Current draw from aux. battery when car is off?

Houston, we have a problem........
At rest it should be in the order of milliamps, 15-20 if I'm not wrong

 

I'll check the "off state" 12V current drain on my 2005 Prius and post the result.

I've measured the 12V rail voltage numerous times but not the standby current drain (or charging current) for the 12V battery.

I replaced my 12V aux battery yesterday. It read only 11.0V during "IGN-ON." Worse yet it dropped to 10.5 V when I turned on the headlights. My new 12V battery measures >12.0V under the same test conditions (IGN-ON and headlights on). I expect this may get a little higher after the new 12V battery charges fully (I didn't put a charger on it before I installed it). My old 12V battery was 5 years old. I'm glad I replaced it before it prevented my car from powering up. I used the O'Reilly "Sure Start" exact replacement 12V battery. It was in-stock at my local O'Reilly store. Price was $ 175.99.

Super Start Platinum PRIUS - Battery | O'Reilly Auto Parts

 

I checked mine, read around 16~18 milliamperes, with occasional upticks to around 40. You want to have the car as "sleepy" as possible: no fobs nearby, doors closed (obviously) and so forth. Good to get your wiring set up, then just let everything sit for about 1/2 hour minimum.

 

If you have the hatch open to measure, the "door lights" (the ones down low) are on and the ones under the dash (floor or foot lights I quess). That's why you are seeing the high current.

 

Yup, you can run the leads out the hatch threshold and drop the hatch on them, they hardly pinch with the thick gasket.

 

Yup, or better yet, with the hatch still open for convenient access to the battery, shove the latch mechanism for the hatch into its fully locked position (two clicks), in order to "fool" the switch into believing the hatch is closed. Then you should see the much lower current Mendel listed, if all other doors are closed and if you wait for things to settle down. Otherwise, you'll see about 0.7 amperes plus current to power whatever combination of interior lights are on. That 0.7A alone will thoroughly deflate the battery within three days.

 

Sorry if obvious:

You put the meter IN the circuit, ie: any current moving has to go THROUGH the meter.

In practice: get yourself a couple of leads about 3~4 feet, preferably with alligator clips. Disconnect battery negative clamp at the post and connect securely to one of the leads. Connect the other lead to neg battery post. Run both leads out across the hatch threshold and close the hatch on them.

Then wait say 1/2 hour, and then hook up your meter leads, one to each of the previous leads. If your meter's NOT auto ranging, start on amperage scale, then milliamperes, just in case.

 

Interesting thread. I asked this question elsewhere, but just in case any of you have the answer here first: Does anyone know the typical lowest current draw the car has in IG-ON with everything electrical except the screen turned off, with a door open, or if easier to say, with a door closed? I killed a new smallish AGM battery by absent mindedly leaving it in IG-ON twice. I'm imagining the current is quite high, seeing this happened with a new aux battery at a pretty good SOC (12.7 or so)

I am technically in the wrong Forum, I realize - this being a Gen 3 forum. I have a Gen 2, but please let me know for whatever Gen you know...

 

karr is a dealership’s car locator tracker. In case people can’t make payments, a dealer can locate it via gps. The gimmick is great, if your car is ever stolen you can always track it with karr. Dealership don’t want you to remove this, their recovery job would be much more difficult to locate the car so you can imagine what it is doing and the power it consumes when engine is off.

 

My Gen2 shows 3-3.5A in accessory and 9.8-10.3A ignition on (not ready).

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