Tewaycell DIY-Gehäuse-Kit für GOTION 340Ah LiFePO4-Akkubox mit JK 200A BMS, Schutzschalter, 2A aktiver Balancer, stapelbare DIY-Akkubox

I received the kit directly from China. Although one picture differed from the manual, the support provided a workaround in less than 24 hours.

Even during shipment, I was already in contact with their support team, and they proactively provided me with additional information regarding the configuration with the Victron system. This specifically concerned the CAN bus protocol, as the Victron protocol needs to be activated inside the BMS. This worked out flawlessly.

The cells were perfectly matched, even after traveling halfway around the globe. The case is very well-designed with no sharp edges and no missing parts. I chose the kit with the 340Ah Gotion cells, and everything fitted perfectly. The only minor issue was a cable that didn't fit the screw specified in the manual, but Tewaycell confirmed it could be safely mounted to a nearby screw instead.

I highly recommend this kit to anyone with the right technical knowledge. I have built a 3-phase system consisting of three Victron MultiPlus-II 48/5000/70-50 inverters, managed by a Cerbo GX and connected to two Lynx Distributors with corresponding Mega fuses.

Out of the box, balancing was active across the entire voltage range, but it did not work well. Because of this, I tried switching to top-balancing only from 3.4V onwards, as many users online recommend. However, this caused frequent cell drift issues at the bottom, especially with cell number 4, which tended to drift at both the top and bottom of the voltage curve. I then reverted to full-range balancing but faced the issue that the balancer was constantly running without effectively leveling the cells. After adjusting the activation delta from 0.01V to 0.015V, performance improved significantly, and at 0.02V, it is now nearly perfect. The balancer now triggers precisely at the bottom and top as expected. If the cell drift ever exceeds 0.03V, I trigger a manual top-balancing cycle via my Home Assistant EMS, pushing the highest cell up to 3.45V. Thanks to the stability of the pack, this calibration run is only necessary every few weeks.

To maximize longevity, I strictly operate the battery between 3.1V and 3.4V per cell under normal conditions. The pack is charged and discharged at up to 7 kW, but the EMS dynamically throttles the power as soon as the lowest cell drops below 3.2V during discharging, or the highest cell exceeds 3.4V during charging. Even during the periodic top-balancing cycles, the 3.4V threshold is crossed with a heavily reduced charging power of maximum 3 kW. This slow approach allows the 2A active balancer to hold cell 4 below 3.45V long enough for the lowest cell to catch up to 3.42V.

Despite this highly conservative voltage window, I consistently get well over 15 kWh of usable capacity in and out of the pack. On some occasions, I have even reached around 17 kWh, though I haven't reproduced this often enough to fully validate it as a regular metric. Additionally, I configured the battery capacity inside the BMS to 350Ah instead of 340Ah, which significantly improved the accuracy of the SoC calculation.

I use this battery to expand my Sungrow SH25T and SBR256 system, orchestrating both Sungrow and Victron via Home Assistant. The Sungrow handles the base load, while the Victron system kicks in during heavy loads like EV charging, infrared heating, or AC operation. This massive capacity allows me to easily bridge multiple days of bad weather without any grid consumption.