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The Major Issue with 12V Batteries in Hybrid Cars

Model: (Various brands) Various
Part: Battery

Video tutorial

There is a known issue with 12V batteries in Toyota and Lexus hybrids: the batteries tend to fail prematurely (for example, in the Yaris Cross before 4,350 miles). The main cause is sulfation, which means lead sulfate crystals form on the plates and reduce the battery's capacity.

In hybrids, the 12V battery undergoes continuous micro-cycles of charge and discharge but is never fully recharged to 100%. This leads to the formation of these crystals, which over time becomes an irreversible problem. Is it a defect? No, it is a design choice by Toyota/Lexus, who prefer to 'sacrifice' the 12V batteries (economical and easily replaceable) rather than stress more expensive components, such as the inverter, converter, or traction battery.

The solution could be to use a smart charger every 3-4 weeks to desulfate the battery or replace the battery with a more robust AGM type that is resistant to micro-cycles.


Posted on 9 October 2026 by ScegliAuto


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AdBlue Tank Fault on Peugeot 2008

If the instrument cluster of your Peugeot 2008 sends an alarming signal as seen in the video, despite having just filled the AdBlue tank, the problem is not that the tank needs replacing - as authorised workshops simplistically suggest - at a cost of around £1,000. The first thing to do is to remember not to wait for the system to remind you that you are low on AdBlue, but to refill it every 5,000 to 6,000 miles, as the fault lies in the measurement of the tank level. Another good practice is to add an additive (yes, an additive in the additive) such as Tunap 988 (£23.99 on Amazon, with free delivery) which will prevent the AdBlue from crystallising.

Watch the video!


by ScegliAuto

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