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Lynx Smart BMS

5. Installation

In this section:

5.1. Important warning


Lithium batteries are expensive and can be damaged due to over discharge or over charge.

The shutdown due to low cell voltage by the BMS should always be used as a last resort to be on the safe side at all times. We recommend not letting it get that far in the first place and instead either shutting down the system automatically after a defined state of charge (this can be done by using the Discharge floor setting in the BMS) so that there is always enough reserve capacity in the battery, or to use the remote on/off function of the BMS as a system on/off switch.

Damage due to over discharge can occur if small loads (such as: alarm systems, relays, standby current of certain loads, back current drain of battery chargers or charge regulators) slowly discharge the battery when the system is not in use.

In case of any doubt about possible residual current draw, isolate the battery by opening the battery switch, pulling the battery fuse(s) or disconnecting the battery plus when the system is not in use.

A residual discharge current is especially dangerous if the system has been discharged completely and a low cell voltage shutdown has occurred. After shutdown due to low cell voltage, a capacity reserve of approximately 1Ah per 100Ah battery capacity is left in the battery. The battery will be damaged if the remaining capacity reserve is drawn from the battery, for example, a residual current of just 10mA can damage a 200Ah battery if the system is left discharged for more than 8 days.

Immediate action (recharge the battery) is required if a low cell voltage disconnect has occurred.

5.3. Mechanical connections

5.3.1. Lynx Smart BMS connection features

  • The Lynx Smart BMS cover can be opened up by unscrewing the two cover screws.

  • Removable rubber sleeves to protect the busbar ends.

Lynx_module_cover_screws small housing.svg

Location of front cover screws and the removable sleeves

5.3.2. Mounting and interconnecting Lynx modules

This paragraph explains how to attach several Lynx modules to each other and how to mount the Lynx assembly into its final location. These are the points to take into consideration when interconnecting and mounting Lynx modules:

  • If Lynx modules are going to be connected to the right and if the Lynx module is fitted with a plastic barrier on the right side, remove the black plastic barrier. If the Lynx module is located as the most right module, leave the black plastic barrier in place.

  • If Lynx modules are going to be connected to the left, remove the red and black rubber sleeves. If the Lynx module is located as the most left module, leave the red and black rubber sleeves in place.

  • Remember that for a Lynx Smart BMS, the left side is the battery side, and the right side is the DC system side.

  • Connect all Lynx modules to each other using the M8 (or M10) holes and bolts on the left and right. Take care that the modules correctly slot into the rubber joiner recesses.

  • Place the washer, spring washer and nut on the bolts in the correct order and tighten the bolts using a torque of:

    M8 Model: 14Nm

    M10 Model: 33Nm (17Nm for units with a serial number before HQ2340XXXX)

  • Mount the Lynx assembly in its final location using the 5mm mounting holes.


Connection sequence when connecting two Lynx modules

5.4. Electrical connections

5.4.1. Connect DC wires

For all DC connections the following applies:

  • All cables and wires connected to the Lynx module need to have been fitted with M8 (or M10) cable lugs.

  • Pay attention to the correct placement and order of the cable lug, washer, spring washer and nut on each bolt when attaching the cable to the bolt.

  • Tighten the nuts using a torque of:

    M8 Model: 14Nm

    M10 Model: M10 nuts: 33Nm (17Nm for units with a serial number before HQ2340XXXX) - M8 nuts: 14Nm


Correct placement of the M8 (or M10) Cable lug, washer, spring washer and nut

5.4.2. Connect RJ10 cable(s)

These instructions only apply, if the system contains Lynx Distributor(s).

There are two RJ10 connectors in each Lynx module, one on the left and one on the right. See below drawing.


Locations of the RJ10 connectors and RJ10 cable recesses on the Lynx Distributor, Lynx Smart BMS and the Lynx VE.Can

To connect the RJ10 cables between the Lynx Smart BMS and Lynx Distributor, do the following:

  • Plug one side of the RJ10 cable in the RJ10 connector of the Lynx Distributor, with the retainer clip of the RJ10 connector facing away from you.

  • Feed the RJ10 cable through the recess at the bottom of the Lynx Distributor, see above picture.

  • Plug the RJ10 cable into the RJ10 connector at the bottom of the Lynx Smart BMS.


Connection example Lynx Smart BMS system - RJ10 cables indicated in yellow

5.4.3. Connect BMS cables

Connect the BMS cables from the lithium battery to the BMS connectors on the Lynx Smart BMS.


Location of the BMS cable connectors

In case multiple batteries (up to 20 batteries can be connected to the BMS) are used, first interconnect the battery BMS cables and then connect the BMS cable from the first and last battery to the BMS connectors on the Lynx Smart BMS.

If the BMS cables are too short, use BMS extension cables.


Lynx Smart BMS battery BMS cable connection examples

5.4.4. Connect the Multiconnector

The multiconnector is the green connector on the bottom of the Lynx Smart BMS. The connector of the Lynx Smart BMS 500A has 11 pins, numbered from left to right starting with pin 1 and ending with pin 11, while the connector of the Lynx Smart BMS 1000A has 13 pins - two additional pins (pin 12 and 13) for future functionality. Do not connect anything to pins 12 and 13.

See the Appendix for a table with pin-out and description.

The multiconnector’s screw terminal can be pulled out of the Lynx Smart BMS, allowing for easy wiring.

The Remote on/off (pin 10 and 11) of the terminal are interconnected with a wire loop by default. If the Remote on/off connection is used with a simple on/off switch, remove the loop and wire as desired.


Multiconnector location

5.4.5. Connect ATC/ATD controlled loads and chargers

The ATC (allow-to-charge) and ATD (allow-to-discharge) are potential free dry contacts of the multi connector that can control chargers and loads in the system, provided they have a remote on/off connector and are wired appropriately. They can be used in several ways.

A common example is by providing +12V wired from AUX + (equal to system voltage) to pin 3 and pin 5. An active high signal is then delivered to the connected remote H ports of the chargers and loads via pin 4 respectively pin 6. In case of a low cell voltage, ATD opens the contact between pin 5 and pin 6. The load is then switched off and further discharge is prevented. If the temperature is too low to charge, the ATC contact between pin 3 and pin 4 opens and switches off the chargers.

Instead of using system voltage on AUX +, system minus can be used on AUX - to generate an active L signal. The functionality is the same as described above, except that the low signal ensures that the loads and chargers are switched off. This active L signal then can be connected to the remote L terminals of a charger or load. In contrast to the H signal, System minus is also present in case the contactor opens and the Lynx Smart BMS goes into OFF mode.

Another option is to use the ATC and ATD contacts as remote switches, for example to control a Smart BatteryProtect to turn off loads in the event of low cell voltage or a charger in the event of low temperature.

See below examples for wiring:



For the system to operate correctly, it is essential that all loads and chargers are able to be controlled by either DVCC or the ATC and ATD signals. Ideally wire the ATC and ATD signals to a devices remote on/off connector, or, if that is not available, a Smart BatteryProtect or Cyrix-Li can be used.

5.4.6. Wiring a Remote on/off switch

Instead of the pre-installed wire loop between pin 10 and pin 11, a simple on/off switch can be wired to remotely turn the Lynx Smart BMS on and off.

See below example for correct wiring:


Simple Remote on/off switch wired between pin 10 and pin 11


For the Lynx Smart BMS to operate, the contact between pin 10 and pin 11 must be closed.

5.4.7. Programmable relay wiring

The programmable relay is an SPDT relay (Single Pole, Double Throw) with 3 contacts:

  • Common (COM)

  • Normally Open (NO)

  • Normally Closed (NC)

The relay makes contact between COM and NC when the relay is not active, while COM and NO makes contact when the relay is activated.

Depending on the Relay mode setting (Alarm relay or Alternator ATC) in the VictronConnect app, an audible (buzzer or external speaker) or visible device (LED signal) or the signal line (usually the ignition wire) for the ATC signal of an external alternator regulator can be connected.


Pinout for the programmable relay

5.4.8. Connect the GX device

Connect the Lynx Smart BMS VE.Can port to the GX device VE.Can port using a RJ45 cable.

Multiple VE.Can devices can be daisy chained, but make sure that the first and the last VE.Can device both have a VE.Can RJ45 terminator installed.

Power the GX device from the AUX + and AUX – terminal of the Lynx Smart BMS.

Lynx Smart BMS VE.Can connections

Location of the VE.Can connectors on the Lynx Smart BMS


Wiring example Lynx Smart BMS and a CCGX

5.5. System examples in detail

5.5.1. Lynx Smart BMS, 2x Lynx Distributor and lithium batteries

A Lynx Smart BMS with two Lynx distributors and a Cerbo GX with GX touch panel form the heart of this system. They continuously monitor the batteries, fuses, connected loads, chargers and inverter/charger(s).

A typical system can contain the following components:

  • Lynx Smart BMS with built-in contactor and battery monitor.

  • Lynx Distributor with 2 fused paralleled lithium batteries and identical cable lengths for each battery (up to 20 batteries can be used per system - see the Lithium Battery Smart manual for details).

  • Lynx Distributor with fused connections for chargers, inverter/charger(s) and loads.

  • A Cerbo GX (or other GX device).


System with Lithium batteries, Lynx Smart BMS and two Lynx Distributors

5.5.2. Lynx Smart BMS, 1x Lynx Distributor and lithium batteries

The same as before, but this time with a single Lynx Distributor on the load side of the Lynx Smart BMS and the lithium battery connected directly to the input of the Lynx Smart BMS. This is useful if only a single lithium battery or a single series string of lithium batteries is used. Otherwise the same components are used.


System with a Lynx Smart BMS and a single Lynx Distributor

5.5.3. Lynx Smart BMS only

For a very slim line system, the Lynx Smart BMS can be used just by itself. This is usefull if the system contains a single lithium battery or a single series string of lithium batteries together with a simple DC system.

Please also note that no GX device is used. It is not absolutely necessary for the operation of the Lynx Smart BMS. However, without GX device it is not possible to control compatible inverter/chargers and MPPTs via DVCC.


System with a Lynx Smart BMS, without other Lynx modules and GX device.