A few of my customers have Victron ESS installations with lifepo4 battery banks. Some are home build battery banks with for example EVE cells (with BMS) others are just from third party’s commercial batteries.
For ease of installation and a clean look I like to use the Victron Lynx products. The battery banks connected individually to the “Lynx power In”, a “Lynx Shunt VE.Can” to determine the total SOC and a “Lynx Distributor” to connect the “Multiplus-II” inverters to. (and sometimes MPPT’s) The more higher-end DIY BMS (like for example Batrium) need an external contactor between the battery banks and the loads for under- and overvoltage situations or other emergencies. Unfortunately, there is no contactor option in the Victron Lynx line-up.
I’ve seen all kind of solutions but none have the same pleasing look as a row of Lynx “boxes”.
For example I found this picture here on the community (post from @Tony)
Because I’m almost certain I’m not the only one struggling with this I hope we all can share our ideas here. And who knows, maybe we give @Victron an idea for a new product in de Lynx line-up.
My shop went fairly far down the path of building such a device. Using an Arduino Nano, 500A TE contactor, pre-charge circuit, embedded SmartShunt, and USB communication to the computer. It was prototyped and we had PCB designed, but we killed it in the end. Machining and plating the copper copper bus bars for low volume production was going to make it as expensive as a Lynx Smart BMS for little margin so I killed the project. We are not really retailers and I wasn’t convinced we could sell enough to even break even. And since I quashed it, we didn’t get around to making a driver for VenusOS.
Many of us have asked Victron over many years for a product like this for smaller configurations but VE has declined to make a product like this.
We found that making the bus bars was a showstopper for us. If anyone out there has the means to cast or bend the copper bar stock, willing to do it in low volumes, and not expect to get rich doing it, speak up and maybe we could collaborate to make a kit for people who have a 3D printer. Injection molding would look better, but would need to be done in volume to bring the price down.
My solution to this is to use the “4 wire BMS” assistant in the Multiplus inverters for emergency shut-down on under voltage. This is normally set to 2.75V min cell voltage, to give some headroom for low level loads before recharging.
I did also use to use a relay in the PV circuit for over voltage situations, but the VE direct control of the MPPT’s has proved sufficiently reliable that this became a weak spot.
