Using a smaller lithium coin battery in a remote

[y_p_w]

I've got a Subaru with one of those Alpine remotes that use a single CR2032 lithium battery. I know where to get them cheap, but I ran out and still have a lot of (Maxell) CR2025 batteries. I've used them before in some applications where there's leaf spring contacts and they typically hold them in place. Worst case is maybe I bend a contact a bit and it holds nicely. However, the Subaru remote uses a sleeve for the positive contact and it kind of shakes. I tried using a piece of aluminum foil as a shim, but I'm not sure if it's a good long term solution. I worried that the dissimilar metals might cause corrosion or something I haven't thought of yet. In the meantime it's working fine. Is it a problem using that or maybe I should just get some more proper size batteries?

 

[spk2000]

Will work fine. Same size just thinner and less amp-hrs rating.

 

[Klutch9]

No problem. Battery wont last as long and is a little thinner, but as long as the +/- tabs can exert enough pressure to make contact, you're all set.

 

[CR94]

Yep, that should work. You might need a slightly thicker shim, ideally about 0.025" thick. Plated steel would be good.

 

[Tegger]

Aren't you an engineer of some kind?

 

[JHZR2]

Originally Posted By: spk2000
Will work fine. Same size just thinner and less amp-hrs rating.


+1. Unless the draw is high enough that the voltage drops too much. If that's not the case, it will work, just not as long...

 

[tom slick]

Can you stack 2 together?

 

[Wolf359]

Well the 25 in 2025 refers to the thickness so it's about 7mm thinner than a 2032 and in terms of power, 2025 is about 163mah and 2032 is 250mah.

But you know you can buy knock off 2032 batteries by the 10 pack on ebay for about $2 and even brand name like Energizer (could be fake) for about $4.

 

[Wolf359]

Originally Posted By: tom slick
Can you stack 2 together?


They're 3 volt batteries, stacking 2 will give you 6 volts. Then it's equivalent to a 2050 so it depends if there's 18mm of room in there and that the 6 volts doesn't blow out the device.

 

[zeng]

0.7 mm thinner.

 

[JHZR2]

Originally Posted By: tom slick
Can you stack 2 together?


They would be in series and the voltage double.

 

[eljefino]

I've found these batteries at dollar tree and harbor freight for $1 to $1.50. The markup elsewhere must be ridiculous.

And I used to shim with aluminum foil, too. Did this when mercury camera batteries became outlawed and I had to "make do."

 

[y_p_w]

Originally Posted By: Tegger
Aren't you an engineer of some kind?

Electrical engineer. However, I live in a world of 1s and 0s these days. I didn't even take a chemistry class in college, and I thought that dissimilar metals was more a chemistry problem than anything else.

Of course I know it works to complete the connections, but I just worry that maybe there's some sort of side effect from sticking a piece of aluminum in there. Leaking batteries are supposed to be pretty nasty.

I've got six more of those CR2025s. I got them for my kid's toys and some other stuff.

 

[y_p_w]

Originally Posted By: eljefino
I've found these batteries at dollar tree and harbor freight for $1 to $1.50. The markup elsewhere must be ridiculous.

And I used to shim with aluminum foil, too. Did this when mercury camera batteries became outlawed and I had to "make do."

I used to ride bikes, and my fairly popular cycling computer originally used mercury cells. The replacement was a 386 silver oxide cell. It fit perfectly, but the nominal voltage was a little bit less. They also didn't last quite as long.

There's a wholesale watch parts dealer in Oakland, CA, and I've bought various batteries there. The retail markup on watch batteries is crazy. I remember going to this parts store to get batteries for maybe 30 cents each, while a drug store might have a similar one for $3-4. These lithium coin cells are used in quite a few of those watches that claim a 10 year battery life. The store has a $5 minimum in-person purchase price, which is actually kind of hard to hit when you just need a few batteries.

http://www.ofrei.com/page_125.html

More recently I bought my batteries from one of several Amazon sellers. The one I used most was MYBATTERYSUPPLIER, but now they seem to only work through Amazon's fulfillment services rather than direct. They used to offer free shipping with no minimum when they shipped directly. I bought stuff like 5-packs of Maxell CR2032 for $2.59 with free shipping. There seem to be quite a few that still have 5-packs for under $3 with free shipping.

I wouldn't really trust Harbor Freight for batteries, since I'd guess they source theirs from China. I prefer Maxell if I can get it. Sony isn't bad although they seem to have offshore their production from Japan to Indonesia. Energizer and Duracell seem to be from elsewhere now. I found one electronics store that sold Renata, but they're primarily a watch battery company.