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How NOT TO destroy your alternator with DROP-IN-LiFePO4 ! | Ask The Expert with NIGEL CALDER
August 2, 2025 · 3 min · 4K views
What this video covers
Connecting drop-in LiFePO4 batteries directly to stock, internally regulated alternators risks catastrophic electrical failure. When a battery management system (BMS) disconnects a lithium battery due to overcharging, the sudden loss of load causes voltage spikes that destroy alternator diodes.0:55 Furthermore, lithium banks accept high charge currents for extended periods, which can overheat and fry alternators not designed for continuous full-output operation.1:40 Yanmar previously issued directives requiring owners to derate 120A alternators to 75% capacity when paired with lithium banks to prevent thermal damage.2:04 To mitigate these risks, install a battery-to-battery (B2B) charger between a lead-acid battery and the lithium bank to regulate current flow.1:19 Alternatively, use external regulators equipped with temperature sensors to automatically throttle alternator output if temperatures rise.2:42 Proper integration requires a communication link between the charging source and the battery to prevent the BMS from disconnecting the circuit while the alternator is under load.
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