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Thread: Linking Lead/Acid and Lithium LiFePO4 Batteries with a VSR

  1. #1

    Linking Lead/Acid and Lithium LiFePO4 Batteries with a VSR

    I need to buy some new batteries for my boat.

    The battery currently used for house duties is just an old lead/acid car battery that has bulged its plastic case. It has to go before it lets me down. I'll need a new deep cycle battery for my recently purchased, but not yet installed, Xi5 MotorGuide.

    Lithium seems the best choice for the trolling motor and house batteries.

    My existing outboard starting battery is a Century Marine Pro 580CCA that is a few years old but in good condition. It currently starts a 2-stroke 3-cyl PTT 35Hp Johnson. I intend to keep this battery for a good while yet.

    At the moment, I have a Blue Seas dual sensing VSR connecting both batteries with the charging output of the outboard. It seems to be working well.

    My questions is, is it a bad idea to link a lead/acid starting battery with a lithium house battery via a VSR?

    Good advice appreciated.

  2. #2

    Re: Linking Lead/Acid and Lithium LiFePO4 Batteries with a VSR

    Id be emailing blue sea and asking them ,you might stuff up your motors charging system or not charge the different battery properly.

  3. #3

    Re: Linking Lead/Acid and Lithium LiFePO4 Batteries with a VSR

    Lithium batteries generally require a specific charging profile which your engine won’t provide, maybe a Dcdc type of battery management with a lithium profile.

  4. #4

    Re: Linking Lead/Acid and Lithium LiFePO4 Batteries with a VSR

    Quote Originally Posted by bobfromblacky View Post
    Lithium batteries generally require a specific charging profile which your engine won’t provide, maybe a Dcdc type of battery management with a lithium profile.
    Correct.

    I'd go VSR to DC/DC charger or alternatively, a solar reg. might be able to take the engine 12v and a decent one can definitely be configured to output for lithium.

  5. #5

    Re: Linking Lead/Acid and Lithium LiFePO4 Batteries with a VSR

    Don’t need a vsr when u have a proper dc 2 dc charger.

  6. #6

    Re: Linking Lead/Acid and Lithium LiFePO4 Batteries with a VSR

    BWR i donno a whole lot about electronics or led acid batteries but you may want to ask some questions

    Did u smell rotten eggs while using your boat the last few times?

    Have u checked your outboards output of power to see if its still regulated?

    What actually cauaed your battery to swell, if your outboards charging isnt regulated u may burn out all the technology your planning on putting in

    Now i have seen bulging batterys but what causes it? Over charging, overheating or both?

    I know i wouldnt like to drop $750 on a lifepo4 battery and whatever a dc/dc charger cost to run it and burn it out

    Just do some checks to make sure u have a healthy electrical system

  7. #7

    Re: Linking Lead/Acid and Lithium LiFePO4 Batteries with a VSR

    And what I know about electronics especially when it comes to LiFePo4 is pretty small but Gazza makes sense here, why did the battery bulge? It does sound like either your motor doesn't have a regulator (surprisingly quite a few earlier 2 strokes didn't) or yours is stuffed. Check it first otherwise as Gazza suggests.

  8. #8

    Re: Linking Lead/Acid and Lithium LiFePO4 Batteries with a VSR

    Too much voltage or current or lack of electrolyte are the causes of lead acid battery swelling

  9. #9

    Re: Linking Lead/Acid and Lithium LiFePO4 Batteries with a VSR

    Quote Originally Posted by gazza2006au View Post
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    What actually cauaed your battery to swell, if your outboards charging isnt regulated u may burn out all the technology your planning on putting in
    .
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    The battery I'm using for house duties was actually swelled before I put it in the boat. I was using it for testing, but it holds voltage quite well so have not yet replaced it.

    The charging performance of my outboard is OK according to my voltmeter.

    Thanks for all the suggestions. I'll do some more research.

  10. #10

    Re: Linking Lead/Acid and Lithium LiFePO4 Batteries with a VSR

    If you are intending to use a LiFePO4 battery you need to have the right battery management & charging system ....... & that means the $$$$ - no VSR will do it .

    I would speak to the people that really know ...... like Enerdrive

    my car (canopy) runs an enerdrive system that charges the battery via a DC/DC charger but also allows solar input - that a huge difference 40amp Vs about 4 amp .

    Chris
    Give a man a fish & he will eat for a day !
    Teach him how to fish
    & he will sit in a boat - & drink beer all day!
    TEAM MOJIKO

  11. #11
    Ausfish Platinum Member
    Join Date
    Mar 2015
    Location
    Kalbarri, WA

    Re: Linking Lead/Acid and Lithium LiFePO4 Batteries with a VSR

    Mixing radically different battery chemistries on the same charging circuit is a minefield, one you'll be unlikely to cross unscathed. Each type has their own charge requirements, and some do not even like to be charged in parallel with another battery, as you are doing when running through a VSR. Consult the experts.

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