The Harley-Davidson Fat Bob 114 uses a 12V 17.5Ah 310CCA AGM battery. Most starting problems trace back to a weak battery or corroded terminals — both easy to check and fix at home.
Test the battery at every service, keep the terminals clean, and use a smart tender if the bike sits more than a couple of weeks.
Harley-Davidson Fat Bob 114 quick service specs
| Item | Specification |
|---|---|
| Engine oil | 20W-50 |
| Oil capacity | 4.7 liters |
| Oil change interval | 5000 miles |
| Chain slack | See owner’s manual |
| Spark plug | 6R12 |
| Tire pressure (F/R) | 36 PSI front / 40 PSI rear |
| Battery | 12V 17.5Ah 310CCA AGM |
How to test and replace the battery, step by step
- Turn the bike off and remove the seat to access the battery.
- Disconnect the negative (-) cable first, then the positive (+).
- Remove the hold-down and lift the battery out — note the orientation.
- Clean the terminals and cable ends with a wire brush; apply dielectric grease.
- Set the new 12V 17.5Ah 310CCA AGM battery in place, secure the hold-down, and connect positive (+) first, then negative (-).
- Start the bike and confirm 13.5-14.5V charging at the terminals with a multimeter.
Common mistakes to avoid
- Connecting positive first on removal — always disconnect negative first to avoid shorts.
- Skipping the tender — AGM batteries sulfate if left discharged.
- Overtightening terminals — you can crack the battery posts.
FAQ
How long does the Harley-Davidson Fat Bob 114 battery last?
Typically 3-5 years. Heat, vibration, and deep discharges shorten life.
Can I use a lithium battery?
Only if it’s a direct-fit replacement with built-in BMS and your charging system is compatible. AGM is the safe stock choice.
Why does my battery keep dying?
Check for parasitic draw, a failing stator/regulator, or simply an old battery that won’t hold charge.
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Dan Heiman
Writer at Helmet Today, covering helmet reviews, fit and riding safety.
