Follow us today…
A recent Reddit r/rav4prime interest group forum reveals a new Rav4 owner who makes a “discovery” that you cannot help but smile about because it probably happened to you as a newbie too and bears reminding: unattended add-on devices will suck voltage from your 12-volt battery aka “parasitic draw.”
In the 2024 Toyota RAV4 Prime, the 12-volt battery serves as an auxiliary power source, distinct from the high-voltage traction battery that propels the vehicle.
The OP writes:
“This week, I discovered a major flaw, and it seems to be a problem with a lot of plug-in hybrid and even electric vehicles. All the electronics inside the vehicle, including door locks and trunk hatch, are powered by a tiny 12v battery. (For the Rav4, it’s located on the right side of the trunk beside the spare tire)…The hybrid battery doesn’t recharge the 12v battery when the vehicle is not running! Since new cars carry a lot of electronic equipment, this 12v battery can be drained in less than a week if the vehicle is not driven.”
Precious…right?! And, how often do you hear about a car’s 12-volt battery as being “tiny”?
This is all very understandable.
According to the OP:
“We went on a holiday for 19 days, and when we came back home, this battery was almost totally dead (2.49V), and absolutely nothing was working. I had to crawl from the driver’s seat to the back, unlock the door with a screwdriver, manually open the hatch, and boost the battery. Everything works fine now but it’s not very good for the battery’s lifespan.
Luckily, Toyota Road Assistance provided free towing to boost the battery. They were very helpful.”
Thread Responses Were Helpful As Well
Firstly, Kudos to the thread comments that were supportive and helpful rather than berating to the OP. It was a refreshing change.
The thread comments point to two most likely scenarios or a combination of both:
- The battery was weak.
- Something was sucking power from the 12-volt battery as the car sat dormant for 19 days.
In the end, the OP attributes the likely cause as due to her installed anti-theft device:
I measured it (the 12-volt battery) after driving around for 10 minutes and it was back at 12.54V. As someone said higher on the thread, it’s probably my anti-theft GPS tracker that drained the battery.
I have an anti-theft system called TAG. I didn’t realize this could drain the battery as well. Thanks!” ―OP
Will a GPS Tracker Drain Your Car Battery?
One thread post from bobosdreams points to an informative link that explains whether or not GPS tracking devices are known for excessive parasitic draws.
As it turns out, there is both a “yes” and a “no” answer to the question.
In short, it depends on the health of the 12-volt battery and/or the device itself. While many GPS tracking devices are designed not to drain the 12-volt battery by shutting down after a set voltage is detected, some devices will literally suck the life out of a battery when a car is not driven for a week or so.
A Fun Parasitic Draw Test
Here’s how you can see just how much parasitic draw your dashcam or any other device like a GPS anti-theft tracker can cause.
Required tools: a Digital multimeter to measure and monitor the parasitic draw and a wrench for removing the battery terminal clamps.
The Steps: Essentially, you are ensuring the vehicle is in its “sleep” mode and observing whether current is being drawn from the 12-volt battery by a device. To accomplish this test, you will:
- Ensure the 12-volt battery is fully charged.
- Turn off everything in the car, including the interior lights. And, remove the key fob from the car.
- Wait at least 10–15 minutes to allow the car’s electronics to enter sleep mode (Toyota vehicles require this time to settle). Do not open or close doors during this time, as it may “wake up” the ECU or other systems.
- Disconnect the negative battery terminal cable using a wrench.
- Set your multimeter to DC amps mode.
- Place the multimeter in series between the negative battery post and the now-disconnected battery cable e.g. one multimeter probe to the negative battery post and the other multimeter probe to the negative battery cable you had just detached from the 12-V battery.
- Read the current draw on the meter:
- A healthy modern vehicle should have a parasitic draw of <50 milliamps (mA) at rest.
- Note how much current is being drawn with and without the dashcam, GPS tracker anti-theft device, etc., being powered, i.e., turn off or disconnect the said device to make the comparison.
- Interpret the results: a 20-50 mA draw is normal; a 100-200 mA draw is likely due to your dashcam or GPS device; greater than 500 mA is a significant drain and could kill your battery in a matter of days.
- If you see no change in the draw after turning off or disconnecting the device, you may have other trackers on your vehicle that you do not know about or the system is not totally asleep and is actively monitoring something.
Note: This is similar to how a mechanic searches for a suspected parasitic draw in a car.
Typically, the systematic unplugging and re-plugging of fuses within each circuit is monitored by the current shown on the millimeter until a change in amperage appears, alerting the mechanic to where to look for a potentially faulty component. For example, a malfunctioning chip, sensor, actuator, etc.
For a portable jump starter that will fit nicely inside your Toyota Rav4 cargo area cubby in case of an unexpected dead battery, check out this article titled “The Toyota Rav4 Accessory From Costco That Looks Like It Was Made For a Rav4 ―”The Way It Fits Is Just So Perfect.”
COMING UP NEXT: Refueling My Toyota Hybrid Went Very Wrong
Timothy Boyer is an automotive reporter based in Cincinnati who currently researches and works on restoring older vehicles with engine modifications for improved performance. He also reports on modern cars (including EVs) with a focus on DIY mechanics, buying and using tools, and other related topical automotive repair news. Follow Tim on Twitter at @TimBoyerWrites as well as on Facebook and his automotive blog “Zen and the Art of DIY Car Repair” for useful daily news and topics related to new and used cars and trucks.
Image Source: Deposit Photos
Follow us today…
Source: torquenews.com
