Portable Battery Charger
The most basic and common way to trickle charge a battery is by using a portable battery charger. A portable battery charger is plugged into an outlet so that it receives power. The plug is inserted into the vehicle or device's auxiliary charging lead, which is the cord that is connected to the actual battery. From here, the portable battery charger is turned on and the battery receives the trickle charge through the connection. This process can be done throughout the year to constantly ensure that the battery is recharged to its full capacity.
Special Trickle Charger
Some vehicle manufacturing companies make special trickle chargers that are specifically used for trickle charging automobile batteries. A trickle charger is also a portable device, but has clamps that fit directly into the vehicle's battery cables in order for there to be a direct communication between the charger and the battery. The is powered on for the vehicle to receive the charge. Special trickle chargers can be left on vehicles to ensure that they never lose their charge.
Time Frame
The trickle charging method is not a quick fix to a dead or low battery. Rather, the process involves a slower distribution of charge to the battery. As the name suggests, the charge trickles into the battery to eventually build it back up. If you need to bring a battery back to full capacity within a short time frame, trickle charging is not a suitable method.
Warnings
You can overcharge and damage your battery through the trickle charging method. If you leave the trickle charger or portable battery charger connected for more than 24 hours, you risk burning out the battery completely. Additionally, it is important to see how much charge the battery needs to begin with. If you are trickle charging a half-life battery, you do not need to trickle charge the battery for several hours, when maybe two or three hours will suffice.