Fob with external push button runs out of battery in a few days

Discussion Questions
#1

Hi there,
as already described here I can not use the fob because of the “slim design” I have a quadraplegy and very limited hand functions.
To ease the use of the fob I constructed and printed a box for the (opened) fob and a second door opener for the house main door- the Fob is meant for opening my appartement door.
I added to push buttons and connect each button with one opener.
Someone elsse desribed something similar here.
I connected the push button with two wires and added an external coin cell holder to power the Fob. I used the same type of battery cell and everything worked fine.
BUT after only two days the battery was empty (although I already replaced the original (and empty) battery).
After I replaced the battery and after doing what the Fob was meant for, the battery was empty again after less than a week every time.
I replaced the battery twice and they both were empty again after a few days only.

I really have no idea why this happens!!
Does anyone have an idea what could be the problem for the Fob.
I can’t imagine a reason for this behaviour.
Perhaps s.o. can give me a hint what could be the reason!

BR,
hoping for an explanation…
Tim

#2

Most likely a similar problem to the one described in the linked threads. The external cable works as an antenna and induces some currents on the input pins, which permanently wakes up the Fob and therefore drains the batterie. Shortening the cable length and using an isolated cable can help. You could also use a bigger battery / coin cell. Everything that outputs 3V should work.

#3

OK, I tried to replace the battery cable with a (ok,two…) well isolated cable(s), but again the battery was empty after about three days.
Any further ideas I could try?
Is it possible that the Fob itself is kind of broken?
BR,
Tim

#4

Is it perhaps possible to connect the batery with the FOB to power him up and then another one to actuate the button? That would save energy and the battery would survive more then 3 days.
I do not know how long the Fob needs to boot after powering on- perhaps I could build some littler electronic curcuit that first powers the Fob, waits two seconds and the push the button- and everything with only one switch/button push.
Any idea out there?
BR,
Tim

#5

You could always remove the battery from the fob when it is not used. So an additional button/switch that (dis)connects the battery to the power pins of the fob would stop the fob from draining the battery. It’s a bit complicated to handle though, because you end up with 2 buttons/switches instead of one.