* Increased electrical demand. Diesel engines require more electrical power than gasoline engines, especially when starting. This is because diesel engines have higher compression ratios and fuel injection systems that require more power to operate. Two batteries provide the extra power needed to start the engine and run the electrical accessories.
* Cold weather starting. Diesel engines are more difficult to start in cold weather than gasoline engines. This is because the diesel fuel becomes thicker at low temperatures, making it more difficult for the engine to inject the fuel into the cylinders. Two batteries provide the extra power needed to start the engine in cold weather.
* Backup power. If one battery fails, the other battery can still provide power to the engine and electrical accessories. This can help to prevent the vehicle from being stranded if one battery fails.
In general, a 1994 Dodge Ram diesel with two batteries will be more reliable and easier to start than a vehicle with only one battery.
