Tesla Only Charging at a Specific Amp: Causes and Solutions!

Tesla Only Charging at a Specific Amp: Causes and Solutions!

After putting on a new charger at home, a lot of folks face issues related to charging. And, that the charger doesn’t want to use more power than a certain amount.

Well, Tesla only charging at a specific amp issue occurs due to various reasons. For example, the adapter is mismatched, the cord is loosened up, bad PCS module, and so on. Based on the situation, the solutions would be diverse.

Here, I’ll help you to figure out all the possible reasons and their solutions along with some helpful details. Let’s Get Started!

Fixing Tesla Only Charging at a Specific Amp!

To fix the issue of your car charging at a certain amp, it’s ideal to find out the root causes before doing anything. Let me share the reasons along with its solutions below:

Why Is My Tesla Only Charging at 8 Amps?

If you have installed a 60A or 50A circuit breaker and it’s only charging at 8 amps or 3 miles per hour, it can happen due to a few reasons. Such as:

Why Is My Tesla Only Charging at 10 Amps
  • Low Voltage Outlet Adapter: Based on the Tesla charger breaker size, the outlet adapter’s voltage may be different than the suggested.
  • Charge Current Limit Is Set To 8A: You might have accidentally or on purpose changed the current limit on the car’s screen to 8 amps. And so, it isn’t charging at higher amps.
  • Disconnected Charger Cord: The loosen-up charger cord which is attached incorrectly can cause this sort of issue.

How to Fix?

  • Replace the Outlet Adapter: Check the outlet adapter’s voltage based on the circuit breaker. If it is supplying less than the suggested, then change it (if required).
  • Change Charge Current Limit Setting: In the car’s screen, hit the lightning bolt sign, and then you’ll find the Charge Current section. Next, reset or change it to 40 amps if using a 50A circuit breaker (based on the breaker).
  • Connect Charger Cord Properly: Simply, push the charger cord all the way into the transformer (not the port) and then retry.

Why Is My Tesla Only Charging at 10 Amps?

In case your home charger is only charging at 10 amps, it may cause slow charging. Here are some reasons for this:

  • Electrical Panel Not Compatible: A mismatched electrical service at home that can’t support the charge rate can cause charging at a low amp.
  • Issues with Wiring: If the wiring harness in your home can’t handle a high charge rate, it can result in this kind of issue. Sometimes a worn-out or thin size wire can struggle to handle the high charging rate.
  • Overheat or Overcharge: The home connector might charge at 10A if the battery is warming up or overcharged.

How to Fix?

  • Change Electrical Panel: If your home’s electrical service is a little undersized, call an expert to upgrade the electrical panel for home charging.
  • Replace Wiring Harness: Check the wiring condition and size with proper inspection. If it seems badly worn out or incorrect in size, simply change the wiring harness. For that, you’ll need the help of an expert.
  • Cool Down or Remove the Charger: If the charger seems hot or the car is overcharged, disconnect the cord from the car and let it cool down. Then again, charge the car if the charger is cooled down.

Why Is My Tesla Only Charging at 12 Amps?

Due to some reasons, your wall connector can charge at 12 amps and doesn’t raise the charge range. Let me share them below:

Why Is My Tesla Only Charging at 12 Amps
  • Set the Operating Current Wrongly: Inside the wall connector’s cover, there’s a rotatory switch that lets you set the current setting of the circuit breaker. If you set it in the wrong position, it will only charge at a certain amp.
  • Incorrect Wiring Size: When you install a wrong-sized wiring harness on the wall connector, it can affect the charge rate. Due to this, it can lessen the amps while charging the car. 

How to Fix?

  • Adjust the Operating Current: Turn off the breaker (if needed) and then open up the wall connector cover. Then, use a small flat screwdriver to set the rotary switch to a specific amp based on the circuit breaker size. Next, reinstall all the parts.
  • Install Right Size Wiring Harness: Ensure the wires used in your wall connector are at least 6 AWG and 90° C-rated copper type. If not, be sure to replace them (green for ground, red for Line 2 or Neutral, and black for Line 1).

Why Is My Tesla Only Charging at 32 Amps?

If your Tesla not charging at 48 amps or only charging at 32A, it can occur when one of the PCS (Power Conversion System) modules is failed to operate.

Why Is My Tesla Only Charging at 32 Amps
Image: cleantechnica.com

In general, all cars of Tesla come with 3 PCS modules inside the battery penthouse (located underneath the car’s right seat).

Each of the modules can receive around 16 amps (16 x 3 = 48 amps) when you insert the cord inside the car’s charging port. But if one module goes bad, it will only receive 32 amps at a full charge rate.

How to Fix?

In that case, you’ll need to replace the problematic PCS module inside the battery penthouse. For that, it’s best to do it via an expert at an auto shop or Tesla Service Center.

Tesla Charging Amp Chart!

If you want to know the ideal charging amps for your wall connector or charger, here’s the chart for all series (including Model 3, X, S, and Y):

Wall ConnectorCharge Speed (Max miles of range per hour of charge)
Circuit Breaker (amps)Max Output (amps)Power at 240V (kilowatt)Model 3 (mph)Model Y (mph)Model S (mph)Model X (mph)
604811.52 kW44423430
50409.60 kW37362925
45368.64 kW34322623
40327.68 kW30292320
35286.72 kW26242017
30245.76 kW22211714
25204.80 kW19181411
20163.84 kW1514118
15122.88 kW111075

Based on the voltage rate, the power of charging (kilowatt) will change. And, the max miles of range per hour of charge is calculated approximately. 

What Amp Should I Charge My Tesla?

If you are talking about Tesla charging at home, the fastest charging amps in the charger that is ideal to use would be:

What Amp Should I Charge My Tesla
Image: Tesla.com
  • For the Tesla wall connector that powers at 240 volts (AC), you should use 60 amps of circuit breaker. That way the charging current would be 48 amps so your car gets 44 mph in M3, 34 mph in MS, 30 mph in MX, and 42 mph in MY (charge rate or speed).
  • For the Nema 14-50 charger that powers at 240 volts (AC), you’ll need 50 amps of circuit breaker. Via this, your car will get 40 amps charging output and the Nema 14-50 charge rate would be 37 mph in M3, 29 mph in MS, 25 mph in MX, and 36 mph in MY.

Is It Better to Charge Tesla at Lower Amps?

Not necessarily! There’s a big myth that charging a Tesla at lower amps helps reduce the aging of the battery. In reality, lower amps charging will cause zero effect on the battery as the Tesla is made to charge 10x faster at the Supercharger.

A rule of thumb is that more energy will be lost if the amps are greater in number while using a suboptimal outlet (Power = Volts X Amps).

So, if you charge your car at a 120V outlet (less than the suggested), it will cause amps to max out and more heat or energy will be lost. And, the result would be slow charging and overheating issues.

As long as you use the suggested outlet (240V type), charging your car at high amps will cause no stress on the battery. However, lowering amps can help protect your house’s electric system.

Overall Thoughts

Now that you know the possible reasons why Tesla only charging at a specific amp, it’s time to fix it. There are some solutions that you can do it yourself. So, be sure to do them when you are free.

However, the other solutions may need complex electrical repairs. It’s better to get a skilled mechanic at the service center to help you with resolve those.

Hope you find this guide informative to figure out the possible causes and fixes. Keep Up with The Good Work!

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