In an EV’s complete operation flow, shunts play a pivotal role in making sure that there’s a low-resistance path running all over the vehicle’s electric current. This silver device is also characterized for being the device responsible for converting the high voltage and current flying all over the cables to something a meter can register. This device also works perfectly well with your ammeter in making sure that the EV you’re using won’t overload in ways that would cause damage to you and your unit in dashboard fires.
The in-car fires you will potentially be a victim to would be avoided by making sure that the shunts you install in your EV are always at their optimal level, bought from a genuine source and will have a product warranty that lasts for the longest time. By the way, if you’re ever curious, the term shunt originates from the verb “to shunt” which means to veer or turn away from a path or to direct something to a different trajectory of direction.
There are many functions of a shunt. From being a reliable circuit protection to applications involving a ladder topology, a shunt is a necessity in any electrical component. Being a low value calibrated resistor, another purpose of the shunt is to accurately and verifiably measure the current that passes through it. This current can be measured in a specified current and a millivolt rating. For example, if you have a 1000A 50mv shunt, then you’d have to have a resistance of about 0.00005 ohms (0.05v/1000a). This implies that when you have an ammeter shunt, you may be able to measure current values that could be too large to be measured with other types of ammeters.
We must add here that the shunts available for EVs may be rated by a variety of maximum currents with reference to a particular voltage drop set on that current. Most shunts are already designed to drop at around 50 mV, 75 mV or 100 mV when operating at their full capacity, but you may be able to use these shunts, still, for full-scale deflections of about 50, 75, or 100 mV.
The derating factors of these shunts also allow the EV to be used for continuous length, which could reach to as high as 2 minutes. You may even be able to expect these shunts to be at 66% operating capacity, which is regarded to be common. Just don’t forget to remind yourself always that these shunts are not advisable to be operated at 330A (and 50 mV drop) or anything longer than that.
Another interesting trivia to learn about shunts involves the Thomas-type double manganin walled shunt. This was the shunt used by NIST and other standard laboratories to also become the prime legal reference of ohm until it was being replaced by what is now known as the quantum Hall effect. Secondary standards will still take account using this type of shunt, but there are now newer alternatives as the EV technology continues to evolve.