Patent ID: 7541778

Claim:
Method of charging a lead acid battery at a battery charger connectable to the terminals of the lead acid battery to be charged, the battery charger being configured to detect a voltage over the terminals of a connected lead acid battery and having a control circuit, for initiating a burst cycle, the method comprising the following steps: applying a voltage at a connected lead acid battery; detecting the voltage over the connected lead acid battery to sense an increase of voltage over said lead acid battery in order to identify whether the internal resistance of the lead acid battery has increased compared to a normal state; initiating a burst cycle if said internal resistance is identified as increased, wherein a plurality of consecutive voltage bursts are applied to a connected lead acid battery to be charged, each burst having a length of at least an order of milliseconds (mS) and each burst delivering an amount of charge to the lead acid battery and thereby successively lowering the internal resistance of the lead acid battery; and initiating a charging cycle to charge the connected lead acid battery when said burst cycle has been terminated.