I have been using a 3.5 mm switching Audio Jack in order to charge/switch-on and off my RC-Glider model. For this I connected the battery of my RC-glider to the one-part of the audio jack and the electronics to the other side. The audio jack I use seems to be a SJ1-3515 (although, I am not sure as this switch was delivered with the model). Here are the schematics: Schematics of my wiring

However I noticed that whenever I plug-in or plug-out a cable, ground is shortly connected to either of the two other pins, which then of course shorts-out my battery! This led to high-current and some very hot wires which desoldered my connections to the switch. Obviously I do not want to short my battery every time I plug-in or plug-out the charger or the on-off insert.

Therefore my question(s):

  1. Is this a normal behavior for a switching 3.5mm Jack?
  2. Can someone tell me if non-shorting-out 3.5mm Jack connectors exist, and how to find those? Or am I just plainly using the wrong tool for the job?

Thanks in advance!

Edit: Per demand I included a (badly drawn) schematic. Edit2: Generalized the question such that I ask for the class of non-shorting products instead of a specific product.

  • \$\begingroup\$ Show the schematic of how both sides of the jack is wired with respect to any other connection, particularly the battery. \$\endgroup\$
    – Andy aka
    Aug 2, 2020 at 16:20
  • \$\begingroup\$ Shorting is normal for audio jacks. Maybe it's preferred behavior. You can put a polymer fuse in series with the battery but if someone leaves the plug half in it will drain the battery fairly quickly. \$\endgroup\$ Aug 2, 2020 at 21:00

1 Answer 1

  1. Yes that is normal, the sleeve connection of the jack most likely touches the tip and ring when plugging and unplugging.

  2. Yes, wiring large battery currents via a short-prone audio connector rated for 1A max current does seem like a bad idea. It is a completely wrong tool for the job. There are far more suitable connectors available that are designed for connecting DC power (instead of audio), such as the common barrel plugs.

  • \$\begingroup\$ 1. Yes I see that. This is exactly what happens 2. Please explain why. The battery is by no means large. As explained in the post, the maximum current I expect is 0.5A, that is a 50% margin. I see why 1. is a deal-braker, but that is why I ask: Is there a way to rectify this problem? \$\endgroup\$
    – U_flow
    Aug 2, 2020 at 16:37
  • \$\begingroup\$ Just a clarification: 1. Yes I see that (the switch has a transparent cover). \$\endgroup\$
    – U_flow
    Aug 2, 2020 at 16:43
  • 1
    \$\begingroup\$ 0.5A when it is running? Short circuit current can be many times that. \$\endgroup\$
    – Justme
    Aug 2, 2020 at 17:05
  • \$\begingroup\$ Yes, that makes sense. But as mentioned before: I don't want to short my battery, as that would definitly violate the specs of the battery. So instead of searching for a switch that can support the current spike of the short circuit, I am searching for a switch (or a suitable alternative) which does *not short the battery. \$\endgroup\$
    – U_flow
    Aug 2, 2020 at 18:17
  • 1
    \$\begingroup\$ Then you have to switch away from 3.5mm audio jacks and switch to connectors that are actually meant for connecting DC power supplies, like DC barrell plugs and jacks. \$\endgroup\$
    – Justme
    Aug 2, 2020 at 19:21

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