How to Change a Motorcycle Battery
Reviewed by CrankDex editorial
Swapping a motorcycle, ATV, or scooter battery is one of the easiest jobs on the bike: a screwdriver, a small wrench or socket, and about 10 to 15 minutes. Here's the safe order to do it in.
Changing a powersports battery is mostly about doing the steps in the right order, not raw mechanical skill. The one rule that actually matters for safety is the order you disconnect and reconnect the cables. Get that right and the rest is just unbolting a tray and swapping a box.
Tools you'll need
Most bikes only need a small wrench or socket for the terminal bolts and a screwdriver for the seat latch or side panel fasteners. Some models use a simple wing-nut or bolt-on terminal, others use a small hex bolt; a compact socket set covers nearly every case. Keep a rag handy for cleaning up any corrosion on the terminals or tray.
Why negative first, negative last
The negative (-) terminal is connected to the bike's frame, which acts as the ground path. If you disconnect the positive terminal first and your wrench brushes any grounded metal while the negative cable is still attached, you can create a short and a spark, right next to a battery. Pulling the negative cable first breaks that ground path immediately, so there's nothing for a stray tool to complete a circuit against. Reconnecting goes in reverse: positive first, negative last, for the same reason.
Finding the battery
Battery location varies a lot across motorcycles, ATVs, UTVs, and scooters. On many street bikes it's under the seat. On some cruisers and older models it's tucked under a side cover. On others, especially some sport bikes, it's under the tank or behind a panel that needs a couple of fasteners removed. If you've never done it on your specific model, a quick look at the owner's manual saves guesswork.
Pulling the old battery
Once both cables are off, remove the hold-down strap or bracket that keeps the battery from bouncing around, then lift it straight out. Powersports batteries are small but heavier than they look for their size, so keep it level to avoid spilling anything from a conventional (flooded) battery.
Setting up a new AGM battery
Most replacement batteries today are sealed AGM, and many ship dry with the suffix -BS on the code, meaning an acid pack is included separately. If that's what you bought, you fill it once, following the instructions that come with it, and give it a short rest before its first charge. Batteries sold already activated, along with most lithium (LiFePO4) drop-ins, are ready to install straight out of the box.
Cleaning and reassembly
Before setting the new battery in, wipe down the tray and terminals of any white or greenish corrosion. A little dielectric grease on the terminals after you reconnect helps keep moisture and corrosion out over time. Reconnect positive first, negative last, refit the hold-down strap, and close everything back up.
Browse battery tool kits on Amazon (we may earn a commission, at no extra cost to you), or look up your bike to confirm the exact battery size and code before you buy.
Frequently asked
Which terminal do I disconnect first on a motorcycle battery?
Always disconnect the negative (-) terminal first, then the positive (+). When you reconnect, do it in the opposite order: positive first, negative last. This order matters because it prevents a wrench or socket from accidentally bridging the positive terminal to any grounded metal on the frame while the negative cable is still attached.
Where is the battery on a motorcycle?
It depends on the model. Common spots are under the seat, behind a side panel, or under the fuel tank. Check the owner's manual if you're not sure; on most bikes the seat lifts off or unlatches with a key, and the battery is one of the first things you see.
Do I need to add acid to a new motorcycle battery?
Only if it's a conventional (non-sealed) battery, or a dry-charged AGM sold with a separate acid pack, usually marked with a '-BS' suffix. Sealed, factory-activated AGM and lithium batteries are ready to install straight out of the box with no acid to add.
How long does it take to change a motorcycle battery?
For most bikes, 10 to 15 minutes once you have the seat or panel open and the right size wrench or socket. Activating a dry-charged battery for the first time (adding the acid pack and letting it sit before its first charge) adds extra time, so plan that step the night before if possible.
Need your machine's exact battery? Look up your battery size →