Is a Harley Davidson Battery 6 Volt or 12 Volt?


Motorcycle batteries are a tricky topic. They are one of the things that have caused a lot of unpleasant surprises to many motorcycle owners. But whether you love them or hate them, you need to understand what batteries your motorcycle uses.

One of the important aspects that can affect your riding experience is your motorcycle’s and battery voltage.

Is a Harley Davidson Battery 6 volt or 12 volt? Harley-Davidson motorcycles use either a 6 volt or a 12 volt battery. Harley-Davidson motorcycles made after the early 1960s are using 12 volt batteries, while older Harleys made before the early 1960s are using a 6 volt battery. If a Harley was made in the last 40 to 50 years, it uses a 12 volt battery.

I believe a more in-depth look into this subject is definitely worth taking.

After all, not everybody is born with an inherent understanding of how electrical systems work. And over the years, I have seen that people will often feel uncomfortable asking some questions.

If you are interested in finding out more about how Harley-Davidson batteries work, read on.

What battery voltage do motorcycles use?

Most motorcycles use either 6-volt or 12-volt batteries. However, if these batteries are in good condition, their voltage will be a little higher than that because the peak voltage of the battery cells is about 2.1 volts. (More on that in a bit.)

Generally, all modern motorcycles manufactured in the last 30 to 50 years use 12-volt batteries. That being said, older motorcycles made during and before the 1960s mostly use a 6-volt battery.

The same applies to Harleys as well.

The majority of Harley’s build in the last 50+ years are predominantly using 12-volt batteries. However, older Harleys do use 6-volt batteries. Generally, Harley-Davidson motorcycles manufactured up until 1964 used 6-volt batteries.

Some of the Harleys that use 6-volt batteries are:

  • 1937-1940 Harley Davidson ULH Flathead
  • 1941 Harley-Davidson WL
  • 1948-1953 Harley Davidson Indian Cheif 
  • 1948-1960 Harley-Davidson Duo Glide FLH
  • 1964 Harley-Davidson DuoGlide Panhead (Which is also considered to be one of the last Harleys to use a 6-volt battery.)

While all of the newer models use 12-volt batteries. Some examples are:

  • 1990 Harley-Davidson Fat Boy
  • 1998 – 2009 Harley-Davidson Night Train
  • 2006 Harley-Davidson Street Bob
  • 2010 Harley-Davidson Iron 883
  • 2011 Harley-Davidson Forty-Eight

How to find out if your Harley Davidson battery is 6 volts or 12 volts

The first way to get a good idea of whether your Harley uses a 6-volt or a 12-volt battery is to consider the year it was made. Harley-Davidson motorcycles made up until 1964 used to run on a 6-volt battery. Harleys manufactured during the 1960s and onwards started to use 12-volt batteries.

Both the car and motorcycle industries started slowly switching to 12-volt systems during the early 1960s. So if your Harley is made before 1964, it is almost guaranteed that your Harley uses a 6-volt battery. 

If your Harley was made during the 1960s, then you may need to do some additional research. And if your Harley was made in the last 40 to 50 years, it is probably using a 12-volt battery.

How to tell if your Harley Davidson’s battery is 6 volts or 12 volts

Although the tips mentioned above can help you identify your Harley battery voltage even without looking at the battery, it is a good idea to actually have a visual inspection of the battery to really confirm what you are dealing with.

After all, it would be best if you were not relying on guesses.

Of course, a 12-volt battery will typically be larger than a 6-volt battery, however, there can be exceptions, so this rule may not always help.

There are a few ways you can tell how many volts is your Harley’s battery.

Check the owner’s manual

The type of motorcycle battery your Harley-Davidson uses should be stated in the owners or service manual. This is by far the easiest and most reliable way of finding what the voltage of your motorcycle’s battery should be.

Check the battery’s label

The next thing you can do if you are unsure what year the motorcycle was manufactured and you don’t have your owner’s manual is to check the battery’s label.

Check the battery’s label. Often manufacturers will mention the various specifications like the rated ampere-hours (Ah), voltage (V), cold cranking amps (CCA), as well as other details like the best charging methods and time, and the type of battery.

Check the number of vent caps

Motorcycle batteries are made of several cells, each of which contains about 2.1 volts, which means that 12-volt batteries have 6 cells and 6-volt batteries have 3 cells.

A quick visual inspection of the number of the battery’s vent caps will allow you to tell if your motorcycle uses a 6-volt or a 12-volt battery. Batteries that are 12-volt will have 6 vent caps on top in accordance with the 6 cells the battery has, and 6-volt batteries should have 3 vent caps.

Even maintenance-free batteries can have those caps, though, they may be flush—although many may not have any cell openings.

Check the battery’s body

If for some reason, you cannot use the methods mentioned so far, there is another way to tell how many volts the battery is.

Inspect the battery’s body carefully. Usually, there should be slight dips (or, in certain cases, discolorations) to the outside molding where the battery cell walls are present. Using those slight dips in the battery’s wall, you might be able to tell how many cell compartments there are.

Measure the electrical system

Lastly, if you cannot tell the battery’s voltage using any of the methods mentioned so far, you will need to measure the motorcycle electrical system using a multimeter or a voltmeter.

Harley-Davidson battery voltage

The right battery voltage for a Harley-Davidson motorcycle will depend on the type of battery it uses. If a Harley-Davidson uses a 12-volt battery, it is considered fully charged when it reads 12.6 to 13.2 volts, and if it uses a 6-volt battery, it is considered fully charged when it reads 6.3 to 6.6 volts.

A 6-volt battery may be considered flat (or dead) at 5.25 volts, while a 12-volt battery is considered dead or fully-discharged at 10.5 volts.

Interestingly enough, a 6-volt Harley should be able to run even on lower-voltage batteries. Although your headlights will go dimmer the faster you move, even a battery with 1.5 to 2 volts could be used.

The resting voltage of batteries usually takes at least a few hours to settle. However, you can use this table as a general guide for your Harley battery voltage ranges.

State of Charge12-Volt Battery6-Volt BatteryVolts Per Cell
100%12.6+6.3+2.1+
90%12.486.242.08
80%12.426.212.07
70%12.306.152.05
60%12.186.092.03
50%12.066.032.01
40%11.885.941.98
30%11.765.881.96
20%11.585.791.93
10%11.345.671.89
0%10.505.251.75

Those readings can be tested using a multimeter that is capable of measuring volts (V). All you have to do is:

  1. Leave the motorcycle switched off for at least a few hours prior to measuring the battery’s voltage in order to prevent incorrect readings.
  2. Set up the multimeter for measuring voltage.
  3. Put the positive (red) probe on the positive (red) battery terminal and the negative (black) probe on the negative (black) battery terminal. At this point, the multimeter should display the voltage reading of the battery.

Motorcycle batteries are designed to be kept nearly fully charged all the time, so they should be recharged if the voltage starts to get below 60%.

What you will find is that when the motorcycle starts, the voltage of the battery will drop. A 12-volt battery can drop down to 11.20 volts. This is normal because the motorcycle draws current from the battery in order to start.

Once the motorcycle is running, the voltage reading should be between 13.6 to 14.5 volts. The noticeable jump in the voltage is a result of the alternator (or generator) charging the battery.

Does it matter if a Harley Davidson battery is 6 volts or 12 volts?

Knowing the right voltage for your Harley battery is necessary because mismatching the battery’s voltage with the charging system and the motor can lead to some problems.

A Harley that has been designed to run on 12 volts should use a 12 volt battery and be charged with a 12 volt battery charger. And vice versa. A 6 volt Harley should use a 6-volt battery and be charged with a 6-volt battery charger.

Putting a 12 volt battery on a motorcycle designed to run on 6 volts can damage or fry the motor and the electrical system.

Alternatively, a 6 volt battery will not be able to power or even start a motorcycle that is designed to run on a 12-volt battery.

If you try charging a 12-volt battery with a 6-volt charger, you will not be able to charge the battery at all as the charger will not be able to provide enough voltage.

Charging or jump-starting a 6-volt battery with a 12-volt charger can be very dangerous as it can quickly damage or completely kill the battery. Although not recommended, a 6-volt battery can be jump-started with a 12-volt battery, but usually, this should be done while exercising extra cautions and while the other vehicle is kept completely turned off.

On top of that, there can also be found 24-volt batteries and battery chargers. They are mostly used on heavy trucks. However, if you try to charge or jump-start your Harley with a 24-volt battery or battery charger, this can quickly damage and destroy the Harley’s battery.

See article: Can you charge a motorcycle battery with a car?

Six-volt batteries are smaller and usually have three cells as opposed to 12-volt batteries, which are made from six cells. So if you have purchased a 12-volt battery for a Harley that uses a 6-volt battery, you may find that you will not have enough space to fit in the battery.

Overall, knowing what battery your Harley uses, you can avoid doing unintentional damage to the motorcycle. You will know what replacement battery to buy, how to jump-start the motorcycle and recharge the battery the right way.

However, keep in mind that the voltage, though, is not the only aspect of the battery that you need to consider. The battery should also provide the right levels of ampere-hours (Ah) and cold cranking amps (CCA).

Mike

Hello, two-wheel enthusiasts! My name is Mike, and I am the person behind motorcyclebrave.com. I am ready to go for a ride at any time of the day (or night). There is something about motorcycles that nothing else compares to. Here I share everything that I learn about motorcycles.

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