265 Change battery on RS265 Start/Stop

Discussion in 'Electrical & Interior - Security, ICE, Wiring Loom' started by E-A, Mar 5, 2023.

  1. E-A


    Changed the battery yesterday and found something that not looked right.

    The Battery Charging Control Module has a connector which seems to have its cable cut off?
    I would appreciate if someone can check if there is a cable attached to this connector?


    The manual doesn’t mention how to change battery more than something along the lines of “It’s complicated, call your main dealer”

    My Meg is parked up in the garage during winter and I use a tickle charger, approximately once a month, this time it wouldn’t charge properly. Stopped charging at 10,2V. Looked around and youtube provided good enough information (I think)

    My step-by-step could be a guide when people search in the future. Please comment if anything seems wrong/not necessary.

    1) Unlock the car with the button on the key
    2) Pull the handbrake – Put gear in neutral
    3) Wait a few minutes to let the car "fall into sleep"
    4) Disconnect grey connector

    5) Disconnect negative terminal
    6) Disconnect positive terminal

    7) Remove clamp (8 mm socket), let the screws stay in the clamp, make sure you don´t drop them when removing the clamp.

    8) Clean battery tray

    9) Put in new battery, I cleaned up terminals with Brakleen and Electronic Cleaner. Battery manual recommend to use vaseline after terminals are connected but I didn't find any trace of vaseline on my old battery so I haven't put anything on the new one. Maybe I should.

    10) Refit in reverse order

    11) Choose “New battery” with trip computer buttons and press and hold one of them to confirm

    The new battery is EXIDE EK700 AGM 70Ah and the specifications says it should be charged with 14,4V instead of 14,7V which I believe is more common when it comes to AGM batterys. In my case, I will use standard mode on my tickle charger instead of AGM mode.

    Manual says "The battery may need recharging when voltage drops below 12.4V"
    12 hours after fully charged the battery is at 12,8V, I will keep an eye on this one to see if recharging once a month is enough.

    2015 Megane RS265
    Wagner Intercooler
    Forge Uprated Turbo Recirc Valve
    van Loon 3" Downpipe incl 200 cell HJS Euro5
    3" Scorpion exhaust non-res
    Engine Dynamics remap
    Cooksport lowering springs
  2. nothing connected on my RS250
    E-A likes this.
  3. E-A


    Thanks! I will now stop worry about it.
  4. Hi,
    I have just changed my battery, the new one is the type mentioned here. (Actually, I charged it overnight in AGM mode.)

    My question is loosely connected to this topic: does the Meg have some "really smart" charge control? I haven't checked it with the old battery, just with the new, fully charged one. After starting from cold, it charged with 14.7V. Then it stopped charging completely, and depending on how many electric consumers I turned on, it let the voltage fall even to around 12V dead. I decided to continue driving and monitor it. Eventually it went up to around 12.8V. The other thing I noticed is that every time I engine braked, it charged with "full power" at 14.7V (like "regenerative braking" in hybrids). So it is capable of charging at 14+V. It just seems it decides not to.
    Previously I have seen similar with my old Ford (which did have smart charge), but it turned off charging completely only at wide open throttle, otherwise it never went below around 13.2V (although perhaps the battery was not completely new in that one when I checked).
    No error messages, or OBD fault codes.
    Start-stop is working well, every time I come to a stop now (with the old battery it displayed "auto stop unavailable" many times).
    So I think it is ok, but I would like confirmation from someone :smile:
  5. (I took the measurements from OBD and the 12V socket, not the battery directly)
  6. Is your charger designed to be used on start stop batteries, some aren’t.

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