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Discussion Starter #1 (Edited)
Is this a sign of a weak alarm module battery?

Went skiing the last few days and was the first time my Fozzie has been in the snow. On returning to the parked car after the first day on the slopes; snowing and 0C; the remote would not work. I unlocked the car with the key, set off the alarm, opened the bonnet/hood and switched off the alarm from the engine bay with its key. The external unit stopped, but the internal siren kept going :icon_confused: Every time we disturbed the system by opening / closing a door or inserting the ignition key activated the internal alarm. I even removed the external unit from the circuit to no avail.

Eventually discovered that after a while the alarm would stop - so - inserted the ignition key, started the car and we sat in the car until the siren stopped (alarm indicator light still flashing). A test drive around the car park and everything was OK. So off we went with the internal alarm light flashing for the 35 kilometer drive. Every now and then the alarm would give a "croak" and flash the indicators a couple of time - which must have looked very strange to the cars behind us!

When we reached our accommodation, with the heater running, the alarm gave a couple more "croaks" and reset itself! It was now off.

From then on I didn't use the remote for locking, but every time I tried when the car was cold inside, it didn't work.

So I suspect the inside module is the problem (as the outside one is removed). Any ideas?
 

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How cold was it?

I teach skiing, so I'm up in the mountains for 15 weekends every year (plus skiing just for the heck of it), I learned years ago to just not use my alarm when up there because the cold does seem to affect it's functioning...No idea of a cause, just wanted to share that alarms do tend to malfuntion in the cold...
 

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Discussion Starter #5
So I've checked the circuit diagrams and spoke with others at the Subie club meeting Friday night. Seems there are a couple of others with MY'03's who share the exact same problem. There doesn't seem to be a back-up battery in the security module; the only batteries are those in the ignition key and in the external siren (not sure if a battery in the siren or some other form of energy store - the external siren will activate with the security key turned even when disconnected from the cars circuits). I've replaced the battery in the ignition key and everything is working OK - but I'll have to wait until I'm in a cold climate again to test.
 

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Discussion Starter #7
Nope! :icon_sad: Other than don't use the remote in the snow! Took my Triton to the snow last year; it was parked for several days at Hotham and covered in snow / ice - remote still worked!
 

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Well Kev, I have a working solution to this problem!

Panasonic CR1620 3.2V battery


The secret is that these are rated @ 3.20 volts (not 3.05 volts) so that it compensates for the voltage drop in the battery at low temperatures!

It seems that the fob is designed to have a specific battery type (Panasonic) and not just a generic coin battery! I have had a talk with the guys who sell and program these keys and they also say that anything else but the Panasonic CR1620 will always fail the cold weather test due to the noticeable voltage drop in generic batteries in colder temperatures.

It's this lack of voltage drop compensation in generic batteries that is the issue here and for some reason Panasonic CR1620 can maintain a working voltage even if there is a voltage drop due to low temperatures.

I use Panasonic Eneloop rechargeables for other devices and they can hold almost a full unused charge for two years in storage! For some reason Panasonic includes an extra bit of chemistry in their batteries to maintain a full charge for longer then it drops off steeply rather than a continuous decline, so they are less likely to be affected by low temperatures like the more generic brands.

Panasonic CR1620 3.2V battery

The secret is that these are rated @ 3.20 volts so that it compensates for the voltage drop in the battery at low temperatures!

I've tested it by leaving the keys outside for an hour and it's works OK @ -4C so give it a try and get back with your findings.

:woohoo:
 

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Panasonic CR1620 3.2V battery is a Subaru originally supplied part and there is a recommendation to replace with the exact same battery every 5 years.

Well after a couple of months I have not had any recurrence of this issue!

I even stuck the key in the freezer for 1 hour and then tried it, no problems!

Then went to the snow country for 2 weeks and tested it on the coldest days!

Problem seems to be solved.

 

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The secret is that these are rated @ 3.20 volts (not 3.05 volts) so that it compensates for the voltage drop in the battery at low temperatures!
...
It's this lack of voltage drop compensation in generic batteries that is the issue here and for some reason Panasonic CR1620 can maintain a working voltage even if there is a voltage drop due to low temperatures.
Actually they use the same chemistry so their voltage when new will be exactly the same. New batteries have a better voltage than old batteries. Old batteries suffer from cold more than new batteries do. (Car batteries are a geed example - most of mine die in the winter.) Generic batteries get "old" sooner than well made batteries.
I use Panasonic Eneloop rechargeables for other devices and they can hold almost a full unused charge for two years in storage!
Eneloops are awesome, but... they're made by Sanyo. Are you seeing Panasonic branded Eneloops? Is that part of their plan to phase out the Sanyo brand now that Sanyo is a subsidiary of Panasonic?
 

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Sorry, none of those pictures have anything to do with lithium coin cells, which is the battery chemistry I was referring to. The pics are pretty, but completely irrelevant because NiMH cells and lithium cells do not use the same chemistry (why on Earth do you say they're similar?) which is why NiMH cells have a nominal 1.2V and lithium cells a nominal 3V. In that very interesting but also completely irrelevant press release Eneloops are clearly still branded Sanyo* and lithium isn't even mentioned on that page! Sanyo Eneloops are completely awesome but have absolutely nothing to do with Panasonic lithium coin cells or how well they perform.

Some relevant links...

List of battery sizes - Wikipedia, the free encyclopedia points out all lithium coin cells have the same chemistry.
The IEC "CR" denotes lithium manganese dioxide chemistry. Since LiMnO2 cells produce 3 volts there are no widely available alternate chemistries for a lithium coin battery.

Manganese dioxide lithium batteries(CR series) | Lithium Batteries | Batteries, Power supplies | Panasonic Industrial Solutions East Asia says they are a nominal 3V (surprise surprise) with a capacity of 75 mAh (the Wikipedia list mentions a range of 75–78 mAh for that size, so nothing out of the ordinary there either) and with an operating temperature range down to -30°C! There's a datasheet linked on that page too. Go on, have a look - it's got voltage graphs at various temperatures.

Why do they work OK in the cold? They should do - they're lithium! A better question is why did the other cells not last OK? How old, tired, overheated or simply how far removed from moulded mud were they when you tried them out? Or... are they not a brand that you sell yourself?


*I found out that as part of an antimonopoly ruling, instead of going to Panasonic "the portable NiMH battery assets will be sold to FDK Corporation, a subsidiary of Fujitsu Ltd." Sanyo were to continue buying the batteries back from FDK.
 

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Sorry cuz, just trying to help.

Use whatever battery that works for you. This battery is recommended for Subaru where most others seem to fail!

Good luck.
 

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Much better info in your previous post now, although when you edited the product photo you should really have changed 3.2V to 3V. The product photo shows the packet says 3V, the pics from the datasheet show the nominal voltage is 3V and the graph of voltage under load shows 3.0V. It's misleading to imply they have a 0.2V advantage.
 

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A better question is why did the other cells not last OK? How old, tired, overheated or simply how far removed from moulded mud were they when you tried them out? Or... are they not a brand that you sell yourself?
:shake: If you have a problem with this thread, complain to Kevin the OP.

I'm an engineer.

Perhaps you should have searched the forum like I did when I was trying to solve this problem and see how no one (including you) had solved it here for over 5 years!

You only chimed in after the fact and offer nothing from experience to better this claim!

So the real question stands: if you have been a member here for ~5 years and you knew the answer to this, why haven't you contributed to other members woes and solved this problem years before me?

Because in this case you only know guff!

These Panasonic batts reliably work in -10° cold where other major brands don't!

QED
 

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:shake: If you have a problem with this thread, complain to Kevin the OP.

I'm an engineer.

Perhaps you should have searched the forum like I did when I was trying to solve this problem and see how no one (including you) had solved it here for over 5 years!

You only chimed in after the fact and offer nothing from experience to better this claim!

So the real question stands: if you have been a member here for ~5 years and you knew the answer to this, why haven't you contributed to other members woes and solved this problem years before me?

Because in this case you only know guff!

These Panasonic batts reliably work in -10° cold where other major brands don't!

QED

Dave Chapelle - "coldblooded!!!" - YouTube :chair:
 

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Because in this case you only know guff!
... which led to you removing the incorrect and irrelevant info (about a battery that hasn't been released yet, even in Japan). Great.

These Panasonic batts reliably work in -10° cold where other major brands don't!
So you claimed. And I wondered why. That's what discussion is all about. As I pointed out, it's not because of the chemistry (I mean the battery, not the way we get on so well :biggrin: ).

You appear to be still claiming they have some sort of voltage compensation that other brands do not have. I think it's probably something simpler.

Energizer CR1620: 79 mAh (datasheet)
Maxell CR1620: 36 mAh (online shop claim)
Panasonic: 75 mAh (datasheet)
Panasonic BACR1620 (LITH-3): 60 mAh (online shop claim)
Renata CR1620: 68 mAh (online shop claim)
Sony CR1620: 75 mAh (datasheet)

It looks to me like some CR1620 cells are well made and have a good capacity, and some are not and do not. There's no need for or reason to believe salesman claims of things Panasonic never mentions in its datasheets.
 

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Discussion Starter #19
Thanks for the input guys, I have enough info to go on now and look forward to testing it out next winter!
 
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