Skip the auto shop - Our mechanics make house calls

Q: Battery dead, car won't start

asked by on

Car won't start, just clicks when turn the key, jumped it and took to autozone to check battery, had 60% charge, brought home and let run for 30 minutes, next morning dead again, no lights left on, is it alternator?

My car has 84500 miles.
My car has an automatic transmission.

A: Hello. The best thing to do is have a batte...

Hello. The best thing to do is have a battery shop perform a "load test" on the battery. That is very standard procedure. The battery has to be in a fully charged state (they can do that, too) before such a test can be performed. If the battery fails a load test (if it’s 6 years old, it may very well fail or be "marginally" good) obviously you have to replace it. If it "passes", be sure to ask the Tech if it marginally passed. That is, batteries don’t last forever and at 6 years (if it is 6 years) you are going to have to replace it soon anyway. If it "marginally" passed the load test, absolutely replace it now to avoid getting stuck on the road.

Regardless of the outcome of the battery test, you need to test the output of your alternator. Once you have a functioning battery, attach a voltmeter to the positive and negative terminals of the battery (don’t short circuit anything as the battery could explode). While the car is running, you should see a volt reading on the meter somewhere in the range of 13.9 to 14.5 volts, however, you must check your Factory Service Manual for the exact specification for your car (which test protocol might also require that you maintain a certain engine RPM during the test).

The range of values for voltage are simply typical and so, for example, if you are reading 12.8 volts or something well below 13.9 you possibly have a faulty alternator OR a wiring problem like corrosion or loose terminals. Even a perfectly good alternator will not charge the battery and run vehicle electronics if, for example, the connections to the battery are in poor shape. If you need assistance, YourMechanic can evaluate both your battery and charging system, during a mobile visit right to your door, and get this issue fully resolved for you while answering any further questions or concerns that you might have.

Was this answer helpful?
Recommended services
Get a Quote

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: My vehicle has a hard staring problem especially after travelling long distances,and what could be the cause?

The first thing that comes to mind is a crankshaft position sensor. It has a very fine coil of wire that sometimes is affected by the heat of the engine. The common scenario is that the car starts easily, but...

Q: Service advancetrac warning light with transmission slipping and slamming pulling away from red light.

A weak battery may cause the several computers on the vehicle to malfunction due to the low voltage so if you have had the battery tested and it fails, it would be a good idea to start there. When a...

Q: EGR valve

Hi there: That statement is very true. When you have a problem with any mechanical or electrical component that has triggered an OBD-II service code, you need to have a professional mechanic who knows how to download and access those...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...