Hi, New to the forum and hope to get some feedback.

USB Car Charger Converter Step Down Module 12V To 5V 3A:
Design Features:
- Input voltage: 12V
- Output voltage: 5V
- Output Current (max.): 3.0A
- Conversion efficiency: 96%
- Soft Start time: 500ms
- Rectification: Synchronous
- Water proof: Not Waterproof
- Output Ripple: 50mV (max) 20M-bandwidth
- Dynamic response speed: 5% 200uS

1) If I were to hardwired this to a constant power fuse with add-a-circuit, will this drain my car battery if no device plug in when car not start? I only charge when car started.

2) If car parked for a week when I'm on vacation and nothing plug to that wire, will it drain car battery?


Thanks,

 

It will still take a small amount of current without a load, perhaps 6-10mA, which is not enough to worry about on a car battery, measure the standby current with a dvm, then you will know.

 

In my experience with similar devices, no. I leave mine plugged in all the time and have never had a problem. That said, if this was in very cold weather and the car was to be parked far away from power, I would be nervous leaving it connected.

It's easy enough to test the quiescent current draw - just use your multimeter on the 200mA range setting. The leads go in series with the adapter, NOT parallel across the power leads.

 

Thank you all for a fast reply. Now, I feel confident about it.

 

If you assume a standby current of, say, 10mA then the converter will use 0.01 x 24 x 7 = 1.68Ah of energy per week. That's not much out of a typical automotive battery.