Motorcycles are not the primary form of transportation for most owners. They usually have a four-wheeled enclosed vehicle for their day-to-day transportation and really, only use the motorcycle as a recreational vehicle. This means there can be long stretches of time the motorcycle sits dormant in the garage. And of course, in many parts of the world, the weather doesn’t allow you to comfortably ride a motorcycle for many months on end. These long periods of time can be bad for your motorcycle's battery. They will drain without the engine running over time and become weak or completely dead.
The best idea is to put your battery on a tender to allow a very low amount of electricity to trickle into the battery to counter the natural drain during inactivity. Then some batteries are old or damaged and need to be replaced because they no longer hold a charge provided by the motorcycles charging system while in operation. This leads to a rider being stranded out on the side of a road. This of course is avoidable with a minor maintenance task of checking your battery every couple of months to ensure it is holding enough charge to turn over the engine and keep you rolling down the road.
This maintenance job will only require hand basic tools and a voltage meter. Then depending on the condition of your battery a charger may be needed to bring your battery voltage back up to a working level. It’s a good idea to set out the required tools before you start the project, so you don’t have search for the correct tool or worse run out to the local tool retailer mid job.
You will need to find your battery box location on your make and model of motorcycle. The location varies depending on manufacturer and model so refer to you owner’s manual for location and access. Here we have an American V-twin motorcycle with the battery box located under the saddle. To access you will need in most cases a Philip head screwdriver to remove the saddle screw in the top of the rear fender. Here we are using the Powerbuilt Pro Tech Double Injection Screwdriver (#646139) Take special care not to dig the paint on the fender by slipping off the screw.
Once you have backed out the screw you can remove the saddle to expose the battery box. You will also see many other wires and connectors adjacent to the battery. You will not be working with any of these while working on the battery but it’s always a good idea to inspect them for any wear, rubbing, cracking or heat damage while you are under you saddle. It’s probably a good idea to take a shop rag and wipe the battery down and the surrounding area. It helps keep the workspace clean and free of dust and dirt. Once you have a relatively clean area you can remove the battery tie down bracket.
Depending on your motorcycle you may have a different bracket to remove. Here we have two screws to back out to gain full access to the battery so we’ll be using a screwdriver from the Powerbuilt Heavy Duty Pro Tech Double Injection Screwdrivers Set (#949018). You’ll find what you need with this 17 piece set complete with both, flat head and Philip head screwdrivers. Now, with the bracket removed we now have access to the battery and terminals.
Checking The Battery
Visually inspect the terminals to see if there is any corrosion or build up on the terminal creating any resistance. There shouldn’t be any corrosion. If there is a new battery is recommended. One of the most important things you can determine while inspecting the battery is to find out what type of battery you have, is it a lead acid, absorbed glass mat, a gel, or a lithium-based battery? This post is based on the lead based and gel batteries protocols which can be checked and charged in a traditional manner. Lithium batteries are a different breed and will require different procedures due to their chemical make-up. So, with confirmation you have either a lead acid AGM or gel battery please continue.
Removing the battery cables is the next thing to do. Most motorcycle batteries have cables with flat circular connector attached to the terminals with a nut. There should be a red cable (positive) and black cable (negative) connecting to the corresponding battery terminals. There should be polarity indicators on the battery itself. The polarity designations are very important. Start by removing the negative cable first. It is most likely be the black one on most motorcycles. Here we are using a wrench from the Powerbuilt 9 Piece Long Arm Wrench Set (#941203) to get into the tight space around the battery terminals. Once removed from the battery set the cable aside making sure it does not come in contact with the battery or the motorcycle. Then remove the positive red cable in the same manner. Again, move the cable aside where it cannot come in contact with the battery or the motorcycle.
With the cables removed from the battery and in safe locations you can now test the health of the battery. There are many different battery voltage meters this one is the Powerbuilt Multimeter Tester (#240315). Set the meter to read 12 volts. Note some multi-meters will have a “20v” selection with no 12v selection. You can set it to the 20v as it is indicative of up to 20v and most motorcycles us a 12volt electrical system. So, set to read the 12v and touch the negative wand to the negative terminal and the positive wand to the positive terminal. You will want to see a voltage reading of above 12.5 volts on a good battery. Anything below 12.5v on most V-twin motorcycles you will need to charge the battery up to optimal voltage.
Charging the Battery
If the battery needs to be charged you will need to pull it from the bike to do so. Pulling the battery from the bike is a safety precaution for a couple of reasons. By pulling the battery you isolate the battery from your motorcycle’s electrical system protecting its components also while charging heat can build up with the battery cells. Excessive heat buildup can damage the battery and surrounding motorcycle components and on the extreme cases, could start a fire inside your motorcycle. So, pull the battery when hooking it up to a charger. Note here, this is for an actual battery charging unit, not a trickle charge you would get from a battery tender unit that you can leave attached to your motorcycle battery while sitting in the garage. These battery tenders are made to work while the battery is inside and connected to your motorcycle. The level of power it takes to keep a batter topped off is minimal to a low battery needing a legitimate charging.
A battery tender is highly recommended to keep your battery healthy during long periods of inactivity. Battery tenders are inexpensive insurance and cost much less than a new battery every riding season. Back to charging your battery; with the battery pulled move it to a well-ventilated location as a small amount of hydrogen gas can be the result of chemical reactions during charging. Now triple check your connection polarity before you attach your charger to the battery. Do not cross the positive with the negative charger cable the negative terminal with the positive charger cable. You will do serious damage to your battery. Securely attach the positive cable to the positive battery terminal and the negative cable to the negative terminal.
Now it is time to plug in the charger. Most current smart chargers have built in software to help protect the battery and keep the charging amperage low. The higher the amperage the more electricity flows into the battery for faster charging. However, this is not good for the battery and can do damage and reduce its longevity. Low and slow is the name of the game for charging motorcycle batteries. Charging can take more than a few hours depending on the level of your initial battery charge. Resist the temptation to pull it off the charger after a couple hours. Let it charge all the way up. Modern smart chargers will let you know when the charge is complete. After several hours or when the smart charger indicates full charge recheck the battery with the multi-meter and see if you have over 12.5 volts.
Reinstall the Battery
Once you have determined you have the proper level of volts in your battery go ahead and reinstall into the battery box. Reattached the battery cables to the terminals starting with the positive cable first. Then reattach the negative battery cable. Remember to fasten down the battery bracket to hold the battery down and in place. Once your battery is locked down and fully attached to the cables try cranking it over with the multi-meter wands on the corresponding terminals. You should see a slight drop in volts at the point of cranking the engine over as it’s drawing more power from the battery at that moment. It happens quick so keep a sharp eye out. If this dip goes bellow 9.6 volts on the meter at this point you know your battery is getting tired and will need to be replaced soon. Once the bike starts up your multi-meter should be reading close to 14 volts which indicates your motorcycle’s charging system is strong and working. If it stays at around 12 to 13 volts this could indicate your charging system may be having some issues or the battery is again tired and will need to be replaced soon. Assuming you have strong crank and idling voltage you can put the meter way. Make sure all your terminals and bracket fasteners are tight and your battery isn’t moving around you can reinstall the saddle. Tighten the saddle screw into the fender wipe everything down and go get out on the road and ride.