Hi all,

I'm aiming to d-i-y a battery discharge alarm that will be 'matched'
to 3 identical 12V Lead Acid Gel traction batteries, used with an
electric outboard.

The quick overview is that it will monitor the battery terminal
voltage and current and using the resultant of both, trigger an
audible alarm that relates to 50% depth of discharge (or thereabouts).

At the moment I have it working on an Arduino Nano feeding a 2 x 16
LCD via I2C interface (to reduce the wiring).

By copying, pasting and tweaking stuff I've found online, I've just
about got it reading and displaying the Volts, the current and
calculating and displaying the Watts and have a field for Wh but not
sure if I can implement Wh just using the Nanos internal timer?

I might not bother with displaying Wh but display the current low
voltage threshold (which will vary, see later) or maybe display both
alternately (as they are really just 'background' information).

Because of Peukerts Law, where it says the capacity of a (Lead acid)
battery will very dependant on the load / current drawn, it is my
thought to continuously calculate that based on a predetermined scale
(hopefully supplied by the battery manufacturer) and the WiKi page on
it gives us some basic rules and values to work from:

https://en.wikipedia.org/wiki/Peukert%27s_law

So, (Q1) given the right input values (instantaneous current and
volts), the variables for that particular battery and the Peukert's
Law formula, should I be able to do what I want?

I'm not particularly looking for lab precision here, just reasonably
repeatable results that I can cross reverence against other / external
meters to confirm it is all at least reasonably representative.

I'm still waiting for some of the bits (batteries and the Hall-effect
current sensor) before I can do any real tests but as a starter, one
of the things I'm struggling with is getting the Watts value to
display properly?

e.g. The volts displays will be to 1 decimal place and typically
always between say 11.0 and 13.8V ( just / always two integers),
making it easy to display as the display control is only the position
of the first character.

The Amps should be between 0.0 and 30.0 and I have been able to use an
IF / ELSE to move the screen print position to adjust between 1.5 and
25.0 A. (1 or 2 integers).

The Watts and Wh though will go between 0 and say 360 (W, for the
motor) or 0 - 180 Wh for the battery, both being 3 integers. It's that
bit I can't seem to get right so would like help with please?

Just to give you the examples, the first bit works (probably more by
luck than judgment (ignore comment wraps):

// Read and display Current (col / row)
readAmps = analogRead(ampsInput);
delay(5);
float amps = readAmps * (50.0 / 1023.0); //this maps the measured
voltage from 0 to 50V (read as Amps)
lcd.setCursor(0,1); // first col, second row
lcd.print(" "); // clear the previous value as it could have a
different number on integers
if (amps 10)
{
lcd.setCursor(1,1); // to cope with 0.0 to 9.9, space display out by
one
}
else
{
lcd.setCursor(0,1); // to cope with 10.0 to 99.9
}
lcd.print(amps,1);

So far, so good?


However, I can't seem to get this one right and I think it's to do
with the IF, ELSE IF, ELSE rules. Changing the second else if to just
else (as I believe it should be) it then won't compile. ;-(


// Calculate and display Watts
lcd.setCursor(8,0);
lcd.print(" ");
float watts = (volts * amps);
if (watts 10) {
lcd.setCursor(10,0);
lcd.print(watts,1); // displays calculated watts to one decimal
place
}
else if (watts = 10) {
lcd.setCursor(9,0);
lcd.print(watts,1);
}
else if (watts = 100) {
lcd.setCursor(8,0);
lcd.print(watts,1);
}

Anything over 100 seems to be 1 character too many to the right so I
think I have the logic wrong somewhere. ;-(

The 16x2 display should look like this:

12.5 V 187.5 W
15.0 A Wh

What I'm getting is this:

12.5 V 187.5W
15.0 A Wh


At the moment all the analogue inputs are just open / floating so it's
just displaying random noise but that is good enough to test the
display. Shorting either input to ground correctly displays 0.0 for
volts and amps (and watts etc) and to 5V displays 15V, 50A and 750W.
;-)

So, (Q2) could someone familiar with Arduino coding help me on this
and any other further hiccups I get please?

Cheers, T i m

On Tue, 5 Sep 2017 17:47:19 +0100, "Brian Gaff"
wrote:

Would not the instantaneous drop on start up give a good indication of
battery health?

Whilst it might to some degree and assuming you mean capacity when you
say health, I would still like to measure the running current and
volts and see the consumed energy in kilowatt hours.

This running project may be a parallel project that would be a
semi-automated test rig that would run the battery at various loads,
logging the values to an SD card for later perusal and evaluation.

Cheers, T i m

On Tue, 5 Sep 2017 17:15:50 +0100, "Dave W"
wrote:

snip

I don't know Arduino coding, but your last 'else' won't work, because the
previous 'else' covers both watts =10 and watts = 100.

Ah ...

I suggest:
if watts 10
... // set cursor 8
else if watts =100
... // set cursor 10
else
... // set cursor 9
end if

Ok, and putting that into Arduino talk and reversing the column
spacing variable resultant (as it counts from the left to right and to
the first digit) it then works perfectly. ;-)


if (watts 10) {
lcd.setCursor(10,0);
(So a 7.0 would be printed with the 7 10 chrs from the left with the
dp at position 11)
lcd.print(watts,1);
}
else if (watts = 100) {
lcd.setCursor(8,0);
(So a 123.4 would be printed with the 1 8 chrs from the left with the
dp at position 11)
lcd.print(watts,1);
}
else{
lcd.setCursor(9,0);
(so a 75.6 would be printed 9 chrs from the left with the dp at
position 11)
lcd.print(watts,1);
}

Brilliant. ;-)

Cheers, T i m

On 05/09/17 23:07, T i m wrote:
On Tue, 5 Sep 2017 17:15:50 +0100, "Dave W"
wrote:

snip

I don't know Arduino coding, but your last 'else' won't work, because the
previous 'else' covers both watts =10 and watts = 100.

Ah ...

I suggest:
if watts 10
... // set cursor 8
else if watts =100
... // set cursor 10
else
... // set cursor 9
end if

Ok, and putting that into Arduino talk and reversing the column
spacing variable resultant (as it counts from the left to right and to
the first digit) it then works perfectly. ;-)


if (watts 10) {
lcd.setCursor(10,0);
(So a 7.0 would be printed with the 7 10 chrs from the left with the
dp at position 11)
lcd.print(watts,1);
}
else if (watts = 100) {
lcd.setCursor(8,0);
(So a 123.4 would be printed with the 1 8 chrs from the left with the
dp at position 11)
lcd.print(watts,1);
}
else{
lcd.setCursor(9,0);
(so a 75.6 would be printed 9 chrs from the left with the dp at
position 11)
lcd.print(watts,1);
}

Brilliant. ;-)

Cheers, T i m


Why not?:

lcd.setCursor((watts10)?10watts=100)?8:9,0);
lcd.print(watts,1);

And save the paint on the curly brace key....


--
The biggest threat to humanity comes from socialism, which has utterly
diverted our attention away from what really matters to our existential
survival, to indulging in navel gazing and faux moral investigations
into what the world ought to be, whilst we fail utterly to deal with
what it actually is.

On Tue, 5 Sep 2017 23:40:24 +0100, The Natural Philosopher
wrote:

On 05/09/17 23:07, T i m wrote:
On Tue, 5 Sep 2017 17:15:50 +0100, "Dave W"
wrote:

snip

I don't know Arduino coding, but your last 'else' won't work, because the
previous 'else' covers both watts =10 and watts = 100.

Ah ...

I suggest:
if watts 10
... // set cursor 8
else if watts =100
... // set cursor 10
else
... // set cursor 9
end if

Ok, and putting that into Arduino talk and reversing the column
spacing variable resultant (as it counts from the left to right and to
the first digit) it then works perfectly. ;-)


if (watts 10) {
lcd.setCursor(10,0);
(So a 7.0 would be printed with the 7 10 chrs from the left with the
dp at position 11)
lcd.print(watts,1);
}
else if (watts = 100) {
lcd.setCursor(8,0);
(So a 123.4 would be printed with the 1 8 chrs from the left with the
dp at position 11)
lcd.print(watts,1);
}
else{
lcd.setCursor(9,0);
(so a 75.6 would be printed 9 chrs from the left with the dp at
position 11)
lcd.print(watts,1);
}

Brilliant. ;-)

Cheers, T i m


Why not?:

lcd.setCursor((watts10)?10watts=100)?8:9,0) ;
lcd.print(watts,1);

And save the paint on the curly brace key....

Whilst I like the idea of the compactness / efficiency of just the one
line of code ... and it seems to compile and run, it doesn't seem to
work properly. ;-(

A value less than 10 (so say 1.2) and with your code we get the dp at
position 11 (I think I meant 12 above (not 11) to put it in the right
place for each value range), 123.4 has the dp at position 14 and 12.3
at pos 13?

The lcd.setCursor seems to set the position of the first character so
it would have to have a lower number position offset the higher the
value printed to the display (if that helps)?

So, (with fixed pitch font) we need:

0000000001111111
1234567890123456
1.2 W
12.3 W
123.4 W

but with your code we are seeing:

0000000001111111
1234567890123456
1.2 W
12.3W
123.4

changing your code from:

lcd.setCursor((watts10)?10watts=100)?8:9,0);
lcd.print(watts,1);

to:

lcd.setCursor((watts10)?8watts=100)?8:10,0);
lcd.print(watts,1);

gives us:

0000000001111111
1234567890123456
1.2 W
12.3 W
123.4 W

So fixes two of them why (or how it works). ;-(

Cheers, T i m

"T i m" wrote in message
...
On Tue, 5 Sep 2017 23:40:24 +0100, The Natural Philosopher
wrote:


Why not?:

lcd.setCursor((watts10)?10watts=100)?8:9,0 );
lcd.print(watts,1);

And save the paint on the curly brace key....

Whilst I like the idea of the compactness / efficiency of just the one
line of code ... and it seems to compile and run, it doesn't seem to
work properly. ;-(

A value less than 10 (so say 1.2) and with your code we get the dp at
position 11 (I think I meant 12 above (not 11) to put it in the right
place for each value range), 123.4 has the dp at position 14 and 12.3
at pos 13?

The lcd.setCursor seems to set the position of the first character so
it would have to have a lower number position offset the higher the
value printed to the display (if that helps)?

So, (with fixed pitch font) we need:

0000000001111111
1234567890123456
1.2 W
12.3 W
123.4 W

but with your code we are seeing:

0000000001111111
1234567890123456
1.2 W
12.3W
123.4

changing your code from:

lcd.setCursor((watts10)?10watts=100)?8:9,0);
lcd.print(watts,1);

to:

lcd.setCursor((watts10)?8watts=100)?8:10,0);
lcd.print(watts,1);

gives us:

0000000001111111
1234567890123456
1.2 W
12.3 W
123.4 W

So fixes two of them why (or how it works). ;-(

Cheers, T i m

Surely TNP's "watts10" should be "watts10"?
--
Dave W

On Wed, 6 Sep 2017 15:26:21 +0100, "Dave W"
wrote:
snip


Surely TNP's "watts10" should be "watts10"?

Yup, spot on, thanks Dave. ;-)


lcd.setCursor((watts10)?10watts=100)?8:9,0);
lcd.print(watts,1);

So, does that translate as (in order though the line):

If the value of 'watts' is less than 10, position the cursor 10 (as it
happens) chrs out from the left hand edge.

Then if it's greater than or equal to 100, position it 8 from the lhe.

If it's anything else (so =10 and 99.9) position it 9 from the lhe?

If it does then I guess I get the basic maths rules and that part of
the coding but I wouldn't be able to create similar from scratch as I
don't really understand the rules of the language so to speak (like
the use of the ? and the ,0 at the end).

I might have a go at using the same format on the other fields and see
how I get on.

I've never been a coder and seem to have a form of number blindness
with anything much past basic arithmetic to the point where it get's
me more frustrated than pretty well anything else I can think of. ;-(

I guess that frustration is because I often want / need the outcome
but don't have the means of getting there myself or the memory or
brain wiring to be able to remember what to do get there, even if I
managed it last week. ;-(

Now give me a machine and I'll take it to bits and put it back
together again without breaking a sweat, the parts 'speaking to me' in
a way numbers or programming doesn't. ;-(

It's like looking at ancient hieroglyphs most of the time!

Cheers, T i m

On 06/09/17 15:26, Dave W wrote:
"T i m" wrote in message
...
On Tue, 5 Sep 2017 23:40:24 +0100, The Natural Philosopher
wrote:


Why not?:

lcd.setCursor((watts10)?10watts=100)?8:9,0);
lcd.print(watts,1);

And save the paint on the curly brace key....

Whilst I like the idea of the compactness / efficiency of just the one
line of code ... and it seems to compile and run, it doesn't seem to
work properly. ;-(

A value less than 10 (so say 1.2) and with your code we get the dp at
position 11 (I think I meant 12 above (not 11) to put it in the right
place for each value range), 123.4 has the dp at position 14 and 12.3
at pos 13?

The lcd.setCursor seems to set the position of the first character so
it would have to have a lower number position offset the higher the
value printed to the display (if that helps)?

So, (with fixed pitch font) we need:

0000000001111111
1234567890123456
1.2 W
12.3 W
123.4 W

but with your code we are seeing:

0000000001111111
1234567890123456
1.2 W
12.3W
123.4

changing your code from:

lcd.setCursor((watts10)?10watts=100)?8:9,0);
lcd.print(watts,1);

to:

lcd.setCursor((watts10)?8watts=100)?8:10,0);
lcd.print(watts,1);

gives us:

0000000001111111
1234567890123456
1.2 W
12.3 W
123.4 W

So fixes two of them why (or how it works). ;-(

Cheers, T i m

Surely TNP's "watts10" should be "watts10"?

yes. it should


--
"When one man dies it's a tragedy. When thousands die it's statistics."

Josef Stalin

On 06/09/17 16:10, T i m wrote:
On Wed, 6 Sep 2017 15:26:21 +0100, "Dave W"
wrote:
snip


Surely TNP's "watts10" should be "watts10"?

Yup, spot on, thanks Dave. ;-)


lcd.setCursor((watts10)?10watts=100)?8:9,0);
lcd.print(watts,1);

So, does that translate as (in order though the line):

If the value of 'watts' is less than 10, position the cursor 10 (as it
happens) chrs out from the left hand edge.

Then if it's greater than or equal to 100, position it 8 from the lhe.

If it's anything else (so =10 and 99.9) position it 9 from the lhe?

If it does then I guess I get the basic maths rules and that part of
the coding but I wouldn't be able to create similar from scratch as I
don't really understand the rules of the language so to speak (like
the use of the ? and the ,0 at the end).

your basic call is lcd.setCursor(a,0);

All we are doing is arriving at the right value for 'a'.

The conditional test is (exp) ? a:b

if (exp) true then a else b.

A string of these evaluate left to right
so (exp1)? aexp2)? b:c

means the whole shebang will be a if exp1 is true, or b if exp2 is true,
or c.

The comma is not an operator, it its a separator, so it has no impact on
te evaluation of 'a'

so (exp1)? aexp2)? b:c, 0

is two variables one of which is conditional. It's like typing x,0

Now a modern compiler of any quality will optimise whatever you write
down to probably e same assembler. so its really a quaqstion of which
you find easier to read a year from now :-)

For me, very familiar with C syntax, the way I wrote it is easier - it
says 'set the cursor depending on the value of watts, and then print the
string'

I.e. its not making a miouthful out of decideing what te cursor ioffset
is, its not setting a seperate vravle to reprsent it and ots not calling
set curseor and indeed the print function from 3 different places when
one will do.

If you want to do the if/ else if/ else

then:-

int offset;
if (watts 10) offset=10;
else if (watts =100) offset = 8;
else offset=9;

lcd.setCursor(offset,0);
lcd.print(watts);

is a far less verbose way of doing it and will result in identical
compiled code to what I posted earlier IF the compiler is smart enough
to put 'offset' in a regsister and not declare space on the stack for it.




I might have a go at using the same format on the other fields and see
how I get on.

I've never been a coder and seem to have a form of number blindness
with anything much past basic arithmetic to the point where it get's
me more frustrated than pretty well anything else I can think of. ;-(

I guess that frustration is because I often want / need the outcome
but don't have the means of getting there myself or the memory or
brain wiring to be able to remember what to do get there, even if I
managed it last week. ;-(

Now give me a machine and I'll take it to bits and put it back
together again without breaking a sweat, the parts 'speaking to me' in
a way numbers or programming doesn't. ;-(

It's like looking at ancient hieroglyphs most of the time!

Cheers, T i m



--
"When one man dies it's a tragedy. When thousands die it's statistics."

Josef Stalin

On Wed, 6 Sep 2017 16:39:35 +0100, The Natural Philosopher
wrote:

On 06/09/17 16:10, T i m wrote:
On Wed, 6 Sep 2017 15:26:21 +0100, "Dave W"
wrote:
snip


Surely TNP's "watts10" should be "watts10"?

Yup, spot on, thanks Dave. ;-)


lcd.setCursor((watts10)?10watts=100)?8:9,0);
lcd.print(watts,1);

So, does that translate as (in order though the line):

If the value of 'watts' is less than 10, position the cursor 10 (as it
happens) chrs out from the left hand edge.

Then if it's greater than or equal to 100, position it 8 from the lhe.

If it's anything else (so =10 and 99.9) position it 9 from the lhe?

If it does then I guess I get the basic maths rules and that part of
the coding but I wouldn't be able to create similar from scratch as I
don't really understand the rules of the language so to speak (like
the use of the ? and the ,0 at the end).

your basic call is lcd.setCursor(a,0);

Yup, I got that bit. ;-)

All we are doing is arriving at the right value for 'a'.

Ok ...

The conditional test is (exp) ? a:b

if (exp) true then a else b.

Yup, I get the concept ...

A string of these evaluate left to right
so (exp1)? aexp2)? b:c

But what are the question marks doing? Is that an abbreviated 'If' in
that context?

means the whole shebang will be a if exp1 is true, or b if exp2 is true,
or c.

Understood (again, the concept).

The comma is not an operator, it its a separator, so it has no impact on
te evaluation of 'a'

Yes, that penny dropped later in your (still too 'scientific')
explanation.

so (exp1)? aexp2)? b:c, 0

exp?

is two variables one of which is conditional. It's like typing x,0

Yup, I got that already ...

Now a modern compiler of any quality will optimise whatever you write
down to probably e same assembler. so its really a quaqstion of which
you find easier to read a year from now :-)

Quite (and I think the truth for me will be) 'none of it'. ;-(

In general, when I do something, I 'understand and remember' it. With
some basic level of coding I first plagiarise it (a good thing with
the Arduino stuff), try to understand / use / apply it for my needs
.... then forget very quickly how (or if) I ever did it. ;-(

I guess this isn't uncommon for someone who has never really done any
/ much coding earlier in life and what little I have done was inter
spaced with huge chunks of time?

For me, very familiar with C syntax, the way I wrote it is easier - it
says 'set the cursor depending on the value of watts, and then print the
string'

Yes, I do appreciate how much 'cleaner' it looks, even though it's
more condensed.

I.e. its not making a miouthful out of decideing what te cursor ioffset
is, its not setting a seperate vravle to reprsent it and ots not calling
set curseor and indeed the print function from 3 different places when
one will do.

Agreed, it gives that need (simple display manipulation) the code
space it deserves.

If you want to do the if/ else if/ else

then:-

int offset;
if (watts 10) offset=10;
else if (watts =100) offset = 8;
else offset=9;

lcd.setCursor(offset,0);
lcd.print(watts);

Ok ... and whilst I can follow that easier (if I put my mind to the
sequencing) I think it's too bulky for the job it's doing.

is a far less verbose way of doing it and will result in identical
compiled code to what I posted earlier IF the compiler is smart enough
to put 'offset' in a regsister and not declare space on the stack for it.

And that would be my only saving grace ... that it might all turn out
ok (or less bad) in the wash.

As long as whatever I need to do can be done in one big loop, then I
feel I stand a chance of getting most of it working (albeit in a
clumsy way).

I'm lucky in that I have a good friend who is a very good coder and
who is as interested in learning some basic electronics as I am
getting code solutions. However, he's not long become a Dad and so I'm
giving him some space. ;-)

The other things is that because I don't really have a rigid plan and
opportunities unfold as I go, I can't ever really plan / lay out my
needs (not a good basis for such projects I know).

e.g. I have two projects going on in my head here ... the first is a
battery discharge monitor that I'll just use as a tool when electric
outboarding and, using much of the same hardware, a sort of semi
automated test jig that I could use to run the outboard though a range
of speeds and log the results (current drawn / speed / thrust etc),
and potentially also cycling the new Lead Acid batteries (to bring
them up to spec).

1) Apply variable load and log results.
2) Monitor battery voltage and cut load at predetermined threshold.
3) Wait.
4) Apply charger and monitor for full charge status.
5) Wait
6) Repeat 20 times.

Etc.

Cheers, T i m

On 07/09/17 00:12, T i m wrote:
On Wed, 6 Sep 2017 16:39:35 +0100, The Natural Philosopher
..

A string of these evaluate left to right
so (exp1)? aexp2)? b:c

But what are the question marks doing? Is that an abbreviated 'If' in
that context?

yes.

means the whole shebang will be a if exp1 is true, or b if exp2 is true,
or c.

Understood (again, the concept).

The comma is not an operator, it its a separator, so it has no impact on
te evaluation of 'a'

Yes, that penny dropped later in your (still too 'scientific')
explanation.

so (exp1)? aexp2)? b:c, 0

exp?
expression. Anytjinbg that evaluates to a value.

1 is an expersion.

(10-3) is an extression. (numerical)
"Today is not Sunday" is an expression (string)
ab is an exoression (boolean)
= is an operator. Or part of an expression -
never a whole one.


is two variables one of which is conditional. It's like typing x,0

Yup, I got that already ...

Now a modern compiler of any quality will optimise whatever you write
down to probably e same assembler. so its really a quaqstion of which
you find easier to read a year from now :-)

Quite (and I think the truth for me will be) 'none of it'. ;-(

True, and thats why I said what I said. Perhaops I should have said so
its really a question of which the you a year from now will find easier
to read :-)

Remember the best code is code you never have to read again.



In general, when I do something, I 'understand and remember' it. With
some basic level of coding I first plagiarise it (a good thing with
the Arduino stuff), try to understand / use / apply it for my needs
... then forget very quickly how (or if) I ever did it. ;-(

Its true even for those og us who made good livings doing thos stuff.
You woork yourself uo to a pitch of understanding, do it, and then its
done and you forget it all complenetely.
#

I guess this isn't uncommon for someone who has never really done any
/ much coding earlier in life and what little I have done was inter
spaced with huge chunks of time?

For me, very familiar with C syntax, the way I wrote it is easier - it
says 'set the cursor depending on the value of watts, and then print the
string'

Yes, I do appreciate how much 'cleaner' it looks, even though it's
more condensed.

I.e. its not making a miouthful out of decideing what te cursor ioffset
is, its not setting a seperate vravle to reprsent it and ots not calling
set curseor and indeed the print function from 3 different places when
one will do.

Agreed, it gives that need (simple display manipulation) the code
space it deserves.

If you want to do the if/ else if/ else

then:-

int offset;
if (watts 10) offset=10;
else if (watts =100) offset = 8;
else offset=9;

lcd.setCursor(offset,0);
lcd.print(watts);

Ok ... and whilst I can follow that easier (if I put my mind to the
sequencing) I think it's too bulky for the job it's doing.

is a far less verbose way of doing it and will result in identical
compiled code to what I posted earlier IF the compiler is smart enough
to put 'offset' in a regsister and not declare space on the stack for it.

And that would be my only saving grace ... that it might all turn out
ok (or less bad) in the wash.

Modern compilers are amazing.

Compared to te heap of ****y I worked on back in the day when you really
had to find the best of 6 ways of writing sonmething to get the compiler
to produce compact code.



As long as whatever I need to do can be done in one big loop, then I
feel I stand a chance of getting most of it working (albeit in a
clumsy way).

I'm lucky in that I have a good friend who is a very good coder and
who is as interested in learning some basic electronics as I am
getting code solutions. However, he's not long become a Dad and so I'm
giving him some space. ;-)

The other things is that because I don't really have a rigid plan and
opportunities unfold as I go, I can't ever really plan / lay out my
needs (not a good basis for such projects I know).

Nothing wroong woth that. Yiou arent part of a bif team. Wrie te obvious
bits first and then when you have a 'livrary' of usefel tested bits -
like te coide you just wrote makes a marvelous subroutne, or fuinction
sp yiou can lock it away knowing it works, and just call

displayWatts( float watts);

whenever you need to do that thing.

The secret of good coing is mnot letting tedious detail interfere with
the logic of what you are doing elsewhere.


e.g. I have two projects going on in my head here ... the first is a
battery discharge monitor that I'll just use as a tool when electric
outboarding and, using much of the same hardware, a sort of semi
automated test jig that I could use to run the outboard though a range
of speeds and log the results (current drawn / speed / thrust etc),
and potentially also cycling the new Lead Acid batteries (to bring
them up to spec).

1) Apply variable load and log results.
2) Monitor battery voltage and cut load at predetermined threshold.
3) Wait.
4) Apply charger and monitor for full charge status.
5) Wait
6) Repeat 20 times.

Etc.


That is your main loop then

You can wrire that and shove all the unkown stiff into as yet unwritten
functions. Ths one way.
Or you can think about te issues of how to apply a e.g. load and log
results and write those functions first..

Either way works.



Cheers, T i m



--
€œSome people like to travel by train because it combines the slowness of
a car with the cramped public exposure of €¨an airplane.€�

Dennis Miller

On Thu, 7 Sep 2017 09:18:27 +0100, The Natural Philosopher
wrote:

On 07/09/17 00:12, T i m wrote:
On Wed, 6 Sep 2017 16:39:35 +0100, The Natural Philosopher
.

A string of these evaluate left to right
so (exp1)? aexp2)? b:c

But what are the question marks doing? Is that an abbreviated 'If' in
that context?

yes.

Gdgd.

means the whole shebang will be a if exp1 is true, or b if exp2 is true,
or c.

Understood (again, the concept).

The comma is not an operator, it its a separator, so it has no impact on
te evaluation of 'a'

Yes, that penny dropped later in your (still too 'scientific')
explanation.

so (exp1)? aexp2)? b:c, 0

exp?
expression. Anytjinbg that evaluates to a value.

1 is an expersion.

(10-3) is an extression. (numerical)
"Today is not Sunday" is an expression (string)
ab is an exoression (boolean)

Ok, thanks.

= is an operator. Or part of an expression -
never a whole one.

Understood.


is two variables one of which is conditional. It's like typing x,0

Yup, I got that already ...

Now a modern compiler of any quality will optimise whatever you write
down to probably e same assembler. so its really a quaqstion of which
you find easier to read a year from now :-)

Quite (and I think the truth for me will be) 'none of it'. ;-(

True, and thats why I said what I said. Perhaops I should have said so
its really a question of which the you a year from now will find easier
to read :-)

Remember the best code is code you never have to read again.

True. ;-)



In general, when I do something, I 'understand and remember' it. With
some basic level of coding I first plagiarise it (a good thing with
the Arduino stuff), try to understand / use / apply it for my needs
... then forget very quickly how (or if) I ever did it. ;-(

Its true even for those og us who made good livings doing thos stuff.

Oh?

You woork yourself uo to a pitch of understanding, do it, and then its
done and you forget it all complenetely.

Oh, ok, that makes me feel a bit better then. ;-)
snip

is a far less verbose way of doing it and will result in identical
compiled code to what I posted earlier IF the compiler is smart enough
to put 'offset' in a regsister and not declare space on the stack for it.

And that would be my only saving grace ... that it might all turn out
ok (or less bad) in the wash.

Modern compilers are amazing.

Because I am an outsider on all of this but just getting in on the
edges, I find all of it amazing and find this whole coding thing both
exciting (in a fairly limited use of the word etc) because Of what you
can make stuff do with it and frustrating because I don't really have
the right mind for it and so can't do it easily.

Compared to te heap of ****y I worked on back in the day when you really
had to find the best of 6 ways of writing sonmething to get the compiler
to produce compact code.

That's good to hear (as I have no 'history' with such things etc).

snip

The other things is that because I don't really have a rigid plan and
opportunities unfold as I go, I can't ever really plan / lay out my
needs (not a good basis for such projects I know).

Nothing wroong woth that.

Ok. It doesn't 'feel' very efficient or structured and I have had to
start from scratch several times when I've typed myself into a corner.
;-(

Yiou arent part of a bif team.

I'm not (whatever that is). ;-)

Wrie te obvious
bits first and then when you have a 'livrary' of usefel tested bits -
like te coide you just wrote makes a marvelous subroutne, or fuinction
sp yiou can lock it away knowing it works,

Well that's sorta what I have been doing. If I get some new hardware
(like an I2C display or BT module) I first test is with some existing
/ example code and if it work, see if I can expand on that to make it
do something else (even if that's only changing 'Hello world' to
something else).

Then I'll often try to prune it down (if there are any bits that I'm
not interested in or don't apply to my scenario) and then maybe make
it actually do something I want. Once I have that bit / module working
I might either (depending on the complexity), repeat the above with
the second bit or try to incorporate it in my first bit.

and just call

displayWatts( float watts);

whenever you need to do that thing.

Understood.

The secret of good coing is mnot letting tedious detail interfere with
the logic of what you are doing elsewhere.

Ok ... and that's the other thing .... I am aware there is 'good
practice' and 'coding convention' (some documented, some not) and I'm
vary aware I'm fairly unaware of much of it. So I look at my code as
someone might after painting a wall with a toothbrush.

So, like it seems 'some people' would rather get me to sort out their
PC's rather than even trying to do so themselves, part of me would
rather just hand the who coding part over someone else, not because I
can't be bothered but because 1) I know it's not 'my thing' and 2)
I've got loads of other stuff I should and would like too be doing.
So, I would rather say service someone's car while they write my code.
;-) That said, I think I'd also prefer to watch them coding as then I
can still be part of that process and wouldn't be sure my brief was
accurate enough for them to give me what I had in my head.

snip

1) Apply variable load and log results.
2) Monitor battery voltage and cut load at predetermined threshold.
3) Wait.
4) Apply charger and monitor for full charge status.
5) Wait
6) Repeat 20 times.

That is your main loop then

Yeah, I have the basic concepts of what needs to happen and even some
of the code that might make it do so. The biggest problem I've had in
the past is fitting it all together. Like needing to nest a loop ...
or setting the right conditional exit etc.

You can wrire that and shove all the unkown stiff into as yet unwritten
functions. Ths one way.

I sometimes drop bits of other code into a commented bit at the bottom
and then copy and paste it back where I think it should go and see
what happens.

Or you can think about te issues of how to apply a e.g. load and log
results and write those functions first..

Ok.

Either way works.

Again, that's good to know, that there *are* more than one way of
skinning this particular cat. ;-)

So, while we are there and assuming you have played with the Arduino's
(and this question should be right up you street g), should it be
reasonably easy to take the continuous 'watts' value and by
multiplying it over the elapsed time since the last reading and adding
it to the accumulated Wh gathered so far, likely to produce a
reasonably meaningful value for Wh do you think please?

https://playground.arduino.cc/Code/Time

I have a RTC shield with an SD card for data-logging (I've tested all
that with example / found code etc).

I've just found thins and might have a read though it later and see if
I can use any of it:

http://www.instructables.com/id/ARDUINO-ENERGY-METER/


Cheers, T i m

On Wed, 6 Sep 2017 16:39:35 +0100, The Natural Philosopher
wrote:

snip


lcd.setCursor((watts10)?10watts=100)?8:9,0);
lcd.print(watts,1);

snip

What seems to be happening now is that 9.9 and under ... and 10.1 and
over are ok but 10.0 dead is shifted one to the right?

Cheers, T i m

"T i m" wrote in message
...
On Wed, 6 Sep 2017 16:39:35 +0100, The Natural Philosopher
wrote:

snip


lcd.setCursor((watts10)?10watts=100)?8:9,0);
lcd.print(watts,1);

snip

What seems to be happening now is that 9.9 and under ... and 10.1 and
over are ok but 10.0 dead is shifted one to the right?

Cheers, T i m

It could be that if watts = 9.99 it gets rounded up to 10.0 as you are only
displaying one digit after the point. I would try changing the condition to
'watts9.95'.
--
Dave W

On Fri, 8 Sep 2017 12:57:00 +0100, "Dave W"
wrote:


"T i m" wrote in message
.. .
On Wed, 6 Sep 2017 16:39:35 +0100, The Natural Philosopher
wrote:

snip


lcd.setCursor((watts10)?10watts=100)?8:9,0);
lcd.print(watts,1);

snip

What seems to be happening now is that 9.9 and under ... and 10.1 and
over are ok but 10.0 dead is shifted one to the right?


It could be that if watts = 9.99 it gets rounded up to 10.0 as you are only
displaying one digit after the point. I would try changing the condition to
'watts9.95'.

Once again, that seems to have done it, thanks Dave. ;-)

ITRW the volts field shouldn't be anything outside 10.5 to 13V or so.

The amps could easily be 10.0 though, as could the watts (as the amps
could potentially be .83r) ;-)

Cheers, T i m