This is a design I did using (2) Tesla model S batteries in a late model 19' Airstream RV upgrade.
1. Wiring the ribbon cables with to the tesla batteries was buggy, I never got them right to work consistently using different methods wire sizes and connection methods.
2. The BMS would then at times fault by attempting to push more power into one of the cell groups (the BMS thought that one of the cell groups was out of balance) I always checked manually with the volt meter and always found the cell balanced. Random volt level checks on the cells always show very near balanced.
3. The BMS had issues with when it “acts” on the LVD and the HVD events. In a HVD event, since it used the single group highest value/lowest Value for HVD and LVD .. this didn’t quite test out either.
Because of the way the BMS seemed to introduce issues I elected to remove it from my design and have since used a “supervised” approach. My rate of discharge is low and charge rate I can easily control to a slower charge setting on my inverter when on shore power. I have also found that the Victron components work flawlessly at HVD, temperature and LVD shutoff events as primary protection. We have used it for one full season and we hardly even monitor anything while boondocking (1 week offgrid) The batteries stay very cool even when we occasionally use the AC.
Since Cell balancing seems always very much in check just using the native Tesla batteries I am thinking of sticking with a design that does not leverage a BMS. Is this a bad idea or should I pursue another BMS solution.
- (2) Model S Batteries were wired in Parallel 24v system
- Victron Inverter, MPPT Solar Charge Controllers converter (for 12v) all components Victron
- About 500 watts of solar panels
- I fused all of the connections and wired 1/0 from the batteries to the Buss
1. Wiring the ribbon cables with to the tesla batteries was buggy, I never got them right to work consistently using different methods wire sizes and connection methods.
2. The BMS would then at times fault by attempting to push more power into one of the cell groups (the BMS thought that one of the cell groups was out of balance) I always checked manually with the volt meter and always found the cell balanced. Random volt level checks on the cells always show very near balanced.
3. The BMS had issues with when it “acts” on the LVD and the HVD events. In a HVD event, since it used the single group highest value/lowest Value for HVD and LVD .. this didn’t quite test out either.
Because of the way the BMS seemed to introduce issues I elected to remove it from my design and have since used a “supervised” approach. My rate of discharge is low and charge rate I can easily control to a slower charge setting on my inverter when on shore power. I have also found that the Victron components work flawlessly at HVD, temperature and LVD shutoff events as primary protection. We have used it for one full season and we hardly even monitor anything while boondocking (1 week offgrid) The batteries stay very cool even when we occasionally use the AC.
Since Cell balancing seems always very much in check just using the native Tesla batteries I am thinking of sticking with a design that does not leverage a BMS. Is this a bad idea or should I pursue another BMS solution.