Your new car battery is dead, although it’s only a few months old. There’s not enough charge to start your car. Did you purchase a dud?
Before you place an angry call to the manufacturer and unload on a hapless customer service rep, consider another reason for your disappointing car battery.
Battery duds are rare. Battery drain is far more common, a hidden killer that can take down any battery.
If it persists, so will your battery problems, regardless of battery age or brand.
What Is Parasitic Battery Drain?
Parasitic battery drain happens when an electrical component or system continues to draw power from the battery even when the car is turned off. This constant draw on the battery can drain it completely, leaving you with a dead battery and an unexpected call to the mechanic.
Some common causes of parasitic battery drain include:
- Electrical components left on
- Faulty alternator
- Short circuits
- Malfunctioning components (e.g., radio, alarm system)
- Old or corroded wiring
Parasitic drain is normal to some extent. Your car’s computer, alarm system, and dashboard clock require little power to maintain their functions. This is known as the “key-off” electrical load. It’s a very low level of battery drain that most batteries can handle.
However, if your battery drains below 75% of its total capacity, you’ll have trouble starting your car or powering electrical features. Your battery may be irreversibly damaged if the discharge drops below 25%.
Checking for Parasitic Battery Drain
Supplies Needed
- Multimeter
- Wrench or socket set (if necessary to disconnect battery)
Steps for Checking
First, the obvious: inspect the vehicle for any electrical components that may have been left on, such as interior lights, trunk lights, or an overhead console. Ensure all doors are closed tight, and lights are switched off.
- Begin with a fully charged battery.
- Disconnect the negative terminal of your car’s battery using a wrench or socket set. This will prevent any power from being drawn while you’re testing.
- Set up your multimeter according to the manufacturer’s instructions.
- Connect the multimeter in series with the negative terminal and the disconnected cable.
- Turn off your car’s systems and accessories (e.g., lights, radio, alarm system) and check for any electrical components still drawing power.
- If your multimeter shows a reading above 50 milliamps, there may be a parasitic drain.
- To find the source of the drain, start by removing each fuse one at a time and checking the multimeter for any changes in the reading.
- When you see a significant change in the reading, you’ve found the circuit causing the parasitic drain. This will help you identify which component or system is responsible.
Fixing Parasitic Drain
- Repair or replace any malfunctioning components identified in the testing process.
- Check for corroded wiring and repair or replace as needed.
- If your alternator is faulty, have it repaired or replaced by a professional.
- Consider investing in a battery disconnect switch to prevent parasitic drain when leaving your car parked for an extended period.
Prevention Tips
- Regularly inspect your vehicle’s electrical systems and components for any signs of malfunction or damage.
- Ensure all connections are secure and no loose wires could trigger short circuits.
- Invest in a quality battery charger to keep your battery charged when the car is idle for extended periods.
- Avoid leaving your car parked for extended periods without starting it. This will ensure the battery maintains a healthy charge and prevents parasitic drain.
FAQs: More About Parasitic Battery Drain
Q: How long does it take for battery drain to occur?
It depends on the severity of the parasitic drain and the condition of your battery. In some cases, it can happen within hours, while in others, it may take several days or weeks.
Q: Can weather affect parasitic battery drain?
Yes, extreme temperatures (both hot and cold) can impact the health of your battery and increase the likelihood of parasitic drain.
Q: Is it safe to drive with a parasitic battery drain?
It’s possible to drive with a small amount of parasitic drain, but if you notice any warning signs, such as slow engine cranking or dimming headlights, you should address the issue before it becomes a larger problem.
Q: How can I prevent parasitic battery drain during the long-term storage of my vehicle?
Investing in a battery disconnect switch or regularly charging your battery with a quality charger are two effective ways to prevent parasitic drain during extended periods of vehicle storage.
Q: What should I do if my battery keeps dying despite repairs?
It may be time to replace your battery or to consult a professional mechanic for recommendations and repairs.
Q: How can I extend the life of my car battery and avoid parasitic drain issues?
Ensure regular vehicle use, maintain clean and secure battery connections, avoid excessive short trips that don’t allow the battery to fully charge, and consider periodic checks of your vehicle’s electrical system to identify potential issues before they escalate.
Q: How do I know if parasitic drain has damaged my battery?
If your battery no longer holds a charge or is difficult to start, repeated incidents of parasitic drain may have irreparably damaged it. Consult a professional mechanic for advice on potential repairs or replacements.
Very good THANK you thank you very much for your help.
Brand new amp brand new radio and the remote wire works it turns off and on but if I leave the breaker switch to the amps battery in the back overnight it drains the battery if I disconnect the breaker switch to the battery in a the back it stays charged I don’t know where it’s draining?
I am having trouble with a similar issue on my 2020 GMC 1500 Denali. I purchased the vehicle from a new truck dealership just 6 months ago and this is the second time that it has been back to the dealership. They replaced the battery once before with a new battery. Now it is 2 months later and again I tried to use my truck and no power. The dealership informed me that they will try the battery drain test overnight.the vehicle is like new with only 15000 miles.I googled this issued and was shocked to learn that GMAC have had thousands of recall on this truck. What do I do. I need ? I need help
Tell me what the problem is because I have new plugs new wires new starter new battery new alternator what seems to be the problem and also I have new distributor and new brain inside the distributor what’s the problem
All these discussions about battery failures within a few days of purchasing a brand new car are very interesting. But the reality is these were never issues with cars bought over a period of many decades prior to new ones. Why don’t selling dealers disclose parasitic drainers, premature dead batteries which they never know how to fix will be issues until you find out on your own after youi’ve bought a new one with expectation it would truly be perfect.
Instructions are poor connect the meter cables to what?
My car is a 2006 Envoy SLT with 135,000 miles. My battery from the dealer is 1.5 years old. I took my car to the dealer when my car wouldn’t start about 2 months ago. They tested it and said the battery was fine and there is something drawing on the battery. I took it home and it was fine for several weeks and when the battery wouldn’t start I jumped it and it lasted another several weeks. So yesterday after another failure we jumped and I drove it to the dealer when they were closed. The next day it continued to start perfectly per the dealer after it sat over n night. I stopped at Auto Zone initially on my way to the dealer and their testing showed everything was okay, no problem with battery, starter and alternator. So, the dealer had it all day and found nothing even put it on their tester. I forgot to mention my headlights have gone out at night 3 times in the last year. Fortunately, I played with the switch and they came back on. So, I limited driving night driving. Should I just purchase a self battery jumper kit or should I just buy another battery? The dealer said I replaced my battery prior to this one 1.5 years ago, so they wouldn’t warranty it for a second time and especially since it tested no problem. What are your thoughts if they couldn’t find the problem after having it all day.
Wish I could find one of these guys replacing 1 year old batteries because it won’t hold a charge.. I’d save some money. A “key off” current demand should be less than 1/10 of a amp or so. The way you test it is to take your DVM on the 10 AMP RANGE (usually have to move the red wire from the usual post to a dedicated “10 amp” post. Be sure it’s set on 10 amp range. KEY OFF. Now disconnect one of the battery cables, easiest one to get to. Convention says the “+” cable but it really doesn’t matter which one. You are looking for a number, not a polarity, and connect the DVM leads from the dangling cable end to the battery post it came off of. The number you see on the DVM display is the “parasitic drain” on the battery that’s constantly discharging it. Ideally, you should be much less than 1 amp. Typically .100 amp or 100 mA. The DVM may “say” 1.000 but actually less because of the way a DVM works. Anything above that is WAY excessive “key off” parasitic battery drain. You need to find it. Above 10 amps, a fully charged battery won’t even crank a engine after sitting for about 5 hours. It’s like leaving the headlights on. 2 or 3 amps is good for a day, maybe 2, until a “door nail” dead battery.
The easiest way to find what’s causing the parasitic drain is to start disconnecting stuff and/or pulling fuses until it disappears. First culprit is the alternator. Disconnect the thick wire off the back and unplug the connector. If nothing changes, put it back, its OK. Next on the list is the starter. This one is a pain. Disconnect the battery cable from the solenoid post leaving any other wires still connected to the cable end. Again, if nothing changes it’s not where the problem is. Put it back. Now it gets easy to isolate. Start pulling fuses until the parasitic drain goes away. When it does, that’s the circuit that has a problem and the ball is entirely in your court. Use the same technique of unplugging everything you can one at a time to isolate it to a specific module.
Hi John, thanks for the great instructions as I’m going through this problem myself atm with a fairly new battery. I assume when doing this test the engine is off the whole time? You’re just looking for a reading change in the meter with each fuse unplugged right? I don’t have constant access to a meter so what I’m doing instead is taking out all the fuses in the evening, replacing them in the morning and trying to start the engine. If it starts obviously I haven’t found the problem circuit yet. As the days progress I would have started taking out less and less fuses until I’ve isolated the right one, that’s my theory anyway. It’s a pain though as my problem seems to be intermittent, as in I’ve left everything connected for 2 days and it’s started fine, then on other attempts it’s been dead after 7 or 8 hours so it’s confusing. If you have any extra advice or comments on my plan of action that would be most appreciated thanks!