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An unknown parasitic draw can ruin your car’s battery. And sometimes it is due to multiple accessories added by insurance companies wanting to monitor their “investment” as well as car owners wanting to monitor their engine’s performance.
In fact, one reader supports the mechanics warnings:
I am one of those who always has my OBDII reader plugged in. For 9 years I had it in my Jaguar and never caused a battery issue.
However, I just bought a 2015 Highlander off a lot…after not driving for a day or two I would go out to the Highlander and the car would not start. Battery is not “dead” but needed a quick trickle charge to turn the car over. That is when I saw it…a tracking unit zip tied around the radiator fan wiring harness, and I traced the wires straight to the battery and there was an orange light flashing on it. So, I had BOTH a tracker and an OBDII reader going after my car goes to sleep. ‒@daddylogan
What Is Parasitic Battery Draw?
If your car struggles to start after sitting for a few days—even though the battery tests fine—you might be dealing with parasitic draw (also called parasitic drain).
- A normal parasitic draw is small (20–50 milliamps) and keeps systems like your clock, ECU memory, and security system alive.
- An excessive parasitic draw happens when something keeps pulling current after the car is off—slowly draining your battery overnight or over a few days.
Modern vehicles often have infotainment systems or modules that never fully shut off. But another sneaky cause is OBD2 devices, like the Progressive Snapshot dongle or third-party OBD2 tracker/monitors.
Why OBD2 Dongles Drain Your Battery
The OBD2 port in your vehicle is always powered because it’s tied directly to the battery. This means that anything plugged into it—such as a Progressive dongle, GPS tracker, or insurance monitoring device—keeps drawing power even when the car is off.
- Normal OBD2 dongle draw: 20–50 mA
- Excessive draw: 100–300 mA or more
If you drive daily and have a healthy battery, you might never notice. But if your car sits for days, or if the battery is slightly weak, the extra draw can leave you stranded.
Case Study: Royalty Auto Service Investigation
On YouTube, Royalty Auto Service highlighted this exact issue in a video titled “You Might Have This In Your Vehicle & This Is Just One Reason Why You Need To Get Rid Of It!!”
In the episode, the host investigated a 2002 Infiniti i35 with repeated dead battery problems. Here is a summary of the diagnosis:
To diagnose the dying battery problem, the host goes through the following steps:
- Verifies a significant parasitic drain of 800 Milliamperes (mA) using a multimeter connected to the car battery
- Detects at least one parasitic drain source from the car’s radio using a Snap-on Elite Diagnostic Thermal Imager with infrared detection capabilities.
- Testing the draw at the radio’s fuse using a multimeter, the host discovers approximately 650 mA of draw out of the 800 detected initially. Leaving at least 150 mA unaccounted for.
- Monitoring the parasitic drain further, the host discovers that the 150 mA fluctuates as high as up to 300 mA―an important observation that is the point of the video.
I’m going to show you the thing that so many people are putting in their car that I have never been a fan of. I did a class in front of a bunch of people, and I mentioned this, and boy, the whole room kind of lit up with, ‘Yeah, those things are problems.’ So, we’re seeing it in the industry. For those of you who are out there and putting this stuff in your car, be careful with it.”
5. The host reveals a Progressive dongle plugged into the OBD2 port, which is actively receiving input from the car’s many modules and transmitting data presumably to the Progressive-powers-that-be for unsubstantiated but possible nefarious reasons some car owners suspect. The occasional beeping from the module is associated with the fluctuating 300 milliamps parasitic draw, separate from the 650mA draw detected from the car’s radio.
One thread comment sums up the host’s findings:
Basically you found a tracker ― which BTW is on almost every single car you buy off a dealer lot (for theft from lot, or to upsell you on services like IKON or a financing company may require it in case they need to repo). And all those companies will sell your data to insurance companies 100%.
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The key point of the video is that many used and new cars have (more-or-less hidden) GPS trackers for theft recovery or financing requirements. Adding any additional devices to the OBD2 port can add to your car’s battery parasitic drain problems.
For additional details about the case study, here is the video discussed:
You Might Have This In Your Vehicle & This Is Just One Reason Why You Need To Get Rid Of It!!
A Step-by-Step DIY Test So You Can Measure How Much Your Progressive Dongle Is Actually Drawing From Your Car Battery
If you have a new or used car with a parasitic draw problem, it may be caused by one or more dongles, such as the type used by Progressive. If so, here is a summarized step-by-step DIY test you can do to determine how much your battery is being drained.
Tools you’ll need
- Digital multimeter with DC amps and mA ranges.
- Small wrench for the battery terminal, a short 10- to 12-gauge jumper wire (or booster cable), and a fuse puller.
- Notepad/phone to record readings
Safety warning before proceeding
- Never start the car or turn on high-current loads (blower, headlights, defogger) while your meter is in the amps mode and wired in series—you’ll pop the meter’s fuse instantly.
- Work on the negative (-) battery cable for safety.
- Keep doors closed and dome lights off so you don’t wake the car’s computers.
Prep the vehicle
- Fully charge the battery first or ensure your battery is healthy.
- Open the hood. Block the hood latch with a screwdriver so the car “thinks” it’s closed, but keep the hood physically open.
- Remove keys/fob from the car, close all doors (with driver’s side window open for access), lock the car if it normally sleeps that way, and wait 30–45 minutes so all modules go to sleep. (Some vehicles need up to 60–90 minutes.)
Perform a baseline draw (without the Dongle)
- Unplug the Progressive Dongle from the OBD2 port.
- Use the jumper wire between the negative battery post and the negative cable. This keeps power flowing so modules don’t wake.
- Loosen the negative cable clamp and lift it off the post—but leave the jumper in place so the car is still connected to the battery.
- Set your multimeter to DC Amps and plug the leads into COM and 10A (high-amp) jack.
- Connect the meter in series: one lead to the negative post, the other to the negative battery cable―the same points your jumper is bridging.
- Remove the jumper so all current flows through the meter.
- After any brief spike, wait for the number to stabilize. If it’s under ~0.3 A (300 mA), switch to the mA range for finer resolution (reinsert the jumper again while you move the meter lead to the mA jack).
- Record the steady mA reading = Baseline mA (typical healthy range: ~20–50 mA while the engine’s ECM is in sleep mode).
Perform a Draw with the Dongle
- With the meter still in series with the negative battery post and the battery cable, insert the Progressive Dongle. Expect a spike (the dongle might wake up the car).
- Wait again for sleep mode (another 30–45 minutes is safest).
- Record the steady mA reading = With Dongle mA
- Subtract: (With Dongle mA) – (Baseline mA) = Dongle’s added draw.
How to interpret your results
- Normal sleeping vehicle (no dongle): ~20–50 mA
- Total with Dongle after sleep:
- ≤ 60–75 mA → Usually fine for daily driving
- > 75–100 mA → May cause issues if parked several days
- > 150 mA → Likely to drain a battery quickly
For peace of mind, many mechanics recommend unplugging the Progressive’s Dongle, GPS trackers, and unnecessary OBD2 devices, especially in used cars where hidden trackers may already exist.
Final Thoughts
If your car battery dies after sitting for just a day or two, don’t assume the battery is bad. The real problem might be a Progressive dongle, OBD2 tracker/monitor dongle, or other hidden dealer-installed GPS units draining power around the clock.
By running a simple parasitic draw test, you can find out exactly what’s leeching your battery life—and decide whether it’s worth keeping.
What do you think? Would you keep a Progressive Dongle plugged into your OBD2 port, or do the risks outweigh the insurance discounts? Have you uncovered a hidden parasitic draw in your vehicle? Share your experience in the comments section below.
Timothy Boyer is an automotive reporter based in Cincinnati who currently researches and restores older vehicles, often incorporating engine modifications for improved performance. He also covers modern cars—including EVs—with a focus on DIY mechanics, tool use and selection, and other topics related to automotive repair. Follow Tim on Twitter (@TimBoyerWrites) and Facebook for daily updates and insights on new and used cars and trucks.
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Source: torquenews.com
