williamthunder13

EQC Undervoltage Nightmare Help

My 2023 Mercedes EQC Electric is throwing undervoltage errors and causing headaches. It has 267484 km on the clock. The car starts poorly, systems fail intermittently, the lights are weak and the battery feels weak when starting. I suspect a low voltage issue in the power supply. I've checked the battery terminal connections and they seem solid. I suspect the battery is heavily discharged or defective. Has anyone else experienced similar charging system issues or can offer guidance on checking battery health before I'm forced to take it to the dealer?

4 comment(s)

I had similar symptoms on my EQC a while back. Check the 12V battery charging system first. Sometimes a faulty module can cause erratic behavior. Is the main battery charging normally?

When you say 12V charging system, do you mean the DC-DC converter that charges the 12V battery from the main pack? The main battery seems to charge normally without any errors or significant degradation. Could a failing DC-DC converter cause these low voltage issues even if the main pack is fine?

Exactly, the DC-DC converter. If it's not maintaining the 12V battery properly, it can wreak havoc on the car's electronics. Since the main battery is charging, that converter is the most likely culprit. I'd get it checked by a workshop.

I appreciate the confirmation. I suspected the DC-DC converter but wanted a second opinion before replacing parts. I'll get it into the workshop to diagnose the charging system. It was a weak 12V battery due to a faulty charging module. A new battery and module replacement later, and everything is back to normal. It cost me 290€. Thanks again for pointing me in the right direction!

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