Why extending ESC wires can be harmful

Did you know that extending the wires on your ESC can actually be harmful for your ESC? Yep, it’s true, extending wires on the battery side of the ESC can put a lot more stress on your ESC. This is for brushless motors.

Cutting ESC Wires - Water Hammer Effect

Cutting ESC Wires – Water Hammer Effect

Why extending wires can be harmful?

Extending your battery wires are only harmful on the battery input side of the ESC. The battery is the source of power that feeds the ESC current at a specific voltage. The ESC is responsible for sending the correct pulses of current to the brushless motor. In order to accomplish this, the ESC must be in sync with the exact rotational position of the motor. When the correct winding position matches up with the correct pole of the permanent magnet on the motors rotor, the ESC sends a pulse of current that allows the motor to rotate to the next position where this process repeats.

During this process the current that is passed by the ESC turns on for a split second and then shuts off for a split second. This repeating process is continuous as long as the motor is on. Now imagine the power coming from the battery rushing toward the motor and then all of a sudden it is shut off. We can think of a similar situation occurring with water within our own homes.

The water hammer effect

The water hammer effect is what many would more recognize within your own home. Take the same approach as we just covered but apply it to your faucet at home. Or even another high volume water valve. When you run the water at maximum velocity through one of these valves and then rapidly shut that valve as quickly as you can, you are inducing the water hammer effect within the pipes that feed that faucet or valve. Depending on a number of different factors within this plumbing in your home, you may very well hear a “hammer” type sound within the pipes.

We hear this hammer type sound as the water is forced to come to a complete stop. Upon coming to a complete stop, a shock wave is produced that ends up travelling back down the pipes.

This type of effect can be very damaging. Especially in areas where there is a very high volume of fluid travelling in pipes and abrupt changes. Although a water hammer in the home can be damaging if it is bad enough, water hammers throughout the house usually don’t cause catastrophic damage.  Either way, you don’t want them.

Water hammer in our ESC

The exact same thing happens within our ESC’s. This ripple effect caused within the wires of the ESC on the battery side, must be dampened in order for proper ESC function. You can see large capacitors on the input side of every brushless ESC. The job of these large capacitors is to smooth out the different pulses that exist in the main input circuit. These capacitors can be seen in the image above. Just the tips of the capacitors are outside of the heat shrink.

However, even large capacitors have a maximum capacity. If these capacitors are pushed hard they eventually can fail. If these capacitors fail, your ESC is destined to fail.

You never want this to happen. If it does, you are left with an ESC that can’t even be used as a paper weight since it will be burnt to a crisp.

Can you safely extend wires on an ESC?

The quick answer is yes. You can increase the length of wire between the ESC and motor quite easily with nothing special added. However, extending the length of the wires from the ESC input side to the batteries is possible but takes a bit of effort to complete successfully and safely. We will cover this in another article.

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