i am in the process of upgrading my battery capabilities by making a house bank of 4-6 volt(2 12's) batteries for the house bank in a series and a separate 2 battery 12 volt bank for the engine and a back up house bank. i want to try to isolate the the 2 house bateries and then isolate the engine batteries. any input on isolators and tips for maximizing this type of set-up for prolonging battery life?
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Larry Watkins
V.A.- Isolators are not the answer. They consume .6 of a volt and as such they will confuse a "smart" regulator unless they are compensated for. In addition, when you connect 6V batteries in series to obtain 12V, you are vulnerable to cell failure. If one or more cells fail, you no longer have a 12V battery, but an 8 or a 10 or whatever. Instead, consider the installation of a "combiner" a device that connects two banks for charging, then disconnects them for draw purposes, all automatically. For house use, consider one or more 8Ds if you have the room, or one or two combo group 27s if room is tight.
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Ron
Disagree with Larry
It is always perferable to have 4 each 6 volt batteries than to have two 12 volt batteries in a curcuit. If you must use 12 volt batteries it is advised to not have more that two tied in together. In fact, Swan Yachts by Nautor of Finland come with EIGH-262 6 volt bateries as standard equipment.They have extra thick 0.170-inch positive plates. Also, two 6 volt batteries equal 12 volts and have more storage capacity than one 12 volt battery of comparable size and cost. And if you should lose a cell in one battery it is cheaper to replace a 6 than a 12. See the video, "The 12 volt Sailor," and also the book, "The 12 Volt Bible for Boats" (pg.44) Ron
It is always perferable to have 4 each 6 volt batteries than to have two 12 volt batteries in a curcuit. If you must use 12 volt batteries it is advised to not have more that two tied in together. In fact, Swan Yachts by Nautor of Finland come with EIGH-262 6 volt bateries as standard equipment.They have extra thick 0.170-inch positive plates. Also, two 6 volt batteries equal 12 volts and have more storage capacity than one 12 volt battery of comparable size and cost. And if you should lose a cell in one battery it is cheaper to replace a 6 than a 12. See the video, "The 12 volt Sailor," and also the book, "The 12 Volt Bible for Boats" (pg.44) Ron
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Carl Dupre
Another Possibility.........
We are also are pondering a battery and charging system for an H340 currently on order, and initially came to the same conclusion as Larry; the battery combiner sounds like a better alternative than the battery isolator. However, we also came up with a third possibility that might be considered; dual output alternators. I don't know what size engine you have, and what size alternator it can handle, but if you are upgrading the battery/charger system a high-output alternator might be an additional upgrade to think about; less mandatory iron genny time required for "battery management". If you are willing to consider an upgraded alternator, some current models do have an option for dual output, which supposedly will independently manage two separate battery banks. For us, this is both a suggestion for V.A. to consider, but also a request for for feedback from anyone else out there who may know some thing about dual output alternators. Carl
We are also are pondering a battery and charging system for an H340 currently on order, and initially came to the same conclusion as Larry; the battery combiner sounds like a better alternative than the battery isolator. However, we also came up with a third possibility that might be considered; dual output alternators. I don't know what size engine you have, and what size alternator it can handle, but if you are upgrading the battery/charger system a high-output alternator might be an additional upgrade to think about; less mandatory iron genny time required for "battery management". If you are willing to consider an upgraded alternator, some current models do have an option for dual output, which supposedly will independently manage two separate battery banks. For us, this is both a suggestion for V.A. to consider, but also a request for for feedback from anyone else out there who may know some thing about dual output alternators. Carl
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Tom Senator
I also disagree with Larry
A cell can go bad in a 6V battery just as easily as a 12V battery. BUT when it goes bad in a 6V you can always trash the one bad 6V instead of having to trash a whole 4D or 8D battery. I have used 6V Golf cart batteries for years and have been happy with them. Problems can arise from leaving 2 batteries in parallel for too long and you are not charging. The one with a lower voltage (or AmpHours) will drain the higher potential battery. (and potentially cause more internal resistance which would drain the good battery more, causing a downward spiral) This will not happen to batteries in serial. I agree a 4D would be more convenient though. Also combiners and isolators are nice, but what about old fashioned 1-2-Both battery switches. Remember- KISS -You can rig them to handle all of your batteries (look at a West Marine Catalog). Low tech approach, but you must remember to turn switches when charging from the engine alternator.
A cell can go bad in a 6V battery just as easily as a 12V battery. BUT when it goes bad in a 6V you can always trash the one bad 6V instead of having to trash a whole 4D or 8D battery. I have used 6V Golf cart batteries for years and have been happy with them. Problems can arise from leaving 2 batteries in parallel for too long and you are not charging. The one with a lower voltage (or AmpHours) will drain the higher potential battery. (and potentially cause more internal resistance which would drain the good battery more, causing a downward spiral) This will not happen to batteries in serial. I agree a 4D would be more convenient though. Also combiners and isolators are nice, but what about old fashioned 1-2-Both battery switches. Remember- KISS -You can rig them to handle all of your batteries (look at a West Marine Catalog). Low tech approach, but you must remember to turn switches when charging from the engine alternator.
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Ron Dague
Dual Output Alternator Solution
I installed a 100 amp., dual output alternator on my h34. I love it. The alternator charging circuit connects to both battery banks, without going through the battery selection switch. This solve several problems. 1) It will charge either or both battery banks, depending on their needs, even if you don't turn the switch. So after starting with the switch in the "start" battery position, you can immediately switch to the "house" battery position. Yet the starter battery bank will still be charged to capacity, as the alternator sends the charge where it is needed most. Then all of the charging amps, up to 100, will be available for onboard use and charging the house batteries. So both banks are always fully charged, and I don't have to flip the battery bank switch to charge the starter battery bank (which I would frequently forget anyway!) 2) Because the output of the alternator is always connected to the battery banks, there is no fear about accidently turning the battery selection switch to off and frying your alternator diodes. The external voltage regulator that I have controls the output to both battery banks, and delays current to the alternator for 30 seconds after starting the engine, to allow a lower load until the engine has been run a bit and settled down in rpm, etc. Install was relatively easy. Basically, this set-up has taken most of the complications out of power management for me. All I have to do is make sure the batteries fluid levels are right. Gels would solve that problem.
I installed a 100 amp., dual output alternator on my h34. I love it. The alternator charging circuit connects to both battery banks, without going through the battery selection switch. This solve several problems. 1) It will charge either or both battery banks, depending on their needs, even if you don't turn the switch. So after starting with the switch in the "start" battery position, you can immediately switch to the "house" battery position. Yet the starter battery bank will still be charged to capacity, as the alternator sends the charge where it is needed most. Then all of the charging amps, up to 100, will be available for onboard use and charging the house batteries. So both banks are always fully charged, and I don't have to flip the battery bank switch to charge the starter battery bank (which I would frequently forget anyway!) 2) Because the output of the alternator is always connected to the battery banks, there is no fear about accidently turning the battery selection switch to off and frying your alternator diodes. The external voltage regulator that I have controls the output to both battery banks, and delays current to the alternator for 30 seconds after starting the engine, to allow a lower load until the engine has been run a bit and settled down in rpm, etc. Install was relatively easy. Basically, this set-up has taken most of the complications out of power management for me. All I have to do is make sure the batteries fluid levels are right. Gels would solve that problem.
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Carl Dupre
Thanks, Ron!!
I apologize for stealing V.A.'s post, but thanks a lot for the input, Ron! You have confirmed exactly the advantages that we saw in the dual output alternators! We are still very much the novices, and it feels good to have someone with direct experience confirm what we thought we were seeing! Carl
I apologize for stealing V.A.'s post, but thanks a lot for the input, Ron! You have confirmed exactly the advantages that we saw in the dual output alternators! We are still very much the novices, and it feels good to have someone with direct experience confirm what we thought we were seeing! Carl
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