Car frequently will not start. Charged battery foe 3.5 hours to 75% with charger and next morning had nothing not even dome lights! put jumper cables on from my pick up for 20 minutes and fired right up. battery is less than a year old. Sometimes when I attach to the battery either charger or jumpers I can hear a clicking similar to an electric fuel pump engaging. Help is appreciated.
You say you hear a clicking sound that tells me something is not shutting down and you have a phantom drain discharging the battery.
Check that the battery connections are clean and tight.
If there’s a bad connection at the battery posts, the clamps on the charger/jumper cables will create a better connection when they’re put on.
Side post battery? Remove your terminals. Inspect for corrosion.
I presume you mean you turn the key to “start” but don’t hear that rrr rrr rrrr sound. the first step is to make sure the battery is good. The symptoms you describe are consistant w/ a bad battery that isn’t able to hold a charge. If the battery tests ok then there must be something discharging the battery when the car isn’t being used. Check for lights remaining on, such as the dome light, or hidden lights, such as inside the trunk, engine compartment, the glove compartment, etc.
another thing to check is you might have a faulty brake light switch keeping your brake lights on intermittently. if you shut your car off during the day and get out you might not see your brake lights are stuck on. the next day you get in and hit the brakes to start your car and it frees up the brake light switch and the brake lights shut off. but now the battery is drained and is too weak to start the car.