Hi All,

my stop/start stopped working, so I charged using a CTEX charger, worked for a day, then stopped again, I installed the CTEX, battery indictor/charger lead, charged agin, all green, then next day back too red.

I use a battery tester on battery in car, went red.

I purchased a new AMG battery, correct spec. I fully topped up, indicator lead, all green, about 6pm,last night.

this morning, the indicator is showing red on the brand new battery 

has anyone any idea, what has drained the battery in about 12 hours.

I have re-tested the old battery with tester, in showing green(its out the car)

appreciate any ideas, thoughts

 

cheers

Any interior lights left on?

Have you got a dashcam or any aftermarket electrics installed?

Is your boot closed properly? - I've had a few issues lately where boot closes but it doesn't latch properly so you can grab it and there is some play in it however you can still lock the car and the interior lights stay on.

Thanks for reply Trent ],

the lights were my first thought, I've checked all, including boot, all go off when I lock the car.

don't how much a light would drain tho, seems a lot of power lost from full to almost dead?.

I have just checked boot, seems tight enough.

 

just back a run, an hour each way, battery incadicator, flashing red

No expert but would guess that means your battery isn't charging. Somebody more clued up than me may have an answer.

But guess from here you could either take it to a garage or if you have a laptop and want to buy one of the forscan adapters (https://www.amazon.co.uk/s?k=forscan&crid=1I01ZGWGHBAQK&sprefix=forscan%2Caps%2C85&ref=nb_sb_noss_1) and download the free ForScan software, just plug it in, set it up and go to the DTC section, that may give you some information where some of us here may be able to help. IT's basically similar to what they would do at a garage anyway.

thanks again Trent, will have look at doing that, although, when I completed the full charge last night, I didn't move the car and charge was depleted.

cheers

Did you reset the BMS after fitting the new battery?  If not, it may not charge properly.

Also just want to check, did you replace an AGM with an AGM or was the old battery an EFB?

Lastly, do you mean the battery light on the dashboard is flashing or the light on your charger?

Hi Tom,

I left the car to sit overnight, without using it.

yes, I replaced like for like, AGM

sorry, its the indicator  light on my CTEX charge lead.

my friend put a multi-meter across terminals today, 12v to start with, engine off, then 14.3v, engine on.

I kind of appears there is something causing a significent drain, when not in use.

 

 

1 hour ago, Goldie Hawk said:

I kind of appears there is something causing a significent drain, when not in use.

Thanks for clarifying.  I agree with this, don't think it's a charging fault.

Your friend can carry out a battery drain test with the multimeter but it is a bit more involved than voltage checks.

Difficult to diagnose a drain over the Internet, of course.  My first thought would be Bluetooth module or Wi-Fi modem (if fitted) not sleeping when the ignition is off.

22 hours ago, Goldie Hawk said:

I kind of appears there is something causing a significent drain, when not in use.

One cause of the cars' ECU's not sleeping is the car not fully locking, i.e. my tailgate had issues in the early days and wasn't locking shut. This stops the alarm being set and stops the ECU's going to sleep. Another cause is third party dash cams fitted directly on fuses that stay alive when the car sleeps. A Ford garage or good tech will test the sleep current draw from the battery when the car goes into sleep mode (usually takes 10-15 minutes after ignition off and locking). There are specific tests in the service manual to diagnose this situation and will pinpoint the specific ECU that keeps the car awake ... and why!

A new fully charged battery that hasn't had the BMS reset, make also cause the car to think the battery is in a better state than it actually is, causing the smart charger to stop charging the battery even though it hasn't really been fully charged.

An overnight discharge does suggest one or more ECU's aren't sleeping though. They all get their 'command' to sleep from the immobiliser, which gets it's command from the locking system .. or from something plugged in where it shouldn't be!

Edit: Just a thought ... you haven't left the spare key in the car have you?!

If you have access to a multi-meter or a good friend armed with one, then here is the section from the service manual to check battery drain ...

Battery Drain Check.pdf

HI Simon, 

thanks for reply, is there a way of checking the BMS reset was successful, I only left it overnight, should I carry out the, lights, brake etc?

no spare key in car, I don't have a dash cam or any third party items being used.

thanks for that test sheet, I will my friend carryout this test,

Cheers