Battery Flat Every Second Morning

No - the number does not add up. At 0.42 A for a 12-hour overnight stand the battery loses 0.42 × 12 = 5.0 Ah, about 7% of a 70 Ah battery and only 14% of a realistic 35 Ah usable capacity. That will not stop an engine cranking. The drain would need to be well over 2 A, or the battery would need to be badly degraded, to produce the reported symptom.

The reading itself is also invalid:

1. Resolution. A clamp meter reading to 0.1 A cannot resolve a 50 mA specification - anything under 0.1 A shows as zero. Only a series multimeter or a low-current clamp reading to 1 mA is acceptable here.
2. Timing. It was taken one minute after shutdown. Body control modules, radios and telematics stay awake for 20–40 minutes; a genuine drain must be measured after the vehicle has gone to sleep.
3. Door open. An open door keeps the body module awake and may light the interior lamp, which alone can draw several hundred milliamps.

So the report is wrong in both directions: the figure is too high to be trusted and too low to explain the fault. The procedure must be repeated properly before any part is condemned.

1. Prepare the vehicle. Battery fully charged and confirmed serviceable; radio code noted; any delayed accessories (seat heaters, coolers) switched off; ignition off and key out of the cabin.
2. Close the circuit up. All doors, bonnet and boot shut and latched - close the latches with a screwdriver or tape the switches so the vehicle believes it is locked. No interior lamps lit.
3. Let it sleep. Lock the vehicle as normal and wait 30–60 minutes, per the manufacturer's stated sleep time.
4. Connect without waking it. Use a multimeter in series at the negative post (10 A range first, then mA), or a low-current clamp with 1 mA resolution. If the circuit must be broken, use a memory saver, otherwise modules wake and the test restarts.
5. Read the stable value and compare with the 50 mA limit. A reading that is still falling has not settled.
6. Isolate. If high, pull fuses one at a time (or measure the millivolt drop across each fuse) and watch the meter, replacing each fuse before moving on. Then unplug components on the offending circuit one by one.
7. Confirm the repair by repeating the full sleep test, not just a quick recheck.

Within-spec drain means the fault is elsewhere. Work in this order, cheapest and most likely first:

1. The battery itself under real load. A conductance test at 82% is an estimate made warm; a battery with a weak cell or an internal intermittent short can pass it and still fail cold. Carbon-pile load test at half the CCA for 15 s, watch the voltage and the recovery. This eliminates or confirms the battery.
2. Intermittent drain. A steady 0.045 A cannot flatten 70 Ah overnight, so if the battery is good the drain must be occasional. Fit a current logger for 24–48 hours, or log battery voltage: a step drop at a fixed time each night points to a module waking (door latch microswitch, boot lamp, telematics unit).
3. Charging side. 14.2 V looks healthy, but check AC ripple at the battery with loads on (should be under about 0.5 V AC) - a failing alternator diode upsets modules and can keep them awake - and check voltage drop on the B+ cable and earth strap under cranking (under 0.2 V each).
4. Starter draw. Measure cranking current and cranking voltage; an excessively high draw plus a marginal battery gives exactly this 'every second day' pattern.
5. Usage pattern. Short trips with lights and blower on can leave the battery below 70% state of charge with no fault at all; charge fully, leave 12 hours, and recheck - a healthy battery sits near 12.6 V.

Do not replace modules until 1–4 are eliminated by measurement.