Does A Motorcycle Battery Have to Be Upright?

Does A Motorcycle Battery Have to Be Upright?

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Does A Motorcycle Battery Have to Be Upright?

Mounting the battery upright helps to ensure proper ventilation, minimize the risk of accidental damage, and simplify battery maintenance. Furthermore, an upright position makes accessing terminals easier and performing routine maintenance tasks like checking fluid levels or connecting charging cables.

Motorcycle battery does not have to be upright. Unlike some types of batteries, such as lead-acid car batteries, motorcycle batteries are typically sealed and designed to be maintenance-free.

This means they are constructed with internal structures that prevent acid leakage, even if the battery is tilted or turned upside down.

The reason why you can use a motorcycle battery in various orientations is due to its internal construction. It usually consists of multiple sealed cells containing lead plates immersed in an electrolyte solution.

The cells are interconnected to provide the necessary voltage and current. The cells have designs that prevent the spillage of electrolytes, ensuring that the battery remains functional and safe even if it is not kept upright.

However, it is essential to note that while a motorcycle battery can operate in different positions, installing and mounting it upright is generally recommended per the manufacturer’s instructions.

Batteries That Are Safe to Mount on Their Side

Battery BrandBattery Model
DeltranBattery Tender Jr.

Places To Mount a Motorcycle Battery on Its Side

Under the SeatBeneath the rider’s seat.Concealed and protected.Limited space.
Tail sectionWithin the rear bodywork.Easy access for maintenance.Limited air circulation.
Side panelInside the side fairing.Doesn’t occupy much space.Potential heat buildup.
FrameAttached to the frame.Secure and stable.May require modifications.
Front forkBetween the front forks.Balanced weight distribution.Limited space, the potential impact.
SwingarmAttached to the swingarm.Low center of gravity.Exposed to dirt and debris.

Can An AGM Battery Be Mounted on Its Side?

An AGM battery is a rechargeable battery that’s sealed, maintenance-free, and spill-proof. AGM batteries boast usage in many applications, such as onboard power systems for boats, RVs, and golf carts.

Yes! You can mount your AGM battery on the side of the motorcycle. The vital thing to consider is that the terminals must be at the top or bottom of the battery, not on one of its sides.

Does A Motorcycle Battery Have to Be Upright?

For a motorcycle like a Honda Shadow, you can mount your battery on either side with enough room for everything underneath it.

If you mount your battery across from one another (left versus right), you might have to remove your rear fender or luggage rack if they obstruct access to that area.

Some motorcycles, like the Honda Gold Wing, have a battery box in the back, which sits underneath your rear fender or luggage rack.

If you want to mount your battery on its side, you’ll need to drill some holes in your fender or luggage rack to allow access to the two bolts on the side of your battery. Alternatively, you can remove the whole tail section of the bike.

You want to mount your battery so that the terminals are at the top or bottom because one of the bolts might touch something metal if it is on its side.

For example, if you mount your battery on either the left or right side of your bike, it might touch a bolt/nut/washer coming directly from a part of your frame.

It’s essential to avoid creating a short circuit like this as it could potentially fry your electrical system.

Will A Bigger Battery Hurt My Alternator?

A bigger battery in a motorcycle will not directly harm the alternator. The alternator’s primary function is to generate electricity and recharge the battery, regardless of size.

However, there are a few factors to consider that may indirectly impact the alternator’s performance when using a larger battery.

Firstly, a larger battery has a higher capacity, meaning it can store more electrical energy. When the motorcycle runs, the alternator must work harder to replenish the larger battery’s capacity.

This increased workload may result in slightly reduced efficiency and enhanced wear and tear on the alternator over time.

However, modern alternators boast designs to handle varying battery sizes within a certain range, so the impact is usually minimal.

Does A Motorcycle Battery Have to Be Upright?

Secondly, if the new battery is significantly heavier than the original one, it can affect the motorcycle’s overall weight distribution. This change in weight distribution may not directly harm the alternator.

Still, it could affect the motorcycle’s handling and suspension, indirectly influencing the overall performance and longevity of various components, including the alternator.

The alternator’s capacity should still boast sufficiency to meet the electrical demands of the motorcycle, regardless of the battery size. Suppose the alternator already operates near its maximum capacity and has a larger battery installation.

In that case, it may result in inadequate charging, causing the battery to drain or not reach its optimal charge.

In such cases, consulting with a professional or referring to the motorcycle’s specifications is recommended to ensure compatibility between the battery and alternator.

Why Is My AGM Battery Draining So Fast?

There could be several reasons why your AGM motorcycle battery is draining quickly. Here are some common causes to consider:

Parasitic Draw: Some electrical components or accessories may draw power from the battery even when you turn off the motorcycle.

These can include alarm systems, aftermarket accessories, or faulty wiring. A parasitic draw can quickly drain the battery over time.

Cold Start: Even a cold start can drain the battery. Cold batteries cannot store as much power as warmed-up batteries. If you leave your bike sitting for extended periods with little or no use, your battery can begin to lose charge completely.

Short Cycle Life: Automotive grade batteries typically have a longer cycle life than AGM motorcycle batteries. They boast designs for handling more discharge cycles before needing replacement.

However, compared to AGM motorcycle batteries, automotive batteries typically have a shorter service life.

Low Charge: If your battery is low on charge, it may be challenging to start the motorcycle. This can also cause problems with erratic behavior and even water loss in your battery.

Poor Position in Water: AGM motorcycle batteries should always be placed appropriately so they are level in the water well of the motorcycle’s battery box.

Boost: Boosted bikes are more likely to drain the battery because of the charging effect created by the alternator.

Variation in Charging Current: If you frequently use your bike on different voltage electrical networks or charge extra batteries with other chargers, it could lead to battery issues.

Why Is My AGM Battery Boiling While Charging?

If your motorcycle AGM (Absorbent Glass Mat) battery is boiling while charging, it indicates that there might be an issue with the charging system or the battery itself. Here are a few possible reasons for the battery boiling:

Overcharging: Overcharging is one of the most common reasons for battery boiling. If the charging voltage is too high or if the charging system is faulty, it can lead to excessive charging, causing the battery to overheat and boil.

Does A Motorcycle Battery Have to Be Upright?

Defective charging system: A fault in the charging system can lead to excessive charging, so the battery can overheat and boil.

Faulty battery: If there is a fault with the battery itself, it can lead to excessive boiling of the battery, which can ultimately boil the acid to the point where it starts to spill out in excessive amounts.

Bad battery terminals: If there are bad battery terminals, there is a higher possibility of corrosion and metal build-up, which can cause the battery to boil. You should check the Coils for corrosion after every season of use.

Battery cables: Battery cables are made with heavy-duty materials and usually withstand over a few years of use. However, over time they can corrode and become brittle, leading to excessive battery heating.

Faulty battery system: If there is a fault in your motorcycle’s charging system, it will emit excess heat, which can cause it to boil.

There is also a possible internal defect in the charging system or a glitch in the regulator feeding voltage into the batteries.

Can AGM Battery Be Reconditioned?

Motorcycle AGM (Absorbent Glass Mat) batteries are generally designed as maintenance-free, sealed units and are not intended for reconditioning.

Reconditioning typically refers to the process of reviving or restoring the performance of a battery by various techniques such as desulfation, equalization, or chemical treatments.

AGM batteries boast construction with a specific design incorporating a fiberglass mat separator, which absorbs the battery acid electrolyte. This design provides several advantages, including:

  1. Resistance to vibration.
  2. Mounting ability to various positions.
  3. Longer service life than traditional flooded batteries. However, it also means that AGM batteries have limited accessibility to the internal components, making reconditioning difficult.

If you’re experiencing issues with your motorcycle AGM battery, such as reduced capacity or inability to hold a charge, the best course of action is usually to replace the battery.

AGM batteries have a finite lifespan; over time, they naturally degrade and lose their ability to provide sufficient power.

Replacing the battery with a new one that meets the manufacturer’s specifications will ensure optimal performance and reliability.

It’s worth noting that attempting to recondition a sealed AGM battery can be dangerous and may lead to damage or even rupture of the battery, posing a safety hazard.

I recommend you follow the manufacturer’s guidelines and consult a professional if you have concerns about your battery’s performance.

What Happens If You Lay the Wrong Battery on Its Side

If you lay the wrong battery on its side in a motorcycle, it can potentially lead to several issues:

Electrolyte Leakage: Motorcycle batteries are typically filled with a liquid electrolyte solution, which can leak out if you do not position the battery correctly.

When you lay a battery on its side, there is a higher chance of electrolyte leakage, which can cause damage to the surrounding components and potentially lead to corrosion.

Corrosion: The electrolyte solution in a battery is acidic. Corrosion is more likely to occur if the solution leaks out.

Damage from Falling: A side-mounted battery can easily fall off its mount in an accident or even from a sharp turn. The damage that can occur depends on the environment the motorcycle falls into when it falls off.

Serious Damage: A battery can lead to a serious loss of power, which could put you and others in danger. If the motorcycle falls off or experiences other accidents, the battery could lead to fire or other serious issues.

Hydrogen Explosion: All Li-ion batteries can suffer from a hydrogen explosion if placed upside down. Because of the electrolyte liquid in Li-ion batteries, there is a risk that they will be able to ignite due to the increased potential for electrolyte exposure.

Damage to Other Components: If the motorcycle falls off, other components can also be damaged, including the frame, engine, and wheels.

When Do I Need to Replace My Battery?

Several signs indicate it may be time to replace your motorcycle battery:

  1. Difficulty Starting: If your motorcycle is struggling to start or the engine is turning over slowly, it could be a sign that the battery is weak and needs replacement.
  2. Dimming Lights: If the lights on your motorcycle, including the headlights and dashboard lights, appear dimmer than usual, it could be a sign of a failing battery.
  3. Frequent Jump-Starting: If you need to jump-start your motorcycle frequently, it’s likely that the battery is no longer holding a charge and calls for replacement.
  4. Battery Replacement Warning: If your vehicle has a built-in battery tester – found on some Harley Davidson models and most cars – the digital reading may indicate it’s time to replace the battery.
  5. Dead Battery: If you turn your key and nothing happens, if the engine is making unusual sounds, or if your motorcycle won’t start, it could be a sign that your battery is dead and needs replacing.
  6. Battery is Over 4 Years Old: The average life span of a motorcycle battery is four years or 500 – 600 charge cycles. If your battery is over four years old, it may be time to replace it.
  7. Battery Leakage: If you notice an unusual chemical smell and liquid on the motorcycle’s battery terminals, it could be a sign of leakage, and you should replace it as soon as possible to prevent damage to the electrical system or other components.

What Causes an AGM Battery To Sulfate?

  1. Shorted battery.
  2. Low electrolyte level.
  3. Excessive load or charging voltage.


Replacing your motorcycle battery can seem difficult and frustrating, particularly if you need help with what to look for.


Hi! I' am Tom. I faced many questions from customers about different products, and there was hardly any help on the internet. After learning all the things about these products as a manager the hard way, I decided to start a blog and help other people.

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