Capacitors on Dlink power feed

Technical Electrical
1

Hello, all.

We have some problems while working with the Dlink access point. The Driver Station is constantly losing communication with the robot. Windows shows that the wireless network is not broadcasting, after a minute it shows again and the robot is back online. This happens every few minutes, most often when the robot starts moving or (but not only) when the battery is low.
We are in Israel and therefore using a custom made AP.
We checked the wiring and it all seems fine. The power supply is from the dedicated 12V terminal on the PDB and through the 12V-5V convertor.

We believe that this is a voltage drop problem. We think of connecting a capacitor on the power cables (4700 μF, the AP works on 5V - 2A). Is this legal?

Do you have other suggestions?

Thank in advance,
Shai Noy, Team Artemis #3083

2

If your PDB and 5 volt converter are working properly, it is not a voltage drop problem. If you have a voltage drop problem, it is because something is broken.

I would suspect the actual power connector on the Access Point.

3

Thanks for the quick reply, we cannot find any problem with the AP’s connection, and we looked at the 5V port of the PDB and noticed that the LED isn’t on, even though the camera works perfectly fine… do you have any tips about the camera connection and the PDB check?

Thanks again…

4

Shai,
Exactly what are referring to as a “custom AP”? The 12 volt supply in the PD is designed to put out a solid 12 volts until the battery voltage falls to 4.5 volts or less. If you have the required jumper on the analog module in slot 1, the robot should stop before that battery gets below 5 volts.
Capacitors on the DAP-1522 power line are not legal for use on FRC robots.

5

Al,

Remember that Israeli teams are not using the same DAP-1522 for the Israeli regional, because 5GHz is a restricted military frequency in Israel. Teams in Israel will be using some 2.4GHz wifi equipment (i don’t know what, exactly) at that regional.

6

The DAP-1522 is a dual band radio. So Shai, if you are using something different, please let us know.

7

Kendrick: I have had a problem like this before with my laptops. I fixed the problem by reinstalling the wireless drivers.

8

Hello all and thanks for the replies.

We use the Dlink access point given to us by FIRST. As
1075guy, we use a 2.4GHz frequency. I don’t suspect the Access point itself as the problem.

Do you have any idea on why does the AP stops broadcasting?
If this is a connection problem, why doe’s it happens mostly when using weak / old batteries? How can we solve this kind of problem?

We checked two PDBs, but none have the 5V indicator LED on when the camera is connected (and working), I don’t think it is connected to the WiFi problem, but why is it off?

thanks for the help

9

Shai,
There a few possible problems that you should check.

  1. You may have a loose battery connection or poor crimp in the Anderson 50 amp connector. Are any of the battery connections getting warm after you practice? This includes any of the #6 AWG wiring.
  2. The main breaker has a known manufacturing defect that allows it to open with vibration. To check, lightly tap the breaker red button. If the lights on the robot flicker, replace the main breaker.
  3. Does the 5 volt LED turn on if the camera is not plugged in? Are you using this year’s camera or last year’s? There is an electrical difference. Last year’s camera has the case tied to the negative lead of the battery. It must be insulated from the frame of the robot.
  4. Is your Crio insulated from the frame of the robot?

If the Dlink is loosing power, it takes 55 seconds to reboot. Is this the length of time you have no communications? When you think you have a low battery, what is the voltage reported on the driver’s station display?