RTC Backup Battery Holder CR-2032 Issues

[steveslim]

Hello all,
I'm in need of some answers regarding the RTC Backup Battery Holder - CR-2032 which is for sale on the Pine store at this link:  https://www.pine64.org/?product=rtc-back...cr-battery.

I purchased two of these with my Backerkit upgrades on the Kickstarter campaign to go with my two Pine A64+ 2 GB models.

These are pretty basic questions to start with, then get a bit screwy, in my opinion.

I have no electrical circuit experience, but have been trying to search on the web for answers (maybe "Electrical Circuits for Dummies" would help me?), but am having trouble, so I turn here for help.  I hope no one minds.

First of all, this model of RTC backup battery holder holds two CR2032 coin cell batteries and this holder has me put one battery into the holder with the negative ( - ) side down and the other with the negative side ( - ) up.  I'm ok with that, but don't really understand how the circuit can be completed this way.

In any case, the first spot for a battery is closest to where the black/red wire leads connect.  That spot for a battery has a ( - ) symbol embossed where that battery gets placed.  The second battery (closest to the rounded end of the battery holder) has a ( + ) symbol embossed where that battery goes.

I wasn't even sure how to orient the battery after seeing those embossed symbols.  For the battery closest to the wires (with the - symbol embossed on the holder), do I put the negative side of the battery face down to touch that symbol, or does it mean that the negative side of the battery faces up for that one?

I did make a guess that the negative side should touch the ( - ) symbol, and installed the battery that way--( - ) face down, and put the other battery in with the ( + ) face down, then connected it to the RTC connector on my Pine, and . . . the battery didn't keep the time on the device when power was pulled.  But, at least I didn't get any smoke from a "reverse polarity" situation, and my Pine seemed to suffer no ill effects from the experiment.

Next, I reversed the battery installation with the battery closest to the wires having the ( - ) symbol face up, and the other battery with the ( + ) symbol face up.  Installed the battery holder again, and . . .  success.  This Pine now has an operating RTC even when power is withdrawn.

I follow the same steps for the second RTC Backup Battery holder, putting the battery closest to the wires with the ( - ) symbol on the battery face up, and the second battery with the ( + ) symbol face up.  I plug it into the second Pine, and . . .  it doesn't work, the RTC doesn't keep time when power is withdrawn.

Ok, lots of things could be wrong.  Maybe I didn't insert the batteries the way I thought I did.  I check, and they are inserted the same way as the first battery holder.  Try it again, and still doesn't work.  So I take the first battery holder (that was working in my first Pine) and plug it into the second Pine, and vice versa.  Now the first Pine's RTC no longer keeps time, and the second Pine's RTC does.  Appears to be something wrong with the second RTC backup battery holder (or the batteries inside that second RTC backup battery holder).

Ok, I swap the batteries between the RTC backup battery holders.  Both batteries from the first one (working) go into the second (not working) and vice versa.  Plug both holders into the Pines, and the originally working holder (with the suspect batteries that maybe weren't working) still works, and the battery holder that, so far, has never worked, still isn't working (with batteries that WERE working when they were in the other battery holder).

So now, it appears that we've narrowed it down to something amiss with the actual second battery holder.  I carefully look at the connection points between the holder and the battery, and pry the metal connections up to ensure that good solid contact between those terminals and the batteries must be occurring.  I also check the wire connections to the little white connector that plugs into the Pine.  There's a little slippage at that connector, but same with the other one (that is working), so I assume that is normal.

It's even possible to open the RTC backup battery holder by unscrewing a couple of small screws, and, at the risk of having all kinds of springs and other magical stuff come flying out of the holder, I go for it (how could I make it worse, it's not working anyway) and open it up and check the connections of the black/red wires to the holder, and as far as I can see, all appears fine.

Well, I'm about to just give up and decide that I just happened to get a bad RTC Backup Battery Holder, and think about whether it's worth it to order another one, when I decide to switch the orientation of the two batteries in the "bad" holder.  So, I do this, and . . . now the RTC is working on this Pine that didn't work previously.  It seems that orienting the batteries exactly the opposite from the first RTC Backup Battery Holder solved my problem.  Now both RTCs are keeping time with power taken away.

As an aside, I'm hoping that I don't need some kind of electrical meter to sort through this quandry.  I don't have any.

So, my questions (if anyone is so inclined):

(1) How does this circuit work with one battery oriented with ( - ) face up and the other with ( + ) face up.  Skip this one if it's not really something to discuss in this forum.  Maybe I should take an electrical circuit 101 class?

(2) Has anyone played with the RTC Backup Battery Holder - CR-2032?  Did you insert the batteries with the battery closest to the black/red wires with the ( - ) terminal face up and the battery closest to the rounded part of the holder with the ( + ) terminal face up, or the other way around?

(3) Does anyone know if there is "reverse polarity" protection built into these holders?  I read that this requires a diode.  Is it possible that there is a diode in in the on/off switch assembly built into the top of this battery holder (the same edge where the black/red wires come into the holder)?  Incidentally, I did check to ensure that the on/off switch was always in the "on" position when doing all my testing above.  I even tested it with the switch in the "off" position in case the switch somehow got "wired wrong" (is that even possible)?

(4) Am I running the risk of frying one of my $29 Pines due to "reverse polarity" now?  Remember, one unit has batteries oriented one way, battery closest to the black/red wires with  ( - ) face up and second battery down at the rounded edge with the ( + ) terminal face up, and the other holder's batteries are oriented in the opposite way.  And both work (and each only works in that orientation and not the other), and again (for emphasis), each holder is oriented the opposite of the other.  I checked and double-checked and triple-checked this, and they are truly oriented the opposite of each other.  This is the screwy part, I think.  So far, no smoke or worse for either Pine.  The CR-2032 batteries are 3 volts each.  If 6 volts is going through that RTC circuit in the wrong direction, why don't I have a problem?  Or is the opposite orientation of each coin cell battery in one holder preventing that (hope, hope)?

For anyone that's read through my novel I thank you.  I hope the explanation is clear.  I also hope someone has some answers.  Thank you.

[MarkHaysHarris777]

I have no electrical circuit experience, but have been trying to search on the web for answers (maybe "Electrical Circuits for Dummies" would help me?), but am having trouble, so I turn here for help.

The CR2032 is a 3 volt lithium ion coin cell typically used on computer mother boards to hold the RTC and CMOS.  

The RTC on the PineA64 requires 3 volts.  The CR2032 battery holder (with switch) is designed to hold two CR2032 cells (in parallel) so that the 'battery' provides 3 volts and 'twice' the available current (~450mah) of one cell.  In this configuration the plus(+) of each cell is tied together (on red) and the negative ( - ) of each cell is tied together on black.

If the cells are installed properly three volts +3v will be present on the plus (red) wire relative to the black (ground) wire when the switch is ON.  If the measurement across the red and black wire is either zero ( 0 ) or six ( 6 ) volts ( or if the polarity is reversed ) then the cells are inserted incorrectly. 

If six volts is plugged into the RTC connector, or if the polarity is reversed damage may occur to the RTC or to the Pine board in general.

[steveslim]

I have no electrical circuit experience, but have been trying to search on the web for answers (maybe "Electrical Circuits for Dummies" would help me?), but am having trouble, so I turn here for help.

The CR2032 is a 3 volt lithium ion coin cell typically used on computer mother boards to hold the RTC and CMOS.  

The RTC on the PineA64 requires 3 volts.  The CR2032 battery holder (with switch) is designed to hold two CR2032 cells (in parallel) so that the 'battery' provides 3 volts and 'twice' the available current of one cell.  In this configuration the plus(+) of each cell is tied together (on red) and the negative ( - ) of each cell is tied together on black.

If the cells are installed properly three volts +3v will be present on the plus (red) wire relative to the black (ground) wire when the switch is ON.  If the measurement across the red and black wire is either zero ( 0 ) or six ( 6 ) volts ( or if the polarity is reversed ) then the cells are inserted incorrectly. 

If six volts is plugged into the RTC connector, or if the polarity is reversed damage may occur to the RTC or to the Pine board in general.

Hello MarkHaysHarris777 and thank you very much for the explanation.  In a perfect world, there would be some more detailed instructions on how to use the battery holder when you purchase one.  But even with instructions, my situation appears odd since for one holder I have the battery closest to the red/black wires with the ( - ) terminal on the battery face up and the second battery in that same holder with the ( + ) terminal face up, and for the second holder I have the battery closest to the red/black wires with the ( + ) terminal on the battery face up and the second battery in that second holder with the ( - ) terminal face up.  They are opposite of each other.  Yet both holders only work when they have batteries oriented this way, and so far, neither seems to have burned up, exploded, or otherwise gone up in a puff of smoke.

For what MarkHaysHarris777 has posted, I have to assume that for any given holder, the parallel configuration of the batteries (as opposed to a series configuration, I guess) is done by having one battery with the ( - ) side face up in the holder and the other battery with the ( + ) side up (at least with these holders).  I guess that doubles the current (amperage), while leaving the voltage at 3 volts.  I guess this makes the batteries last longer while controlling the RTC.  I'm assuming that if I WAS really sending 6 volts down the RTC circuit, I'd have noticed it by now (snap, crackle and pop, followed by blue smoke and a noxious odor), even if I don't have a meter.  And some voltage and current must be going down the circuit since the RTC keeps working when I disconnect it from AC power and then reconnect it.  I think I've ruled out 6 volts or 0 volts going down the RTC circuit.

But I still don't know if the battery next to the black/red wires should be inserted with the ( - ) side facing up or down and the second battery (in that same holder) facing in the opposite direction.  Or, in the opposite orientation.  I also don't understand why my two holders seem to require different orientations to work at all.  If the batteries are inserted in the opposite way in either battery holder, then they don't work at all.  This IS a good thing since otherwise, they may fry my board or RTC circuit it seems.  And I still have no idea how to tell if the polarity is reversed.  Is positive polarity always how things should be configured?  Or do some devices require negative polarity to operate?  Guess I do need an electrical meter to really troubleshoot this.  If I did have a meter, would I want to ensure that the circuit has positive polarity?   And could inserting the batteries in the wrong orientation cause the wrong polarity (negative polarity)?  So many questions.

Apparently not a project that a person with my current expertise should dabble in.

Since so far, neither Pine has suffered any ill effects, I'll chalk it up to magic, and update the post if either of them fry.

If all of this is just nonsense, feel free to just ignore it.  But if anyone has anything to add that might help explain this to this ignorant person, I'd be happy for additional lessons.  Thanks again to you, MarkHaysHarris777.  I do appreciate your post.  It did explain some of the puzzle.

[MarkHaysHarris777]

As long as we're having this stupid conversation , would you do everyone a favor please , and post pics of the CR2032 battery compartment 'open' with the cells removed ? Thanks.

[pfeerick]

If all of this is just nonsense, feel free to just ignore it.  But if anyone has anything to add that might help explain this to this ignorant person, I'd be happy for additional lessons.  Thanks again to you, MarkHaysHarris777.  I do appreciate your post.  It did explain some of the puzzle.

I haven't bought the pine64 battery holder myself, but according to a discussion that was going on over in this thread about the RTC battery holder, it appears that for starters, the battery holder markings are wrong (if they were right, no more instructions would be needed!) In that thread, the guys indicated that the batteries should both be placed in the holder positive (+) side down. There was also mention that if you had dud, or counterfeit batteries, you could get the expected 3v from the battery if you had one + up and one + down.

Unless you can test with a multimeter, it's all just guessing from here in. You could be unlucky and have dud batteries or a mis-wired connector... is the red wire on the same side of both connectors? And is it or the black wire connected to the same place in the two different holders? There is such a thing as positive polarity, and negative polarity (with respect to ground - polarity is only negative or positive with respect to some reference), but you'll encounter mostly positive stuff in everyday electronics. One way you can check the batteries if you have a LED handy is to fit batter between the leads of an led and see if it lights up - if the LED lights up with the long lead on the positive (+) side of the battery, that battery is fine (the polarity is correct and it isn't flat).

[MarkHaysHarris777]

If all of this is just nonsense, feel free to just ignore it.  But if anyone has anything to add that might help explain this to this ignorant person, I'd be happy for additional lessons.  Thanks again to you, MarkHaysHarris777.  I do appreciate your post.  It did explain some of the puzzle.

I haven't bought the pine64 battery holder myself, but according to a discussion that was going on over in this thread about the RTC battery holder, it appears that for starters, the battery holder markings are wrong (if they were right, no more instructions would be needed!)

Why does that not in the slightest surprise me ...  everytime I think this project is going to level out a fly right , something else really dumb pops up and exposes itself...   unbelievable.

[steveslim]

As long as we're having this stupid conversation , would you do everyone a favor please , and post pics of the CR2032 battery compartment 'open' with the cells removed ?  Thanks.

I'm sorry that you find the conversation in this thread stupid.  This was not my intent.  I can tell you that I was hesitant to respond to your request for fear of this post continuing to appear so to you.  But since I do believe that posting pictures may further the discussion, I do post pics here.

---

If all of this is just nonsense, feel free to just ignore it.  But if anyone has anything to add that might help explain this to this ignorant person, I'd be happy for additional lessons.  Thanks again to you, MarkHaysHarris777.  I do appreciate your post.  It did explain some of the puzzle.

I haven't bought the pine64 battery holder myself, but according to a discussion that was going on over in this thread about the RTC battery holder, it appears that for starters, the battery holder markings are wrong (if they were right, no more instructions would be needed!) In that thread, the guys indicated that the batteries should both be placed in the holder positive (+) side down. There was also mention that if you had dud, or counterfeit batteries, you could get the expected 3v from the battery if you had one + up and one + down.

Unless you can test with a multimeter, it's all just guessing from here in. You could be unlucky and have dud batteries or a mis-wired connector... is the red wire on the same side of both connectors? And is it or the black wire connected to the same place in the two different holders? There is such a thing as positive polarity, and negative polarity (with respect to ground - polarity is only negative or positive with respect to some reference), but you'll encounter mostly positive stuff in everyday electronics. One way you can check the batteries if you have a LED handy is to fit batter between the leads of an led and see if it lights up - if the LED lights up with the long lead on the positive (+) side of the battery, that battery is fine (the polarity is correct and it isn't flat).

Hello pfeerick,

Thank you for the referral to the other thread on this topic.  I did try to search for other threads about the battery holders before opening a new one.  Obviously, I missed it.  Thanks for the advice about the multimeter.  The pics I posted show that the red and black wires ARE connected in the same manner in both holders, so I don't know why the batteries seem to require different orientations in the holders.  Thanks too for the hint about using a LED to test the battery.  The batteries I bought were purchased in a department store, but I suppose that doesn't prevent counterfeits.  So far, I have placed both of the batteries in opposite orientations in one holder.  I was afraid to put them in the same orientation as I thought that would send 6 volts down the circuit (each CR-2032 battery is supposed to be 3 volts when new).

Edit:  I've now seen that the other post suggests putting both CR-2032 cells with ( + ) side down.  I've now done that with both of my Pines, and both RTCs hold the time when disconnected from power and then reconnected.  Thank you for this.

My apologies to you if I still got something wrong.  It isn't intentional.

Thanks for your post.  I appreciate all your helpful hints.

[MarkHaysHarris777]

The discussion is 'stupid' because there shouldn't even BE a discussion about something like this.

... the case is clearly designed for serial installation and modified for parallel installation. The black wire is not soldered where it can be effective (should be at the center), and the switch is more than likely soldered wrong too.  

The good news is that the case can easily be corrected to function normally.  The bottom line is that the red lead must be positive, and the black lead negative... and with both cells installed the voltage must not be greater than 3v.

What a fit.

Thank you for graciously posting the pics; my sincere apologies for thinking you were pranking... this is just unbelievable.

[androsch]

The discussion is 'stupid' because there shouldn't even BE a discussion about something like this.

... the case is clearly designed for serial installation and modified for parallel installation. The black wire is not soldered where it can be effective (should be at the center), and the switch is more than likely soldered wrong too.  

The good news is that the case can easily be corrected to function normally.  The bottom line is that the red lead must be positive, and the black lead negative... and with both cells installed the voltage must not be greater than 3v.

What a fit.

Thank you for graciously posting the pics;  my sincere apologies for thinking you were pranking...  this is just unbelievable.

What makes me really shudder in this context: If the Pine guys are selling battery holders for their board with such 'quality', what can we really expect from the quality of the board itself?

...something to think about...

[steveslim]

Hello MarkHaysHarris777,

Thank you for your latest post. I DID misunderstand your intent in your prior post for which I apologize. I do hope that someone from Pine will provide some guidance at some point in the future regarding the use of this RTC battery holder.

I know that there are much more pressing issues to deal with right now. Hopefully this will go into the pipeline for resolution some time in the future.

Thank you too for your apology. I am happy to accept and want to thank you too, for providing guidance to users like me as a moderator in these forums. I know that this task cannot be an easy one, and it can be difficult to know sometimes if questions are legitimate or not. I'm glad that you found the pics helpful as well.