Low battery problem

[ArtofGrunt]

Just a small issue that is bugging me

Had a flat battery the other day and I used my booster to start it using the terminals under the bonnet. It started fine and ran fine with no issues, ran the car for about 60 miles and returned home. Started fine the next morning and ran a few errands and then this morning it is flat again. I connected a trickle charger to the terminals under the bonnet and left it. Before I went in the house I noticed the dash lights were on, ESP, Ign, etc etc. I disconnected the trickle charger and connected the booster pack. Switched the ignition off and locked the steering lock. Disconnect booster and reconnect trickle charge and the lights come on again. Is this normal behavior while charging the car via a trickle charger

If I connect the booster and start the car there are no lights on the dash and all runs well as expected. The voltage across the terminals is 13.8v at cold idle and if I switch if off it reads around 6v

The car is booked in for a new battery and coding on Tues but would like to know why the dash lights are coming on at low voltage. Is this normal behavior from the car or something a bit deeper

This is the charger i used,

https://www.amazon.co.uk/gp/product/B07 ... UTF8&psc=1

Thanks in advance

[ATinOf]

If the battery is registering only 6V static then you may have a cell down on the battery; so the trickle charger is probably having a hard time pulling the voltage up. In which case you may be flagging up spurious faults purely because of low voltage supply. Deffo a new battery required.