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The Official Dual Battery Thread

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  • MLA
    replied
    Continuous-duty solenoids only, are my least favorite means to allow 2 banks to receive a charge when the engine is running, mainly because you have no means to use the house bank for emergency starting. Thats why I like some form of a dual-bank switch.

    If one is going to go the solenoid only route, I prefer to have it controlled via the key switch rather than manual. Way to easy to forget, and end up with a dead house bank early in the day.

    The one huge advantage of an ASR/VSR like the BS 7610 has over just a solenoid, is that the ASR/VSR is controlled by voltage and load, where as when the solenoid is closed, both banks are effected by each others draws. Its either open or closed vie the key switch or manually by the captain.

    Leave a comment:


  • waterlogged882
    replied
    Originally posted by CheeseSteak1 View Post
    I actually sat down and read this entire thread last night and decided to do just the relay (Kiss). Any idea what happened to Diesel's diagrams? Nothing is showing up on my end. Also, the Brog relay isn't manufactured anymore, so should I use the equivalent Stinger relay? Didn't know if it needs to be marine grade. Thanks for all the links.
    This thread since Diesel posted has been through two server crashes or upgrades that I know of and someone failed to transfer the photo files or lost the pictures by not transferring them along with the rest of the upgrade. It's gone.

    The relay has been re-identified with a cross reference (I think it is here in this thread somewhere) but certainly can be cross-referenced easily enough OR you can use the isolation switch that Blue Seas makes without the Perko switch. I think they are too expensive but who am I? Certainly not a smart paralegal to know it all.

    That Stinger isolator will serve the same purpose at half the price.

    The diagram that Blue Seas has on their site is just as good for all practical purposes.

    Leave a comment:


  • CheeseSteak1
    replied
    Originally posted by waterlogged882 View Post
    Your ignition switch will do just that - accessory position will separate the batteries and on/run will combine them (through the relay) for charging (so a higher capacity alternator output is recommended).

    Don't let me persuade you into something you do or do not want but from my experience, I like to keep it simple.

    Don't forget the fuses on each hot lead for each battery, etc- there is more to the complete install than meets the eye (extra cable, etc) I like http://www.genuinedealz.com/ for cables and block fuses
    I actually sat down and read this entire thread last night and decided to do just the relay (Kiss). Any idea what happened to Diesel's diagrams? Nothing is showing up on my end. Also, the Brog relay isn't manufactured anymore, so should I use the equivalent Stinger relay? Didn't know if it needs to be marine grade. Thanks for all the links.

    Leave a comment:


  • waterlogged882
    replied
    Originally posted by CheeseSteak1 View Post
    Thanks! I'll go with Diesel's method with a switch at the dash to control the relay.
    Your ignition switch will do just that - accessory position will separate the batteries and on/run will combine them (through the relay) for charging (so a higher capacity alternator output for two batteries is recommended).

    Don't let me persuade you into something you do or do not want but from my experience, I like to keep it simple.

    Don't forget the fuses on each hot lead for each battery, etc- there is more to the complete install than meets the eye (extra cable, etc) I like http://www.genuinedealz.com/ for cables and block fuses

    Leave a comment:


  • CheeseSteak1
    replied
    Originally posted by waterlogged882 View Post
    This kit and the cumulative parts have been discussed http://www.mastercraft.com/teamtalk/...&postcount=305

    Look at other posts where the entire kit is not necessary and read a few more threads. http://www.mastercraft.com/teamtalk/...&postcount=307

    It is easy and all of that kit is not needed for battery isolation.

    go to post number one and follow those recommendations and call it a day, KISS and economical - all you need is an isolator and two batteries, cable, fuses, and the correct schematic. everything is in this thread

    Buy one of these for each battery. http://www.amazon.com/NOCO-G1100-Bat.../dp/B004LX3AXQ

    i'd also recommend an upgraded alternator if yours is less than ~100 amps

    good luck on the install.

    Thanks! I'll go with Diesel's method with a switch at the dash to control the relay.

    Leave a comment:


  • waterlogged882
    replied
    Originally posted by CheeseSteak1 View Post
    Anyone have any thoughts or reviews of the Blue Sea Systems Add-a-Battery Kit?
    This kit and the cumulative parts have been discussed http://www.mastercraft.com/teamtalk/...&postcount=305

    Look at other posts where the entire kit is not necessary and read a few more threads. http://www.mastercraft.com/teamtalk/...&postcount=307

    It is easy and all of that kit is not needed for battery isolation.

    go to post number one and follow those recommendations and call it a day, KISS and economical - all you need is an isolator and two batteries, cable, fuses, and the correct schematic. everything is in this thread

    Buy one of these for each battery. http://www.amazon.com/NOCO-G1100-Bat.../dp/B004LX3AXQ

    i'd also recommend an upgraded alternator if yours is less than ~100 amps

    good luck on the install.
    Last edited by waterlogged882; 12-13-2014, 01:20 PM.

    Leave a comment:


  • CheeseSteak1
    replied
    Anyone have any thoughts or reviews of the Blue Sea Systems Add-a-Battery Kit?
    Attached Files

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  • JimN
    replied
    Originally posted by paintpollz View Post
    Yes that is my definition of a hous/aux batt. The idea is not to deplete them, I was just throwing out a what if scenario



    Correct, I'm aware that I will need a new alternator

    My understanding of charging systems is limited. Now that I know that I can purchase a high output alternator designed for a system like this, I will go that route.
    In the '90s and into the early 2000s, people who competed in IASCA and other car stereo "sound off" competitions were running a lot more power than your boat, often in small imported cars. The OEM alternators were often good for 65A, maybe. Your boat's alternator is probably good for 75A and in general operation, there's about 20% of safety margin, so figure that it's using about 50A-60A on a regular basis. What the competitors or installers would do is fabricate a bracket and mount a second alternator, completely isolated from the one that runs the car. This way, the starting batter is never affected by the audio system and vice versa. In this configuration, you shouldn't have any problem charging the audio system's batteries- at 12V (used for system design purposes because it's a real-world number), 95A works out to 1140 Watts. Now, this isn't likely to support that load for long, but it does give a ballpark for estimating what you'll need for recharging the batteries for the audio system. At 14.4 VDC, which is the typically-stated full charging voltage in a car or boat and this is not going to be seen at idle unless an alternator is "under-pulleyed", meaning that the alternator's pulley is smaller than normal, causing it to spin faster than it would if the larger pulley was on it. You would need to find the max RPM for the alternator, in order to avoid damage at/near WOT.

    The trick- finding space for a second alternator in a boat. On a V-drive, it should be easier than in a mid-engine model.

    Leave a comment:


  • paintpollz
    replied
    Yup, read that article, thanks Tim. Now in the hunt for the product # for an HO alt to fit this motor. I'll likely install the alt and then have an automotive shop around me upgrade the big 3.

    Leave a comment:


  • CantRepeat
    replied
    Originally posted by paintpollz View Post
    Yes that is my definition of a hous/aux batt. The idea is not to deplete them, I was just throwing out a what if scenario



    Correct, I'm aware that I will need a new alternator



    My understanding of charging systems is limited. Now that I know that I can purchase a high output alternator designed for a system like this, I will go that route.
    http://www.onallcylinders.com/2012/1...an-alternator/

    Leave a comment:


  • paintpollz
    replied
    Originally posted by JimN View Post
    Do you define 'house battery', as "the one used for the boat's electronics and engine"? You want a cranking battery for the engine, if the engine's electronics will be sharing the battery used for cranking and if you want to use deep cycle for the audio, that's fine, but you WILL need a heavy duty alternator if you expect your batteries to recharge and be able to supply all of the other electronics with the proper voltage and current. If you were to use a separate battery for cranking and ONLY for cranking, a deep cycle would work, but if you expect to run the battery voltage down below 10VDC, you're not using them according to their design. 'Deep cycle' doesn't mean "deplete them so they're stone dead".
    Yes that is my definition of a hous/aux batt. The idea is not to deplete them, I was just throwing out a what if scenario

    Originally posted by JimN View Post
    How loudly do you play the stereo, do you crank it while the engine is off, at idle, or at/near WOT and what other accessories would be used at a given time? Those will determine the demands on the batteries and charging system. The charging system must be designed for "worst case" scenarios if it's expected to survive and operate correctly.
    Correct, I'm aware that I will need a new alternator

    Originally posted by JimN View Post
    Why would you "replace the alternator every so often as preventative maintenance insurance", rather than just design the system correctly in the first place?

    If you use a heavy duty alternator, you'll need to use a heavier charging wire, too.

    List the stereo equipment by brand and model, too.
    My understanding of charging systems is limited. Now that I know that I can purchase a high output alternator designed for a system like this, I will go that route.

    Leave a comment:


  • CantRepeat
    replied
    I wouldn't use an isolator. I'd suggest a VSR.

    https://www.bluesea.com/products/761...12_24V_DC_120A
    Last edited by CantRepeat; 11-09-2014, 08:13 AM.

    Leave a comment:


  • Kweisner
    replied
    The Official Dual Battery Thread

    When you turn the key, both batteries are joined by the isolator relay so which one is drained is not a factor. Essentially they become one battery at that moment so the "good" battery energizes the relay unless I am mistaken.

    As for the alternator, I do not know enough about electrical engineering to be an authority. That said, the point of the isolator is to protect the starting battery and therefore it should typically remain at full charge capacity. Assuming the house/accessory battery were completely drained, when joined you'd really only be charging the depleted battery off the alternator (plus a little to top off the starting battery). I have been using the classic dual battery setup as originally described by Diesel in this thread and have never had any kind of issue getting started, charging and operating the stereo/amps/accessories while floating.

    Leave a comment:


  • JimN
    replied
    Originally posted by paintpollz View Post
    OK I need the dual batt setup. I just bought a 197 with 1500w of amps and one battery, trouble waiting to happen. What I've gotten from this thread:

    -use the BW isolator. KISS. there will be other people driving this boat, I do not want to have to go thru battery tutorials with them.

    -you should use two of the same batteries, although it would be nice to have a deep cycle as the house battery.

    -there will be unavoidable strain on the alternator while charging the two batteries when the boat is running. boo hoo.

    Question:

    -Do I need to rewire the stereo switch to the house batt so that the amps & stereo turn on when flipping the stereo switch, and all pull from the house batt? Otherwise, if I just connect the amps to the house batt, won't the stereo still draw from the starting batt when the key is in the off position?

    -When running a dual battery setup in this manner, is it wise to replace the alternator ever so often as preventative maintenance insurance? No one wants to get stranded........

    Thanks
    Do you define 'house battery', as "the one used for the boat's electronics and engine"? You want a cranking battery for the engine, if the engine's electronics will be sharing the battery used for cranking and if you want to use deep cycle for the audio, that's fine, but you WILL need a heavy duty alternator if you expect your batteries to recharge and be able to supply all of the other electronics with the proper voltage and current. If you were to use a separate battery for cranking and ONLY for cranking, a deep cycle would work, but if you expect to run the battery voltage down below 10VDC, you're not using them according to their design. 'Deep cycle' doesn't mean "deplete them so they're stone dead".

    How loudly do you play the stereo, do you crank it while the engine is off, at idle, or at/near WOT and what other accessories would be used at a given time? Those will determine the demands on the batteries and charging system. The charging system must be designed for "worst case" scenarios if it's expected to survive and operate correctly.

    Why would you "replace the alternator every so often as preventative maintenance insurance", rather than just design the system correctly in the first place?

    If you use a heavy duty alternator, you'll need to use a heavier charging wire, too.

    List the stereo equipment by brand and model, too.

    Leave a comment:


  • paintpollz
    replied
    Question on the isolator, I'm just trying to get the science down. Say I had one of these installed, and someone left the stereo on all night, and the main/house battery completely drains. Theoretically, there wouldn't be any power in the main/house battery to close the isolator and connect the two batteries for charge. So this is the primary reason why we connect the starter to the second battery? Once the engine fires, power draws from the second battery to the main/house battery, closes the isolator, and then the alternator starts charging both batts, correct?

    Leave a comment:

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