FOB battery issue ?

[WranglerMan]

Not sure if this is the right place to post but have a battery FOB question.

I started having trouble with my remote start but this was related to my main batteries being bad, they charged ok but had low CCA’s and resistance and was advised old or possible cell shorage but that's another story and just replaced both and all seems to work good so on to my main question.

I got in my jeep today and remote start worked fine several times I used it today and at a good distance but I got out to pump some gas and left it running as its cold here and momma don't want to sit in a cold vehicle but when I got back in it said FOB not detected but I shut it off and tried to restart and it said FOB not detected so I had to push FOB against the push-button and message went away.

I had this issue before I replaced the main batteries along with the remote start but that's working fine now, I checked the FOB battery voltage and its right at 3 volts %(3.01 volts) so I cleaned the contacts and put the battery back in and remote started and it worked so I got in and pushed the button and got out with the FOB and did some checks with having it close and in the house and it worked like its supposed so should I replace the battery anyway.

Just looking for some advice

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[Reinen]

Not sure if this is the right place to post but have a battery FOB question.

I started having trouble with my remote start but this was related to my main batteries being bad, they charged ok but had low CCA’s and resistance and was advised old or possible cell shorage but that's another story and just replaced both and all seems to work good so on to my main question.

I got in my jeep today and remote start worked fine several times I used it today and at a good distance but I got out to pump some gas and left it running as its cold here and momma don't want to sit in a cold vehicle but when I got back in it said FOB not detected but I shut it off and tried to restart and it said FOB not detected so I had to push FOB against the push-button and message went away.

I had this issue before I replaced the main batteries along with the remote start but that's working fine now, I checked the FOB battery voltage and its right at 3 volts %(3.01 volts) so I cleaned the contacts and put the battery back in and remote started and it worked so I got in and pushed the button and got out with the FOB and did some checks with having it close and in the house and it worked like its supposed so should I replace the battery anyway.

Just looking for some advice

Fob batteries are cheap. If there is any question, replace the battery. Worse case scenario is it doesn't solve the problem and you significantly kick the can down the road for a dead fob battery.

 

[WranglerMan]

Fob batteries are cheap. If there is any question, replace the battery. Worse case scenario is it doesn't solve the problem and you significantly kick the can down the road for a dead fob battery.

I did put a battery in the FOB a few weeks ago when I was having remote start issues but then I had the main batteries tested and they failed the test that auto parts stores use so I replaced the main batteries on my duel Genesis system and all worked well until yesterday.

The FOB batteries I had already but they were never used but a few years old sitting in storage with other batteries I keep on hand.

All seems to work fine with the FOB like lock, unlock, remote start but on occasion I get the FOB not detected so I ordered some new ones and they will be here Monday.

I do have a new unused FOB so ill carry that and see if I get the issue with it as its never been used, not sure whats inside the FOB that detects its within range

 

[jav_eee]

Apple airtags are sensitive to the bitterant that is applied to button cell batteries (so kids wont eat them) and it has to be wiped off of the new battery for them to work.

Not saying this is the issue BUT you might try wiping both sides of the new battery with some rubbing alcohol and see if that helps.

 

[ppjcs]

Not sure if this is the right place to post but have a battery FOB question.

I started having trouble with my remote start but this was related to my main batteries being bad, they charged ok but had low CCA’s and resistance and was advised old or possible cell shorage but that's another story and just replaced both and all seems to work good so on to my main question.

I got in my jeep today and remote start worked fine several times I used it today and at a good distance but I got out to pump some gas and left it running as its cold here and momma don't want to sit in a cold vehicle but when I got back in it said FOB not detected but I shut it off and tried to restart and it said FOB not detected so I had to push FOB against the push-button and message went away.

I had this issue before I replaced the main batteries along with the remote start but that's working fine now, I checked the FOB battery voltage and its right at 3 volts %(3.01 volts) so I cleaned the contacts and put the battery back in and remote started and it worked so I got in and pushed the button and got out with the FOB and did some checks with having it close and in the house and it worked like its supposed so should I replace the battery anyway.

Just looking for some advice

I had that issue last week with the fob not being found this week it quite altogether, could not open the doors. Replaced the fob battery and all is well now.

 

[WranglerMan]

I had that issue last week with the fob not being found this week it quite altogether, could not open the doors. Replaced the fob battery and all is well now.

Well I can lock, unlock, remote start etc..but the intermittent Fob not detected is a nuisance.

I switched to the second FOB and it to has had the battery replaced with what I had in stock at home, I think I got them like 3 years ago but never used. Anyway I did some testing with the 2nd never used FOB and it functioned on locking, unlocking, remote start so then after starting the jeep remotely I got in and pushed the stat button and then did some testing with the new FOB and took it away from the jeep like 25’ and looked in and it said no FOB detected so then I grabbed the FOB and hopped in and the message on the EVIC showing it not detected went away and I did this several times and it never failed.

My thinking is the one I carried everyday has a weak battery or is going bad as the main batteries are less than a week old and charge fine, not sure what the voltage is supposed to be on the CR2450 battery but the one in the older FOB tested just at the 3 voltage threshold but from my research the FOB battery should have nothing to do with the RFID chip being detected by the receiver and all other functions of the FOB work.

Maybe its just a Jeep thing

 

[WranglerMan]

Just an update Gents,

First off I was wrong on my RFID chip not being dependant on the FOB battery, I have exchanged a few PM’s with @Nvdardx28 and he passed on to me some great info about the RFID’s role in the FOB and its need for a good fob battery so if your curious take a read below.

I also received new batteries today and took a few volt readings and a new CR2450 has in my case 3.25 volts and the ones in the FOB’s I have are at 3.01 volts so I took the fob apart and cleaned its internals with contact cleaner and put a lite coat of dielectric grease on some contact points and the battery and will do some testing to see if all is 100% with two new FullRiver 750-25’s and new Fob batteries

This is actually not true. When it comes to RFID and how the fob works there are two modes. First mode is passive mode for RFID, this is when there is no other source or the battery (fob) is dead. The RFID circuit wakes up when a signal from the main device or receiver sends out an RF pulse. The source of voltage for the RFID circuit comes from RF pulse. As you can imagine this is extremely low power, then the RFID circuit in the fob attempts to transmit a RF data signal from the low power it absorbed from the incoming signal. This is why you have to hold the fob against the push to start button when the batteries in the fob dies. The power is so low, it's range is almost nothing.

The second mode is active mode. The RFID circuit is always awake and active and anytime it detects a signal coming in it responds by send an RF data signal out by drawing power from a battery source. Since the battery has plenty of capacity the fob can send a much stronger signal and effectively cover a wider area or range. If the battery is weak than your range is also affected.

So the fob battery absolutely has a role in how well the range works on the fob. If your fob still has range issues I would recommend a fresh battery. If it still doesn't work well enough there could be an internal problem with your fob. The fob cases aren't great in my opinion and if water, dirt and dust can get inside it can mess with the sensitive antenna the RFID uses or anything else within the circuit.

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