If I dont use my car for seven days the battery is flat. 12 mile drive on Thursday battery was only reading 12.3 volts when I stopped. Battery checked out good, alternator good. Today, Saturday battery 12.1. Auto electritian says I have a drain of 28mv. with the fuse box in the engine bay disconnected, alternator disconnected, and all live fuses removed from fuse box passenger footwell, the discharge is still there. Any suggestions?

There is nothing wrong with your car.

The behavior is very typical for any modern Ford, especially at this time of year. A drain of 28mA (not 28mv) is actually spot on, most cars these days have a constant drain up to 34mA.

How old is the vehicle battery ? If it is 4 years or more then it is very likely to need replaced.

Get yourself a Smart Battery Charger, something like the Maypole (less than £25) and charge the battery for a minimum of 12 hours every 5 weeks. This is sadly the normal behavior of modern cars, especially those that are not regularly used and don't do many miles.

Remember to connect the negative charger lead to the chassis earth point and not to the battery.

The battery is 14 months old and load tested ok twice. I have been informed that the car might not be "going to sleep", because my keys are to near the car. 20 feet, inside the house.

5 minutes ago, Eddieshotton said:

The battery is 14 months old and load tested ok twice. I have been informed that the car might not be "going to sleep", because my keys are to near the car. 20 feet, inside the house.

Put the keys in a Tin while in the house if you want to test that theory.

 

13 minutes ago, Eddieshotton said:

The battery is 14 months old and load tested ok twice. I have been informed that the car might not be "going to sleep", because my keys are to near the car. 20 feet, inside the house.

I keep my keys in a tin box a lot further than 20 feet from the car, but it still behaves as you describe and has from new. My previous Mk 8 Fiesta was just the same.

It is, unfortunately, as @Unofix has advised you on this (and another) thread, normal for modern cars with charging systems set to 80% SOC for environmental reasons. 

You will find similar threads on most makes forums these days, eg:

 https://www.toyotaownersclub.com/forums/topic/217673-12v-battery-maintenance-issues-etc/

1 hour ago, Tizer said:

Put the keys in a Tin while in the house if you want to test that theory.

Or leave them indoors and go try the door handle...  Well worth doing that test anyway if parked in a publicly accessible area.

20 hours ago, unofix said:

.

Remember to connect the negative charger lead to the chassis earth point and not to the battery.

 

I've always assumed that this practice is simply to create a distance from the battery prevent any spark igniting battery gas.   I always put (dead) charging leads on first before  connecting the charger to the mains and when charging is finished, always  switch mains off before disconnecting leads for the same reason but what you say is good practice and I do it anyway.   Hydrogen is dangerous.

As an aside, many years ago someone I knew was charging an old-type battery with removable caps on the cells and used a match or lighter to see if the battery was gassing.   Took some time for his eyebrows to regrow!

3 hours ago, Magenta said:

I've always assumed that this practice is simply to create a distance from the battery prevent any spark igniting battery gas.  

It's to ensure the BMS detects that the battery is charged - see this thread:

https://www.fordownersclub.com/forums/topic/124161-best-place-to-connect-negative-to-chasis-when-charging-battery/

 

5 hours ago, Magenta said:

I've always assumed that this practice is simply to create a distance from the battery prevent any spark igniting battery gas. 

That was the case back in days on the 'Model T' 🤣

On Ford cars from approx 2010 onwards it's to ensure that the Battery Monitor System sensor detects that a charge current is flowing in to the battery.

On 2/27/2021 at 11:34 PM, iantt said:

BMS is always active. 

The Battery Monitoring Sensor continuously monitors the condition of the battery.

 

The sensor is equipped to vehicles which have Smart Regenerative Charging or Start-Stop. These systems require knowledge of the battery state of charge. The Battery Monitoring Sensor is the sensor used to provide this information.

 

Battery Monitoring Sensor connection

 

The Battery Monitoring Sensor is clamped directly to the negative terminal of the battery and grounds to the vehicle at the chassis ground connection point by means of a thick (25 to 35mm²) cable and eyelet. External customer loads must only be connected to the vehicle at the customer battery connection point. If the external customer load is connected at the negative battery post, the Battery Monitoring Sensor accuracy cannot be guaranteed.

 

It is recommended that the Battery Monitoring Sensor pole clamp is not removed unless a battery replacement is required. Should the battery need to be isolated, this should be done by disconnecting the ground eyelet at the chassis ground.

 

How does the BMS know the difference between a bolt on the chassis (e.g. one of the Mcpherson strut  securing studs that I use) and the -ve battery terminal when they are about 40 cms apart connected by a large csa cable?

There is a BMS sensor fitted in series with the negative cable that is attached to the battery.

All current flowing in to, or out of, the battery negative terminal has to pass through the BMS sensor and so the current can be monitored.

If you connect a battery charger directly to the battery negative post, then the BMS will not have the charging current passing through it and hence it will not know the battery has been getting charged.

An Example of the BMS sensor. Part of the battery post clamp.

Thanks, I hadn't noticed that device.  I'll look for it  next time I open the bonnet.  Modern car engine bays are so full of 'black boxes' these days that I've no idea what half of them are.  Fault finding as late as on my Mk1 VW Golf, for instance, (this was in the 80's) , was dead easy and I knew 100% what everything did. 

I did say that the 'eyebrow' incident was years ago when batteries had liquid electrolyte.  I still have a hydrometer and a Lucas distilled water dispenser from those days somewhere!  I assume gel batteries do 'gas' though.  Some have a vent valve.