M151A2 pulsed battery tender.

This is how I use a 24VDC, 2.0 amp pulsed battery tender to maintain my two (2) each 12 VDC connected in series batteries resulting in the vehicles designed 24 VDC pressure. I believe using a 24VDC "pulsed" low amp battery tender is necessary. Using something like a 24VDC battery charger with 10 or more amps will cause the vehicles ignition coil to stay sourced and possibly overheat and fail resulting in charged batteries but a engine cranks but will not start condition.