Locating, Charging, and Replacing the Battery in a Harley-Davidson Motorcycle

Why do I need a battery in my Harley?

A battery stores electrical energy that is not needed for ignition, lighting, or other electrical consumers and delivers it again when required, e.g., for the electric start. Rechargeable batteries are also called accumulators. They are available in different types and designs.

What types of batteries exist for Harley-Davidson?

There are two different voltages: 6 V and 12 V. However, it should be noted that these are only approximate voltages, known as “nominal voltage.” On a fully charged 6 V battery, you measure 6.3–6.4 V, and on a fully charged 12 V battery, 12.7–12.8 V. If you measure only 6 V or 12 V, the battery urgently needs recharging. How to do this is explained further below.

All Harley-Davidson motorcycles up to the mid-1960s have 6 V batteries.

All Harleys from the mid-1960s onward have 12 V batteries. Here are the transition years:

• Servi-Car from 1964
• F(LH) models from 1965
• Sportster models from 1967

All model lines introduced after that have 12 V batteries.

As original equipment, all Harleys come with lead-acid batteries. Lead-acid batteries are proven and inexpensive but heavy. To deliver high currents for electric starters, they have to be quite large.

In the aftermarket, there are lithium-ion batteries, e.g., from Antigravity. They are characterized by low weight and compact dimensions while simultaneously delivering very high currents.

Which battery for which Harley model?

The batteries in your Harleys have numbers and codes on them, and you can use these to find the correct battery. These codes indicate voltage (6 or 12 V), capacity (Ah rating), dimensions (width, depth, height), position of the positive and negative terminals, and so on.

If it is an original Harley battery, it will also carry a part number. If you enter this number into the search function on our website, you will get a selection of suitable batteries: OEM, HVT, YUASA …

If you have installed an aftermarket battery, enter the code in the search function, e.g., YTX20-BS. You will then be shown a selection of options.

Here is a list of the most common batteries:

• 66000207 — 12V/18Ah — Sportster 1997–2003, Softail and Dyna 1997–2016
• 66000208 — 12V/12Ah — Sportster 2004–2021
• 66000209 — 12V/19Ah — FXE, FXR, Sportster 1979–1996, Softail 1984–1990
• 66000210 — 12V/22Ah — Touring models up to 1996
• 66000211 — 12V/19Ah — Softail and Dyna 1991–1996
• 66000212 — 12V/28Ah — Touring models from 1997

Disconnecting the Harley-Davidson battery

This is usually only done if you won’t be riding for an extended period, typically over winter, or of course when removing the battery.

If you leave the battery in the bike, it is sufficient to disconnect the negative cable (“ground cable”) from the negative terminal.

For removal, of course, both cables must be disconnected. See the next section for removal instructions.

Anyone who disconnects a cable will eventually have to reconnect it. All terminal bolts (whether M6 or M5, Phillips or hex head) should be tightened no more than slightly more than hand-tight. For y'all who love numbers: 5 Nm. And for all ye “imperial users”: 30 lbs-in.

Removing the Harley-Davidson battery

Unscrew the two thick cables from the battery terminals. Always start with the negative terminal. Which terminal is which is indicated on the battery case. Then remove the positive wire. The positive terminal even is red cap equipped if the previous owner hasn’t lost it.

Then release the rubber strap or unscrew the steel hold-down strap and lift the battery out of its holder.

Note: On Softails or FXR models, sometimes a clever person has already placed a thin strap or cable tie around the battery. You then just pull on it to lift the battery out of its compartment. If not so, you might consider placing such a strap yourself before re-installing the battery.

Why is the battery on my Harley-Davidson constantly dead?

Motorcycle batteries that are constantly dead are not being properly recharged. Two things can cause this:

• The battery is not fully charged when the Harley is parked. Do you only ride short distances? Do you often start up your Harley in the garage to show your friends how awesome it sounds? After an electric start, possibly with several tries because the Harley didn’t start immediately, you should ride a longer distance —at least 15 to 20 mls— to fully recharge the battery. The alternator does its best to recharge the battery, but give it time. Also, higher engine RPM are helpful —the higher the RPM, the better the charge. For this reason, the ride should be at minimum 15 mls to warm up the engine, because you don’t rev a cold engine unnecessarily.
• The battery isn't properly charged either if it is defective. In that case, it’s time to replace it. Otherwise, the regulator may fail next. Whether a battery is defective can be tested with measuring devices.
• The battery discharges "by itself". Then it is either defective (a test will show this) or you have silent power drains in your Harley-Davidson. Alarm systems in the first Twin Cam model years were such power drains. After no more than four weeks, a Softail battery could be completely drained. The instruments on newer bikes have constant power supply, e.g., to keep the clock running. Small faults in the wiring harness or in electronic components can also create such silent drains, as can tolerances in electronic component parts.

May I jump-start my Harley-Davidson?

You don’t always have time to wait for a charger to fully trickle your battery. So yes, you may jump-start your Harley. Here are a few tips to ensure everything goes alright:

• If you are jump-starting from a car, the car engine should not be running. Car alternators deliver high currents that can harm the electrical system in your Harley. First, connect the positive terminals of the car and motorcycle with the red jumper cable. Then connect a ground terminal on the car to a ground point on the Harley (e.g., engine case, cylinder fins, engine mount bolt) using the black jumper cable. Once the Harley has started, disconnect the black cable first, then the red one. Don’t turn the Harley off immediately; ride at least 50 km.
• If you are jump-starting from another motorcycle, that bike's engine should be running. Again, first connect the red cable to both positive terminals, then the black cable to both negative terminals or to ground terminals as described. Once your Harley engine is running, disconnect the cables (black first, then red) and ride a longer distance —30 mls are appropriate.
• There is a third option: a lithium-ion jump starter. Connect the device’s red cable to the positive terminal of your Harley battery and the black cable to the negative terminal. Turn on the device, switch on the Harley ignition, and start. Disconnect the device immediately: black cable first, then the red one. Ride 30 mls to fully recharge your Harley’s battery.
• All common jump starter devices have built-in protection electronics to prevent damage to your Harley’s electronics. Especially for bikes with CAN-Bus (HDLan), a jump starter is the best option.