Are higher voltage batteries safe for electric vehicles?

[PhysicsTest]

TL;DR Summary

General query on the operating voltages of the battery

I have few questions on the battery voltages for electric vehicles. Some vehicles operate at 48V battery and when i read the standards regarding these they mention above >60 V is hazardous and may lead to electrical shock and shall be avoided under all conditions. But i also see batteries with 72V used for electric vehicles, does this not raise any conflict as it is by default above 60V?

 

[DaveE]

Summary:: General query on the operating voltages of the battery

I have few questions on the battery voltages for electric vehicles. Some vehicles operate at 48V battery and when i read the standards regarding these they mention above >60 V is hazardous and may lead to electrical shock and shall be avoided under all conditions. But i also see batteries with 72V used for electric vehicles, does this not raise any conflict as it is by default above 60V?

Modern electric vehicles (Tesla, et.al.) use battery packs that operate at 100's of volts (Tesla's use about 450V). Your house is powered with 100's of volts (AC). Yes, these could kill you. However, if built and designed properly, the entire system can be safe. Perhaps like your lawn mower, which is also scary inside.

So, why >60V is dangerous? Well, safety standards have to have limits/rules. So, it's a bit arbitrary if you look closely, but still based on the likelihood of injury. They had to pick a number (numbers, actually). The most common limits for accessible voltage is 60Vdc or 30Vrms.

 

[anorlunda]

Where did you read that? Please give a link. Are you sure it did not refer to golf carts?

Here is some data posted recently.

 

[Baluncore]

The difference between an electrical contractor and a telephone linesman grew from the nominal 48 VDC battery used in telephone exchanges. When fully charged the voltage could peak at just less than 60 VDC.
Power distribution, employing higher voltages such as 110 VAC, with low impedance, were the domain of electrical contractors.

Each trade was trained, certified and standardised differently, so it was sensible to use the telephone system voltage as the upper bound to what became classed as “Low Voltage”.

There is no theoretical voltage at which things suddenly become dangerous. I expect that voltages as low as 32 V could be dangerous in some environments. High-current electric arc welding usually operates at about 24 V. It is not unusual for the operator to feel a “tingle” when surfaces are wet, but the current is not sufficient to cause an involuntary muscle contraction.

 

[Rive]

But i also see batteries with 72V used for electric vehicles, does this not raise any conflict as it is by default above 60V?

The high voltage parts are well built/covered: the equipment the user can directly interact still works with only low voltage.

The 'no user serviceable parts inside' warning is dead serious.

 

[Windadct]

OSHA has also specified that 50V is the safety limit for many industries (LINK) - above which presents enough of a hazard requiring the workers to be properly trained. So - for systems where it is commonly expected that unqualified the people working on the equipment will be exposed - they stick to 48V. ( Many trucks, fork or lift trucks, etc)

As is pointed out we have many cases using voltages higher than this - and in many cases the protections necessary to prevent unintended contact - especially by unqualified persons is significant.

In EVs this is a particularly difficult challenge, EV's are operated in hundreds of volts with a lot of discussion to have 1200-1500V systems in the 5 to 10 year range.

 

[Baluncore]

In EVs this is a particularly difficult challenge, EV's are operated in hundreds of volts with a lot of discussion to have 1200-1500V systems in the 5 to 10 year range.

There is an energy and cost penalty to buying and driving around with a heap of copper in the vehicle. Insulation is cheaper and it weighs less. Higher voltages cost less to buy and less to run.

I believe that now in Australia, you can work on automotive systems up to a nominal 50 V without certification. You need a high voltage ticket to work on higher voltage electric cars.
That is wise, as most people would be surprised by HV DC.

The same goes for solar panel arrays. Anyone can wire them in parallel, but you need a high voltage ticket to wire them in series.

Last time I looked at the rules in Australia, a ham radio operator needed a special exemption certificate before they change a vacuum tube in an old wirless set or their linear amplifier, even if they built it themselves when they were younger and more foolish.