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Parasitic Draw

Discussion in 'LR4' started by avslash, Apr 7, 2020.

  1. avslash

    avslash Full Access Member

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    So I'm looking for things to occupy my time instead of watching this quarantine flush my business down the toilet, and decided to take a little dive into the electrics on my LR4.

    To set up a baseline, I charged the battery for a full 24 hours, and then let the truck sit roughly another 30 hours.

    Baseline measurement of voltage at both batteries was 12.61 at this point. This indicates to me that they are in reasonable shape.

    I then measured amperage draw after the truck had been sitting for the same 30 hours and measured around .18 amps. The only difference when making this measurement from a normal park was that the hood had been open for the same 30 hours.

    Next I will start pulling fuses one by one to see the effect of each on the parasitic draw, and if needed disconnecting my accessory mods one by one to quantify the effect.

    What I'm hoping to understand is if there is a procedure I could document to set the Rover up for a several day camp secure in the knowledge that the battery will be able to start the truck when I'm ready to move again, and also to understand if my solar setup is able to cope with the parasitic draw of the truck.

    I'm curious if any of you guys have taken a similar measurement and what your results were.

    Please post up if you have done so.
     
  2. f1racer328

    f1racer328 Full Access Member

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  3. avslash

    avslash Full Access Member

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    I do the same thing. It rides in the cubby beside the third row.

    Good for emergency use, but if I can manage the draw that is another layer of reliability.
     
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  4. blake aiken

    blake aiken Active Member

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    Looking forward to your reliability journey.

    Could you use a multimeter to check for ghost voltage or so you need to pull the fuses?

    This is a different process from voltage drop right?
     
  5. avslash

    avslash Full Access Member

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    What I have done so far is to get the truck as "put to sleep" as I can make it. I then used my clamp-on amp meter to measure amperage coming out of the positive wire from the battery. That amperage is going somewhere, so my next thought was to pull fuses one by one while measuring the amperage to see where it is going, with an ideal result of being able to pull some fuses and bring the "truck is asleep" amperage draw to zero. I kind of doubt zero is possible, but we will see.

    If someone has a better methodology, by all means, chime in.
     
  6. djkaosone

    djkaosone '11 LR4 HSE LUX 5.0L V8

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    Here's a good video breaking down how to trace down parasitic draw.

    Some of the main take aways are open and simulate the closed lock on your hood, door(s) to access fuse panels, and use a multimeter to check every single fuse without removing the fuse.

    I think I should do the same thing soon. My new battery drops to 12.1V and never charges over 77% (IID Tool). I really hate that bms and I disconnect it only when off roading to keep a constant charge.
     
  7. bbyer

    bbyer Full Access Member

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    I regard it as near impossible to figure out what is taking power and what not.

    Since the procedure requires keeping the bonnet open, I would jump the bonnet open/closed sensor to emulate the bonnet being closed.

    You could then pull fuses from the engine compartment fuse box and and watch the current sensor on the battery cable.

    For the interior fuse box, that is where it gets silly.

    I claim you cannot open a door to get inside so you have to leave a window open initially, crawl thru it, and then curl up on the two front seats and "access" the glove box fuse box.

    Your significant other reads the current sensor at the battery while you cramp up.

    If you were having a dead battery problem (which you are not) due to a minor current draw somewhere, I would suggest you disconnect / remove that rubber covered rear hatch micro switch. It can fail in some sort of closed manner that draws some kind of door latch opening control system signal without actually opening the rear hatch - near impossible to detect other than the rear hatch does not always unlatch.
     
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  8. avslash

    avslash Full Access Member

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    Played with it a bit.

    Checked all engine compartment fuses with the hood latched engaged and got 0.0 on all fuses in that block, so that part looks good.

    I did find my solar charge controller that is mounted under the hood was responsible for about half of my measured amp. With that disconnected, I am down to a measured .1a. I will be dabbing up a quick connect/disconnect for that device.

    Still need to check the interior fuse box and also the auxiliary fuse box I added in the cargo area.
     
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  9. djkaosone

    djkaosone '11 LR4 HSE LUX 5.0L V8

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    I gave up on my charging issues... This one is a good read for those trying to trace down their charging issues. I've had these symptoms and tried a lot of things to deal with it, especially with a secondary battery. https://www.overlandbound.com/forums/threads/land-rover-lr4-charging-profile-lessons-learned.3771/

    What I found useful is before heading out on an off road trip, I will start the truck, pop off/on (10 sec wait) the BMS plug, and I'll have 14.xV on both batteries for a few days.
     
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  10. bbyer

    bbyer Full Access Member

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    That is a good link - much appreciated.
    I have about the same setup on my 3, a Traxide SC80 but Interstate batteries on both sides.
    I use the CTEK US3300 and maybe every 3 months, hook same alternately to each battery for a week of nights or so.

    The jpg's below show fused wiring from both batteries joining at a grill located junction box. The toggle switch I can operate thru the grill to set which battery will be charged.

    I noted comments in the link about the Land Rover electrical design people deciding it was OK to not always charge the batteries, but instead to allow them to draw down.

    He is correct; the reason apparently has to do with emission requirements - low engine rpm at idle while stopped at traffic lights etc, and LR chose to draw the battery down rather than raise engine rpm. LR also load sheds - heated seats, the amp, heated windows etc cycle on and off to reduce load and hence keep battery draw to a minimum.

    Additionally, for some reason, (probably fuel mileage numbers), LR decided it was a waste of fuel to allow the battery to even get more than an 80% State of Charge, or we would call, a fully charged battery.

    Drive NY to LA and the battery or batteries will never get near a 100% State of Charge.

    As such, for me, the only solution was the CTEK for bringing the batteries up to near 100% every few months.

    My belief is that LR knew the engine would always start in warm weather if the battery had at least ten volts but did not or does not yet understand that the computers needed closer to 12.5 volts at startup for the systems to operate. Their thinking was that since the computer systems run at 5VDC, there would never be a concern.

    My view is that the inverters on the PC boards are not very good and want to see at least 12.5 VDC to yield a clean strong 5VDC. Once the engine is started, then yes, the system does generate above 12.5VDC so the computers are happy, however upsets they caused at startup do not readily clear.

    As such, the CTEK thing is what I regard as the only solution.
    Apparently Ford has now mainstreamed our electrical systems for their vehicles and I have wondered what changes they made to avoid our routine problems.
    I now have newer Interstate batteries on both sides without the removable caps - the caps I miss. IMGP0434.JPG LR3 Battery Charger Grill View 0481.JPG LR3 Battery Charger switch box and connector 0478.JPG LR3 Battery Charger switch box_plug_CTEK charger 0479.JPG Aux Battery vent 8.jpg IMGP0434.JPG


    LR3 Battery Charger Grill View 0481.JPG LR3 Battery Charger switch box and connector 0478.JPG LR3 Battery Charger switch box_plug_CTEK charger 0479.JPG Aux Battery vent 8.jpg LR3 Battery Charger Grill View 0481.JPG LR3 Battery Charger switch box and connector 0478.JPG LR3 Battery Charger switch box_plug_CTEK charger 0479.JPG Aux Battery vent 8.jpg
     
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