Page 1 of 4 1234 LastLast
Results 1 to 10 of 36
  1. #1
    Join Date
    Mar 2018
    Posts
    379

    Default Charging batteries wired in parallel.

    I am about to change my two house batteries and a friend has suggested wiring them in parallel to cut down individual cycles.

    I will end up with 280 amps instead of 2x140.

    As I will be able to run the bank longer before needing to recharge I’m just wondering if the engine alternator and existing battery charger will struggle with the increased amps or do they give their maximum output normally and now it will be just for a longer period?

    Assume nothing “smart” in the system, I don’t know and it’s run fine charging two individual batteries for 15 years.

    Thanks

    Edit: Just surprised myself by finding out that the charger says: 12V/DC 27A on the side.
    Last edited by XDC; 20-10-19 at 04:31.

  2. #2
    Join Date
    Jul 2009
    Location
    Winter in Falmouth, summer on board Rampage.
    Posts
    5,241

    Default Re: Charging batteries wired in parallel.

    If you’ve got a 12v system and two domestic batteries, then they’re already wired in parallel.

  3. #3
    Join Date
    Mar 2018
    Posts
    379

    Default Re: Charging batteries wired in parallel.

    Quote Originally Posted by duncan99210 View Post
    If you’ve got a 12v system and two domestic batteries, then they’re already wired in parallel.
    Nope, they go through individual battery connectors. I chose which battery I want to use, it runs down I select the other, but only one gets charged at a time.

  4. #4
    Join Date
    Jul 2009
    Location
    Winter in Falmouth, summer on board Rampage.
    Posts
    5,241

    Default Re: Charging batteries wired in parallel.

    Why? If you have the batteries in parallel you get access to the whole of their capacity all the time, you charge both of them equally. Sounds like a weird system, did you inherit it with a. New boat?

  5. #5
    Join Date
    Mar 2018
    Posts
    379

    Default Re: Charging batteries wired in parallel.

    Quote Originally Posted by duncan99210 View Post
    Why? If you have the batteries in parallel you get access to the whole of their capacity all the time, you charge both of them equally.
    Duncan, my question was “will my battery charger and alternator charge my batteries in parallel without struggling ”

    I’ve been told exactly what you just said, parallel is better, and plan to do it IF someone confirms that I won’t be overloading the charging set up i.e. from 140 amps to 280.

    Thanks

  6. #6
    Join Date
    Apr 2002
    Location
    Cornwall
    Posts
    9,273

    Default Re: Charging batteries wired in parallel.

    Quote Originally Posted by XDC View Post
    As I will be able to run the bank longer before needing to recharge Iím just wondering if the engine alternator and existing battery charger will struggle with the increased amps or do they give their maximum output normally and now it will be just for a longer period?
    The alternator / charger will just give there max output, may get hotter ( working harder ) may / will take longer to recharge, but batteries in parallel is standard practice.

    Brian
    Kddpowercentre VASR charge

  7. #7
    Join Date
    Jul 2009
    Location
    Winter in Falmouth, summer on board Rampage.
    Posts
    5,241

    Default Re: Charging batteries wired in parallel.

    I’ve got a 500 amp hour bank with a 40 amp charger. It works without a problem. The charger cannot be overloaded, it’ll only deliver the current that it’s rated for in your case 27 amps. By paralleling your batteries, you’ll simply get the job done without having to mess about switching the batteries on and off charge.
    The only worry you might have is the opposite from your concern; you have a 140 amp hour battery with 27 amps being delivered to it. You’d need to check your battery makers instructions but about 20% is the usual suggestion for the charger, yours is delivering to a single battery somewhere over 20%, reinforcing the idea that you’d do well to get them paralleled.

  8. #8
    Join Date
    Nov 2009
    Location
    Home UK Midlands / Boat Croatia
    Posts
    21,143

    Default Re: Charging batteries wired in parallel.

    Quote Originally Posted by XDC View Post
    Duncan, my question was ďwill my battery charger and alternator charge my batteries in parallel without struggling Ē

    Iíve been told exactly what you just said, parallel is better, and plan to do it IF someone confirms that I wonít be overloading the charging set up i.e. from 140 amps to 280.

    Thanks
    The fact that it appears that none of us have ever heard of a system where multiple house batteries are not connected in parallel seems to suggest that wiring in parallel will be fine.

    Richard

  9. #9
    Join Date
    May 2001
    Location
    UK East Coast
    Posts
    37,063

    Default Re: Charging batteries wired in parallel.

    Quote Originally Posted by XDC View Post
    I am about to change my two house batteries and a friend has suggested wiring them in parallel to cut down individual cycles.

    I will end up with 280 amps instead of 2x140.

    As I will be able to run the bank longer before needing to recharge I’m just wondering if the engine alternator and existing battery charger will struggle with the increased amps or do they give their maximum output normally and now it will be just for a longer period?
    Both the alternator and the charger will cope fine. With 2 batteries in parallel, your batteries should enjoy a longer life too.

  10. #10
    Join Date
    May 2001
    Location
    UK East Coast
    Posts
    37,063

    Default Re: Charging batteries wired in parallel.

    Quote Originally Posted by duncan99210 View Post
    The only worry you might have is the opposite from your concern; you have a 140 amp hour battery with 27 amps being delivered to it. You’d need to check your battery makers instructions but about 20% is the usual suggestion for the charger, yours is delivering to a single battery somewhere over 20%, reinforcing the idea that you’d do well to get them paralleled.
    He doesn't; he has a charger which theoretically can deliver 27A - whether it does so depends on the ability of the battery to accept charge. A well-discharged 140Ah battery might accept 27A for a few minutes, but the charge current would rapidly drop.

Page 1 of 4 1234 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Latest YBW News

Find Boats For Sale

to
to