Extra power in January

Discussion in 'Tech/Mech General' started by kaasbroodje, Oct 15, 2014.

  1. kaasbroodje

    kaasbroodje Funster

    Joined:
    Sep 14, 2013
    Messages:
    710
    Likes Received:
    772
    Location:
    Bristol
    I will be off grid for a week in January and am trying to work out the best way to manage my electrical supply.
    I have a decent 180 amp battery, all LED lights, don't watch too much telly. The main drain will be the blow air heating and charging phones/tablets etc.
    Now I also have a spare 90amp battery that's just sat in my garage. Can I use this to my advantage by temporarily connecting it to the 180amp battery ?
    Would it be better to connect them both fully charged, or better to connect the 90amp once the bigger battery had drained.
    If possible, don't want the hassle of physically swapping batteries / resetting panel and so on - was intending to use small cable run and croc clips. Hook it all up on arrival, disconnect, before moving on, so as not to create any charging issues.

    Any advice appreciated.
     
  2. JeanLuc

    JeanLuc Funster

    Joined:
    Nov 17, 2008
    Messages:
    2,782
    Likes Received:
    1,857
    Location:
    Warwickshire
    I'm not an electrical expert but here are a few thoughts that occur to me.
    • If the temperature falls very low in January, I'm not sure that 270 Ah will last a week. I have drained 2x110 Ah in a weekend when it was well below freezing. Remember the battery(ies) will give less than their rated power at low temperatures and ideally, you don't want to take more than 50% out of your good 180Ah battery anyway.
    • You refer to 'resetting the panel' so I assume you have a later model Schaudt system with the LCD control panel (mine is the old two meters with needles version - nothing to reset). Because the EBL is more than just a charger - it controls and fuses all 12V circuits - you might find that adding a battery would still require a reset as the EBL would suddenly be confronted with a change in capacity whilst it was monitoring 12V supply - I'm not certain about this.
    • If you add a charged 90Ah battery in parallel with a disharged 180Ah battery (using croc clips in your example) will the discharged battery not pull down the charged one, obviating the benefit?
    • If possible, I would stick with the existing 180Ah capacity and hire/borrow a small inverter generator to run for a couple of hours every other day. I realise this may not be possible in the location you will be in, but it would be my choice.
     
    • Like Like x 1
  3. Chockswahay

    Chockswahay Funster

    Joined:
    May 29, 2012
    Messages:
    3,095
    Likes Received:
    4,767
    The power killer will be the heating fan, especially if it's really cold! If you are staying in one place then I think you will be lucky to get past 2 days, on the other hand if you are touring and charging on the road then no problem.

    In real terms you can only really rely upon an operating range of 85% max and 50% minimum so 35% will give you just over 90 amps to play with....
     
    • Like Like x 2
  4. jonandshell

    jonandshell Funster

    Joined:
    Dec 12, 2010
    Messages:
    5,253
    Likes Received:
    7,858
    Location:
    West Norfolk
    That is a very good point about maximum charging levels. Many standard split charge circuits wont even achieve that much due to inadequate wiring and voltage drop.

    Another good reason for a B2B or A2B charging system. Of course, traction batteries help here to due the ability to discharge reliably down to 20%. You get more power from a similarily rated battery.
     
    • Like Like x 1
  5. Barclaybasher

    Barclaybasher Funster

    Joined:
    Apr 13, 2012
    Messages:
    2,447
    Likes Received:
    7,090
    Location:
    Derby


    Would running the van engine a couple of times a day help?

    Engine heater would also help with heating the van


    The fully charged spare battery should be carried but may not be needed

    (y)
     
    • Like Like x 1
  6. kaasbroodje

    kaasbroodje Funster

    Joined:
    Sep 14, 2013
    Messages:
    710
    Likes Received:
    772
    Location:
    Bristol
    Last time we went off grid in Jan the cold absolutely nailed the battery, couldn't believe the difference.
    Hence better planning this year....
    I figure that I'll use between 20-30 amps a day. I can borrow a generator , there are no noise issues and it would be lighter than an extra battery, just seems overkill to run a genny for a few amps of electric...

    I did have a b2b charger on my last van and yes a quick drive would help. I haven't fitted one to this van, mainly because I haven't noticed a sharp drop in charging rates( previously had Nasa battery monitor now use the EBL digital screen).

    Thanks to all (y)
     
  7. JeanLuc

    JeanLuc Funster

    Joined:
    Nov 17, 2008
    Messages:
    2,782
    Likes Received:
    1,857
    Location:
    Warwickshire
    • Like Like x 1
  8. jonandshell

    jonandshell Funster

    Joined:
    Dec 12, 2010
    Messages:
    5,253
    Likes Received:
    7,858
    Location:
    West Norfolk
    No problem so long as you fit an isolating relay between the EBL and leisure battery.

    The only thing that wont work is the counting of the amps going in during charging.

    It depends if you are interested in minor details or decent charging.
     
Loading...

Share This Page