Split Charge Diodes
Marine Split Charge Diodes for Battery Isolation
Simple, reliable battery isolation using split charge diodes. Our collection features diode-based battery isolators that prevent house battery discharge from affecting engine starting batteries.
Split charge diodes provide automatic battery isolation with no moving parts, ensuring your starting battery remains charged while allowing house batteries to charge from the alternator. Essential for safe operation on all vessels.
Battery Isolation: Part of our Battery Isolators collection. Compare with split charge relays (VSR) for more efficient charging. Use with AGM or lithium batteries. Essential for multi-battery systems. Pair with battery chargers and battery monitors.
Diodes versus split charge relays
A split charge diode isolates battery banks passively, using the one-way nature of a diode to let charge flow from the alternator to both banks without allowing one bank to draw down another. It has no moving parts and nothing to switch, which makes it simple and reliable, but it also causes a small voltage drop across the diode, meaning the house bank receives slightly less charge than a direct connection would give it.
A split charge relay, or VSR, avoids that voltage drop by switching a solid connection between banks once the engine is running, so it charges more efficiently but relies on a mechanical or electronic switch that can eventually wear or fail. Diodes suit simpler two-bank systems where ease of installation and no moving parts matter more than the last few percent of charging efficiency; check current rating against your alternator output before choosing a diode size.
