steve crr

Thanks, I was looking for a ready-made app. I don't really have the time to study this at the moment. Thanks anyway.

Hi Sensei,

Thanks for your reply, but I'm afraid this is beyond me.

thanks again,

unfortunately, that's the easy bit, is finding the equation that's the problem.

Hi Sensei,

Wow, I wasn't expecting that amount of effort. Thank you very much.

Whilst it would be handy to have something that would run on the browser. I am fairly familiar with programming in Visual Basic.net. So that would actually give me the most flexibility.

I do not profess to follow the code with any degree of certainty, however it appears to assume a linear relationship.

If that is the case, I am afraid it will not work.

page 12 on https://pdfs.semanticscholar.org/10b9/3c3ce7adae76e1ef0b5ca1f0c83d660f6090.pdf

contains a manufacturers  graph that clearly shows the relationship is non-linear.

Once again, many thanks for your effort.

hi Prometheus,

thanks for taking the time to reply.

From the data graphs shown, professionally carried out battery tests, and my own experience, a battery can be considered to have used the majority of its useful Charge when the voltage drops to 11 Volts. By extrapolating the graph back to 11 V and repeating it, it will give me an indication of the maximum range. Furthermore the Reproducibility of this value will give me an indication of the reliability of the findings.

I probably could discharge the battery fully once or twice. But there are so many variables involved that this would not give me a very good indication of range. I guess truly it is something I don't need to do, but it's something I want to do.

Thanks again.

Hi Capiert,

Thank you very much for spending time on this.

The data is behaving exactly as expected, it is a curve.

The initial 2 Points are where the battery voltage drops rapidly as surface charge is taken from the Cells I agree these can be ignored.

I agree we are.lacking data towards the high discharge end Of the data, but believe me it is non-linear I have been using scooters for far too many years and the drop-off from about 12 V Increases rapidly. Also, curvature can be seen.

Below is an article on modelling battery Behaviour.  Battery discharge curves can be found on page 12. Which confirms this.

it is really the software application I am after, rather than how to calculate it.

If I can't find the software, I'll simply take more readings towards the high discharge end, plot a curve manually and extrapolate that, but it's not as elegant, I really would like a formula so I can get a simple prediction of distance left.

Once again, many thanks for your efforts.

NimrodTheGoat

Thanks for taking the time to reply.

I could not see how to enter raw data into Demos.

yes, this approach would work. However, discharging the battery  fully reduces their life i.e. the number of times they can be recharged. So I do routinely discharge the battery is fully. So cannot use this method.

I am looking for some software that will find the equation for the discharge data. (see previous post).

Thanks again for replying,

Steve

thanks for your offer of help.

I am actually using open office, but it seems almost identical in function.

I can plot graphs and add trendlines, but there are only a limited number of options for the trendline, non  of them seem to fit the data.

A set of data is below (file attached)

Voltage  distance miles.

-

test data.xls

Thanks for your replies

Quote

You can fit other curves.

can you give me a clue how please?

thanks for your reply, doesn't that only work for linear graphs?

thanks for your reply,

There were a whole list of equations such as-

Y=mx+c

y=m²+c

y=M+1/x^2+C

^Logs

^Polynomials

^Trignometric

^Quadratic

^{exponential etc.}

^{The The algorithm would then find the expression that match the entered data closest. It may not be an exact match, but close enough to make approximate predictions}

hi, I wonder if you can help me please?

I am not a mathematician, but used to teach science, so I have a little knowledge.

I am now disabled and use mobility scooters, I am trying to reasonably accurately predict the discharge of my batteries.

way back in the day, I used to use a Dos program called XY math ( I think).

It allowed you to enter experimental results and  plot them.

an algorithm would then test the data against about 20 equations of various types.

it would then give an indication of correlation and display the line (curve) of best fit.

I have searched Google that I can only find a program in French.

does anyone know of a current app. That I could use to do this.

preferably windows, if not android. Sorry, no Mac.

 Alternatively,can somebody suggest he correct search terms to use.