UK postal module repairs · Please confirm your part number before sending. Start a repair request
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Contact hours

Monday–Friday08:30–17:30
Saturday09:00–14:00
SundayClosed

UK time. Postal service and mobile visits by arrangement. Parts drop-off by prior arrangement. Contact us before visiting.

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Repair service by post
Warranty on repair
Tested in-house
⏱ Turnaround confirmed on receipt
Repair service

12V Lithium Battery BMS Reset & Repair – Mercedes-AMG, Porsche & Others

Repair from £275.00Assessment only — £45.00
Assessment fee deducted from an approved repair. Repair is not included in the assessment price.
Bench test & quote – deducted from repair
£45.00
No VAT added – we are not VAT registered
● Available to order
Choose your service REQUIRED
Unit & vehicle details
Not on our list for this repair – we will check it before any work starts.
Attached to your order, so we can match the unit when it arrives.
Current selectionBench test & quote – deducted from repair
£45.00
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Service overview

Professional repair, testing and return.

Bench testing, BMS reset and repair of 12V lithium (LiFePO4) starter batteries used in Mercedes-AMG, Porsche and other cars with a lithium 12V battery. A deep discharge often makes the battery management system lock the battery – it then shows 0V or will not take a charge, even though the cells are still usable.

Typical symptoms

  • Battery shows 0V or very low voltage after the car stood for a long time
  • Battery will not take a charge from a normal charger
  • Car completely dead or will not start
  • 12V battery or charging system warning on the dash

What we do

  1. Intake – photos, label, housing and terminal condition.
  2. Bench test – cell voltages, BMS communication and charge acceptance are checked and the fault is confirmed.
  3. Reset and repair – the BMS is reset, cells are balanced and recharged, and the battery is tested again.
  4. Report and return – written report and tracked UK return.

Price and payment

BMS reset and repair from £275. If the cells are worn out or damaged and the battery cannot be recovered, you pay only the £45 bench test, which is deducted from the repair if it goes ahead. Swollen or physically damaged batteries – contact us before sending.

Send a photo of the battery label on WhatsApp or through the repair request form and we confirm before you post it. Garages and fleets: trade terms. No VAT added – we are not VAT registered.

How to order

  1. Send us the battery part number from the label.
  2. Remove the battery and post it using our packing instructions, or drop it at the lab in Rainworth by appointment.
  3. We test, reset and return it with the report.
VEHICLE FITMENT
Compatibility guide
Compatibility is confirmed by part number – include it in your request
SystemRepair service

Vehicle lists are identification guidance, not a fitment guarantee. Send the complete part number and hardware revision for confirmation before ordering. A similar-looking unit is not proof of compatibility.

Find. Send. Fixed.

How the service works

Find your partCheck image, vehicle and part number.
Send your unitPost it or book a collection.
Initial testingWe inspect and confirm the fault.
RepairThe confirmed fault is repaired.
Final testingRetested before approval for return.
Back to youReturned with a test report.
Repair assurance

Warranty included

Service warrantyCovers the repair we carried out, for the period shown in our warranty terms.
Return for inspectionContact us before returning the unit – we guide you through the inspection.
Costs not coveredVehicle diagnosis, removal, fitting, coding and unrelated faults unless agreed.
Important: water ingress, physical damage, incorrect fitting or third-party modification may be excluded.