Question: How critical is recharge voltage? Why are SVR batteries so charge-sensitive? Answer: SVR (Sealed Valve Regulated) batteries work on the recombination principle. This means that during charging, the hydrogen produced on the negative plate and oxygen produced on the positive* are recombined to produce H20 or water. This water replaces the moisture in the gel or in the absorbed mat separators. * All lead acid batteries, regardless of type, give off hydrogen from the negative and oxygen from the positive during charging. An SVR battery has special pressure-sensitive valves to keep the cell under approximately 1 1/2 psi of pressure. This pressure is necessary for the recombination of the H and 0 to work properly. Without pressure, the H and 0 would be lost to the atmosphere, which would eventually dry out the gel or the absorbed separators. Remember that voltage is electrical pressure and current (amps) is electrical flow. Also remember that battery plates can be subjected to too much charge (overcharging). If a battery's plates are subjected to too much electrical pressure (excessive on-charge voltage), they will give off more H and 0 than can be recombined. The excess gas raises the pressure in the battery which is vented outside through the safety, pressure release valves. When this gas is released, H and 0 (moisture) are lost. With excessive charging, any SVR battery will dry out and fail. Therefore, charging must be carefully regulated: 13.8-14.1V for gel cells 14.1-14.5V for SRG absorbed A reliable, automatic temperature sensing, voltage compensating charger must be used. NEVER use constant current chargers!