France in Focus

When I was ten, my father gave me a crash course in the secrets of electricity: the difference between alternating and direct current, resistors, capacitors, transformers, fuses, wiring. And also a bit about lead-acid car batteries: ageing, internal resistance (voltage drop) and the danger of sulphation of the plates. Those basic concepts take you a long way, but nowadays, in automotive engineering, there is a lot more involved in testing, for example the batteries in EVs. Somewhat to my surprise – or should I honestly admit, my preconceptions - the average state of health of EV batteries isn’t too bad. But there are exceptions that are particularly important when buying a second-hand EV.

Compared with more or less old-school measuring techniques for lead-acid batteries there are now more advanced instruments (left) on the market, within reach of a DIY's budget. It checks 6/12/24 V batteries, including a lot of other measurement options. A handy, compact and versatile meter. Is it yes or no, replace? A car battery delivers the massive electrical surge required to crank the engine and initiate combustion. State of health okay, it supplies 400 to 800 Cold Cranking Amps (CCA) instantly, but as it ages or loses charge, the starting behavior changes noticeably, voltage drop. A dip lower than 9 volts is not a good sign, see what happens when you start the engine, voltage drop and then it goes up, the alternator springs to life as illustrated here with a Launch OBD2 scanner. And now on to the professionals.

Industry Benchmark Report.

If the "Industry Benchmark Report" is telling the truth about battery longevity, I am impressed. I have maybe paid too much attention to reports of the inherent dangers of sitting inside a metal box with an unstable bomb under my seat.

I still don't want one.

A bit confusing mixing up EV batteries with the normal car battery. It must be remembered that EVs have both except the aux battery is only for lighting, fans, small stuff and has no substantial CCA as it has no starter motor to crank. Notably, EV aux batteries must not be used to jump start another car.

Just a quick clarification, in the hope of not adding to the confusion. Although these lead-acid batteries are not designed to crank a starter motor, they share the same vulnerabilites with the batteries for ICE engines. The rather dangerous high voltages in the EV/hybride battery packs (up to 800 V) don't mix with standard and affordable 12 V parts. The main battery pack is disconnected when you switch off the car, high voltages are to be treated with some respect. Charging of the 12 V battery with a DC/DC converter, goodbye alternator. The 12V battery also supplies power to the relays that activate the main battery pack. According to the German ADAC organisation, the most common cause of breakdowns in almost every car: problems with the 12 V battery, 50 % of breakdowns in EVs are attributable to the starter battery, compared with 45 % for combustion-engine vehicles.

These problems have been taken into account in an Austrian research project. Aim: to fundamentally transform the electric car – and trying to make the traditional starter battery obsolete. Scientists from the Silicon Austria Labs research centre, alongside the companies Infineon Technologies Austria and AVL List, have been working together on new solutions for modern electric vehicle electrical systems. How to get more compact and reliable electrical systems. After two years this so called REDSEL research project has now been completed. According to the researchers, the focus was on developing a redundant electrical system architecture, a fail-safe power supply in electric vehicles.

Promises, promises, but as far as I can tell, as a DIY enthusiast, there won’t be much change in the testing methods for our old friend, the lead-acid battery (for the time being).