Motorcycle Battery Charger Harness Install

Motorcycle Battery Charger InstallationLike many things mechanical, disuse of a motorcycle battery is even worse for it than regular use. Up in the snow belt, winter-long disuse of motorcycles enforces disuse of the motorcycle’s battery. If the battery gets no charge during extended periods, its level of charge decreases and that can cause a problem called sulfation.

Sulfation happens during long periods of battery inactivity when the charge level declines. It can also occur when the bike’s charging system fails to produce the necessary voltage to maintain a full charge. Sulfation occurs when lead sulfate crystals that occur in small amounts during normal operation convert to crystalline deposits on the negative plates in the battery.

Large crystals eventually develop, reducing the battery’s active material and as a result, its capacity. Left to progress long enough, it can destroy a battery making it incapable of taking a charge and unable to deliver any energy.

The way to prevent sulfation is to maintain the best motorcycle battery at full charge, but when the bike is not being ridden, the charging system doesn’t do it. In some cases, it may not do the trick even if the bike is started and run—if not ridden—during the months of down-time. Some would argue that just getting the bike started in cold conditions is rough on the battery, you won’t know if full charge has been reached (unless you break out the multimeter) and in the case of a bike that is difficult to start or fails to start at all, the drain on the battery could be substantial and not made up by idling the engine.

Fortunately, there is a solution that takes the guess-work out of maintaining the bike’s battery, even over long periods of inactivity: a battery maintainer.

A battery maintainer (a motorcycle Battery Tender is a specific brand of this type of charger) is a charger that has the ability to prevent over-charging when the battery is at the required state of charge and automatically charge when it drops below that level. A maintenance or “float” charge need only be a couple of tenths of a volt above the voltage of the fully charged battery in a resting state—that is, not being otherwise discharged or charged.

The microprocessor-controlled type of maintainer varies from the typical “trickle” charger in that it will not allow the output voltage of the charger to rise to an unacceptably high level, which could be higher than 16 volts DC depending on the type of charger and the battery. That condition can damage the battery and ultimately shorten service life.

There also may be temperature compensation built in that addresses the different rate of charge and internal losses in a battery depending on ambient temperature. These are also generally reverse polarity protected, which is good if you’re like me and occasionally lose the ability to tell red (+) from black (-).

Putting this technology to work is relatively easy; battery maintainers may come with simple alligator clips similar to those on those jumper cables you probably forget to carry along in your car in the winter and they also usually include a ring terminal harness with in-line fuse pig-tail that can be connected to your bike’s battery.

The alligator clips work well enough, but will usually require the battery to remain exposed while they are in use. They also have the unsettling potential to come unclipped if not applied properly or if the wiring is bumped or disturbed, with the potential to short out and create sparks in an area where flammable materials and fuel are present. Those factors make the pigtail wiring a good option.

The maintainer simply plugs into a 12 V wall receptacle and then the device connects to the battery terminals, either in the bike or on the workbench. The accompanying images show the following steps of the process to hook up the pig tail for the battery left in the bike: