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#1
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Buying Boat Batteries - Check My Thinking
Gary Warner wrote:
The electrical setup I've created calls for two 12 volt batteries. They are on an A/B/ALL switch with a battery-combiner (BC) between them. It would be simpler, cheaper, and more foolproof to simply have each battery on a key switch. The A/B/Both/Off switches create all sorts of problems from dead batteries to fried alternators. Normally I plan to run with the switch in just the "A" or "B" position. So when the engine is running the BC will combine the batteries and both will be charged. When the engine stops and we are drawing current for light & such, only one battery will be supplying power. If that one got drained we could switch to the other to restart the boat. Exactly! QUESTIONS: TYPE OF BATTERY: I know that Gel or Absorbent Glass Matt (AGM) are supposed to be better. But for this application where these is not much vibration, no need to mount the batteries in any position except "normal" and where the battery may not get 100% proper storage (ie no trickle charger all winter) I'm thinking the extra cost is not worth it. I'm thinking just use regular flooded batteries. Agree. I don't see enough advantage in your usage to get AGMs, unless the boatteries are in an inaccessible place and will be difficult to service. Also, you don't mention it but are you putting in a hard wired charger? Definitely get & use a 3-stage smart charger no matter how you rig it. SIZE will be group 24. I believe the space that I have for the batteries (under the passenger seat) will take two Group 24 batteries. Might be too small. If you're using 2 dual purpose instead a starting & a deep cycle, then you're getting less cranking amps and less amp-hours capacity. http://www.cs.ucf.edu/~matt/leadacid/guide.html CCA/MCA: I really don't know what size Cold Cranking Amps or Marine Cranking Amps is necessary/good to turn over the engine I have. I'm guessing that anything in around about 550 is fine. If I can get more for not much more $$ than that's what I'll do. Agreed. This is one case where more is better. RESERVE CAPACITY: I really don't have much draw on these batteries so pretty much whatever the RC rating is will be fine for my use. TYPE: I'm thinking that Dual-Purpose is the way to go. It is possible that I'd draw a batter down when occasionally sleeping on the boat overnight and Starting batteries don't like that very much. neither do dual purpose, for that matter deep cycle batteries get rather upset if you discharge them past 50% TWO OF THE SAME: Since they will be charging in tandem (together) it's best to have two of the same. Also, I'll sometimes have the switch on "A" and sometimes on "B" so both get approximately the same useage pattern. If you were oversizing the batteries so that there wasn't risk of damaging or hard sulfating them starting the engine, I'd say fine. But since you're limited in size I'd suggest getting a starting battery and a deep cycle and marking the switches as such. You might also consider getting two dual purpose batteries and then finding a place for two golf cart batteries somewhere else for house loads. BUYING: + Check the date manufactured on the battery and try to get ones that are less than 3 months old. + Try to get them with a longer free-replacement period as this is a good sign of quality + Watch out because replacement are sometimes pro-rated and based on the LIST price, not retail. Good. I bought two Exide Gr-31 batteries that were approx 6 months on the slef and they are not really satisfactory. If you can buy dry batteries and have the vendor fill & charge them, that'd be better too. Only a battery store will do this though. Fair Skies Doug King |
#2
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Buying Boat Batteries - Check My Thinking
Thanks Doug & John H for your comments & thoughts! |
#3
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Buying Boat Batteries - Check My Thinking
"DSK" wrote in message .. . Gary Warner wrote: The electrical setup I've created calls for two 12 volt batteries. They are on an A/B/ALL switch with a battery-combiner (BC) between them. It would be simpler, cheaper, and more foolproof to simply have each battery on a key switch. The A/B/Both/Off switches create all sorts of problems from dead batteries to fried alternators. Normally I plan to run with the switch in just the "A" or "B" position. So when the engine is running the BC will combine the batteries and both will be charged. When the engine stops and we are drawing current for light & such, only one battery will be supplying power. If that one got drained we could switch to the other to restart the boat. Exactly! QUESTIONS: TYPE OF BATTERY: I know that Gel or Absorbent Glass Matt (AGM) are supposed to be better. But for this application where these is not much vibration, no need to mount the batteries in any position except "normal" and where the battery may not get 100% proper storage (ie no trickle charger all winter) I'm thinking the extra cost is not worth it. I'm thinking just use regular flooded batteries. Agree. I don't see enough advantage in your usage to get AGMs, unless the boatteries are in an inaccessible place and will be difficult to service. Also, you don't mention it but are you putting in a hard wired charger? Definitely get & use a 3-stage smart charger no matter how you rig it. SIZE will be group 24. I believe the space that I have for the batteries (under the passenger seat) will take two Group 24 batteries. Might be too small. If you're using 2 dual purpose instead a starting & a deep cycle, then you're getting less cranking amps and less amp-hours capacity. http://www.cs.ucf.edu/~matt/leadacid/guide.html CCA/MCA: I really don't know what size Cold Cranking Amps or Marine Cranking Amps is necessary/good to turn over the engine I have. I'm guessing that anything in around about 550 is fine. If I can get more for not much more $$ than that's what I'll do. Agreed. This is one case where more is better. RESERVE CAPACITY: I really don't have much draw on these batteries so pretty much whatever the RC rating is will be fine for my use. TYPE: I'm thinking that Dual-Purpose is the way to go. It is possible that I'd draw a batter down when occasionally sleeping on the boat overnight and Starting batteries don't like that very much. neither do dual purpose, for that matter deep cycle batteries get rather upset if you discharge them past 50% TWO OF THE SAME: Since they will be charging in tandem (together) it's best to have two of the same. Also, I'll sometimes have the switch on "A" and sometimes on "B" so both get approximately the same useage pattern. If you were oversizing the batteries so that there wasn't risk of damaging or hard sulfating them starting the engine, I'd say fine. But since you're limited in size I'd suggest getting a starting battery and a deep cycle and marking the switches as such. You might also consider getting two dual purpose batteries and then finding a place for two golf cart batteries somewhere else for house loads. BUYING: + Check the date manufactured on the battery and try to get ones that are less than 3 months old. + Try to get them with a longer free-replacement period as this is a good sign of quality + Watch out because replacement are sometimes pro-rated and based on the LIST price, not retail. Good. I bought two Exide Gr-31 batteries that were approx 6 months on the slef and they are not really satisfactory. If you can buy dry batteries and have the vendor fill & charge them, that'd be better too. Only a battery store will do this though. Fair Skies Doug King Hard to get a nice setup with just the key switches. And my alternator has survived since 1991 with a Guest 1/2/off switch. 351W Ford motor. I run 2 batteries and use a starting battery in #1 and a dual purpose in #2. Run the electronics off #2 with a key switch to shut off power to the electronics and a battery combiner from West Marine to charge the #2 battery. Then I just run the dual battery switch to #1 and turn on the other switch to run the electronics. If #1 is bad, I can then switch to #2 for starting. Just did this 2 weeks ago, as #2 battery was bad, and only had $2.69 of warranty left. Running the electronics off their own battery prevents a couple of problems. Running down the starting battery, the electronics do not cycle from low power when starting, and the EMF kickback from the starter / solenoid is isolated from the the electronics, and saves them. Bill |
#4
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Buying Boat Batteries - Check My Thinking
And my alternator has survived since 1991 with a Guest 1/2/off switch. My understanding is that what can kill an alternator is if the Alt is putting out power and you switch from, say, #1 to #2. At that moment when you switch there is no battery connected to the charging system to take the power thus creating a momentary surge in power. Some switches are "make-before-break" so they make the connection to the #2 battery BEFORE breaking the connections to the #1. (or whichever way you are switching). But these better type switches can look exactly like the cheaper type. You have to check the part number (or study it's design and operation) to determine which type you have. |
#5
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Buying Boat Batteries - Check My Thinking
Gary Warner wrote:
And my alternator has survived since 1991 with a Guest 1/2/off switch. My understanding is that what can kill an alternator is if the Alt is putting out power and you switch from, say, #1 to #2. At that moment when you switch there is no battery connected to the charging system to take the power thus creating a momentary surge in power. It's not a "momentary surge," it's a voltage spike attempting to reach infinite! From a Buddhist point of view this might be Nirvana but for the alternator regulating circuit it is a guaranteed trip to the afterlife ... Some switches are "make-before-break" so they make the connection to the #2 battery BEFORE breaking the connections to the #1. (or whichever way you are switching). But these better type switches can look exactly like the cheaper type. You have to check the part number (or study it's design and operation) to determine which type you have. Yes exactly. Bill's point about using one battery to buffer his electronics is also worth noting. We have a somewhat similar set-up but it's accomplished in the breaker panel. Doug King wrote Also, you don't mention it but are you putting in a hard wired charger? Definitely get & use a 3-stage smart charger no matter how you rig it. Gary Warner wrote: On such a smally boat with such low electrical draw and only weekend use do I really need/want a charger? Won't my generator take care of charging up the batteries? Depends on how you use the boat & generator... you've got a genset in a 22 footer? If true then you can skimp on the house banks, fer sure. Other question: I do have a good home based battery charger. It has both a full charge & trickle charge setting. But I see that trickly charging all winter is going to kill the battery. Yes, whereas a smart charger which has a third stage which "floats" the battery at a full-charge but less-than-charging voltage will greatly extend a battery's life; usually they also have a desulfating function. ... So are my choices are basically as follows ?? A: Charge it when taking it out, then leave it all winter B: Go to the shop every 2 or 4 weeks and charge it for a while C: Buy a "smart" or "float" charger and leave that running A trailer boat can be plugged in at home, whether the charger is wired in or kept on a shelf is a matter of convenience... I'd go for option "C" since that will pay for itself by extending the batteries working life and getting you underway with batteries at peak charge every time. And is it really OK to leave a smart charger running and connected to a battery for weeks at a time without checking on it? The thought of that just makes me a little nervous. It shouldn't. Of course it is a good idea to check the cells every couple weeks, but a smart charger will not boil them like a taper charger or trickle charger (which is basically a taper charger with very low amperage) will... I go several months without having to top mine up. Our boat had a large & expensive ferro-resonant taper charger (80 amps according to it's nameplate!!) wired in when we bought it... top of the line 1970's technology! But it consistently boiled off the batteries according to the previous owners maintenance log, and the previous owners were in the habit of buying new batteries every 18 ~ 24 months. Expensive! One of the first upgrades was a Xantrex smart charger, which we used to desulfate (or "condition") the old batteries... gave them a last hurrah... Fair Skies Doug King |
#6
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Buying Boat Batteries - Check My Thinking
"DSK" wrote: It's not a "momentary surge," it's a voltage spike attempting to reach infinite! I think you're mincing words there. It IS a surge and it doesn't last very long. And I'm not sure what you mean by "attempting to reach infinite" but there is no way it comes close to "infinite". It it were that easy to generate huge (infinite) amounts of power we wouldn't need much oil. And it is momentary - that is lasting a fairly short amount of time. Depends on how you use the boat & generator... you've got a genset in a 22 footer? If true then you can skimp on the house banks, fer sure. What I have is an engine and a generator. The generator is a device bolted to the engine and runs off the engine via a belt. As in the type of power generating device that was popular on cars and boats before alternators took over. The generator connects to a voltage-regulator and "sends" power to run the boat. Excess power will charge the batteries. And is it really OK to leave a smart charger running and connected to a battery for weeks at a time without checking on it? The thought of that just makes me a little nervous. It shouldn't. Of course it is a good idea to check the cells every couple weeks, but a smart charger will not boil them like a taper charger or trickle charger (which is basically a taper charger with very low amperage) will... I go several months without having to top mine up. OK, thanks. And thanks for the tip about connecting my electronics via a seperate battery so they they are more protected from spikes when starting the engine, etc. I'll consider how I might do that in my system. Again, thanks. |
#7
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Buying Boat Batteries - Check My Thinking
Gary Warner wrote:
I think you're mincing words there. Yeah, I was trying to be funny. What I have is an engine and a generator. The generator is a device bolted to the engine and runs off the engine via a belt. As in the type of power generating device that was popular on cars and boats before alternators took over. D'oh! I am old enough to remember these thingies, it's just been a long time. IIRC they are not sensitive to open circuit damage anyway, so the above comments are even more fruitless. Again, thanks. Very welcome... I don't claim to have any great expertise but am glad to relate my experiences & observations. BTW last year when we were shopping for batteries, I drew up a spreadsheet to compare battery capacities & prices. It helps make a good pick, the ones that seemed to offer best performance for the price were Trojan and Exide. The best performance, and highest price, where the Rolls/Surrette batteries, which have approximately twice as much power, weight noticeably more for the same group size, and cost about 3X. The West Marine batteries are Exides with a different label and a big mark-up. Did I already say this? Fair Skies Doug King |
#8
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Buying Boat Batteries - Check My Thinking
"Gary Warner" wrote in message ... And my alternator has survived since 1991 with a Guest 1/2/off switch. My understanding is that what can kill an alternator is if the Alt is putting out power and you switch from, say, #1 to #2. At that moment when you switch there is no battery connected to the charging system to take the power thus creating a momentary surge in power. Some switches are "make-before-break" so they make the connection to the #2 battery BEFORE breaking the connections to the #1. (or whichever way you are switching). But these better type switches can look exactly like the cheaper type. You have to check the part number (or study it's design and operation) to determine which type you have. I think all the Guest switches are make before break, At least the newer ones. |
#9
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Buying Boat Batteries - Check My Thinking
"DSK" wrote in message .. . Also, you don't mention it but are you putting in a hard wired charger? Definitely get & use a 3-stage smart charger no matter how you rig it. On such a smally boat with such low electrical draw and only weekend use do I really need/want a charger? Won't my generator take care of charging up the batteries? Other question: I do have a good home based battery charger. It has both a full charge & trickle charge setting. But I see that trickly charging all winter is going to kill the battery. So are my choices are basically as follows ?? A: Charge it when taking it out, then leave it all winter B: Go to the shop every 2 or 4 weeks and charge it for a while C: Buy a "smart" or "float" charger and leave that running And is it really OK to leave a smart charger running and connected to a battery for weeks at a time without checking on it? The thought of that just makes me a little nervous. |
#10
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Buying Boat Batteries - Check My Thinking
Gary Warner wrote: "DSK" wrote in message .. . Also, you don't mention it but are you putting in a hard wired charger? Definitely get & use a 3-stage smart charger no matter how you rig it. On such a smally boat with such low electrical draw and only weekend use do I really need/want a charger? Won't my generator take care of charging up the batteries? Other question: I do have a good home based battery charger. It has both a full charge & trickle charge setting. But I see that trickly charging all winter is going to kill the battery. So are my choices are basically as follows ?? A: Charge it when taking it out, then leave it all winter B: Go to the shop every 2 or 4 weeks and charge it for a while C: Buy a "smart" or "float" charger and leave that running And is it really OK to leave a smart charger running and connected to a battery for weeks at a time without checking on it? The thought of that just makes me a little nervous. |
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