Controlling current flow in multi-battery systems is essential in many vehicles, including RVs, boats, utility vehicles, aircraft, huge trucks, and off-road vehicles with auxiliary loads and high current loads, such as a recovery winch. As their name implies, battery isolators keep your backup power source from depleting your primary one. Conversely, battery separators are installed between the primary and secondary batteries to prevent the charging system from being overloaded by electricity. By isolating them, the separator may prioritise battery charge.
When using a single battery system, the engine may be unable to be started if the battery is depleted due to the usage of auxiliary loads while the engine is turned off. That problem can be solved by installing a second battery system dedicated to auxiliary loads, but only if it is expertly connected to the car’s existing electrical network. System performance trade-offs exist between battery separators, a redarc battery isolator, and different battery isolator implementations.
Isolators for batteries – An isolator for batteries is used to split the DC bus into numerous, independently-operating branches, each of which can only carry current in one direction. This allows several batteries to be charged at once from a single alternator or another power source, without the need to be connected in parallel. By isolating the batteries, a dead or failing battery (often the backup battery) won’t be able to drain power from a functioning one (often the primary battery). Since a common diode-based isolator adds a diode drop to the circuit between the charging power source and the batteries, system efficiency suffers. However, basic general-purpose diodes are the most often used battery isolator technology, partly due to their low cost. However, they are also the least efficient, need large heatsinks, and are hence quite bulky.
Separators for batteries – Battery separators (also known as “smart battery isolators”) are more complicated devices that serve a number of purposes, while battery isolators serve only one. When the engine is turned on, for instance, the battery separator checks the voltage of the primary battery, the secondary battery, and the charging system. The battery separator detects the charge levels of both batteries and cuts power to the auxiliary battery when the engine is initially started. When the alternator is unable to keep up with the total charge requirements, the battery separator will cut power to the backup battery and charge just the primary battery.
Comparatively, battery isolators are often diode-based devices that only permit current to flow in one way, whereas battery separators allow current to flow in both directions. A battery separator can help with engine starting and prevent damage to the charging system and the main battery. When the engine start is turned on, the battery separator checks the combined voltage of the primary and backup batteries. The separator will combine the power from both batteries to kickstart an engine if the voltage from the primary battery is below that of the auxiliary battery.