Only 4 in stock
SVB price: €122.65
Excl. VAT, excl. shipping costs.
This is a NET-price excluding German VAT. Shipments to countries outside of the EU may be subject to import duties and taxes.
€122.65 This is a NET-price excluding German VAT. Shipments to countries outside of the EU may be subject to import duties and taxes.
Item no.
Model no.
Automatic charging relay 120A
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Product details

This charging relay connects automatically while charging batteries, isolating them when discharging and starting engines. The automatic switching function can be blocked via a control input (6.3mm plug-contact), by means of a POS-voltage (for example, from the starter). Your sensitive onboard electronics are protected by brief separation when the engines are started. The waterproof case (IP67) has an LED indicator that displays current status with a steady or flashing light (see below). The electronic components of the relay require a NEG connection (1.5 mm line on to the 6.3mm plug-in contact).
ACR 120: A 6.3 mm blade-contact allows the connection of an optional indicator LED.
Connections 3/8"-16 (10 mm), 15.8 Nm (140 in-lbs), 6.3mm plug contacts for NEG, external control input and optional LED status display. Multivolt: 12/24 V, quiescent current (open contacts) 15 mA, max cable cross section: 50 mm². Continuous load: 120 A. Dimensions: 99 x 89 x 47 mm.

LED-Display Status
Continuously on The relay contacts are closed,
the batteries are connected to each other, and the charging process is active.
Off The relay contacts are open,
The relay contacts are open,the batteries are seperated, the charging process is not active.
Slow blinking The relay contacts are open,
the batteries are seperated by the optional control input (ACR 120).
Quick blinking The relay contacts are open,
the batteries are seperated, one or both of the batteries are under 9.5V (or 19V with 24V power systems).

Useful practical notes: we often receive enquiries as to why the charging relay does not swich on.
Please observe the following points!

  • This charging relay detects the presence of a battery or charging voltage at both terminals. It can therefore not be used as a "simple" cut-off relay.
  • This means that the charging relay only switches when a sufficiently high battery or charging voltage is present at BOTH CONNECTIONS
  • Therefore, deeply discharged batteries are not accepted. The battery voltage must be > 10 (20)*V!
  • The charging relay also works as overvoltage protection in a 12V onboard electrical system. At charging voltages > 16 V, the relay remains switched off - batteries are not connected.
  • This charging relay does not switch / disconnect the batteries immediately, but the unit incorporates a DELAY !!!
    The time delay depends on the level of the charging voltage, see the following table.

Switch function Time delay DC-charging voltage(12-/ 24V-power)
Contacts closed 30 secs 13 V 27.2 V
2 mins 13.0 V 26.0 V
Contacts open 10 secs 12.35 V 24.7 V
30 secs 12.75 V 25.5 V
Overvoltage protection 16.0 V 32.0 V
Undervoltage shut down 9.5 V 19.0 V
Undervoltage reset 10.0 V 20.0 V

This charging relay is designed for use in wiring systems with lead-acid battery types (also AGM and gel).

It monitors voltage levels matched to lead-acid battery types and automatically switches on or off at specific levels.
We strongly advise against using this relay in conjunction with LiFe(Y)PO4 batteries, as the higher nominal voltage or working voltage range of lithium batteries is not compatible with the levels for lead-acid types.


en-flag Manual
PDF, 1,07 MB
de-flag Manual
PDF, 177,77 KB
Item no.: 20114

What other SVB customers have to say

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14 customer reviews

4.5 (out of 14 ratings)
3 Stars
1 Stars
Wolfgang G.
by Wolfgang G. Flag of Germany 9/5/2018 Verified purchase
top Qualität
Ralf D.
by Ralf D. Flag of Germany 7/18/2016 Verified purchase
Works easy and again it is ok
Fergus G.
by Fergus G. Flag of Germany 6/21/2015 Verified purchase
Great piece of kit. I had used a VSR before (not Blue Sea) but not with the disconnect on start. The disconnect function is a must. If you do not have the disconnect function there is a great danger of melting the system and causing a fire.
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