry. Usenet only has a memory of about, er.... forever. So you'll only look stupid for about, er.... forever. I love people like you. You are so clever in your own little fairy world, that you forget, you are actually very stupid. You girlfriend told me so. I love you all. Cuddles. Folklore Killer. |
So what you're saying is no need to turn in those old batteries, just hook up a new one in parallel ... and oh yeah, no problem running a starting battery (my understanding that's what GC has) for accessories until it's dead ... they can be recharged over and over and over? Geez ... even a deep cycle's life is shortened by doing that. I do agree that a healthy lead acid fully discharged has a very high internal resistance ... as a matter of fact, so high that it cannot be charged using the alternator ... my jeeping buddy found that out. But about that old starting battery (that GC has) that's maybe dry to the plates or maybe bridged or ... my quick and dirty risk assessment ... adios old batteries ... I for one would do not connect an old battery in parallel with my only way back to shore. So post us a picture of your batteries configuration ... I'm always up for a good laugh .... adios ... "killer" :-) "Folklore killer" wrote in message ... "bowgus" blathered.... in Message-id: ... "GC" wrote in message ... I'm about to wire up a battery switch so that I can switch between two batteries. (one or the other or both) Don't use the "both" setting ... read on Just wondering if I should put the switch on the positive or negative?? Or doesn't it matter? Positive is the norm around here (geez ... hurts the head to even think about switching the negative since that's normally the electrical reference) Also, do both the batteries have to be the same age/rating??? I was hoping to use my old battery for powering accessories when I'm stopped, but charge it when the engine is running with the other battery. In your situation, I would ... (get myself a deep cycle for the accessories ... e.g. my accesory is my electric trolling motor) a) make sure the switch is a make before break type which they normally are so that the alternator is never without a load if switched while running; b) when stopped select the old battery (if it's a regular starting type battery it won't tolerate many cycles of being discharged), before starting, switch to the new battery; c) while running charge batteries by switching between the two (hmmm ... when are they charged ... well, maybe your batteries have indicators of the green it's charged variety?); d) never connect the batteries ... it's my understanding that the charged one could pump a lot of current into the discharged (my theory ... a battery (let's just say for the sake of argument rated 800 cold cranking amps) has no current limiting feature like a battery charger does) which could result in 800 amps going through wiring/switch resulting in fire, exploding battery, ... Thanks in advance! :) My 2 cents worth ... And worth slightly less than 2 cents. Where do you people get your information? Disneyworld? A typical engine start battery would be 600 to 650 CCA As you have quoted 800 CCA we shall use that as the example. A brand new 800 CCA engine start battery will have an internal resistance of around 0.004 ohms and an _open circuit_ voltage of around 12.7 volts (you can calculate the fully charged internal resistance of an engine start battery using the given CCA and the _definition_ of what CCA means - but of course you didn't know that). A flat deep cycle battery will have an _open circuit_ voltage of around 11.9 volts and an internal resistance of around 0.06 ohms. The voltage _difference_ between the 2 batteries is therefore 0.8 volts dropped across the two internal resistances of 0.004 + 0.06 = 0.064 ohms = 12.5 amps. And that is making the simple assumption that the voltage of the fully charged engine battery does not fall under load (in addition to the voltage drop caused by the internal resistance) which in practice it will, by about 0.2 volts at this sort of loading. So the _real_ current draw will be approximately 9.4 amps. Further, there is a dead band between the open circuit voltage and the voltage at which charging will commence. This dead band varies quite dramatically depending upon the state of charge of the battery in question. A typical figure for a flat deep cycle battery would be about 0.2 volts. So an even closer figure for the current draw (that you assert is 800 amps) would be (12.5V - 12.1V) 0.4V/(total internal resistance) 0.064R = 6.25 amps. And of course you won't believe me. So instead of using half a theory that you don't understand anyway, either go learn the rest of the theory or try it and take some measurements. Connectng the batteries in parallel is perfectly safe, quite normal, will achieve what is desired and is used in millions of installations the world over. Idiot Folklore Killer. |
Hi GC,
We'll just let those have their fun. I have had the type of setup you're talking about in both a boat & a motor home. Go with the positive to the switch even though it's not quite so important in a boat but in a vehicle (metal frame) it's essential as unless you have an old 1955 bedford or something, most are negetive earth. ALWAYS put your best battery on your motor start side. (say position 1 on the switch) NEVER be tempted to use that battery for accessories while on anchor. (it's hard to push start a boat!) Never forget to turn it over to No 2 when stopped. Never forget to return to battery No 1 before starting motor. Get a switch that will rotate either way through full 360degrees. Have an amp gauge to monitor charge. Once under way for several minutes when amp meter drops to zero switch to No 2 but AWAYS go in direction of No1 to BOTH to No2 so (like he said) you always have current to alternator. Doing it that way you also don't lose your GPS briefly. I've said enough. What ever you do make sure that bilge pump is ACTIVE!!!!! (get that?........ ) Regards..... BruceM "Folklore killer" wrote in message ... "bowgus" miserably failed in attempting to insult his superior..... in Message-id: .... By blathering..... So what you're saying is no need to turn in those old batteries, just hook up a new one in parallel ... Which is not what I wrote so you clearly need to go back to "baby school" to learn how to read. and oh yeah, no problem running a starting battery (my understanding that's what GC has) for accessories until it's dead ... That is because either A) You misunderstood what OP wrote or more likely B) You did not read it (or perhaps _couldn't_ read it). or even more likely C) were so busy trying to prove your superior knowledge (and failing quite dramatically) that you forgot to read the entire thread before collapsing your lower jawbone muscles. they can be recharged over and over and over? Now please quote where that was stated by anyone. Geez ... even a deep cycle's life is shortened by doing that. You don't say! I do agree that a healthy lead acid fully discharged has a very high internal resistance ... as a matter of fact, so high that it cannot be charged using the alternator ... my jeeping buddy found that out. Well you've improved your standing because now you have actually posted something that is correct. Well done. Have a banana. As they say... "there's a first time for everything".... Now the whole of usenet knows that you know _one_ thing, whereas before they all thought you knew _nothing_. Well done. But about that old starting battery (that GC has) that's maybe dry to the plates or maybe bridged or ... my quick and dirty risk assessment So you forgot the read the sentence that said... "unless the battery is U/S" U/S being "un-servicable". As in broken, faulty, kapputt. Can you actually read? Or perhaps that sentence did not fit in with your plans of trying to attack a superior knowledge? ... adios old batteries ... I for one would do not connect an old battery in parallel with my only way back to shore. Again you show your inability to read. I did not tell OP to do that. Learn to read. Apparently, even in your hick ridden town, there are some people who read. Even better there are some people who can _teach_ you to read. So post us a picture of your batteries configuration ... I'm always up for a good laugh ... adios ... "killer" :-) You can laugh at your own inability to read. That is assuming you didn't actually post using your own name. You didn't did you? Post using your own name I mean. Not really? Well now you must feel really stupid. Don't worry. Usenet only has a memory of about, er.... forever. So you'll only look stupid for about, er.... forever. I love people like you. You are so clever in your own little fairy world, that you forget, you are actually very stupid. You girlfriend told me so. I love you all. Cuddles. Folklore Killer. |
What ever you do make sure that bilge pump is ACTIVE!!!!! (get that?........ ) Thanks for your tips :) When you say the bilge pump is ACTIVE, what do you mean by that? :) and it directly across one of the batteries, not through the switch?? Do you think I'm better off just getting a cheapy battery for my accessories?? So at least its new :) Thanks again! |
On Sun, 7 Nov 2004 18:10:25 +1030, "BruceM"
wrote: Once under way for several minutes when amp meter drops to zero switch to No 2 but AWAYS go in direction of No1 to BOTH to No2 so (like he said) you always have current to alternator. =================================== I consider switching batteries with the engine running to be a high risk regardless of whether or not the switch is claimed to be "make-before-break". Contacts and switch wipers can become worn or corroded creating switching transients that can toast the alternator in a heart beat. It happens all the time. If you have to switch with the engine running for some reason, I'd recommend doing it only at dead slow idle speed, and never switching it to the off position. For what it's worth, here's what I do if the #2 has become run down. Start the engine on #1 and let it warm up so that it will restart easily. Shut down and restart on "both". In the "both" position the charge will flow to the battery that needs it. Periodiaclly test #2 by trying to start the engine with it. If it will not crank and start a warm engine it is shot and should be replaced. Ideally it should be capable of starting a cold engine also but that may be asking a lot if it has been frequently deep cycled. |
Exactly ...
"BruceM" wrote in message ... Hi GC, We'll just let those have their fun. I have had the type of setup you're talking about in both a boat & a motor home. Go with the positive to the switch even though it's not quite so important in a boat but in a vehicle (metal frame) it's essential as unless you have an old 1955 bedford or something, most are negetive earth. ALWAYS put your best battery on your motor start side. (say position 1 on the switch) NEVER be tempted to use that battery for accessories while on anchor. (it's hard to push start a boat!) Never forget to turn it over to No 2 when stopped. Never forget to return to battery No 1 before starting motor. Get a switch that will rotate either way through full 360degrees. Have an amp gauge to monitor charge. Once under way for several minutes when amp meter drops to zero switch to No 2 but AWAYS go in direction of No1 to BOTH to No2 so (like he said) you always have current to alternator. Doing it that way you also don't lose your GPS briefly. I've said enough. What ever you do make sure that bilge pump is ACTIVE!!!!! (get that?........ ) Regards..... BruceM "Folklore killer" wrote in message ... "bowgus" miserably failed in attempting to insult his superior..... in Message-id: .... By blathering..... So what you're saying is no need to turn in those old batteries, just hook up a new one in parallel ... Which is not what I wrote so you clearly need to go back to "baby school" to learn how to read. and oh yeah, no problem running a starting battery (my understanding that's what GC has) for accessories until it's dead ... That is because either A) You misunderstood what OP wrote or more likely B) You did not read it (or perhaps _couldn't_ read it). or even more likely C) were so busy trying to prove your superior knowledge (and failing quite dramatically) that you forgot to read the entire thread before collapsing your lower jawbone muscles. they can be recharged over and over and over? Now please quote where that was stated by anyone. Geez ... even a deep cycle's life is shortened by doing that. You don't say! I do agree that a healthy lead acid fully discharged has a very high internal resistance ... as a matter of fact, so high that it cannot be charged using the alternator ... my jeeping buddy found that out. Well you've improved your standing because now you have actually posted something that is correct. Well done. Have a banana. As they say... "there's a first time for everything".... Now the whole of usenet knows that you know _one_ thing, whereas before they all thought you knew _nothing_. Well done. But about that old starting battery (that GC has) that's maybe dry to the plates or maybe bridged or ... my quick and dirty risk assessment So you forgot the read the sentence that said... "unless the battery is U/S" U/S being "un-servicable". As in broken, faulty, kapputt. Can you actually read? Or perhaps that sentence did not fit in with your plans of trying to attack a superior knowledge? ... adios old batteries ... I for one would do not connect an old battery in parallel with my only way back to shore. Again you show your inability to read. I did not tell OP to do that. Learn to read. Apparently, even in your hick ridden town, there are some people who read. Even better there are some people who can _teach_ you to read. So post us a picture of your batteries configuration ... I'm always up for a good laugh ... adios ... "killer" :-) You can laugh at your own inability to read. That is assuming you didn't actually post using your own name. You didn't did you? Post using your own name I mean. Not really? Well now you must feel really stupid. Don't worry. Usenet only has a memory of about, er.... forever. So you'll only look stupid for about, er.... forever. I love people like you. You are so clever in your own little fairy world, that you forget, you are actually very stupid. You girlfriend told me so. I love you all. Cuddles. Folklore Killer. |
"Wayne.B" wrote in message ... On Sun, 7 Nov 2004 18:10:25 +1030, "BruceM" wrote: Once under way for several minutes when amp meter drops to zero switch to No 2 but AWAYS go in direction of No1 to BOTH to No2 so (like he said) you always have current to alternator. =================================== I consider switching batteries with the engine running to be a high risk regardless of whether or not the switch is claimed to be "make-before-break". Contacts and switch wipers can become worn or corroded creating switching transients that can toast the alternator in a heart beat. It happens all the time. If you have to switch with the engine running for some reason, I'd recommend doing it only at dead slow idle speed, and never switching it to the off position. Or you could get a "zap-stop" for $30. For what it's worth, here's what I do if the #2 has become run down. Start the engine on #1 and let it warm up so that it will restart easily. Shut down and restart on "both". In the "both" position the charge will flow to the battery that needs it. Periodiaclly test #2 by trying to start the engine with it. If it will not crank and start a warm engine it is shot and should be replaced. Ideally it should be capable of starting a cold engine also but that may be asking a lot if it has been frequently deep cycled. If it won't start the engine its pretty far gone. I've always taken it as axiomatic that there should be two independent starting systems. I suppose it depends on the engine, but every one I've used would start in a few seconds. Any reasonable battery should be able to start a small engine even if age has diminished it's capacity a bit. |
On Sun, 7 Nov 2004 12:41:48 -0500, "Jeff Morris"
wrote: Or you could get a "zap-stop" for $30. ================================= No question that something like that is a help but I tend to put it in the same category as make-before-break switching. It's supposed to work, but it might not. Having lost a few alternators over the years for various reasons, I've gotten very conservative, and I've learned to live with not switching under load as a good first step in prevention. |
Guess it depends on your situation & how deep your pockets are.
Mine aren't very deep so I tend to always replace the start one each year & put the original one in place for anchor accessory use (if you know what I mean?). Usually by then that one is just about had it from too many low drains. (Sharking at night with lights on & music playing & mobile phone plugged in & depth/fish sounder on etc,) About the bilge pump bit. Once again it depends on your situation. Are you cruising the big blue? etc, etc. In my case I only had an ex fishing boat & had it on a mooring. Only used it in fairly good weather to "do" the lobster pots & some fairly "heavy" fishing trips. While on anchor I used to isolate both batteries. (off) I also had a two way switch so that "under way" the bilge pump ran on the "start" battery through the big switch. (battery to battery one). Once back on the mooring I threw the little two way one that fed power to ONLY the bilge pump. This was just in case of a wire shorting etc, etc (or I left equipment on?) One chap here has rigged his bilge pump so that if it starts up (auto level start), it sends a message to his house. Rigged it up somehow through an old CB radio to act like a kid is flipping the TX button. ps, I reckon you got some pretty good info here but you need to now work out the best for YOUR useage. BruceM "GC" wrote in message ... What ever you do make sure that bilge pump is ACTIVE!!!!! (get that?........ ) Thanks for your tips :) When you say the bilge pump is ACTIVE, what do you mean by that? :) and it directly across one of the batteries, not through the switch?? Do you think I'm better off just getting a cheapy battery for my accessories?? So at least its new :) Thanks again! |
"BruceM" wrote in message
... Guess it depends on your situation & how deep your pockets are. Mine aren't very deep so I tend to always replace the start one each year & put the original one in place for anchor accessory use (if you know what I mean?). If you replace a battery every year, you must have deep pockets! On my previous boat I replaced all the batteries once in 8 years, and they had a number of years on them when I bought it. On my new boat the house bank is going strong after five years. I replaced the starter batteries with Optima's because they were stashed in a location impossible to properly maintain - I expect them to go a number of years. A cheap battery goes 4 years in a car ... why shouldn't a quality battery do the same in a boat? Usually by then that one is just about had it from too many low drains. (Sharking at night with lights on & music playing & mobile phone plugged in & depth/fish sounder on etc,) If you look at the "discharge depth/service life" curves maybe you would size your batteries appropriately. A deep cycle battery should be good for hundreds of cycles as long as you don't drain it too far. A starting battery will only give you a handful of deep cycles. Perhaps I don't appreciate your situation (do you have to carry a recharged battery to a moored boat?) but it seems like something is wrong if you're only getting one year of good service from a battery! |
OK, I might have slightly deeper pockets than some but I fish in some areas
& times of the year where there isn't other boats around & it's vital I don't have failures unexpectedly. Also for THAT piece of mind, for the cost of forgoing a couple of meals out at a restaurant, I reckon it's money well spent. Where do you live? In Australia the size battery I use is $A120.00 & a good night out would cost about the same with drinks included. (for 2 of us) BruceM "Jeff Morris" wrote in message ... "BruceM" wrote in message ... Guess it depends on your situation & how deep your pockets are. Mine aren't very deep so I tend to always replace the start one each year & put the original one in place for anchor accessory use (if you know what I mean?). If you replace a battery every year, you must have deep pockets! On my previous boat I replaced all the batteries once in 8 years, and they had a number of years on them when I bought it. On my new boat the house bank is going strong after five years. I replaced the starter batteries with Optima's because they were stashed in a location impossible to properly maintain - I expect them to go a number of years. A cheap battery goes 4 years in a car ... why shouldn't a quality battery do the same in a boat? Usually by then that one is just about had it from too many low drains. (Sharking at night with lights on & music playing & mobile phone plugged in & depth/fish sounder on etc,) If you look at the "discharge depth/service life" curves maybe you would size your batteries appropriately. A deep cycle battery should be good for hundreds of cycles as long as you don't drain it too far. A starting battery will only give you a handful of deep cycles. Perhaps I don't appreciate your situation (do you have to carry a recharged battery to a moored boat?) but it seems like something is wrong if you're only getting one year of good service from a battery! |
"BruceM" wrote in message
... OK, I might have slightly deeper pockets than some but I fish in some areas & times of the year where there isn't other boats around & it's vital I don't have failures unexpectedly. Also for THAT piece of mind, for the cost of forgoing a couple of meals out at a restaurant, I reckon it's money well spent. Whatever it takes. Where do you live? Boston, MA. Of course, I sail in a variety of places on the US East Coast, some of them rather remote. But I've never had a problem starting an engine. In Australia the size battery I use is $A120.00 & a good night out would cost about the same with drinks included. (for 2 of us) If you didn't use starting batteries as your "house bank" you woulldn't cook them in a season. That way you would actually have a reasonable backup for your starting battery. But if your system works for you, feel free. BruceM "Jeff Morris" wrote in message ... "BruceM" wrote in message ... Guess it depends on your situation & how deep your pockets are. Mine aren't very deep so I tend to always replace the start one each year & put the original one in place for anchor accessory use (if you know what I mean?). If you replace a battery every year, you must have deep pockets! On my previous boat I replaced all the batteries once in 8 years, and they had a number of years on them when I bought it. On my new boat the house bank is going strong after five years. I replaced the starter batteries with Optima's because they were stashed in a location impossible to properly maintain - I expect them to go a number of years. A cheap battery goes 4 years in a car ... why shouldn't a quality battery do the same in a boat? Usually by then that one is just about had it from too many low drains. (Sharking at night with lights on & music playing & mobile phone plugged in & depth/fish sounder on etc,) If you look at the "discharge depth/service life" curves maybe you would size your batteries appropriately. A deep cycle battery should be good for hundreds of cycles as long as you don't drain it too far. A starting battery will only give you a handful of deep cycles. Perhaps I don't appreciate your situation (do you have to carry a recharged battery to a moored boat?) but it seems like something is wrong if you're only getting one year of good service from a battery! |
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