Strange Battery Drain - Honda Accord

Thread: Strange Battery Drain - Honda Accord

  1. piggzy's Avatar

    piggzy said:

    Default Strange Battery Drain - Honda Accord

    Battery recently let me down so went out and bought a new one.

    Happened few weeks later so thought okay not battery. Dodgy connections as they did look a bit fucked.
    New terminal connectors and new earth strap. Everything cleaned and firmly attached.

    Week goes by then happens again. Alternator tested and putting out a strong 14 volts.

    So I assume something is draining it when car is off. Leave car standing for 10 hours and check battery before and after and it does show a drop in the battery.

    Any ideas where to start looking ?? I thought ignition off cuts everything from draining battery but guess I am wrong.
    I suppose its possible they sold me a duff battery but it charges up fine ?!?!?!?

    One of those cars where it has too much electronics so not sure where to start.

    Thanks for any advice guys.
     
  2. Over Carl's Avatar

    Over Carl said:

    Default Re: Strange Battery Drain - Honda Accord

    To actually nail this you probably need to get a full set of wiring diagrams for the car.

    It would also be handy to have a normal ammeter, two is better. Also a clamp style ammeter can be handy.

    Idea is to disconnect battery and put ammeter inline to check the current draw. Should be a tiny fraction of an amp.

    However modern vehicles can take some time for all the computers in the car to go to sleep, it can take 15-30 mins from when you turn off the car and lock it until it all shuts down. Sorry I haven't got anything to lookup this value for your vehicle.

    Once it's all gone to sleep, then you check the current draw. Yours will probably be a little high (I'm guessing something like 0.5A).

    Prior to this I would have loosened the fusebox so I can get access to the wiring at the rear. (Be very careful when doing this, you wouldn't want to short anything against the car's body/earth).

    Now pop the clamp meter onto each wire out the back, and try to figure out which is drawing excess power.

    Once I've figured out which one is drawing excess power, I will remove this fuse and put an ammeter across this fuse to determine the exact current draw because clamps aren't precise.

    Note just by removing and restoring power can wake up control modules, so need to start car up, then let it go to sleep again before taking this next reading.

    Then check out wiring diagram to see what that fuse gives power to, and unplug these items one by one until you have found the actual problem.

    On older stuff you could often just pull fuses one by one until the car's current draw dropped to find the culprit, but on modern cars you could just end up resetting control units further confusing any readings.

    To be honest I would also use a diagnostic scanner to check for fault codes that may give an idea what is going on before doing anything, but not everyone has easy access to these. CAN bus errors (often caused by a faulty control module) can sometimes keep other computers on the same bus awake which can be fun to fault find.
    Last edited by Over Carl; 9th October 2016 at 11:03 PM.
     
  3. piggzy's Avatar

    piggzy said:

    Default Re: Strange Battery Drain - Honda Accord

    Really appreciate the detailed post. Looks like I am fucked as this seems a little over my head.

    Gonna get my hands on a meter though and give it a try. Thanks Mr Carl
     
  4. EvilBoB's Avatar

    EvilBoB said:

    Default Re: Strange Battery Drain - Honda Accord

    Recently had this issue with my missus Corsa. It's an auto and if the handbrake isn't on when you remove the keys from the ignition a red light flashes on the dash. This, it would seem, is enough to drain the tiny battery in just a day or two. You probably have a sensor somewhere that isn't doing it's job properly. Some electrics do stay on in all modern cars. From stereos that you can switch on without a key in the ignition to things like internal lighting. Check the light sensor in your glove box That's caught me out in the past so the light stays on all the time which drains the battery surprisingly quick.

    Grab a multimeter, get in your car, turn everything off, close the door too. Remove a fuse and jumper the points with a multimeter. It should read zero. Move on to the next one and keep going. Hopefully you will find one of these will be a switch that's failing and easy to fix.
    DF Moderator
    XBox One | Panasonic 4k | MS Surface Pro 3 | 3DSXL | WiiU | RPi3
    XBL : TheSumOfAllEvil
     
  5. EvilBoB's Avatar

    EvilBoB said:

    Default Re: Strange Battery Drain - Honda Accord

    Straight after posting the above I found this helpful guide : [Only registered and activated users can see links. ]

    They pretty much say what I said but with photos and more words
    DF Moderator
    XBox One | Panasonic 4k | MS Surface Pro 3 | 3DSXL | WiiU | RPi3
    XBL : TheSumOfAllEvil
     
  6. piggzy's Avatar

    piggzy said:

    Default Re: Strange Battery Drain - Honda Accord

    Thanks all for info.

    It is an auto/tiptronic and tbh I never bother with the handbrake. No light on the dash though lol
     
  7. roybach's Avatar

    roybach said:

    Default Re: Strange Battery Drain - Honda Accord

    Worth checking that no lights are stuck on, my friend had similar problem and after fitting a new battery and still had the problem he took the car to an Auto Elec who found that the boot light was permanently on, another source of battery drain on older cars was the rear window heater.
     
  8. plug1's Avatar

    plug1 said:

    Default Re: Strange Battery Drain - Honda Accord

    Measure the current across the fuses
    when can is switched of .
     
  9. cosmicma's Avatar

    cosmicma said:

    Default Re: Strange Battery Drain - Honda Accord

    going off the honda civics they are known to have a problem with the blue tooth module causing the battery to go flat
    i know yours is an accord but if your car has blue tooth hands free the chances are it's the same blue tooth module in both models
    find it and unplug it to see if it cures the battery drain
    [Only registered and activated users can see links. ]
     
  10. doughboy's Avatar

    doughboy said:

    Default Re: Strange Battery Drain - Honda Accord

    What evilbob said is the way to find out your drain. Did this myself recently on my own car

    Sent from my SM-N910F using Tapatalk
     
  11. piggzy's Avatar

    piggzy said:

    Default Re: Strange Battery Drain - Honda Accord

    Turns out it was/is the tailgate ECU.

    Yes that's right the boot has it's own fucking ECU. BAD DESIGN
     
  12. Over Carl's Avatar

    Over Carl said:

    Default Re: Strange Battery Drain - Honda Accord

    New car's have shitloads of ECU's. Each door might have it's own ECU inside it, even front seats might have their own ECU. Heater controls - another ECU, interior light+switch console another ECU, indicator and wiper stalks another ECU.....

    Just using the bootlid example:

    In the old days, there would have been separate wires run front to back for locking functions, wiper/wash functions, boot open/closed signal, and lighting functions.

    Now they just run power and data from front to back, and a module at the back handles all the functions, meaning a lot less cable needed.

    Ok things might not be quite as simple as my example, but that is the general direction things are going.

    It does make some sense though, just for example in the old days your speedo might have been driven by a direct cable from the gearbox or a sender on the gearbox would convert the speed into digital pulses which was was directly connected to your instrument panel.

    One day they realised they can already monitor road speed from the ABS sensors. Why not just have the ABS pump send the road speed over the car's network to the instrument panel instead?

    Or I've read about fancy systems that can prepare a car before a crash- If ABS is showing very hard braking and the Airbag computer can back this up with a high G force reading, airbag computer can tighten up the seatbelts, whatever handles the lighting can flash the brake lights at high intensity, and the door modules can close the windows before crash.

    Things were getting ridiculous with top end German motors having more ECU's than anyone could dream of (E65 7 series springs to mind), but the current direction seems to be incorporating the function of 2/3 ECU's into one big combined one.

    Here's an example that I found on the net of BMW E65 network structure. Grey I believe are options that are not fitted, if it was fully loaded it would have 76 different control units. Car has 6 different networks (MOST & Byteflight networks use fibre instead of twisted pair) that can all speak to each other via SGM-ZGM Gateway module - almost car equivalent of a router joining up separate networks.

    [Only registered and activated users can see links. ]

    Edit: I just found an example of control units working together for safety features as I mentioned earlier:

    "Mercedes' "Pre-Safe" system was exhibited at the [Only registered and activated users can see links. ] on the 2003 [Only registered and activated users can see links. ]. Using [Only registered and activated users can see links. ] sensors to measure steering angle, vehicle yaw, and lateral acceleration and [Only registered and activated users can see links. ] (BAS) sensors to detect emergency braking, the system can tighten the seat belts, adjust seat positions including rear seats (if installed), raise folded rear headrests (if installed), and close the sunroof if it detects a possible collision (including rollover). A later version of the Pre-Safe system was supplemented by an additional function that can close any open windows if necessary" [Only registered and activated users can see links. ]
    Last edited by Over Carl; 29th October 2016 at 07:49 PM.
     
  13. plug1's Avatar

    plug1 said:

    Default Re: Strange Battery Drain - Honda Accord

    In a civ 8 there's a yaw sensor that conects to the abs for Vsa (traction control)
    if its switched on it brakes b4 it will in understeer .
     
  14. doughboy's Avatar

    doughboy said:

    Default Re: Strange Battery Drain - Honda Accord

    Wasn't the tailgate ecu a previous issue for someone on this forum?

    Sent from my SM-N910F using Tapatalk
     
  15. piggzy's Avatar

    piggzy said:

    Default Re: Strange Battery Drain - Honda Accord

    That might have been me doughboy.


    Problem I got now is no boot or boot and dead battery ffs.
    If it is ECU I can get one for £45, but reading around the tinternet it could be ECU, or motor for boot or switches or a number of other things involved in opening/closing boot e.t.c
    Not economically viable to replace everything. What a cunt lol
     
  16. piggzy's Avatar

    piggzy said:

    Default Re: Strange Battery Drain - Honda Accord

    Well bugger me. The drain is back so it wasnt what I thought and must be an intermittent drain ffs.

    Right cannot for the life of me find my old Multimeter so quick question do I need any particular type of multimeter or will any old cheap ebay job do the trick. Seen one on the bay for just under a tenner.

    Sometimes I bloody hate cars.
     
  17. doughboy's Avatar

    doughboy said:

    Default Re: Strange Battery Drain - Honda Accord

    Any meter that reads dc current will do

    BTW, how many days will it take to go flat?

    If I don't drive mine for 2 weeks I start to worry about a flat battery.
     
  18. piggzy's Avatar

    piggzy said:

    Default Re: Strange Battery Drain - Honda Accord

    Seems to vary but not more than 3. Sometimes overnight and we are talking DEAD even the clock loses the time etc. Got a spare battery that I am keeping topped up and just jump starting it so I don't have to keep removing battery e.t.c

    Once I jump start it and drive it for 15mins then it is ok for the rest of the day.
     
  19. piggzy's Avatar

    piggzy said:

    Default Re: Strange Battery Drain - Honda Accord

    Okay got my hands on this:



    Please could someone tell me where I should point the dial to for testing for the drain. I assume I would touch it the the battery first to confirm drain then each fuse in turn until I locate it ??!?!?!?!?

    What numbers would be normal and what would indicate a drain (as in the readout on the LCD)

    Thanks for helping a noob .
     
  20. plug1's Avatar

    plug1 said:

    Default Re: Strange Battery Drain - Honda Accord

    Put it to 10A and and move the red probe to amps
    look in the fuse box , pull the fuses you suspect and
    put the meter across the terminals . Look for anything thats
    drawing current more than a few mA . Your best bet would be to start with relays
    and test them first , start with the ac relay as these are common
    fail on Honda . And you need to put the meter in
    the circuit to mesure at the battery draw.
    is take the positive lead off and connect between the
    terminal and the lead
    Last edited by plug1; 20th November 2016 at 10:22 PM.