RTC Backup Battery Holder CR-2032 Issues
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  This Pine now has an operating RTC even when power is withdrawn.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.

Messages In This Thread
RTC Backup Battery Holder CR-2032 Issues - by steveslim - 09-06-2016, 06:34 PM

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