VBCS 30/20/250 Triple CI (3242)
Votronic VBCS 30/20/250 Triple CI 3242 connections
Review the Votronic VBCS 30/20/250 Triple CI 3242 connections, setup and installation requirements. This overview does not calculate cable or protection sizes.
- Compatible systems
- 12 V
- PV open-circuit limit
- 36 V
Connection overview
VBCS 30/20/250 Triple CI (3242) connections.
See how this component fits into a system. Use the manufacturer’s installation instructions for the complete connections.
Installation notes
Before you install.
Open a question for model-specific guidance and sources.
Verified against the manufacturer's documentation (rev. German VBCS Triple CI manual, 11/2020; manufacturer-authored distributor mirror), checked 2026-10-01. Manufacturer documentation →
Three sources, one house-bank charger
This record is the 3242 VBCS 30/20/250 Triple CI documented in the November 2020 manual, not a later similar-looking Triple version. It provides up to 30 A from the alternator booster, 20 A from mains and 18 A from the 250 W solar stage. Do not add those numbers together. Mains and solar operation can allocate up to 4 A to starter maintenance within their respective totals. See mode-specific ratings, PDF p. 18.
Read the common-negative diagram
Bord I positive feeds the house battery; Start II positive carries booster input and reverse-direction starter maintenance. The common negative terminal serves the battery system, and the solar negative returns to that common negative arrangement. Solar positive connects to its dedicated input. The AC input uses line, neutral and protective earth. D+, temperature T/T, voltage sense S+/S−, BMS switching input and CI bus are control circuits, not spare charging outputs. See connection diagram, PDF p. 3.
Fuses and cable lengths
The 3242 cable table specifies a 50 A starter-side fuse and 40 A house-side fuse. It permits 6 mm² starter cable to 5 m and 6 mm² house positive/negative conductors at 1–2.5 m each. Use the table for the actual layout; a large alternator fuse cannot protect every small sense wire. The diagram separately shows 5 A protection for relevant small feeds. Keep PV below 36 V open circuit, 15 A input and 250 W. See 3242 installation table, PDF p. 6.
Configure and test each source
Set the house-battery charging program and connect the temperature sensor as instructed. Provide the specified ventilation space. Test mains, real engine/D+ operation and solar separately, recording battery voltage and current for each mode. A voltage-sensing D+ simulator can interact with reverse starter charging and cause cycling; use the vehicle signal specified by the manual. The planner lists the interfaces and mode ratings, but leaves generation unpredicted until source-specific input routing is modeled. Selecting a mode must not make another connected source produce that mode’s current. See startup and troubleshooting, PDF p. 16.
Technical reference
Specifications and terminal map.
Check the model, ratings and connection points against your own unit before choosing installation hardware.
Catalog specification
Combined 30 A alternator booster, 20 A mains charger and 250 W solar controller. Source-mode ratings are not additive; starter maintenance output shares charging capacity.
- Compatible systems
- 12 V
- PV open-circuit limit
- 36 V
Terminal map
Catalog connection points, current direction and planning limits. Check the manufacturer's pinout and connector ratings before installation.
START II +
positive · bidi
BORD I +
positive · output
COMMON −
negative · bidi
SOLAR +
positive · input
AC L
neutral · input
AC N
neutral · input
AC PE
ground · input
D+
signal · bidi
T / T
signal · bidi
S+ / S−
signal · bidi
SW / BMS
signal · bidi
CI BUS
signal · bidi
AES
signal · bidi
A dash means a current rating is not specified here.
Sources and sizing method
Equipment specifications. Model details, ratings and terminal roles come from the catalog. Check your unit’s label and current manufacturer documentation for its exact revision.
Connection overview. This diagram explains the connection arrangement; it does not calculate cable sizes or protection for the installation. Follow the manufacturer’s complete wiring and protection instructions.
Read how the sizing worksNext step
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