Schumacher SP1 4/2A Powersport Extreme Charger/Maintainer
1 Year Warranty
How do I choose a battery charger?
First find the voltage on the battery you will be charging. Make sure to match the voltage on your charger with the voltage of battery you are charging (example a 12v battery should be charged with a 12v charger).
Your next step is to identify the Ah (amp hour) rating on your battery. Each battery charger is rated for a range of batteries based on Ah. As a general rule of thumb when selecting a charger for a lead acid battery, match the voltage and use one that is no more than 20% of the capacity rating of the battery (at a 20hr. rate).
Example; to charge a 12 volt / 7.5Ah battery select a charger with a maximum charge output of 1.5 Amps (7.5 x 0.20 = 1.5).
How can I tell if my lead-acid battery is charged or not?
Lead acid batteries are made up of cells. Each cell is rated at approximately 2 volts. A fully charged lead acid battery cell is around 2.15 volts, and a fully discharged cell is 1.9 volts. So a 12V lead acid battery would measure at 12.9 volts when it is fully charged, and around 11.4 volts when fully discharged.