Best way to charge a motorcycle battery
Step 1. Temper your expectations
Small batteries, like the one in your motorcycle, do not take kindly to being discharged. They really don’t like being discharged and left that way for a period of time. Sometimes batteries can be brought back from the dead, but even when salvageable, permanent and irreparable damage has been done by both the discharge and subsequent rapid charging you’re probably going to attempt. Expect to buy a new battery, and if yours can be saved, think of it as serendipity.
Step 2. Figure out what kind of battery you have
Lead acid, absorbed glass mat (AGM), and gel batteries can all be charged in the conventional way. Lithium-based batteries (lith ion, lith-iron, lithium phosphate, etc.) need special chargers depending on manufacturer, which brings us to the next step.
Step 3. Figure out what kind of charger you need
There are a few types of battery chargers. The simplest type is a trickle charger, which converts the AC power coming out of your wall to DC, and blindly pumps it into your battery until it is turned off. Note that this type of charger must be monitored throughout the charging process. That phrase has gone out of vogue somewhat, so you may also see these referred to as “fully manual” chargers.
“Float chargers” are the next type of charger. Modern float chargers get a battery charged and then switch on and off automatically to keep the battery’s charge rate at the optimal charge level.
The final type of charger is a smart charger, which monitors the battery’s charge progress. Normally, it will charge at different rates in order to minimize the damage done to the battery. Often these have what’s known as a “desulfation” mode, which is usually used to knock sulfur off the lead plates inside the battery. It usually does this with varying voltages and electrical “pulses.”
Many times those smart chargers cannot be used with lithium batteries. The problem is that chemically, lithium batteries are different from their lead counterparts, and most have an on-board management system that cannot cope with the pulsing. Look to your battery manufacturer for guidance with this style battery, as not all brands can be treated the same.