Why Is My Traxxas ESC Flashing Red and Green?

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An issue I recently encountered with my Traxxas ESC flashing red and green. It was somewhat alarming when I first saw it, as I thought it meant a serious problem with my ESC. But here’s what I found out about why my Traxxas ESC was flashing red and green.

A Traxxas ESC that’s flashing red and green is giving an over-voltage warning. It usually indicates the connection of an overcharged battery to the ESC. It can also happen when trying to use a NiMH battery if the ESC is in Low-Voltage Detection (LVD) or LiPo battery mode.

It turns out I didn’t need to be alarmed by the flashing red and green lights on my Traxxas ESC. I’ll explain why in more detail below. So if you’re experiencing the same issue, stay with me to find out why it happens and how you can fix it. 

Why Is My Traxxas ESC Flashing Red and Green?

Why Does a Traxxas ESC Flash Red and Green?

The flashing red/green light on a Traxxas ESC is an over-voltage warning light. It can be frustrating when it seems to happen for no apparent reason, as the guy in this video found:

Hopefully, I’ll save you from that sort of frustration by highlighting a couple of reasons why a Traxxas ESC flashes red and green.

The Battery Voltage Is Too High for the ESC

The most obvious cause of the ESC flashing red and green is because the ESC has detected a battery with a voltage higher than it can cope with.

To clarify this potential cause, I’ll explain a little about the two battery types that Traxxas ESCs can take.

Nickel-Metal Hydride — NiMH

Some remote control (RC) vehicles come with a NiMH battery included because such batteries are relatively cheap. But they’re also pretty sturdy and easy to take care of.

One NiMH cell carries 1.2 volts, and most NiMH batteries come with 6 or 7 cells. You can get a maximum voltage on NiMH batteries of 8.4V.

Lithium Polymer — LiPo

LiPo batteries are lighter and produce more power than NiMH batteries, which is why they’re often more expensive.

LiPos usually have 2 to 6 cells. But, each LiPo cell carries 3.7 volts. A 6-cell LiPo has a voltage of 22.2V.

Now, let’s assume I’m using the Traxxas XL-5 ESC. It can take a maximum of 8.4V from a NiMH battery and a 2S LiPo. As I’ve explained above, 8.4V is the maximum voltage on a NiMH. I’ll have no problem using a 7-cell NiMH battery on this ESC. 

However, LiPo batteries go up to 6 cells or 22.2V. If I try to attach a 6-cell LiPo to the XL-5 ESC, I’ll get the red and green flashing over-voltage warning light. The ESC effectively prevents me from using the battery by locking itself.

The solution is to use a battery with a voltage compatible with the ESC’s maximum voltage limit.

But, the over-voltage warning can happen even if the battery voltage is okay. Here’s another potential cause.

Traxxas ESC Was in LVD Mode When Powered On With NiMH Battery

One drawback of LiPo batteries is they don’t appreciate it if you over-discharge them. 

LiPos generally have a minimum discharge voltage of 3V. Discharging them below that level can cause irreversible damage and reduce battery life.

It can also cause the battery to swell up. Now, that’s something LiPos does over time, but over-discharging accelerates it. A swollen battery creates a fire hazard and needs safe disposal.

ESC Low Voltage Protection Mode

For this reason, most Traxxas ESCs have a Low-Voltage Detection (LVD) setting for use when using LiPos. This setting protects the LiPo from over-discharging. 

The LVD setting monitors the battery’s voltage to ensure the voltage doesn’t drop below the battery’s minimum voltage. Once the battery nears the minimum, LVD reduces the power to the throttle. Eventually, the LVD system will shut down the motor to prevent the battery voltage from falling below its minimum voltage.

NOTE: It’s vital to have LVD turned on when using LiPos. But, it’s not necessary when using NiMH batteries. 

I can run a NiMH battery right down without impacting its performance or damaging it. In fact, using a NiMH battery with LVD turned on can reduce the runtimes.

When a Traxxas ESC with LVD is set for LiPo use, its light glows solid green. When set for NiMH use, the light is red, indicating LVD is off.

By why, when powering on a Traxxas ESC using a NiMH battery, does the ESC light sometimes flash red and green.  

It seems Traxxas ESCs sometimes don’t like it when they’re powered on with a NiMH battery. 

What Causes the Lights To Flash Red and Green When Powering On With NiMH?

I have to admit; I was confused by the ESC light flashing red and green. Because usually, when I swap out my LiPo for a NiMH battery, it’s as simple as connecting up the NiMH battery.

Then I turn on the ESC. If the light glows green to indicate it’s in LiPo mode, I just press and hold the blue EZ Set button on the ESC. After about 10 seconds, I’ll hear some beeps, and the light changes to red. That tells me LVD is now off, so I can use my NiMH battery.

This clip from Traxxas shows what I mean:

There are no flashing red and green lights in the video. So, why does it sometimes happen?

Traxxas suggests a likely cause of the flashing red and green light is holding the EZ Set button on the ESC down too long when powering it off. The red and green flashing may occur at the next power on with a NiMH battery. To stop this from happening, turn off the RC vehicle by unplugging the battery instead of turning it off with the EZ Set button. It’s simple but effective.

How To Get Rid of the Flashing Red and Green Light

That’s why the flashing red and green light on the Traxxas ESC occurs and how to avoid it happening in the future. 

Now I’ll explain how to eliminate the flashing red and green light because it effectively locks the ESC. While the red and green light is flashing, it’s impossible to switch off LVD mode in the usual way. 

There are two ways to solve the problem. Which one to use depends on whether you have a LiPo battery to hand or not. I’ll run through both methods now.

Get Rid of Flashing Red/Green Light When a LiPo Is Available

With a LiPo battery to hand, it’s very easy to get rid of the flashing red and green light. Here’s how:

  1. Just turn off the ESC.
  2. Disconnect the NiMH battery, and connect up the LiPo.
  3. Then turn the ESC back on.
  4. The light should now glow green instead of flashing red and green because LVD is on, and the ESC is connected to a LiPo battery.
  5. Now, switch LVD mode off by pressing and holding the EZ Set button on the ESC for around 10 seconds.

Once done, the ESC light changes from green to red. The red light tells me LVD is now turned off.

I can now turn off the ESC, disconnect the LiPo, and connect my NIMH battery. When I turn the ESC back on, I should see the red light come on again so I can now run my RC on the NiMH battery.

Get Rid of Flashing Red/Green Light When No LiPo Is Available

Without a LiPo battery to hand, the procedure for getting rid of the flashing red and green light is a little more involved. But, it’s not too complicated. 

Although this procedure doesn’t need a LiPo battery, it does require a fully charged NiMH battery. It also uses the RC vehicle’s radio transmitter.

Let me break it down step-by-step.

  1. First, turn off the ESC by pressing the EZ Set button.
  2. Turn on the transmitter.
  3. With the transmitter on, connect a fully charged NiMH battery to the ESC.
  4. Then, press and hold down the EZ Set button on the ESC.
  5. Initially, the ESC light will be green but quickly turns red.
  6. As soon as that red light appears, release the EZ Set button.
  7. Now, wait for the red light to flash once.
  8. When you see the single flash, pull the transmitter to full throttle and hold it there.
  9. The ESC light should then flash red twice.
  10. Once the red light has flashed twice, switch the transmitter to full reverse throttle and hold it there.
  11. Keep the transmitter in reverse until the light on the ESC turns solid or flashing green.
  12. Then, press and hold the EZ Set button while keeping the throttle at full reverse.
  13. The ESC light should then go off for a few seconds.
  14. A short series of notes or beeps will play when it comes back on, and the ESC light should then glow red.
  15. At that point, immediately release the EZ Set button on the ESC and put the transmitter into neutral.
  16. The steady red ESC light indicates that LVD is now off, so it’s ready to run an RC vehicle on a NiMH battery.

Even without a LiPo battery to hand, it’s quite straightforward to deal with the flashing red and green light on a Traxxas ESC. 

Having learned why it happens and how to fix it, it’s clear a Traxxas ESC flashing red and green is no cause for alarm.

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