Battery Swap for high-performance and stock applications
No matter how well they’re cared for, eventually motorcycle batteries will crank out their last start. You don’t want to be there when that happens, because that tends to mean you’ll be stuck wherever you are for awhile. I didn’t want that to happen while riding my 2010 Sportster, which has been cranking over a little on the slow side lately with the original factory battery.
With a set of performance cams, and hopefully some more go-fast goodies in the future, it was important to choose a battery that’s designed to work just as well in high-performance applications as it does in stock ones. I turned to Twin Power for its high-performance Factory Activated AGM battery (#48-5007/$96.49), which works in 2004-14 Sportsters. The battery uses advanced lead-calcium technology that allows it to hold its specific gravity more than three times longer than conventional batteries. It features a longer shelf life, improved charge recovery capability after a deep discharge, and extreme vibration resistance to make it a higher performing battery overall.
Twin Power batteries are also great for custom applications due to their heavy-duty, flush-mounted terminals that allow the battery to be slid in anywhere. And because it’s filled, sealed, and charged straight from the factory, it’s completely maintenance free, which makes it perfect for hard-to-reach placements. However, any battery will eventually discharge if left idle, so use a trickle charger whenever possible.
Swapping out the battery on a Sportster is more difficult than on Big Twins thanks to its location, but it definitely classifies as a do-it-yourself maintenance project. Only a handful of basic tools are required, and the whole thing should take less than an hour from start to finish.
• 3/8″ socket
• 10mm open-end wrench
• Blue threadlocker
• Pick tool
• Phillips screwdriver
• Ratchet wrench
• Torque wrench (in-lbs.)
1 – Our 2010 Sportster Nightster is up on the lift with its seat and left side cover removed.
2 – Twin Power recommends checking the voltage of the new battery before installation. 12.8 volts or higher is perfect, but we’re not far off with 12.68. We’ll throw a trickle charger on before use.
3 – Detach the main fuse holder from the battery strap by pulling it towards you and backwards until it pops out. It will come out easily, so don’t force it.
4 – Do the same for the data link connector. It should also pop out easily.
5 – Using a 3/8″ socket wrench, remove the battery strap bolt at the bottom of the left side of the battery. Then, remove the battery strap by separating it from the plastic top strap.
6 – After slipping off its protective cover/holder, remove the main fuse from its housing.
7 – Using a large Phillips screwdriver, unscrew the positive cable bolt. Pull the battery out far enough to access the negative cable bolt.
8 – Using a 10mm open-end wrench, unscrew the negative cable bolt. Be careful not to accidentally let the wrench contact the positive terminal; even though the fuse is removed, this is still a live battery. Slide the battery out the rest of the way.
Tip And Tricks
The factory service manual says to unbolt the negative cable from its grounded location on the engine case, but that is a massive pain in the ass. It’s possible to swap out the battery without doing this. If the negative battery cable isn’t long enough to slide the battery out and access the negative terminal on the battery, however, unbolt the cable from the top of the transmission and slide the battery out with the negative cable attached. When putting the new battery back in, this is a great time to upgrade with a longer cable, so that the next battery change will be much easier.
9 – Slip a supplied block nut into the negative terminal before sliding the new battery in, negative first, so it can be easily attached to the negative cable.
10 – Slide a long bolt through the negative cable eyelet (as well as any accessory leads), then apply blue threadlocker and put it through the lock washer, brass spacer, battery terminal, and block nut. Tighten it with a 10mm open-end wrench, but go slowly, so that the bolt can catch the nut’s threads. A pick tool helps to hold the nut in place.
11 – Slide the battery in all the way, and attach the positive cable (and accessories) in the same order using a 10mm wrench and blue threadlocker. Now’s a good time to pop in the main fuse and turn the key to make sure the electrical system works before going any further.
12 – Secure the stock metal battery strap under the stock plastic top strap, and then bolt it down with a 3/8″ socket using the stock bolt. Torque to 36-60 in-lbs. Then stuff the main positive cable into the factory holders on the electrical bracket.
13 – Snap the fuse cover onto the battery strap, then slide the fuse into its cover. Make sure you hear a nice “click.” Snap the data link connector in place now, too.
14 – Attach the stock left side cover by placing the bottom slit over and down onto the catch hook underneath the battery. Then press the top latches into place.
15 – Reinstall the seat using the factory hardware and a Phillips screwdriver. Switch on the ignition, thumb the starter, and enjoy how strongly your bike starts with a new Twin Power battery! AIG