Some automotive technicians are going to be killed by the high voltages on electric vehicles. I have written many textbooks about automotive technology where I have highlighted safe working practices, but the one I have just completed the script for will save lives. This book is called, ‘Electric and Hybrid Vehicles’, and will be out early in 2016. By the way, we use the term EV to cover all the different types there are such as hybrids and pure-EVs.
Did you know the voltages on some EVs can be several hundred volts, which is almost three time the mains voltage in our houses? The majority of EV batteries are well over 300 volts. If the human body experiences a current of just fifty thousandths of an ampere (50mA, which is not very much) for over two seconds it can be fatal.
Now that I have scared you away from ever touching high voltage components (which are all labelled and usually coloured orange) I would add that working on EVs is perfectly safe! You just need to be trained and know what you are doing. Driving an EV is also perfectly safe and don’t expect poor performance either. My EV will do well over 80 miles per hour (on a private track!) just using the battery and electric motor.
Of course as well as saving lives, the book is packed with really interesting information and technology relating to EVs. For example, whether it is safe to plug in the charging lead in the rain. How most motors on EVs are AC motors but we call them DC motors! The book even covers things like what ‘first responders’ should do if a lithium-ion battery is burning after an accident. The book covers all the requirements for the Institute of the Motor Industry (IMI) awards and accreditations for those who need a qualification. Look out for the amazing eLearning that will also be available soon to support the book.
I have also included a short case study on charging my own EV (actually a PHEV) from solar panels. This may or may not save the planet but in the meantime it does save me money as I can now do a large proportion of my motoring for about 1p a mile.
Here are three more interesting facts to finish on:
A formula-e (fully electric racing car) will accelerate from 0 to 100 kilometres per hour in under 3 seconds
- The Tesla Model S (a fully electric car) has a range of up to 330 miles
- In the year 1900, electrically powered cars were the best-selling road vehicles in the USA
Now back to the final proof read of the script!
it before that we don’t need 300 mile range e.v’s but a relaly good fast charge network and today’s fast chargers will be slow in just a few years.For most people the range is good enough but it’s the trips to the sea, the mountains, the West coast etc that will not be practical and e.v owners may not want a normal car sitting in the drive.I also don’t get why there are charge points in train stations ? most people driving to a train station isn’t driving 60+ miles to catch a train and I would imagine one charge will probably do them a week. The only thing I think they will be useful for is having your car hooked up so as to have it warmed up or cooled down when you get in Also where are the fast AC charge points ? the 44 KW ones suitable for Zoe ? not one installed yet. Look on the ecars site and you will find maybe 22 fast DC points. and 0 44 KW AC, which may not be available yet, I’ll give them that. Beatrice, I’m sorry to rant on your blog, I bet they told you people like me might appear ? I relaly want e.v’s to succeed and I wish you luck with the leaf.Please blog more and take it for weekend trips, I’ll be interested to see how you get on.
Hey Waka, my local train station has charge points and it is just a few miles from me so i don’t need one – however, many people drive say 20 miles to the station and then take a train to the city – so idea for them I guess!
It takes about 60VDC to kill a healthy adult. So after an EV has crashed the insulation be have been pierced by a part of the chassis the whole car will be sitting on rubber tyres with a deadly potential of 300VDC plus. Anybody touching any part of the car will die as the current goes to earth – and you say that EVs are safe!!
Good to be debating this Andrew but I stand by my statement that EVs are safe. You are correct about the 60VDC (but you would actually have to be quite unlucky to die from this). In an EV accident, the high voltage battery is automatically disconnected. But extreme strange happenings are always possible, such as the battery positive shorting to the chassis. However, even if this happened and if you touched the chassis or car body you would not get a shock because there is no circuit to complete because the negative side of the battery is not connected to earth. You DO get a shock from house electricity like this becasue the neutral side is effectively earthed. Driving and working on EVs is very safe – as long as you are fully trained of course!
DC is very dangerous because it can hold on to you which is why electrical engineers always keep one hand in their pockets. Your comments on batteries being safe if they are dead shorted is just plain wrong Batteries will simply explode after abut of ‘arc welding’ which will set the car alight
Check out dummies.com for more info
I am unsure what point you are trying to make here. My original posting was that EVs are very dangerous to work on unless you have the knowledge and training. You seem to be supporting this but trying to say I am wrong at the same time. DC is dangerous I agree. However, another point to clear up here is that EV batteries are insulated earth return so are NOT already connected to the chassis. One pole accidently touching the chassis is NOT a dead short across the battery, and I didn’t say it was. To cause a short circuit both poles of the battery would need to short to the vehicle body. This can happen and certainly could cause arcing and a fire, but is unlikely as the battey cut out contacts would open. More likely is that the battery could be damaged and cause fire. All of these awful scenarios are possible but in use the EVs are no more dangerous than a vehicle with a tank full of flamable liquid. I stress again, working on these vehicles is dangerous – unless you know what you are doing. Same for electrical engineers and what they do (although hardly any work on DC anymore). Perhaps you should refer yourself to dummies.com.
Are you saying that you insulated ‘earth return’ goes straight back to the negative pole without and is covered with an impenetrable plastic sheath that no shard of chassis can penetrate in the event of a bad accident – like a head on. If so, where can I get this wonderful stuff?
No but we still seem to be arguing for the same thing here! Of course anything is possible but like with all safety aspects, it is a matter of reducing the risk as much as possible. In the same way as fuel tanks are made to survive an accident (not all of them of course), high voltage wiring, and batteries are positioned and designed to reduce the chance of any or both terminals being shorted at the same time ie. the dead short scenario. Nothing will survive a catastrophic incident and this is the same for EVs or IC vehicles. Under normal operation, and even in many acccident situations, I still mantain that EVs are safe and arguably, safer than sitting next to a large petrol tank! Same when working on high voltage (be it up a 400,000 volt ac pylon or on an 800 volt dc vehicle (coming soon!!) it is safe if you reduce the risk as much as possible, but hey, accidents will still happen.