Hello Everyone! Firstly, I'll just say I'm not looking to start another capacitor debate, etc. Read through way too many of those threads in the past couple hours while searching for this
I'm more interested in the actual electrical theory behind this.
For a while now, my car battery would drain to the point of not being able to start after sitting for 3-5 days (shorter in the winter when it gets down to -35C... Yikes!). Battery replaced last year, alternator replaced 2 years ago. Just figured I'd finally look into this issue a bit more.
Anyway, there is definitely some parasitic draw while the car sits off. Measured this with a multimeter/ammeter in series between the battery negative terminal and ground. The sitting current draw is around 150mA after letting the vehicle sit for a while to make sure everything goes to sleep. An acceptable/normal current draw (depending on vehicle) should be anywhere around 20mA-80mA.
While measuring, I started disconnecting aftermarket stuff on the car to see if the current draw changes. Came down to 3 things that are drawing current at rest. I should add that the devices were definitely off as I even had the remote turn-on wires disconnected during these tests. Also that my two amps, when isolated, don't produce any draw even with the remote turn-on wires present.
1) An older Motorola Bluetooth module that replaces the GM OnStar module to add hands-free Bluetooth calling. Draws 50mA at rest.
2) AudioControl DQL-8 (DSP/line converter). Draws 40mA at rest.
3) Tsunami 2 Farad Capacitor (gotta be like 13 years old). Was able to take it out of the system and had the rest of the stereo components directly to the battery to see the difference. Draws 40mA at rest.
My question around the capacitor: is the parasitic draw of 40mA when the car is off normal for a cap? Or is this a sign of it going bad? How do you generally know when a car capacitor has aged and is no longer capable of operating within spec?
And what of any other electronic device? What generally makes a device develop a parasitic draw while off? Have the internal caps or other electronic components gone bad in order to produce this?
Much thanks!!
I'm more interested in the actual electrical theory behind this.For a while now, my car battery would drain to the point of not being able to start after sitting for 3-5 days (shorter in the winter when it gets down to -35C... Yikes!). Battery replaced last year, alternator replaced 2 years ago. Just figured I'd finally look into this issue a bit more.
Anyway, there is definitely some parasitic draw while the car sits off. Measured this with a multimeter/ammeter in series between the battery negative terminal and ground. The sitting current draw is around 150mA after letting the vehicle sit for a while to make sure everything goes to sleep. An acceptable/normal current draw (depending on vehicle) should be anywhere around 20mA-80mA.
While measuring, I started disconnecting aftermarket stuff on the car to see if the current draw changes. Came down to 3 things that are drawing current at rest. I should add that the devices were definitely off as I even had the remote turn-on wires disconnected during these tests. Also that my two amps, when isolated, don't produce any draw even with the remote turn-on wires present.
1) An older Motorola Bluetooth module that replaces the GM OnStar module to add hands-free Bluetooth calling. Draws 50mA at rest.
2) AudioControl DQL-8 (DSP/line converter). Draws 40mA at rest.
3) Tsunami 2 Farad Capacitor (gotta be like 13 years old). Was able to take it out of the system and had the rest of the stereo components directly to the battery to see the difference. Draws 40mA at rest.
My question around the capacitor: is the parasitic draw of 40mA when the car is off normal for a cap? Or is this a sign of it going bad? How do you generally know when a car capacitor has aged and is no longer capable of operating within spec?
And what of any other electronic device? What generally makes a device develop a parasitic draw while off? Have the internal caps or other electronic components gone bad in order to produce this?
Much thanks!!
