Battery voltage too low - top disabled

  • HI all,


    I keep getting the message "Voltage too low - top disabled" after the car has stood for a couple of days and cannot understand why as the car is charging ok (do about 250 miles a week) and had a new AGM battery last year.


    Has anyone had this problem before? If so what was the fix, could it be a bad bettery sensor?

  • Did you mount additional electrical parts that have a canbus interface e.g. a tow-bar or a happyblue module or a throttle control box? If it is like this have you disconnected the battery afterwards? It seems like disconnecting the battery do some kind of reset of all interfaces.

  • I fitted a tow bar about 2 years ago and had a new battery 1 year ago and not had a problem until about 2 months ago

  • Do you have a measuring device to measure the standby current? When you want to measure it lock the car and then wait a few minutes until all control devices in the car are in standby. Probably we can then compare your standby current with the standby current of my car.

  • Hi Fighter1968,


    I haven't tried locking the car and testing it so will try it tomorrow whilst i'm changing the rear brakes and suspension.


    The tests I have done without locking the car are:


    Engine off: 12.44V

    Engine on at idle: 13.64V


    I did one test at both battery terminals and one test at the positive terminal and body earth, both tests came out the same.

  • Let me explain:

    assuming your standby current is 0,5 ampere.

    After 10 hours this is 0,5 ampere x 10 hours = 5 ampere per hour = 5Ah

    After 100 hours this is 0,5 ampere x 100 hours = 50 ampere per hour = 50Ah


    When your battery has 70Ah capacity the battery is empty after about 140 hours.

  • Ah I see, so used to checking battery voltage not current. Does these need checking across the battery terminals?

  • sorry not sure if translation ok.


    Do you put amp meter to the positive and negative terminals on the battery itself?