Batteries

Lead-Acid Battery - Most, if not all, production motorcycles come stock with this type. These batteries are what you’ve seen a hundred times in everyday vehicles. They weigh a metric ton and are (in short) filled with lead plates and a mixture of sulfuric acid and water - hence the term “flooded battery” or “wet battery.” These batteries are tried and true and, despite what it feels like in your bank account, are typically the least expensive option. They can take one hell of a beating and can be brought back to life even on the brink of death. Overcharged? Sure. Undercharged? You betcha. Give it your best shot.

As far as functionality goes, these batteries can work in your custom application, but they are hard - if not impossible - to hide and can only be mounted upright. Another thing to consider when upgrading or customizing your bike is whether you will be upgrading the stator to a high-output stator or upgrading any electrical components in general. A lot of the time, these types of batteries can’t compete with newer upgrades. If you’re going to revamp your bike with newer technology, why not go all the way and upgrade that old, huge, stinky battery as well? Can’t afford not to!

Pros:

• Readily available

• Serviceable

• “Inexpensive”

• Great exercise

• Can take a beating

• Can technically be put on any battery tender/charger

Cons:

• Require maintenance

• Weigh as much as a small child

• Not good with vibration

• Shorter lifespan in extreme weather in any direction

• Off-gassing while charging is highly flammable

• Can cause chemical burns when servicing

• Smells like farts when leaking or overcharging or both (also could be in the pro category depending on what you’re into. No judgement)

Gel Battery - At the time of their release, gel batteries were the wave of the future. Instead of the typical water-and-acid mixture found in lead-acid batteries, gel batteries introduced a new way of packaging this solution inside the battery case. Yes, there are still plates and a solution to allow ion flow, but unlike flooded batteries, gel batteries use a gelling agent that, when mixed with sulfuric acid inside the battery, forms a thick gel (surprise, surprise).

This gel solution remains immobile inside the battery, which eliminates all that sloshin’ around. Because of this, the battery can be mounted in any position - a whole new, radical idea at the time. This design also eliminates spillage, eliminates maintenance, and makes the battery overall safer and more reliable.

At a generally higher price point, and depending on what you’re wanting out of your battery, gel batteries can be a decent upgrade for stock or custom applications. But honestly, compared to the next battery we will discuss (AGM), you may not even consider a gel - especially when, at this point in the technological timeline, there are better options for roughly the same cost. Despite being a huge improvement over traditional lead-acid batteries, gel batteries still have their limitations.

Pros:

• Can be mounted in any configuration

• Vibration resistant

• Weigh less than Lead Acid batteries

• Maintenance free (sealed - no filling or spilling!)

• Better in extreme weather

• More durable than a standard lead-acid battery

• No need to upgrade (not to be confused with update) any other part of your charging system

Cons:

• Despite its name it’s not fit for consumption

• Weighs more than Lithium batteries

• Pricey, considering its actual benefits

• Lower cranking amps than lead-acid, AGM and lithium batteries (lithium batteries are rated differently)

• Not good with higher charging output voltage or voltage spikes

AGM (Absorbent Glass Mat) Battery - These batteries are the next step forward in advancement from not only the common lead-acid type, but also gel batteries. Because of their size, weight, and ability to be mounted in virtually any position, they are a great upgrade from a standard flooded battery for a custom or modified motorcycle - or even a stock motorcycle, for that matter.

While it is true that these batteries are also filled with sulfuric acid and water, just like standard lead-acid and gel batteries, the difference is that instead of the liquid solution moving freely inside, the liquid in an AGM battery is absorbed by a fiberglass mat between the plates, making it spill-proof. Because of the different internal materials, AGM batteries have a lower internal resistance, allowing them to produce more voltage, charge at a faster rate, and deliver stronger cranking capabilities.

Unlike a standard lead-acid battery - and similar to a gel battery - AGM batteries are maintenance-free, meaning they are sealed: no filling and no spilling! This also means they are not serviceable. If they are subjected to overcharging, the liquid inside off-gasses, and you are unable to refill it to extend the battery’s life. This is another reason these batteries tend to swell when overcharged - there is no vent or exit for the gases to escape.

AGM batteries are used quite often in stock bikes but truly shine in custom applications. As mentioned, when considering the benefits and cost of these batteries in comparison to gel batteries, choosing AGM over gel when upgrading may be a bit of a no-brainer - (see pro’s and con’s list to see what we mean).

Pros:

• Can be mounted in any configuration

• Vibration resistant

• Maintenance free (sealed - no filling or spilling!)

• Lightweight (to comparable size)

• Better in extreme weather

• Slower discharge rate than a LA or GEL (longer lifespan - can sit unused for a longer period of time, granted you don’t have a parasitic draw in your system)

• More durable than a standard lead-acid battery

• Will make you look like you know what you’re doing

• Higher output

• Higher charge rate (quicker to charge)

• Stronger cranking amps

• No need to upgrade (not to be confused with update) any other part of your charging system (but still great with upgrades)

Cons:

• More expensive than a standard lead-acid battery

• More sensitive to overcharging

• Requires an AGM specific battery tender/charger (add that to the overall cost)

• Heavier than Lithium batteries (we’re getting there)

Lithium Battery - When it comes to customization, performance and or wanting the smallest and lightest battery you can get your hands on... This is probably what you’re after. The most advanced battery on this list. So what if they cost as much as your rear tire? It’s a lithium battery, dammit! Compared to lead-acid, gel and AGM batteries, lithium batteries are comically lighter, last longer (if used properly - we’ll talk about that), and have a higher output.

Internally, they are much different as well. Unlike the maintenance-free batteries such as gel and AGM, lithium batteries have no solution inside whatsoever. No sulfuric acid, no water, no gelling agent - not even plates. Inside the case are lithium-ion cells and a battery management system. Hence why they're so dang light.

Everything you’d ever want out of a battery you can get with one of these beauties, but… just like all great things... It comes with a cost - on multiple fronts. First of all, they are quite pricey by themselves. In most cases (no pun intended), they can cost anywhere between 40-100% more than a lead-acid, gel or AGM battery. While you’re at it, you can add the cost of a new lithium-compatible regulator/rectifier to replace your stock one, as well as a lithium-compatible battery tender. Sounds like a bit too much of an investment right?

Well the truth is, if you go all the way and upgrade to everything this battery needs to survive, you won’t be disappointed. You’ll end up with a system that can last longer, perform more efficiently and improve your bikes overall electrical system in general. $ounds pretty cool, right?

Now, back to that “if used properly” comment… Nine times out of ten, if that very expensive lithium battery you saved your hard-earned cash for “shit’s the bed”, as they say, it’s probably from user error. No offense - we’ve learned about these batteries from user error on our part as well. It happens to the best of us. As mentioned, these batteries are amazing and work great, but they do require a bit more care and know-how to keep them from failure.

Unlike lead-acid, gel and AGM batteries, lithium batteries are extremely sensitive to overcharging and undercharging. Yes, technically all batteries are, but lithium batteries have a lower tolerance than the rest. Because of this, they require a lithium-specific regulator/rectifier and lithium-specific battery tender.

The reason being is that, in general, stator output on most vintage bikes is all over the place. It can range anywhere from 12.2v (+/-) to 15v, depending on the bike. Stock reg/recs and even most aftermarket ones do not regulate that voltage to the specifications needed for lithium batteries, and they simply just can’t handle that instability. They love a stable environment of 14.1v - 14.2v maximum. On the other side of things, unlike the other battery types, lithium batteries are extremely difficult to be brought back to life once the voltage gets too low. Again: nice, stable conditions.

This is why upgrading your reg/rec is critical - to stabilize/regulate all of that wild voltage. If you don’t, it will lead to a battery failure. It could be a day, it could be a week, it could be a month, but it will happen. The only question is how catastrophic will the failure be. We’ve seen them do everything from simply swelling to full bike meltdowns - and it ain’t pretty.

If you’re going to go this route, you must go all the way.

Pros:

• Significantly lighter than any of the batteries on this list (up to 75% lighter in some cases)

• Significantly smaller than any of the batteries on this list (to comparable cell size)

• Can be mounted in any configuration

• Fancy as fu*k

• Maintenance free

• Lower discharge rate when not in use (granted you don’t have a parasitic draw)

• Higher voltage output

• Stronger cranking amps

Cons:

• Can cost as much as a night on the town

• You, If you don't do your research beforehand.

• Must upgrade your regulator/rectifier and battery tender (add that to the overall cost)

• Not good in extreme weather in either direction

Yeah, yeah - your battery is in fact part of your overall charging system, but this page is dedicated to a brief overview of a few of the most common batteries and their differences, to help you decide what you may be looking for. We’ll also touch on maintenance, testing, and what they can do when they're going bad.

The top question that often gets asked is, “What size or kind of battery should I put in my bike?” And the short answer is… it depends. Are you looking for something small and hideable for your trimmed-down, bare-bones, electrical-component-relocated bike? Are you looking for something to pair with your upgraded, high-output stator? Do you need something to turn over that giant new high-compression performance engine you just built? Or are you simply looking for an “upgrade”?

Let's discuss...

Have you decided what direction you’re going in as far as a battery option? Good. Let’s talk about how to take care of your new prized possession…