Harley-Davidson ® FXD (Dyna) All (1991 - '17) Motorcycle Batteries

Reliable Power for the FXD Series: Dyna Battery Guide

The Dyna series (1991-2017) is famous for its versatility and performance-oriented geometry. Because the battery on a Dyna is housed in a dedicated external box or under a side cover, it is exposed to the elements and significant engine heat. Using a premium AGM battery like the Big Crank ensures your power source stays protected against heat-cycling and external road grime.

The Advantage of American Engineering

The Big Crank ETX20L is the definitive alternative to expensive dealership batteries. Because it shares the same manufacturing lineage as the original equipment, you get a perfect fit every time. The patented terminal design is especially important for Dyna models, as it provides a secure, flush connection that won't vibrate loose during aggressive riding.

Frequently Asked Questions

Does this battery fit all Dyna models from 1991 to 2017?

Yes. Whether you ride a 1991 Sturgis or the final 2017 Low Rider S, the Dyna platform utilized the "20L" battery footprint throughout its entire production run. These include the FXD, FXDL, FXDB, FXDC, FXDF, and FXDWG sub-models.

How does the Big Crank compare to other aftermarket AGM batteries?

While many aftermarket batteries use AGM technology, they aren't all created equal. Many "budget" batteries are imported and use thinner lead plates or lower-purity lead, which leads to shorter lifespans and lower actual cranking power. The Big Crank ETX20L is made in the USA with high-density oxide and premium separators, providing the long-term reliability that Dyna riders expect.

Can I upgrade my Dyna to a Lithium battery?

Many Dyna riders, especially those building performance-oriented bikes, opt for Lithium (LiFePO4) batteries. Lithium offers a massive weight reduction (nearly 12 lbs less than AGM) and provides an exceptionally fast cranking speed. If you choose lithium, make sure you use a compatible lithium-specific charger to maintain the battery’s health.

How can I make my Dyna battery last longer?

To get 3 to 5 years (or more) out of your battery, we recommend keeping it on a smart maintainer during the off-season or when the bike sits for more than a week. The Battery Tender is an industry standard for maintaining the ETX20L and preventing the sulfation that kills lead-acid batteries.

Model Fitment Reference

This category covers all Harley-Davidson Dyna sub-models (1991-2017), including:

• FXDB: Street Bob.
• FXDL / FXDLS: Low Rider and Low Rider S.
• FXDWG: Wide Glide.
• FXDF: Fat Bob.
• FXDC: Super Glide Custom.
• FXD: Super Glide / Sturgis.