Build up on FOB battery arms causing no response when pressing down the key.

[julianm]

Today was cleaning day and I used my spare transponder fob (supplied when I bought the bike) to switch the ignition on to raise the windscreen. When I did this, it gave the Transponder Low Battery warning so I thought after cleaning I would quickly replace the battery. . Finished off cleaning and replaced the battery . Went to test it and no response from pressing the key . Tried a few times , still nothing , took the fob apart to see the battery was the right way around, (which it was) , tried again and still no "click" .Fetched  the other fob which worked first time.
Opened the spare and checked the voltage on the contacts that engage with the PCB when the fob is closed and read only 1.9 volts . Took the battery out and it read 3.25 .
Has a close look at the two silver arms which run each side of the battery and could see a slight deposit at the points where the positive disc made contact with these.
Cleaned these deposits off with a fine jewelers screw driver and actually was able to feel a slight build up .
Replaced the battery and on checking the contacts found that it was now reading reading 3.25 volts. Seemed to me that whatever had built up on the arms was causing some kind of resistance and dropping the voltage to such an extent that it was not being detected by the ECU. Put it together and now received the normal welcoming "click" when pressing the key.
Went back and measured the original battery which was 3 volts and thought I'll put it back and see if it still had the Transponder Low battery warning.
When I was putting it back and twisting it slightly to locate it ,I saw a pin point red glow for about a second from the plastic insulation on the one side. Thought that's not a good sign so took it out and put the new one back. No red glow
Checked the edge of the the old battery carefully to see if there was any signs of electrolyte leakage but couldn't see or feel anything. Remeasured it's voltage and it had dropped to 2.6 volts. Must have been some breakdown in the insulation over time and maybe this allowed some electrolyte to deposit on the arms. It was a Maxell battery by the way which I believe to be good quality.

Thought this may be of interest and something else worth checking if no response from pressing the key

 

[gPink]

Thanks. Good info.

[VirginiaJim]

 

[Conrad]

While you had the batteries out of your fobs it would have been a good time to double check that the passive portion of the fobs worked.

[lather]

a close look at the two silver arms which run each side of the battery and could see a slight deposit at the points where the positive disc made contact with these.
Cleaned these deposits off with a fine jewelers screw driver and actually was able to feel a slight build up .
.... saw a pin point red glow for about a second from the plastic insulation on the one side. .....Must have been some breakdown in the insulation over time and maybe this allowed some electrolyte to deposit on the arms.

This is interesting but I am not clear on what plastic insulation may have broken down, can you clarify please.

[gPink]

Sounds like he's speaking of the battery casing.

[julianm]

While you had the batteries out of your fobs it would have been a good time to double check that the passive portion of the fobs worked.

Good idea , didn't even think of that

[julianm]

This is interesting but I am not clear on what plastic insulation may have broken down, can you clarify please.

If you look at the battery from the negative side , you will see a thin strip of transparent plastic like material running around the circumference between where the positive disc has been crimped over and the flat negative disc. This, I assume, to be the insulation which separates the positive and negative poles to prevent the battery shorting out

[lather]

Thanks for both the replies. I was thinking of it as the battery casing as was gpink but I can see how it could be considered insulation. At any rate if you saw a red glowing hot spot there then I would think that had to be a short due to a bit of metal shaving or conductive grit bridging the  pos and neg electrodes. Could it have been a bit of the deposits you cleaned off?

Another question: Where do you keep the fob when you are riding?

[VirginiaJim]

Another question: Where do you keep the fob when you are riding?

Getting a bit personal, don't you think? 

[julianm]

Thanks for both the replies. I was thinking of it as the battery casing as was gpink but I can see how it could be considered insulation. At any rate if you saw a red glowing hot spot there then I would think that had to be a short due to a bit of metal shaving or conductive grit bridging the  pos and neg electrodes. Could it have been a bit of the deposits you cleaned off?

Another question: Where do you keep the fob when you are riding?

Thanks Jim , no problem , my riding jacket has a small front zip pocket  high chest and the riding fob is zipped in there . The spare fob is hanging on the key rack in the house and it was this spare that showed the problem. Don't think the short was from the debris as I only saw it once I started to flex the battery to slide it into the housing and it appeared to come from underneath the thin plastic strip

[lather]

OK, I have no more ideas except maybe a defective battery. The reason I asked about where the fob was kept was the possibility that vibration was the culprit but that is clearly not the case. How old was the battery in question?

[elp_jc]

After bad experiences with many such battery brands, I've stuck with Panasonic, and never a battery issue again. According to some experts, their 'cross-hatched' negative side is what makes them a lot more reliable (instead of smooth, like the '+' side). Plus they're supposedly constructed better, so leakage is not an issue. You can buy several on the cheap on eBay.

[Conrad]

After bad experiences with many such battery brands, I've stuck with Panasonic, and never a battery issue again. According to some experts, their 'cross-hatched' negative side is what makes them a lot more reliable (instead of smooth, like the '+' side). Plus they're supposedly constructed better, so leakage is not an issue. You can buy several on the cheap on eBay.

I've been using Panasonic batteries exclusively in my fobs.   

[julianm]

OK, I have no more ideas except maybe a defective battery. The reason I asked about where the fob was kept was the possibility that vibration was the culprit but that is clearly not the case. How old was the battery in question?

Think about 2 years or so. I re-examined the battery today and if I ran my finger nail around the battery on top of the insulation strip , I did find a residue very similar to what was on the 2 contact arms . So it would appear there was some electrolyte leakage which deposited on the arms and caused the low voltage.
Will stick to Panasonic's in future