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Questions about Meow Toast battery replacement

joshc

Well-known member
BTW, your footprint for C10 is empty and it's triggering my OCD.
IIfx is one of the (the only?) unusual Mac boards that has two sets of pads for each capacitor, one for tants and one for electrolytic, I assume because of the different package sizes at the time.
 

Breathing

Member
@Breathing Do you have a single-PCB version of that battery holder? That looks really slick.
Not really but I can modify the design to fillup the place a single PCB would take. However the pins on the back would still need to be taken into account.
I don't mind sharing the FreeCad source, it's just that I'm quite ashamed of the "Methods" use to accomplish the result... far from professional... but here it is.
 

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s_pupp

Well-known member
Not really but I can modify the design to fillup the place a single PCB would take. However the pins on the back would still need to be taken into account.
I don't mind sharing the FreeCad source, it's just that I'm quite ashamed of the "Methods" use to accomplish the result... far from professional... but here it is.
Far from professional?
I'll show you far from professional:
 

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Nixontheknight

Well-known member
Nice. Between this, 3d-printed interrupt/reset buttons, and 3d-printed face plates, I may need to reconsider my position on having a 3d printer.

BTW, your footprint for C10 is empty and it's triggering my OCD.
If you don't know which 3D printer to get, I recommend the ender-3
 

bigmessowires

Well-known member
I am fighting hard against collecting more stuff that gets rarely used, so I was thinking about using the 3d printer at my local public library. I previously had a 3d printer (an old Printrbot) but rarely used it, and it was a pain to configure and adjust whenever I did want to use it. It just ate up lots of space and was not a good experience, and soured me on the whole idea of home 3d printing. If I did buy a new one for home, I would prioritize small size and ease of setup / ease of use. I've never used the library's 3d printer before, so I'm not sure how well maintained it is or how long I'd have to hang around waiting for a 3d-printed power button to print. It might be a false time savings. There is also the option of just ordering things printed from Shapeways, which isn't cheap, but is a good option if you're only printing a few already-designed parts each year.
 

Phipli

Well-known member
I am fighting hard against collecting more stuff that gets rarely used, so I was thinking about using the 3d printer at my local public library. I previously had a 3d printer (an old Printrbot) but rarely used it, and it was a pain to configure and adjust whenever I did want to use it. It just ate up lots of space and was not a good experience, and soured me on the whole idea of home 3d printing. If I did buy a new one for home, I would prioritize small size and ease of setup / ease of use. I've never used the library's 3d printer before, so I'm not sure how well maintained it is or how long I'd have to hang around waiting for a 3d-printed power button to print. It might be a false time savings. There is also the option of just ordering things printed from Shapeways, which isn't cheap, but is a good option if you're only printing a few already-designed parts each year.
JLCPCB and PCBWay both do 3D printing. Others too.
 

tt

Well-known member
Why not get a CR14250 type battery with the same chemistry as the CR2032 but with the correct size for the original battery holder? Do they have reliability issues or is there a concern they contain more volume of battery chemistry?
 

bigmessowires

Well-known member
I did not know those existed. Maybe there's a concern they'll eventually leak or explode, similar to the original batteries?
 

Breathing

Member
@tt Basically they are the same as the original you get mounted in the original Macintosh Motherboard.
The problem with them is, the cost as they are more expensive (and less convient to source).
The second problem is they will eventually leak and explode the same way the original does. But obviously it would take one decade at least until it occurs...
 

tt

Well-known member
I recently came across a reddit comment that suggested the CR14250 3 V nominal, which I also wasn't aware of. They claimed the "CR" chemistry (Lithium Manganese Dioxide (Li-MnO2)) is much safer than the "ER" chemistry (Lithium Thionyl Chloride batteries (Li-SOCl2)).

@Breathing The batteries seem to be a little less expensive than the stock type, and while more expensive than a CR2032, they have more than 3x the capacity and don't need adapters and 3D printed supporting parts. They are a little over $4 on Digikey and have a 10 year shelf life. I likely would want to get a reputable brand for either, so that'll drive the cost up for the CR2032 batteries. Also, based on the chemistry differences, I am not sure it can be said they will explode in the same way, but any battery poses some risks.
 

s_pupp

Well-known member
I recently came across a reddit comment that suggested the CR14250 3 V nominal, which I also wasn't aware of. They claimed the "CR" chemistry (Lithium Manganese Dioxide (Li-MnO2)) is much safer than the "ER" chemistry (Lithium Thionyl Chloride batteries (Li-SOCl2)).

@Breathing The batteries seem to be a little less expensive than the stock type, and while more expensive than a CR2032, they have more than 3x the capacity and don't need adapters and 3D printed supporting parts. They are a little over $4 on Digikey and have a 10 year shelf life. I likely would want to get a reputable brand for either, so that'll drive the cost up for the CR2032 batteries. Also, based on the chemistry differences, I am not sure it can be said they will explode in the same way, but any battery poses some risks.
I bought one of those a few weeks ago, and put it in my MDD G4. My PRAM settings are maintained properly. Even if the battery does eventually leak, my understanding is that the contents are much less toxic than the lithium thionyl chloride batteries.
 

bigmessowires

Well-known member
CR14250 does sound like an appealing option. My experience with Meow Toast thus far has been frustrating - not only does it require a tiny adapter PCB and/or a 3D printed adapter, but I've found them difficult to insert and difficult to keep aligned correctly.
 

Stephen

Well-known member
Or maybe I'm confusing MeowToast with MeowTWOast which is designed for 5V. Which Mac models need a 5V battery?
The MeowTWOast is two cells in parallel so that the voltage is the same but the charge is doubled. It’s been a while since I made the designs, there are a few more stylish (and arguably better named) options available now.
 

jmacz

Well-known member
I recently came across a reddit comment that suggested the CR14250 3 V nominal, which I also wasn't aware of.

Hmm, if I knew about these, I would have gone with them.

But given I have a bunch of MeowToast holders on my existing Macs with CR2032s that are secure with my 3d printed holders, I am going to stay with the CR2032s.

That said, I am out of MeowToasts now, so if I end up picking up another Mac at sometime, I will probably go with these.
 

bigmessowires

Well-known member
I just ordered a bunch of the EEMB brand CR14250. They're suspiciously cheap and at first I thought they must be junk, but they claim to be the original battery manufacturer and they even have a legitimate UL listing and a proper datasheet.

It's the same battery chemistry as a CR2032 coin cell, so in theory if you trust a CR2032 not to leak corrosive goo then you should trust the CR14250 as well. I found this discussion on Reddit, which is maybe the post that @tt was referring to:

The ER (LS) chemistry is lithium Thiony Chloride (Li-SOCl2). They have a 3.7V cell voltage, very high capacity, and excellent temperature stability. But the Thiony Chloride (the cathode) is a liquid and very corrosive. So after 20 or so years, it leaks out and destroys everything. They are also hard to get a hold of now since they are considered dangerous and are not used for consumer applications anymore. They are still produced for Military and Medical devices.

The CR Chemistry is Lithium Manganese Dioxide (Li-MnO2). They have a voltage of 3v and are much less volatile. The only thing that can leak out of the cell is the electrolyte which is a gas. This electrolyte will make contacts green but shouldn't destroy anything. They are very cheap to manufacture so getting a pack may cost the same as 1 ER battery.

I'm going to install this CR14250 in my LC475. Check back in 2043 and I'll let you know whether it leaked!
 

tt

Well-known member
Yeah, that was the comment I read and I found a couple other comments. It's surprising that this battery isn't widely known, but it seems like it is used in different applications and can be found cheaply.

I recently saw Bolle's SE/30 reloaded board using the coin cell and thought that was interesting. A few weeks ago had the idea of making some plug to adapt the coin cell to a stock battery holder, but then I later saw someone already made an adapter. After learning about the CR14250, adapting a coin cell to a 1/2 AA battery holder seems a bit like a solution looking for a problem, but I can see why you'd go there. Maybe someone could argue the coin form factor is easier to manufacture more reliably as far as sealing is concerned.

I bought one of those a few weeks ago, and put it in my MDD G4. My PRAM settings are maintained properly. Even if the battery does eventually leak, my understanding is that the contents are much less toxic than the lithium thionyl chloride batteries.

At least it has been established a 3 V battery is serviceable for this application and people think the "CR" chemistry is more acceptable than the "ER" chemistry to keep inside their machines. Cheap coin cells are plentiful, but I don't know how trustworthy they are in the long run. I have seen small button cells leak in old toys from the 80s and 90s, though those use a different chemistry.

I'm going to install this CR14250 in my LC475. Check back in 2043 and I'll let you know whether it leaked!
Looking forward to it 😄

I just received a 1/2 AA Tadiran battery with a Digikey order, otherwise I would try a CR14250. I only need 1-2 Macs with the PRAM battery installed. I'll set a reminder for 3 years to inspect it.
 
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