High-voltage battery repair for Tesla Model 3 and Model Y near Lviv, Ukraine. We find the cell group that causes the imbalance and the BMS_a066, BMS_a064 or BMS_a079 alerts, restore it and balance the battery — without replacing the whole pack.
The battery management system (BMS) monitors the voltage and capacity of every cell group. When one group falls behind the rest, the BMS raises an alert and limits charging or power. These are the alerts people most often come to us with.
An early sign of imbalance: one or more cell groups hold a lower state of charge than the rest of the battery. The car is still drivable, but without repair the imbalance usually grows.
May show: “Maximum charge level and range may be reduced”
The next stage after BMS_a066: the gap between cell groups has widened and the BMS limits the maximum charge (often to about 50%).
Result: less range, the car won't charge fully
The BMS has detected a problem inside the high-voltage battery and won't let it charge above 50%. The most common cause is imbalance or a weak cell group.
On screen: “Unable to charge – maximum charge level reached”
The capacity of cell groups in one module has drifted apart: one group holds less energy than the others. The BMS limits power and charging; with BMS_a068 it requires service.
On screen: “High voltage battery performance limited”
Similar alerts on 2012–2020 Model S and Model X: imbalance between cell groups or a weak group. The BMS lowers the maximum charge level.
On screen: “Maximum battery charge level reduced”
Codes differ by model and year, and the same alert can have different causes. So we don't just clear the alert — we check the voltage of all 96 cell groups and the battery's behaviour under load, and fix the actual cause.
BMS_a027, BMS_a035 are isolation alerts, not imbalance
On a full charge the car goes noticeably less far than before, or the charge percentage drops sharply while driving.
The Tesla won't charge above a certain level (often 50%), charging doesn't start, or the battery limits power.
One module of the pack behaves differently from the others (for example, it was replaced before). We see it in diagnostics and offer a solution.
We read the BMS and the voltage of every cell group with our app and test the battery under load. We show you the results.
We explain exactly what is faulty and quote the price before starting work.
We restore the faulty part and balance the battery, recording the state before and after.
A repeat diagnostics run and handover of the car with a warranty on our work.
