A 12V automotive battery is a great way to store electrical energy, but it's also likely to go dead if it's been sitting for some time. The same is true with your lawn mower battery, since it's essentially designed the same as a car's. After all, nobody is doing much mowing during the winter!
The good news is, it's pretty easy to get that battery charged and ready to go again.
Older battery chargers were a pretty simple affair and often didn't have protections against overcharging a battery, which can lead to a dangerous release of gas from the battery's cells.
Newer microprocessor-controlled chargers such as this model from Schumacher offer a variety of options and safeguards, making it easy to figure out how to charge a lawn mower battery. Most newer-design chargers have the following features:
- Automatic adjustment of amperage rate to prevent overcharging
- Trickle charge or fast charge with jump-start mode
- Float-mode monitoring (to keep battery at optimum charge long term)
- Reverse hookup protection, making it impossible to start unit if polarity of clamps is reversed
- Clamps to fit top-post or side-post batteries
- Timer option
- 2-amp slow charge option
Just like with a cellphone or laptop battery, a slow charge is best for a deep, thorough charge on a riding mower battery.
When you're learning how to charge a lawn mower battery, remember that batteries are hazardous. Be sure you charge in a ventilated area and remember to wear personal protective equipment (gloves and safety glasses) whenever handling the battery. The good news is that actually charging the battery is as simple as connecting the cables to the proper terminals, setting the charger to your desired charge setting, and leaving it to do its job. There's not anything more to it than that!