Steve Carter, Director of Train4Auto Consultancy provides us with some information of the dangers surrounding EV batteries and how as a dismantler, understanding these dangers are key to remaining safe on site.
I have been involved in automotive training for almost twenty years and in the last 12 years have become more specialised in electric vehicles.
First there were just hybrid vehicles, then plug-in hybrid vehicles, and now, battery electric vehicles.
Clearly all these vehicles share some similarities; a battery pack a power delivery module (Inverter/converter) to provide the 3 phase AC for the electric motors and to convert the 3 Phase from the motor when the vehicle is coasting in to DC in order to recharge the battery pack.
The most obvious risk is the high voltage that this system uses. However, there is a wide variation of battery and motor voltage throughout the industry.
There is the associated risks of chemical burns from the battery depending on its chemistry and this will also dictate the level of fire risk that is associated with the individual batteries. We have hidden risks with regard to the electric motors. Some of these motors will contain rare earth magnets which can produce enormous clamping forces, these magnets will affect the function of pacemakers.
The 1st generation of hybrid vehicles by Toyota and Honda used battery cells manufactured from nickel metal hydride chemistry NIMH. The Honda IMA Insight battery was around 100v. There is no voltage boosting for this system as the electric motors would also run at 100v but would now be 3 phase AC.
In the Toyota, most notably the Prius, the battery voltage is 201 volts. There is however a voltage boosting system that would now increase this voltage to 500v 3 phase. For the electric traction motors after 2009, this voltage was increased further to 650v 3 phase AC.
Even when the vehicle is powered down, it still has the potential for a fatal accident due to the ability of the power distribution unit (PDU) to store sufficient energy in the internal capacitor for up to 15 minutes.
The electrolyte used in NIMH battery chemistry is of an extremely strong alkaline with a PH of 14, fortunately, the electrolyte is of a thick paste rather than a free flowing liquid. However, if you were to become contaminated by this you would need special medical attention and the rapid application of boric acid to neutralise this electrolyte.
Over the last several years most manufacturers have moved to lithium-ion batteries which provide significant increase in range and performance over NIMH batteries.
The 1st application of this chemistry was the Nissan Leaf which started with a 24 kWh battery sufficient for about 90 miles of range. The latest generation Nissan Leaf has a 62 kWh battery giving a range of about 200 miles.
With higher end models, namely the Jaguar i pace which has a 90 kWh battery sufficient for over 270 miles of range and in excess of 400 horsepower, the guarantee on these batteries is long, in excess of 8 years in most cases, but at some point they will need to be dismantled or recycled. That could mean a second life as an energy store or using the recycling method to recover the raw materials including lithium and cobalt.
The biggest concern for the lithium-ion (Li-ion) battery is of course the potential for a thermal runaway and when a Li-ion battery enters thermal runaway there is no stopping it.
In the next article we will look at what can cause a thermal runaway and what actions you can take to minimise the effect of such an event.
For further information or guidance on the subject of EV batteries and the dangers that lie behind them, contact Steve at firstname.lastname@example.org