MV1C coin cell battery holder recommendations? and/or supercapacitor?

[Kujako]

Tried a number of options over the years, including the ones JNX lists, none have really been a home run. I know folks have designed and built some decent ones, but I can't find files or sources. So, anyone have any recommendations?

Thanks,

EDIT: Alternatively, anyone have a recommended 3v supercapacitor to use instead?
Example: https://www.ebay.com/itm/192664230986

 

[avramce]

I use these in the OMVS builds I made, they work well but will require shaving off the mask to expose the ground plane:

Dahszhi Button Cell Battery Holder for CR2032-10pcs https://a.co/d/5Eoxdpo

 

[Kujako]

I use these in the OMVS builds I made, they work well but will require shaving off the mask to expose the ground plane:

Dahszhi Button Cell Battery Holder for CR2032-10pcs https://a.co/d/5Eoxdpo

So you're going to a secondary pad for the positive connection? Interesting, hand't considered that. My only concern here would be the extra width this ads for systems going into a consolized case. Not found a good fit for those. Wracking my limited knowledge on the subject re: supercapacitors since that's such an easy solution.

Edit: might take some measurements and see if a similar CR1620 holder will work.

Edit 2: turns out I had some around for use in GameBoy cartridges, same issue with the overhang unfortunately.

 

[avramce]

I havent seen a JNX case internals yet, but I believe that a CMVS Ultra, Omega and OMVS case all allow some space to the left and right edges of the MV1C. I have a PCB I used previously that lines up with the holes, but I just went with the socket for ease of installation

 

[Kujako]

I havent seen a JNX case internals yet, but I believe that a CMVS Ultra, Omega and OMVS case all allow some space to the left and right edges of the MV1C. I have a PCB I used previously that lines up with the holes, but I just went with the socket for ease of installation

Looking at an old school aliexpress "CBOX", things are pretty tight. But one option would be to go somthing like this.

 

[Neo-Alec]

For what it's worth, I've battery modded multiple boards, and the ones JNX recommends always worked out fine for me, and even fit just fine in a case without much clearance.

 

[Kujako]

For what it's worth, I've battery modded multiple boards, and the ones JNX recommends always worked out fine for me, and even fit just fine in a case without much clearance.

I have some (same part number ordered from Mouser) but they don't align right. Always have to build a bridge for them to connect to. I dont know if the dimensions changed or if I just have ones that are a different size but they've never worked well.

More and more I'm thinking of going the supercapacitor route, something around 10F, can't think of why it would be a bad idea.

 

[ack]

Another option is something like these

https://www.arcade-projects.com/threads/mvs-mv1b-1c-battery-replacement.18079/

 

[Kujako]

Another option is something like these

https://www.arcade-projects.com/threads/mvs-mv1b-1c-battery-replacement.18079/

Yeah that's what I was looking for, but availability is limited. Had the files been posted I'd build a run of them myself, but I'm too busy (lazy) to do a design myself right now.

What I'm considering is using a 10 Farad 3V supercapacitor with an ESR of ~0.02 Ohms at 20c. That seems like it should work perfectly, but I admit to not having done all the math required to know for sure... but for comparison most LIR2032 coin cells batteries are in the 0.02-0.03 Ohm ESR range.

 

[Neo-Alec]

I have some (same part number ordered from Mouser) but they don't align right. Always have to build a bridge for them to connect to. I dont know if the dimensions changed or if I just have ones that are a different size but they've never worked well.

More and more I'm thinking of going the supercapacitor route, something around 10F, can't think of why it would be a bad idea.

Yeah, it's not a perfect fit, but it didn't bother me. If you do ever try a supercapacitor, please let us know how that goes.

 

[Kujako]

Yeah, it's not a perfect fit, but it didn't bother me. If you do ever try a supercapacitor, please let us know how that goes.

I've ordered a supercapaitor, still mulling if I'll use it. If I do I'll definitely post here. I'm just trying to think through how I would test it other than letting it run for a year or two.

Edit: thinking through it, fairly sure the capacitor I ordered won't work... but this is where I get a bit out of my depth.

i = 0.005amp (much lower in practice)
Δt = 10^6 seconds (one month of shelf life)
Vmax = 3.7-4v (what is supplied to the battery/capacitor by the charging circuit)
Δv = Vmax - 3 (3v being what the RAM needs to stay alive)
𝐶 = 10 farads

So time, voltage, current relationship to farads
𝑖𝐶=ΔvΔt
𝐶=iΔvΔt
So 10 farads is over kill, but... 3v isn't enough due to a higher Vmax.
With a 0.02Ohm ESR...

Vcap = VMax+(iR)
Vcap = 4+(0.005)(0.02)
So I need a voltage capacity of 3.7 to 4v realistically. Which I can't seem to find with a similar low ESR.

Looking at products that are designed to replace 2032 coin cell batteries, I think 5v is a more realistic target.
https://www.eaton.com/content/dam/e...pacitors-coin-cells-data-sheet-elx1175-en.pdf

 

[Kujako]

It may be too early for any sort of reasonable thoughts, but I think I found a decent super capacitor option.
https://www.digikey.com/en/products/detail/eaton-electronics-division/PM-5R0V474-R/2185064

5v with 500mOhm ESR, but only 0.470F. That should be enough for a month or two of shelf life I think...

[Suspect math ahead warning]
Had formulas wrong yesterday I think... it's Δv over Δt. Multiply, divide same thing!

i = 0.005amp (much lower in practice)
Δt = seconds
Vmax = 5v
Δv = 2v : Vmax - 3 (3v being what the RAM needs to stay alive)
𝐶 = 0.47 farads

𝑖 / 𝐶=Δv / Δt
(0.005)/(0.47) = (2)/Δt
Δt=188 seconds? That seems wrong...
Let's try another way.
𝐶=𝑖Δ𝑡 / Δ𝑉
𝐶=(0.005)(10^6)(2)
gets 5kF needed...

Think I see my mistake, amperage value is way higher than expected. SRAM should need around 1E-6 Amps (0.000001). I'll use 0.000005

𝐶=(0.000005)(10^6)(2)
5F needed for a month of shelf time, 1F if I use 1E-6 Amps. So 0.470F is less than two weeks... not great, but I think I'll try it anyhow. Worse case, I give up and go with a battery (well fire would be the worse case).

Edit: there's a 5F version https://www.digikey.com/en/products/detail/eaton-electronics-division/PHB-5R0H505-R/2770532

 

[Kujako]

I use these in the OMVS builds I made, they work well but will require shaving off the mask to expose the ground plane:

Dahszhi Button Cell Battery Holder for CR2032-10pcs https://a.co/d/5Eoxdpo

Question, checking a MV1C that via you show connecting to (-) on the battery isn't used by anything. Did you run a wire on the underside? Or did you scrape away the ground pane next to it. Still exploring options...