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[Solved] Arduino Issue on Zalophus

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Inq
 Inq
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Posted by: @zander

and not sure about my two mature friends so perhaps electricity works different now and we old guys are just too old to understand the modern way. I know @frogandtoad posted some documentation that pointed out his problem, but who knows if it is valid, it could be fake docs.

I must have missed that @valerio was of a significantly younger generation than us.  Maybe, once he has smoked as many as we have, enlightenment will come.  😉   

VBR,

Inq

 

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Ron
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@inq Some folks do fill in their profile, here is his. I stopped smoking 98/2/28.

Screen Shot 2022 06 27 at 06.31.27

 

 

It is considered poor judgement to traverse a chasm in 2 leaps.


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Valerio
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@zander @inq @frogandtoad

Ok, understood.

I will modify the robot so that it can work with 2 3.7v Li-Ion batteries or some other source above 7 volts.

It is going to take some time, but it should work.

Thanks for your help

Have a nice day


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Ron
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@valerio Yes, 2 of the 3.7V batts will be a good choice but 3 is even better. The reason is that depending on batt age, %C draw and time you could drop below 7V thus jeopardizing the system 5V including the 5V pin as mentioned in the docs. with 3, you will stay above 7V all the way down the curve until they are at 0% SOC which if memory serves is 3.0V. Either will work, one is just a little more reliable. Personally I would go with 4 for 14.8V

It is considered poor judgement to traverse a chasm in 2 leaps.


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Inq
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Posted by: @zander

@valerio Yes, 2 of the 3.7V batts will be a good choice but 3 is even better. The reason is that depending on batt age, %C draw and time you could drop below 7V thus jeopardizing the system 5V including the 5V pin as mentioned in the docs. with 3, you will stay above 7V all the way down the curve until they are at 0% SOC which if memory serves is 3.0V. Either will work, one is just a little more reliable. Personally I would go with 4 for 14.8V

I defer to your hardware experience, but the Uno documentation says above 12V is also bad.  4 cells would be bad??? 

Also, 3.7V sounds like LiIon (18650???).  Minimum SOC for typical BMS disconnect is 2.5V... but his Uno would close up shop somewhere around 3.5V (with 2 cells 👍 👍 ) which would be a good thing.  That way he doesn't have to use a BMS or worry about drawing them down too far.  

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Even usable on ESP-01S - Quickest Start Guide


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Ron
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@inq I could be wrong, but I thought the regulator could handle between 6 and 20V so over 12 is ok, and no shutdown until 2x3V roughly.

It is considered poor judgement to traverse a chasm in 2 leaps.


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Inq
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@zander - I'd take you word over mine on the subject.  The last time I used an Arduino was the day I received my first ESP8266...   I can't think of a valid use for an Arduino any more.

3 lines of code = InqPortal = Complete IoT, App, Web Server w/ GUI Admin Client, Access Point Manager, Drag & Drop File Manager, OTA, Performance Metrics, Web Socket Comms, Easy App API, All running on ESP8266...
Even usable on ESP-01S - Quickest Start Guide


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DaveE
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Hi @zander Ron et al,

Re: I could be wrong, but I thought the regulator could handle between 6 and 20V 

I haven't checked a specific Arduino/ESP board specifically, but this "theme" seems a common one that I have tried to explain at least a couple of times before.

Many of the Arduinos, etc. have on board regulators, often based on AM1117 or similar. (NB At least one board design uses a different regulator whose max input voltage is less than 20V.)

It is true that at least some of these regulators is claimed to tolerate up to 20V input, though that is an absolute maximum rating, with most of the data sheet characteristics specified as 12V, suggesting that it is 'designed' for a maximum of 12V, and 12V to 20V is more of a 'safety margin area' for spikes, tolerances, etc.

However, there is at least a second specification to take into account.

The onboard regulator is a 'linear regulator' ... this means that the voltage difference between the input and the output results in heat dissipation, with the regulator acting as a 'magic resistor' whose 'resistance' automatically changes to achieve the correct voltage drop.

If the current demand on the regulator is small, which maybe true in some cases, then the dissipation will be small, and everything will be fine. But this is not always the case..

If your input voltage is more than about 7.5V, it is worth considering if you need a 'pre-regulator', such as one of the small switch mode power supply boards, with the output adjusted to about 7V for 5V Arduinos and about 5V for the 3.3 V Arduinos and ESPs.

Best wishes, Dave


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Ron
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@davee In fact in my personal projects I do use a LM2596 to drop the 12V I normally have available down to about 8. The 6 to 20 is from the earlier post of @frogandtoad where he included Arduino documentation.

It is considered poor judgement to traverse a chasm in 2 leaps.


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DaveE
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Hi Ron @zander,

   Sounds like you have a wise strategy ... but maybe a small part of the Arduino documentation is not so wise... unless you like living on the edge with 'unexpected' failures as a norm.

Best wishes, Dave


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Ron
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@davee I have absolute in the American legal system. If the 6-20 caused harm, they would mount a class action suit so fast.

I got paid in the RAM class action, and just got notified of my payout in the Microsoft class action so I am very comfortable saying if 6 was too low (they actually advise 7) and 20 too high they would get sued. But like you, I know a bit about this stuff and don't like the heat the LVR's produce so I use the DC-DC converters, buy them by the dozen for a couple bucks from China.

It is considered poor judgement to traverse a chasm in 2 leaps.


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DaveE
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Hi Ron @zander,

  Luckily I am at some distance from the US legal.

And as you didn't provide a full reference I couldn't readily check if your alleged quote had additional contextual information to qualify and explain the statement, which may not be strictly inaccurate, but I think can mislead people with limited experience, and for that reason I think it is unwise to quote without context.

I did not say that applying the statement would necessarily produce harm.

But given Arduino and similar boards, are apparently designed for people who may only have a limited experience of certain aspects of hardware and software, I do not personally think it is wise to make such statements without explaining aspects such as the difference between a 'recommended' and an 'absolute maximum' voltage rating, or the need to consider the heat dissipation limitations, given that in the case of the Arduino and similar boards, the loading will be dependent upon the board's components, software and external components connected to it, only one of these three being under the control of the board's designer.

Thus, in the spirit of this forum being 'friendly and helpful', I have consistently tried to provide explanatin and information to minimise the risk of disappointment.

I hope that is both legally and morally a reasonable course of action - I apologise for any unintended infringement or annoyance.

Best wshes to all. Dave


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Inst-Tech
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Posted by: @davee

Hi Ron @zander,

  Luckily I am at some distance from the US legal.

And as you didn't provide a full reference I couldn't readily check if your alleged quote had additional contextual information to qualify and explain the statement, which may not be strictly inaccurate, but I think can mislead people with limited experience, and for that reason I think it is unwise to quote without context.

I did not say that applying the statement would necessarily produce harm.

But given Arduino and similar boards, are apparently designed for people who may only have a limited experience of certain aspects of hardware and software, I do not personally think it is wise to make such statements without explaining aspects such as the difference between a 'recommended' and an 'absolute maximum' voltage rating, or the need to consider the heat dissipation limitations, given that in the case of the Arduino and similar boards, the loading will be dependent upon the board's components, software and external components connected to it, only one of these three being under the control of the board's designer.

Thus, in the spirit of this forum being 'friendly and helpful', I have consistently tried to provide explanatin and information to minimise the risk of disappointment.

I hope that is both legally and morally a reasonable course of action - I apologise for any unintended infringement or annoyance.

Best wshes to all. Dave

@davee, Very good advice!  Indeed, the mpu manufactures probably did take that into consideration that users of their products would not always be well versed, in the very broad sense, of electronic theory and application..but, I suspect that since most of these boards are of low coast, that "letting the smoke out of a few" would be classified as lessons learned, no harm done. The fact of the matter, as far as I'm concerned, is the probability of thermo run away, caused by excessive heat generated by the components,which is the cause of most semi-conductor failures. Heat sinks should be provided, even if your not anticipating heat problems just to be on the safe side. Using multiple LVR in series can also help, but does tend to complicate the circuit design somewhat. I try not to use voltages higher than what is required for proper circuit operation.. but that's just me..lol

The absolute ratings are indeed a safety factor, but it is highly recommended not to go there.. Higher the voltage input, the more voltage drop across the device, generating more current, which dissipates more heat, and leading to thermo run away generating more current until the device self destructs..

 

BTW, no need to appoligise for stating the obvious..

Regards,

LouisR

 

LouisR


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DaveE
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Hi Louis @inst-tech,

Thanks for your support, which is much appreciated.

You are of course correct in saying multiple regulators add complexity to the project ... and complication is usually best avoided. Clearly, you (Louis) have a full understanding of the issues. But, for the benefit of anyone else following this thread, I should like to explain my thinking.

------------------------------------

To clarify one point that I may not have explained fully (my sermons are too long as it is!) You (Louis) said:

Using multiple LVR in series can also help, but does tend to complicate the circuit design somewhat. I try not to use voltages higher than what is required for proper circuit operation.. but that's just me..lol

---------------

The reason I suggested them was I had the impression that the thread (at that point) was considering applications with power sources that would need to drive motors, etc., and these can often result in power voltages considerably higher than Arduinos, etc. need. (e.g. 14.8V was mentioned.)

Hence, my suggestion of a switch mode pre-regulator was based on:

  1. Efficiency ... reduces heat dissipation generally, increases battery run time (not always, by much)
  2. Availability and cost - small boards readily available - some less than $1 when buying a few at the same time through the usual bazaars.
  3. Flexibility .. output voltage usually controlled by resistor potential divider/potentiometer ... so if you buy (say) a pack of 5, each can be adjusted as necessary
  4. Reduces heat dissipation to onboard Arduino, etc. regulator .. cool components usually live longer.

Of course, these points must be balanced against the extra work, extra components that can themselves fail as well as needing space and so on.

--------

Had I been considering something like the thread was discussing, if my battery voltage was 7.4V (or less), then my preference would have been to just use the onboard regulator, (after checking the actual current demand and consequent regulator dissipation is within reasonable limits).

However, if my battery voltage was appreciably higher than 7.4V, such as 14.8V mentioned, then a pre-regulator would probably be preferred, and may be essential.

---------

I hope this discussion is useful and helpful.

Best wishes, Dave


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Inq
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Posted by: @davee

But, for the benefit of anyone else following this thread, I should like to explain my thinking.

I can deal with long sermons... please continue.  Between you and @inst-tech, my hardware knowledge is improving and I like that you explain more than just what, but also why.  Although I may no know the EE theoretical aspects behind these devices, you have both explained enough for the concept to sink in.  I don't retain monkey see, monkey do very well and if I understand the basis, it stays longer and can even sometimes be extrapolated to something new.

THANKS.

VBR,

Inq

3 lines of code = InqPortal = Complete IoT, App, Web Server w/ GUI Admin Client, Access Point Manager, Drag & Drop File Manager, OTA, Performance Metrics, Web Socket Comms, Easy App API, All running on ESP8266...
Even usable on ESP-01S - Quickest Start Guide


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