Votronic StandBy-Charger Pro 3063 connections

StandBy-Charger Pro moves energy from one 12 V battery to another at up to 8 A output, with input draw up to 12 A. Both banks must be nominally 12 V; it is not a 24 V converter. Set the output voltage and input cutoff to suit the actual batteries and their BMS requirements. Its adjustable 12.5–14.5 V output must not be assumed suitable merely because a battery is sold as lithium. See ratings, PDF p. 1.

IN+ and IN− connect to the source bank; OUT+ and OUT− connect to the maintained bank. EN enables charging when supplied with the permitted 12 V control signal, or with the documented IN+-to-EN bridge. DIS overrides EN; connecting the vehicle D+ signal here can stop this charger while the alternator is charging the destination bank. The control terminals do not carry the charging output.

The manufacturer's cable table specifies a 15 A input fuse and 10 A output fuse. With 2.5 mm² wire, the maximum combined positive-plus-negative lengths are 4.6 m input and 7 m output. A one-metre positive and one-metre negative run on each side fits both limits. The removable screw terminals accept 1–4 mm² installation cable, stripped 6 mm and tightened to 0.5 Nm. The manual recommends stranded wire without ferrules for these terminals. See wiring and cable table, PDF p. 2 and terminal data, PDF p. 6.

Use the wire size calculator to compare ampacity and voltage drop for each side's current, one-way cable length and installation conditions, then check the result against the manufacturer's limits above. If either bank is LiFePO₄, the LiFePO₄ fuse size calculator helps review that bank's main protection separately from the charger's input and output branch fuses.

Connect the input battery first. Set the input cutoff, enable the device, and adjust output voltage while measuring the unloaded output. Only then connect the output battery. Verify that DIS stops charging and that input undervoltage prevents unwanted discharge of the source bank. Recheck voltage at the destination battery under load; excessive cable drop can leave maintenance charging incomplete. See commissioning, PDF p. 3.