Optima RTF 4.2 Red Top Starter Battery 8078-209 Type: Sealed Lead Acid - Spiralcell Capacity (EN) Ah: 50 Nominal Voltage V: 12 Cold Cranking Amps (EN) CCA: 815 Reserve Capacity (BCI) min: 100 Weight Kg: 17.9 approx Length mm: 245 Length Top Cover mm: 254 Width mm: 172 Width Top Cover mm: 184 Height Excluding Terminals mm: 183 Recharge Time: 100amp 35min, 50 amp 75min, 25amp 140min approx Extreme Vibration Resistance: Yes Fast Recharge: Yes Optima Spiralcell batteries are the optimum lead acid battery. Alternator: 13.8 to 15 volts. Battery charger 13.8 to 15 volts, 10 amps, 12-15 hours approx. Float charge 13.2 to 13.8 volts, 1 amp maximum current (All assuming a room temperature of 25 degrees C). All measurements are approximate.