Connecting power and battery to X4 when switched off, X4 has flashing red led. If X4 powered on with the battery disconnected led also flashes red. How do you know when the battery is charged?
could you measure battery voltage with multimeter?
12.2V. Must have arrived fully charged. I assume the red led will stay lit if charging?
The charging indicator meaning:
Off - charged or DC not connected.
On - charging.
Blinking - charging error or battery not connected.
There is a known issue where (internal) battery protection circuit cuts power too early, before battery is fully charged, so charging indicator starts blinking as “battery not detected”.
So battery charges fully, just indications is misleading. To put it simple:
On - battery is charging.
Blinking - battery is charged.