Short Review: DS3231 RTC Breakout Board

[MrAl]

Hello again,

Give me one good reason why you would seem to like to keep the circuit as is without any modification after what i have already told you up to this point, before reading this post.

You seem to be wanting to push this back inside the limits of safe operating. I cant understand what could motivate you to want to do such a thing.
This is an Li-ion battery, period.

If you want to prove that it cant blow up, good luck. In a court of law you would need at least one expert witness who is willing to testify that there is no way ever possible for it to cause a fire. While i have agreed that it is more likely to just cause an energy storage failure, i cant close the door on the possibility of a real safety issue.

I already gave the information of where to find it on the Arduino site...the Sensor part of the forum and labeled as such. A link to one of the threads would be:
https://forum.arduino.cc/index.php?topic=363083.0

But dont limit yourself to that, look around some more on the web.

BTW, one guy had a CR2032 blow up, pop right off the board, ha ha, but that was because it was being charged and that's a primary battery.

 

[Nigel Goodwin]

Give me one good reason why you would seem to like to keep the circuit as is without any modification after what i have already told you up to this point, before reading this post.

Have you ever heard of the story of "the boy who cried wolf"

As I said before you seem to be seriously over-reacting, with little or no evidence to back your claims.

Personally I'm also EXTREMELY dubious that it would cause prompt failure of the battery, which is another of your claims.

 

[jpanhalt]

Hello again,

I already gave the information of where to find it on the Arduino site...the Sensor part of the forum and labeled as such. A link to one of the threads would be:
https://forum.arduino.cc/index.php?topic=363083.0

That link merely reiterates what you have said here. Simply repeating your concerns does not make them real. Your analogy to a court drama is not very realistic either. It is extraordinarily rare that one has to try to prove something can't happen. That's can't be done, and American courts are aware of that. That is one reason our courts focus on proving actual damages.

In all the years that I have been involved in science, I have never seen an instance in which a researcher claimed something and then responded to a request for validation by saying, you have to do those experiments yourself. Well, that is not exactly true. Human-caused global warming may be an exception.

In any event, LIR2032 batteries (type BR) appear to be extremely safe, and the worst thing that is likely to happen from using the charging circuit that you feel is poorly designed is decreased service life. Again, I you have evidence to support your assertion of danger, please present data or links to it.

John

 

[MrAl]

Hello again,

The bottom line is that the Li-ion battery, by reckoning with every data sheet ever published on Li-ion batteries, is being over charged, so the final question is what YOU would do with the circuit now:
1. Do nothing.
2. Disable the charge circuit.

John:
Did you see the link to the 'other' thread where it was talked about in more detail?
Also, did you find one site that said that the charge circuit IS GOOD ?
When so many witnesses say that something is bad, it's up to you to show it is good.
You seem very intent on proving something with no proof, but didnt answer my question.
My question was:
From what you have read SO FAR in this thread do you still want to leave the charging circuit alone, with no modifications?
Simple yes or no question.


Nigel:
Hey man, do it the way you want to do it, but i see you did not read all the posts here or on the other site. But same question to you:
From what you have read SO FAR in this thread do you still want to leave the charging circuit alone, with no modifications?
Simple yes or no question.

All:
In the end, it is YOU who is responsible for your circuit safety. It's always your choice.
People on EVERY site i have seen so far say the same thing, that the charge circuit is NOT GOOD.
Also, i have actually reviewed this product and circuit, i will wait to see other reviews here but i dont see anyone actually doing this yet while still claiming things. I did it, measured it, made a conclusion. Live with it or do your own review.

 

[jpanhalt]

MrAl: Referring to an entire forum to support your contentions is about like saying in the old days that the answer in in the library. You present the design as a danger. It is up to you to present the data supporting that assertion. Not all less-than-optimal designs blow up. You seem to respond to any criticism with a lecture that simply goes OT.

Yes, I did go to the link you posted, and I did follow a link therein (https://forum.arduino.cc/index.php?topic=278270.0 ) to this statement:

Hi
Thought this might help....
The use of a LIR2032 could well work fine if you leave the circuit as it is and use a 5V supply.

I think that answers your first two questions in post #44.

Now, how about you answering the direct question that was posed well before that post: Do you have any data that show the circuit using that particular battery is dangerous? That is, has it ever exploded, caught fire, or harmed anyone. YOU are the one who suggested that it blows up.

John

 

[MrAl]

Hello John,

I understand your concern so i'll try to find the original post about the explosion.

But you seem to be reading anything that seems to indicated that there is no problem, and ignoring everything else. I dont understand that. You also have to realize that if a person connects their board for the first time and tests it, it may look good because it takes time for the voltage to rise.

Here is a quote from THAT THREAD about a reply that said it was "good":
START QUOTE
I just tested this and it's not true. Without a battery inserted the voltage reading at the battery terminals is 4.67V
After 20 hours of charging a LIR 2032 (3.6V) in the unmodified ZS-042 module the voltage at the battery is 4.4V and the LIR is already a bit bloated.
END QUOTE

Even that spells a problem to me, but i dont even need that or any other site to tell me that there is something wrong because i did measurements myself. I dont think my battery is bloated though, but it's a little hard to tell as i dont want to remove it from the holder. I already removed the 200 ohm resistor though for safety.

I guess sometimes we can get a little over 'worried', but when it comes to Li-ion batteries i dont fool around or take chances. Same goes for Lead Acid batteries as i have seen the remains of explosions.

 

[Nigel Goodwin]

Nigel:
Hey man, do it the way you want to do it, but i see you did not read all the posts here or on the other site. But same question to you:
From what you have read SO FAR in this thread do you still want to leave the charging circuit alone, with no modifications?
Simple yes or no question.

Simple answer, yes - I've no plans to alter anything.

 

[MrAl]

Simple answer, yes - I've no plans to alter anything.

Hello again,

Oh ok, well in that case i wish you good luck with it. I would also be very interested in hearing your experience with this over time.

Related but not exactly the same thread:
https://www.candlepowerforums.com/v...uy-hand-crank-lights-with-LiIon-cells-in-them!

 

[MrAl]

Hello again,

Another small update...

It's now been running for about 11 or 12 days and there is still no error in the seconds, and the seconds change over is still synced with the watch although that was only measured for a few days now.

Maybe this should not be too much of a surprise, because the data sheet says plus or minus 2 ppm from 0 to 40 degrees C, and it's been room temperature in here for the last 12 days at least. Maybe fluctuation from 70F to 80F but that's about it. So if it is 2ppm over 0 to 40C then for a relatively constant temperature around 25C it should hold pretty darn well.

Also, the concensus on other sites is that if you can not be sure that the battery is safe then you must go by the written rules for Li-ion which is 4.2v max for example or else you take the risk into your own hands.
Look at it this way, if keeping the circuit as is really did not do any harm then pulling the 200 ohm resistor certainly will at least do that, plus protect against any possible future problems which can take a long time to show up. I know the CR type battery is not the same, but it took one guy's battery 4 years to blow up. All that time it worked, then one day it blew right off the board.

 

[MrAl]

Hi,

Little update...

About 20 days now, clock appears to be about 0.25 seconds fast, but it could be the watch is 0.25 sec slow, or a little of each.
Still that's not bad.

 

[MrAl]

Hello again,

Just another tiny update...

It's been about 30 days now, and the max error is hard to tell because it is less than 1 second. I'd say max of 1/2 second fast over one month. Since there are approximately 32 million seconds in one year, that means about 6 seconds per year at the current error rate. That equates to an error of about 0.2 parts per million, which is better than the specified 2 parts per million, but that 2ppm is specified over the full temperature range and this sits at room temperature all the time.

This has got to be the most accurate non-signal-receiving clock i've ever dealt with. It's not hard to deal with 6 seconds per year

As i mentioned previously, since i am using a watch for the comparison this small difference can be partly due to the watch. Even though i know the watch keeps good time, i have no actual data to show what the error is. If the error of the watch is 1/2 second slow per month then the RTC is very close to perfect, but if the watch is 1/2 seconds fast per month then the RTC is actually 1 full second fast per month. I probably wont actively pursue any more accurate measurements though, as this seems good enough.

 

[jpanhalt]

Why not use NIST as your reference? https://www.time.gov/ Or here: https://tf.nist.gov/tf-cgi/servers.cgi
Also, there is so-called Internet time.

John

 

[MrAl]

Why not use NIST as your reference? https://www.time.gov/ Or here: https://tf.nist.gov/tf-cgi/servers.cgi
Also, there is so-called Internet time.

John

Hi John,

Very good idea. I guess i just got a little lazy and didnt think it would matter that much, but now that you mention it i guess it would not be that hard to do because i can pick up WWV on short wave now and then (not all the time unfortunately) and they broadcast precise time references. Now i'll just have to determine the distance from them to me (some 2000 miles i think) and see if there is any lag that matters, but i dont think there is much more than about 10 milliseconds which would be good enough for me.

 

[jpanhalt]

Even with the worst of lag, the precision will be much better than that lag (about 10 ms to where you are). I would be worried about multi-paths and such affecting precision, but their contribution to what you are doing would be trivial. As for accuracy, I doubt your wristwatch holds 10-ms absolute throughout the day, which begs the point, how did you synchronize it that closely? You have a bionic finger too?

BTW, as mentioned in another thread, I get WWVB well late at night, but in the afternoon, my reception is sporadic.

John

 

[MrAl]

Even with the worst of lag, the precision will be much better than that lag (about 10 ms to where you are). I would be worried about multi-paths and such affecting precision, but their contribution to what you are doing would be trivial. As for accuracy, I doubt your wristwatch holds 10-ms absolute throughout the day, which begs the point, how did you synchronize it that closely? You have a bionic finger too?

BTW, as mentioned in another thread, I get WWVB well late at night, but in the afternoon, my reception is sporadic.

John

Hi John,

Couple questions...

What is better than what lag?
Why would you get the impression that my watch is somehow sync'd to some reference by 10ms?

I never said i sync'd my watch, i just said that the lag for 2000 miles (line of sight) is about 10ms. That means if i use the radio there will be 10ms (min) between the time i get the minute 'tone' (could be electrically too for faster detection) and the real time, so the clock would be 10ms off. I just mentioned that in case it was longer, but it's not so it should not be a problem for this application.
Also, it may be even less because i dont really need absolute time, relative time is ok too, so with the delay of 10ms one day it should be close to 10ms the next day too, etc. If that time lag mattered (and it really does not) then it would still be ok as long as the signal followed the same atmospheric path each day, and if i was measuring that precisely, i'd be able to tell because the time sync would fluctuate from day to day or time of day.

But in any case, 10ms does not matter so this should work Down side is, when i have some of my micro controllers running there is so much interference that i cant pick up the WWV station on any frequency. I might have to go outside and set the watch again, then use the watch, then check the watch periodically.

Long story short though, i am kind of satisfied with the 1/2 second per month thing.