Have you ever walked out to your car with an interlock device installed, stuck the ignition key in the hole, and turned it only to hear an ominous click or sad whirring from the engine? The dreaded dead battery strikes again.
An interlock device drain has left you stranded one too many times. Why does this keep happening, and what can you do about it?
The short answer: Ignition interlock devices draw a small amount of power when the car is off, draining the battery over time. Cold weather, infrequent driving, old batteries, and faulty electrical systems can worsen the battery drain. But there are steps you can take to stop getting left with a dead car and battery due to your interlock device.
In this comprehensive guide, we’ll cover:
- How interlock devices drain your car battery
- Tips to prevent interlock battery drain
- Signs your battery is being drained
- When to replace a worn out battery
- What to do if your car battery dies with the interlock installed
- Troubleshooting drains and dead batteries
- Special considerations for cold weather
- FAQs about interlock devices and car batteries
After reading, you’ll understand exactly why interlocks kill batteries, how to avoid it, and what to do if you find yourself stuck with a dead car battery died with interlock. Time to stop getting stranded!
Table of Contents
How Do Ignition Interlock Devices Drain Your Car Battery?
First, a quick recap on ignition interlock devices (IIDs) in case you need a refresher. An IID is a breathalyzer connected to a car’s ignition system. It requires the driver to pass a breath test to prove sobriety before the car will start. IIDs are mandated for DUI offenders in most states.
Some key facts about interlocks:
- The handheld interlock device connects to your car’s electrical system.
- You give a breath sample by blowing into the handset.
- If your BAC is under the limit, the device lets you start the engine.
- It will randomly require more breath tests while driving.
- Failing a retest or tampering can trigger a violation and car lockout.
Now here’s the downside of interlocks – they continue to draw a small amount of electricity even when your car is parked and turned off.
This is because the device goes into a “sleep mode” rather than fully powering down. The interlock needs to stay semi-active so it can wake up when you attempt to start the car and require a breath sample.
Over days or weeks of your car sitting unused, the interlock device drain can completely sap your battery’s charge and leave it dead. It’s just like leaving your headlights on overnight, except it happens gradually.
Obviously, this slow draining effect is worse if your car already has an aging battery nearing the end of its lifespan. Once a battery is about 5 years old, its ability to hold a charge starts to diminish.
Cold temperatures also impede a battery’s charging capacity. An nearly-dead battery that barely hangs on in warm weather may go kaput once winter hits.
Speaking of cold, extremely frigid winter temperatures themselves sap battery life quicker. The interlock device drain is hastened when it’s 5 degrees Fahrenheit outside your garage.
And if your car’s alternator or electrical system is malfunctioning, the battery won’t recharge properly during use. That makes the gradual interlock drain between drives even more detrimental.
The combination of a worn out old battery, an ignition interlock device pulling power 24/7, and cold weather is a recipe for getting stranded with a dead car.
Tips To Prevent Your Interlock From Draining The Battery
Luckily, there are steps you can take to stop your interlock device from killing your car’s battery. Here are some tips to prevent the drain:
- Drive regularly – By far the best way is to simply drive your car often. Regular use will recharge the battery and counteract the interlock’s drain. Try to drive at least 2-3 times a week if possible.
- Disable the device – Most ignition interlock providers have a process to temporarily disable the unit if your car will be sitting unused for weeks. This totally stops the power draw and preserves battery charge. Just re-enable it afterwards.
- Check the battery and electrical system – Have your battery tested frequently and watch for signs it needs replacement. Also have your alternator checked to catch any issues charging the battery.
- Replace weak batteries – Don’t delay swapping out an old, worn down battery. Its diminished capacity will make it die much quicker with an interlock installed.
- Use a battery tender – Also called trickle chargers, these devices plug in and maintain a charge when a car is stored. It counteracts the passive interlock drain.
- Park in a garage – Getting your car out of the elements, especially winter cold, will reduce the battery drain from both the interlock device and ambient weather.
- Disconnect when storing long term – If you won’t drive for a month or longer, disconnect the negative battery cable. This isolates it from the interlock device and prevents drain.
Following those best practices will go a long way towards preventing your interlock from draining your battery. Take action before you find your car immobilized again!
Next let’s review the warning signs that your battery is being sapped by the continual draw from the device.
Signs Your Car Battery Is Being Drained by the Interlock
A dead battery with no warning is always a frustrating surprise. But in many cases, there are symptoms that point to an impending dead battery caused by interlock drain days or weeks before it leaves you stranded:
- Lights and electronics start dimming or shutting off when driving – The undercharged battery can’t provide enough sustained power to all systems.
- Difficulty starting the car – Slow cranking when turning the key or ignition button is pressed indicates a weak battery.
- Battery tester shows low voltage – Use a meter to check the charge level. Below 12.4V indicates undercharge.
- Dashboard battery or check engine light comes on – These warning lights often indicate problems charging or provide voltage alerts.
- Electrical issues worsen in cold weather – Weak batteries struggle much more in winter temperatures.
- Interlock device gives error messages or stops working – Severely drained batteries can’t provide enough power to operate interlocks.
Catching battery drain early allows you to recharge or replace the battery before the interlock device renders your car undrivable. Don’t ignore the signs!
Next let’s talk about knowing when it’s time to retire your old battery and get a new one.
When To Replace Your Car Battery?
Car batteries inevitably wear out over time. And an old, tired battery will be quickly annihilated by the constant power draw from an interlock device.
Here are signs it’s time to replace your car’s battery:
- The battery is over 5 years old – Car batteries typically last 3-5 years. It’s pushing its limits at that point.
- The battery voltage is very low and it won’t hold a full charge – Despite recharging, it quickly loses power.
- The battery cables are corroded – This impedes electrical flow. Bad connections accelerate drain.
- You frequently jump start the car – Needing frequent jumps indicates insufficient starting power.
- The battery fails a load test – Most auto parts stores can do a diagnostic load test for you.
- Your car has sat unused for weeks – Long dormancy allows the interlock device to fully drain the battery.
- You live in a climate with extreme winters – Cold weather performance decreases as batteries wear out. Time for a replacement.
- You see warning lights for the charging system – Lights indicating problems charging or voltage suggest the battery is on its way out.
As soon as you notice any of those indicators, have your battery checked and head to the auto parts store for a replacement if it’s worn out. Don’t delay – an interlock device will destroy an old battery in short order.
Now what should you do in the moment when your car battery dies unexpectedly from the interlock device drain? Let’s talk about dealing with a dead battery when it happens.
What To Do When Your Battery Dies With The Interlock Installed?
It’s the moment every interlock user dreads – turning the key and getting nothing but silence or a sad clicking sound. The device has drained your battery dead once again. Follow these steps to get back up and running:
- Try a jump start if you have access to jumper cables and another vehicle – Connect the jumper cables properly between the good Samaritan’s car and your dead battery. Let the working car run for a few minutes then try starting yours.
- Call for a tow truck if no one is around to jump the car – Most auto service memberships like AAA offer free tows for dead batteries. Have the car taken to a repair shop.
- Contact your ignition interlock provider – Let them know the continual drain has killed your battery again. They may have additional troubleshooting tips.
- Get the electrical system tested – A diagnostics check at a repair shop can identify any underlying issues draining the battery. Catching problems now prevents repeat deaths.
- Consider disabling the interlock temporarily – If it happens repeatedly, ask your provider about process for temporarily disconnecting the device if the car will be unused for a while.
- Purchase a battery tender/trickle charger – These can be left connected to maintain a full charge when the car sits for extended periods. It counteracts the parasitic interlock drain.
- Park in a garage if possible – Getting your car out of the elements reduces drain, especially in extreme cold.
With the right preparation, you can get back on the road quickly when your interlock equipped car battery dies. Don’t let it keep you stranded!
For recurrent dead batteries, some additional troubleshooting can zero in on the root cause. Let’s go over that.
Troubleshooting An Interlock That Drains The Battery
An ignition interlock device killing your car battery once or twice can be chalked up to bad luck. But if it becomes a frequent issue, take the time to troubleshoot what exactly is causing the excessive drain:
- Get the battery tested – A diagnostic load test at most auto stores will reveal if your battery is simply old and worn out. Time for a replacement.
- Test the alternator – A malfunctioning alternator won’t properly recharge the battery while driving. This exacerbates any parasitic interlock drain.
- Check for lights or accessories left on – Interior dome lights and trunk lights are common current draws if accidentally left on.
- Do a parasitic draw test – This measures current draw with everything off. It can pinpoint excessive drain from a particular system.
- Inspect all electrical connections – Corroded battery cables or contacts create resistance that impedes charging.
- Review driving habits – Don’t just make short trips. Take a highway drive weekly for at least 20 mins to get a full charge.
- Consider an interlock recalibration – If it tries to draw current excessively when parked, the interlock techs can adjust the device’s energy usage.
Pinpointing what exactly is draining your battery will allow you to correct the problem and get your car back in reliable running condition.
One final battery-killing culprit is extreme winter cold. Let’s discuss special considerations for cold weather operation.
Preventing Dead Batteries In Cold Weather
As discussed earlier, cold temperatures exacerbate the battery drain caused by an ignition interlock device. The car battery is already working harder in cold conditions. Add in the continual power draw from the interlock, and you’ve got trouble. Here are tips for preventing winter dead batteries:
- Garage park the car if possible – Getting your car out of sub-freezing temperatures will significantly reduce drain on the battery. Letting it warm up helps too.
- Insulate the battery – Wrap the battery case in an insulating jacket when temps drop. This retains battery capacity.
- Use a battery warmer – Warming elements that attach to the battery boost cold cranking amps when it’s frigid outside.
- Disconnect the interlock if the car will sit for weeks – Talk to your provider about temporarily disabling it during long-term winter storage to prevent a full drain.
- **Use a trickle charger ** – Maintaining a constant charge all winter counteracts the passive interlock drain. It keeps the battery tip-top when parked.
- Start your car periodically – If parked outside, run the engine every week or two for at least 15 to 30 minutes. This tops off the charge the interlock is draining.
- Check the battery and connections – Inspect for corrosion buildup from road salt and weather. Tighten and clean as needed.
Proper attention and care for your battery during cold snaps and winter storage will help prevent getting stranded by the interlock device. Don’t let dead batteries leave you out in the cold!
Interlock Battery Drain FAQs
If you’re still scratching your head about batteries, interlocks, and drain issues, here are answers to some frequently asked questions:
How much power do ignition interlock devices draw when the car is off?
Most interlocks only draw 50-85 milliamps – not a huge amount. But that small current drain continuously over days or weeks can drain a battery, especially if it is already old or weak.
Do I need a special battery with an ignition interlock installed?
You don’t necessarily need a more powerful battery. But you do need one that is well-maintained and frequently recharged to counteract the passive power drain. Higher capacity batteries have more resilience.
Should I disconnect my interlock if parking at the airport for a week?
Yes – any parking longer than 5 days should involve temporarily disabling the interlock device to prevent it from killing your battery while you’re gone.
How can I tell if my battery is being drained by the interlock versus the alternator being bad?
A battery load test will reveal if the battery itself is still good. Alternator diagnostics at a shop can determine if it has failed and needs replacement.
Why does the interlock drain my new battery but not my old one?
This counterintuitive scenario happens because a worn out battery has very little charge for the interlock to drain. A new battery has much more capacity, which is then depleted by the constant draw.
My interlock drains the battery in 2 days when parked. Is it defective?
Not necessarily defective, but something needs adjustment. Contact your interlock service provider to have the device inspected and recalibrated to reduce the parasitic current when the car is off.
Hopefully these battery and interlock FAQs clear up some of the mysteries and misconceptions around keeping your car powered up!
Conclusion and Final Takeaways
Dead car batteries are always an inconvenient and frustrating surprise. But they can be downright dangerous if an interlock device has drained your battery, leaving you stranded.
The key points to remember are:
- Ignition interlocks draw a slight current even when the vehicle is off. This can drain a battery over weeks.
- Driving regularly, replacing weak batteries, and proper electrical system maintenance will prevent interlock-caused dead batteries.
- Be proactive and watch for warning signs of low voltage and discharge. Don’t get stranded with no advanced notice.
- Use a trickle charger or disconnect the interlock if the car will sit unused for long periods.
- In winter, insulate the battery and store the car in a garage to retain charge.
Avoiding a dead car battery comes down to understanding what conditions lead to excessive drain, and being vigilant about battery maintenance. An ounce of prevention is worth a pound of getting towed to the service station.
With the tips in this guide, you can keep your car starting smoothly and confidently, rather than getting nerveracking clicks and silence when you turn the key. Never fear the interlock device leaving you with a dead battery again!