CR2032 Battery holder - sanity check

[xalius]

Amongst other things I got today one of the CR2032 battery holders from the Pine shop.

Someone correct me please if I am wrong - but I think the polarity markings inside seem to be off?

After looking at how the contacts are wired, I had to place both coin cells with the negative side up into the holder to get a parallel connection (3V at the connector),
if I put them in as marked, they just seem to short out (measured 1.8V at the terminals....) ?

[pfeerick]

Amongst other things I got today one of the CR2032 battery holders from the Pine shop.

Someone correct me please if I am wrong - but I think the polarity markings inside seem to be off?

After looking at how the contacts are wired, I had to place both coin cells with the negative side up into the holder to get a parallel connection (3V at the connector),
if I put them in as marked, they just seem to short out (measured 1.8V at the terminals....) ?

  Well, that sounds like it would work great!  Maybe an example when RTFM isn't the best of ideas? 

[@lex]

You need both coin inserted. It seems it gets 6v dropped to 2.85v and this works.

      
---------|    + up  |  - up  |

[DonFL]

You need both coin inserted. It seems it gets 6v dropped to 2.85v and this works.

      
---------|    + up  |  - up  |

So you're saying its not meant to be two 3V cells in parallel, its meant to be 6V, and then regulated on-board?

I'm very leery of that in that the AAA battery holder looks like its 2 AAA cells, so 2x1.5V, a 3V output...would expect the 2032 holder to be the same design since its intended for the the very same function. Schematic for the 1 GB board that's posted on the wiki also indicates, if I'm interpreting the schematic correctly, 3V for RTC, with a direct connection to the PMIC chip, which also shows a spec of 3V max for RTC input.

[xalius]

RTC domain voltage is definitely 3V, 2 cell CR2302 holder only makes sense if they are connected in parallel.... not sure why it's two cells in the first place, RTC should only draw a couple uA anyways....

Edit: Then again the datasheet says 1mA@3V max. , while that is a lot for a RTC domain, it kind of explains why two CR2032 are needed....

[@lex]

I mean two CR2032 (3v), the left coin (near the cable) (+) facing up, the second CR2032 (3v)  (-) facing up.

** and don't forget to switch it ON

[DonFL]

I mean two CR2032 (3v), the left coin (near the cable) (+) facing up, the second CR2032 (3v) (-) facing up.

That puts them in series, giving you 6V rather than 3 as we are confident is correct. If you look at the scehmatic, there doesn't appear to be any on-board regulation for the RTC, so you're feeding that pin on the PMIC with 6V, spec appears to be 3V max.

I would tend to agree with xalius that the holder is mis-marked.

[@lex]

I mean two CR2032 (3v), the left coin (near the cable) (+) facing up, the second CR2032 (3v)  (-) facing up.

That puts them in series, giving you 6V rather than 3 as we are confident is correct. If you look at the scehmatic, there doesn't appear to be any on-board regulation for the RTC, so you're feeding that pin on the PMIC with 6V, spec appears to be 3V max.

I would tend to agree with xalius that the holder is mis-marked.

I mesured at the conector, it is 2.85v, so it is not feeding with 6v.

[DonFL]

I mean two CR2032 (3v), the left coin (near the cable) (+) facing up, the second CR2032 (3v)  (-) facing up.

That puts them in series, giving you 6V rather than 3 as we are confident is correct. If you look at the scehmatic, there doesn't appear to be any on-board regulation for the RTC, so you're feeding that pin on the PMIC with 6V, spec appears to be 3V max.

I would tend to agree with xalius that the holder is mis-marked.

I mesured at the conector, it is 2.85v, so it is not feeding with 6v.

When you measure the output of the battery holder, not connected to the board, what do you see? 6V?

And then when you plug it in, where are you taking your measurement?

[@lex]

I mean two CR2032 (3v), the left coin (near the cable) (+) facing up, the second CR2032 (3v)  (-) facing up.

That puts them in series, giving you 6V rather than 3 as we are confident is correct. If you look at the scehmatic, there doesn't appear to be any on-board regulation for the RTC, so you're feeding that pin on the PMIC with 6V, spec appears to be 3V max.

I would tend to agree with xalius that the holder is mis-marked.

I mesured at the conector, it is 2.85v, so it is not feeding with 6v.

When you measure the output of the battery holder, not connected to the board, what do you see? 6V?

And then when you plug it in, where are you taking your measurement?

Q: When you measure the output of the battery holder, not connected to the board, what do you see? 6V? 
A: 2.85v

Q: And then when you plug it in, where are you taking your measurement?
A: Did not take, just made sure that i did not have anything higher than 3v at the cable end, never seen anything like this on any SBC, but the only thing i can think it is that will last longer.

There seems to be a little circuitry inside this Battery holder that drops the voltage, if you insert only ONE battery you get ~1.8v or less.