Lynx BMS NG Install: lynx to Power-In vs. lynx to Distributors? Have to choose

DIY
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1

Hello there!
I’m doing a full lithium + solar + DC distribution refit on a sailboat and due to space constraints I have to choose wether to install the Smart BMS 1000NG either:
Option A: in the battery compartment linked directly to x2 Class-T Power-Ins that are the battery busbars, and from the BMS a 2metre long thick backbone wire to 2x Lynx Distributors

Option B: in the electrical compartment (2 metres away from battery compartment) linked directly to x2 Lynx Distributors, wired to the Power-Ins via a 2 metre long thick backbone wire.

From both functionality and safety perspectives, is there any preference as to where to place the BMS of these 2 options? I have reviewed all Manuals and example diagrams and cant find anything related to this scenario.
Obviously best option would be to connect all Power-Ins + BMS + DIstributors via the lynx mechanism, but it’s simply not an option with the space I have.

Thank you!

2

The safest approach is always to have the fuses as close to the batteries as possible with the shortest length of unprotected cable. AYBC in the US and ISO standards in Europe have specific rules regarding how close fuses must be to the batteries/ how well the cable between the battery and fuse is protected.

3

Thanks for the feedback , much appreciated.

Fully agree on the fusing, hence the T-Class Power-Ins planned right next to the batteries as a must, but my doubts are about the BMS itself, wether to install lynxed on the battery power-ins(busbars) alongside the batteries, or to install lynxed to the Distributors, in a separate distribution compartment further “downstream”.

I assume it likely works fine both ways, but for sure there is a prefered way…

4

I have wiring between Class T fuses next to the batteries and the Lynx BMS, the Lynx BMS is connected to the Lynx distributor. I could not fit them all together either. One factor in my choice is the batteries are in the engine bay which is normally dry but does have a risk of water being present, wheras the electrical locker is dry and the Lynx BMS does not have a high IP rating. I have no idea if this applies in your case. Another factor is the fuse sense connection to the Lynx distributor, this is easier if the BMS and distributor are connected. Otherwise I see no difference functionally.

5

The Lynx BMS NG is also acting as a shunt if I understand correctly. Shunts should be as close as possible to the battery for better accuracy.

6

For voltage accuracy yes, so the extra wire will have some voltage drop, good point, but for coulomb counting for SOC it makes no difference. The NG batteries also have full voltage and current measurement within the batteries, which is then communicated to the BMS.