BATTERY MANAGEMENT SYSTEMS (BMS)

What Does the BMS Do?

The Battery Management System (BMS) is what keeps a hybrid or EV battery pack safe and performing at its best. It continuously watches the voltage, current and temperature of every individual cell, and uses that data to work out the battery’s state of charge (how full it is) and state of health (how much capacity it has left compared to new).

One of its most important jobs is cell balancing. Individual cells in a large pack inevitably charge and age at slightly different rates, so the BMS redistributes charge between them so no single cell ends up overcharged or over-discharged, a fault that would otherwise shorten the whole pack’s life or, in a worst case, create a safety risk.

The BMS also controls the contactors that connect or disconnect the high voltage battery from the rest of the vehicle, and it will cut power immediately if it detects something unsafe, like overcurrent, overheating, or a fault anywhere in the pack.

Below you’ll find new, used and refurbished OEM BMS modules for your make and model, tested before shipping and covered by warranty.

Signs of a Failing BMS

• Inaccurate range or state of charge readings
• Battery refusing to charge or discharge normally
• Vehicle disabling the high voltage system as a safety precaution
• Fault codes pointing to a specific cell or a communication error
• Uneven power delivery, or unexpected loss of power

New, Used & Refurbished OEM BMS Modules

These BMS modules are available new, used or refurbished depending on your model. Each one is tested before shipping, with a 12-month warranty.

Compatible Makes & Models

Filter by make below, or search by part number.

Testing, Warranty & Exchange Service

Every BMS module is tested before it leaves our warehouse, and comes with a 12-month warranty. Exchange parts require a refundable deposit, returned once your original defective part is received.

Frequently Asked Questions

What happens if the BMS fails?

It can cause inaccurate range readings, unexpected loss of power, the battery refusing to charge or discharge, or in some cases the vehicle shutting down the high voltage system entirely as a precaution.

What is cell balancing and why does it matter?

It’s the process of equalising charge across all the individual cells in a pack. Without it, weaker or more-charged cells degrade faster than the rest, which drags down the pack’s total usable capacity and lifespan over time.

Can a BMS fault be mistaken for a battery fault?

Yes. Since the BMS is what reports charge and health to the rest of the vehicle, a faulty sensor or communication issue within the BMS itself can sometimes look identical to an actual battery problem, which is why correct diagnosis matters before replacing parts.