Page 1 of 2 12 LastLast
Results 1 to 10 of 14

Thread: Solar input to existing accessory cable

  1. #1
    LRD414's Avatar
    LRD414 is offline Super Moderator Subscriber
    Join Date
    Oct 2014
    Location
    Brisbane
    Posts
    3,723
    Total Downloaded
    0

    Solar input to existing accessory cable

    For the sake of convenience and minimising cables to the aux battery, I am wondering if it's ok to splice into an existing cable running between the aux battery and an accessory fuse box.
    The cable then becomes both an accessory supply and a battery supply.
    The cable size is sufficient for the maximum current, which will be the solar controller if it is outputting its peak (15A).
    Thoughts? Rough sketch below.



    Cheers,
    Scott
    Attached Images Attached Images
    D4 TDV6 MY14 with Llams, Tuffant Wheels, Traxide DBS, APT sliders & protection plates, Prospeed Winch Mount w/ Carbon 12K, Mitch Hitch & Drifta Drawers
    Link to my D4 Build Thread
    D3 2005 V8 Petrol
    Ex '77 RRC 2 door. Long gone but not forgotten.

  2. #2
    Johndoe is offline AULRO Holiday Reward Points Winner!
    Join Date
    Nov 2019
    Location
    Australia
    Posts
    162
    Total Downloaded
    0
    Plug it in and try.
    If it sparks then try it the opposite way.
    Still sparks then call a sparky.
    Theory works for me.

  3. #3
    Join Date
    Jan 1970
    Location
    Queensland
    Posts
    7,768
    Total Downloaded
    0
    Hi Scott and is there any specific reason for not going straight to the battery terminals.

    With solar, it is always best to go over kill with the cable running from the regulator to the battery, particularly if the reg is some distance from the battery.

    NOTE, this is just a guesstimate, but with that diagram, you may cause some voltage reference problems for the solar regulator, with the solar wiring taping in to wiring that is going to have a load from the devices connected to the same wiring.

    NOTE AGAIN, his is just theory.

  4. #4
    LRD414's Avatar
    LRD414 is offline Super Moderator Subscriber
    Join Date
    Oct 2014
    Location
    Brisbane
    Posts
    3,723
    Total Downloaded
    0
    The existing cable does go direct to the battery and the regulator will be approx 1m from the battery so that side of it seems solid. Is it not similar to putting the solar regulator into the rear Traxide Anderson plugged cable? It is connected to the battery but also has accessories spliced off that cable. I have used it for solar input successfully but now want to mount the regulator.

    Scott
    D4 TDV6 MY14 with Llams, Tuffant Wheels, Traxide DBS, APT sliders & protection plates, Prospeed Winch Mount w/ Carbon 12K, Mitch Hitch & Drifta Drawers
    Link to my D4 Build Thread
    D3 2005 V8 Petrol
    Ex '77 RRC 2 door. Long gone but not forgotten.

  5. #5
    Join Date
    Jan 1970
    Location
    Queensland
    Posts
    7,768
    Total Downloaded
    0
    Hi Scott, I based my comment on that you posted the cable you were intending on tapping into was good for the 15 amp loads.

    The cable in your Traxide kit to the rear Anderson plug is rated at 100 amps so far less likely to cause much of a voltage drop with a maximum solar input of 15 amps.

    4mm Auto cable ( 2.5mm2 ) is rated at 25 amps but a 15 amp solar input would still cause quite a bit of voltage drop even over a short distance.

    Do you know the exact size of the cable running between your battery and the fuse box?

  6. #6
    LRD414's Avatar
    LRD414 is offline Super Moderator Subscriber
    Join Date
    Oct 2014
    Location
    Brisbane
    Posts
    3,723
    Total Downloaded
    0
    Ok I see your point. The concept is ok but cable size needs to be suitable. I’ll have to check the existing cable size but what’s your thoughts on a size that would be enough, given that the accessory load is only small and the solar very rarely actually generates 15A and would typically only get to 10A.
    D4 TDV6 MY14 with Llams, Tuffant Wheels, Traxide DBS, APT sliders & protection plates, Prospeed Winch Mount w/ Carbon 12K, Mitch Hitch & Drifta Drawers
    Link to my D4 Build Thread
    D3 2005 V8 Petrol
    Ex '77 RRC 2 door. Long gone but not forgotten.

  7. #7
    Join Date
    Jan 1970
    Location
    Queensland
    Posts
    7,768
    Total Downloaded
    0
    Hi again Scott, the actual solar current load is not that important, as long as the cable size is adequate.

    The size and length of the cabling for the accessories is really the ruling factor.

    If I were doing this setup, I would use at least 6mm Auto ( 4.5mm2 ) from the solar panel to the solar regulator.

    Then same again from the solar regulator to the junction and on back to the battery.

    From the junction to the fuse box is pretty well irrelevant, but to keep it simple, run the same 6mm Auto for this section as well.

    NOTE, cable lengths are still a consideration.

    If the lengths are more than a few metres, then it would not hurt to go up to 6mm2 ( usually called 6mm Marine ).

    Overkill on solar wiring is never a disadvantage.

  8. #8
    Join Date
    Jan 1970
    Location
    Queensland
    Posts
    7,768
    Total Downloaded
    0
    Scott, something to consider, if you are not ready aware of it, but when planning a solar setup, the minimum loss possible is best practice.


    To put this in a way that may be easier to understand.


    When powering accessories from a battery and/or an alternator, any power lost through voltage drop is simply going to increase the current draw on the battery and/or an alternator.


    This is an exaggerated and simplified example, but say you have a fridge drawing 10 amps at the end of a length of long but thin cable.


    The voltage drop in the cable means that the power source will need to provide 12 amps to meet the 10 amps the fridge requires and cover 2 amps the cable’s resistance causes ( heat ).


    The above is not a problem when there is, for all practical intention, an unlimited power source.


    This is not the case with solar power as there a defined limited power available.


    With solar, if the fridge wants to draw 10 amps and the solar has a total output capacity of 10 amp, the 2 amps lost because of the cable’s resistance, can not be made up, so the fridge will only get 8 amps,


    The same goes where you are charging a battery with solar ( obviously the most common use for solar ) where you may have a 10 amp capability at the panel, but loose 2 amps in the cabling.


    The 2 amp loose is wasted energy, but by using thicker solar cabling, the loss can be dramatically reduced. And this means more charge going into the battery.

  9. #9
    Join Date
    Jan 1970
    Location
    NSW SW Slopes
    Posts
    11,475
    Total Downloaded
    0
    Maybe not directly related to the addition of the solar regulator, but if there is any possibility of the insulation of the +ve wire between the battery and fuse panel or the proposed solar regulator ever being compromised such that a short circuit could occur then a fuse should be installed close to the battery, if indeed one istn't already installed.
    MY12 RRV 4.4 TDV8 AB, +LLAMS, +e-diff, +ACC stop/go. Produce LLAMS for LR/RR, Jeep GC/Dodge Ram
    VK2HFG and APRS W1 digi

  10. #10
    Join Date
    May 2012
    Location
    Wannanup WA
    Posts
    1,477
    Total Downloaded
    0
    Quote Originally Posted by drivesafe View Post
    Hi Scott, I based my comment on that you posted the cable you were intending on tapping into was good for the 15 amp loads.

    The cable in your Traxide kit to the rear Anderson plug is rated at 100 amps so far less likely to cause much of a voltage drop with a maximum solar input of 15 amps.

    4mm Auto cable ( 2.5mm2 ) is rated at 25 amps but a 15 amp solar input would still cause quite a bit of voltage drop even over a short distance.

    Do you know the exact size of the cable running between your battery and the fuse box?
    Genuine question:

    Ok you auto electric types, please explain why auto cable is being quoted by what appears to be the OD of the insulation, and not the mm2 of the conductor. I trained as an electrical fitter / armature winder where wire sizes were often quoted in different sizes, such as B&S, SWG and if stranded the old English types such as 23/0076 or similar where we fitted flexible leads to the windings.

    Automotive cables are available with different thickness insulation, so how do you class a cable by how thick the insulation is?
    I spent years working with American cable sizes, which are completely ridiculous! Some of the cables that I worked with were supplying 800hp DC traction motors, but the OD of the insulation had nothing to do with amp carrying capacity, although the insulation material itself was classed for the operating conditions.

    I also thought that Australia had converted to metric in all things, under threat of legal action if not followed! So again, why are cables not obliged to be quoted in metric sizes, rather than B&S(AWG)? Cheers

Page 1 of 2 12 LastLast

Tags for this Thread

Bookmarks

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
  •  
Search AULRO.com ONLY!
Search All the Web!