donpb

No, my battery is not bad.

I've wrestled with battery issues for years and will share some things I have learned as follows:

1. Invest in a battery charger.
- You'll need to fully charge your battery prior to testing. You should be able to find them for around $30 (US). If your battery won't charge, the charger will error out.
2. Charging system quick-check
- Use a digital multimeter to measure voltage across the battery terminals with ignition OFF and then again with engine running. Battery voltage should be about 12.6 volts with key OFF and between 13.2 and 14.5 volts with engine running.
- Run engine at about 2000 rpm and switch ON electrical loads (fans, lights, rear window defroster, and wipers). With all accessories on, battery voltage should be above 12.6 volts.
- The regulated voltage (engine running, battery charged, accessories and light OFF) is usually between 13.2 and 14.5 depending on temperature and operating conditions. If the voltage is higher than 14.8, the voltage regulator is most likely faulty.
3. Check sleep mode
- Exit car and arm alarm. Car should go to sleep in 20-60 minutes. P light on shifter should turn off.
4. Check IBS (Intelligent Battery Sensor)
- Buy a BMW Code Reader to test the IBS. You can find readers for around $49 (US).
5. Battery open-circuit voltage test
- Before testing, load battery with 15 amperes for one minute with battery load-tester or switch headlights ON for about one minute without engine running. Connect digital voltmeter across battery terminals. Open-circuit voltage levels are given in Table c.
Table c. Open-circuit voltage and battery charge
Open-circuit voltage
12.6 or more (Fully charged)
12.4 (75% charge)
12.2 (50% charge)
12.0 (25% charge)
11.7 or less (Fully discharged)
If your voltage drops under 12, it should slowly rebound. If not, battery is most likely bad.
6. Have store do a test?
- I did not have much success with store tests because they'll say your battery is good when its not. That's why I prefer to check it myself.
7. You'll need a digital multimeter
- I got one for $5 (US). You can find some for free even.
8. Last but not least
- Believe in yourself. You can do this!

temashkab27

I will definitely try
saved for the future
Thank you!