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Charging a 7 amp hour (AH) sealed lead acid (SLA) battery with a 10AH charger can be done, but it is detrimental to the health of your battery. Charging a battery with the wrong charger results in overcharging or undercharging.

Amp Hours

The capacity of a 7AH battery is significantly less than a 10AH battery. Since the 10AH battery holds a greater capacity, its charger provides an increased electrical flow. Using a 10AH charger with a 7AH battery results in overcharging. Unplugging the battery early results in undercharging.

Overcharging

Overcharging is caused by thermal runaway. Increased voltage will decompose the water in the electrolytes of the battery. Overheating occurs, allowing more voltage to enter the battery. Overcharging ages batteries very quickly.

Undercharging

Undercharging occurs when lower voltage is applied to a battery. Charging ends early and lead sulfate adheres to the electrodes. Due to the remaining lead sulfate, capacity is reduced. Removing a battery early also results in an incomplete charge. The risk of residual lead sulfate damage is still present. Charge your batteries completely to avoid diminished capacity.

Car batteries work when the chemical reactions in the battery cause electrons to gather at the negative terminal. Turning the key into the "on" position connects a circuit between the negative and positive terminal, causing the electrons to rush from the negative terminal to the positive, providing the spark necessary to power the starter engine and turn the car over. When a car battery dies, it means there is a shortage of electrons gathering at the negative terminal. Car battery chargers work by reversing the flow of electrons from the positive terminal to the negative terminal, eventually causing enough electrons to gather at the negative terminal for a quick current to run from the negative terminal to the positive terminal when the circuit is connected. Testing the effectiveness of a car battery charger requires a field experiment whereby you connect the charger to a dead or dying battery and turning it on.

Instructions

1

Clean the terminals of your battery sufficiently with a clean cloth.

2

Connect the alligator clips of your charger to the terminals of your battery. Connect the negative (black) alligator clip of your charger to the negative terminal of your battery before connecting the positive (red) alligator clip.

3

Plug your battery charger into a wall socket if it is DC/outlet powered, or turn it on if it is AC battery powered.

4

Wait two to three minutes or the specified amount of time indicated in the operators manual that came with your specific battery charger. For most car battery chargers, two to three minutes is sufficient to check whether the charger itself is functional, as it will likely charge the battery enough to turn your car over.