Epacsim

[10mph]

While I was on the German Pedelec forum, before it crashed for me, I downloaded some interesting software EPACSIM- an EPAC Simulator. I cant get it to work, since I am struggling with the German instructions, but it looks a sophisticated attempt to measure then model a pedelec.

It impresses me.

I cant find any reference on this forum to EPACSIM and when I googled, I only found the German forum pages.

Has anyone studied this work? It had been going since 2009. Is it unkown outside that forum?

 

[flecc]

So many meanings of EPAC.

Here's a simulator for e-bike hub motors, posted by Miles Hellon:

Crystalyte simulator
.

 

[10mph]

flecc: Yes, I had seen the ebikes.ca simulator which is referred to in that link. In fact that was one of the things that prompted to try and make my own model on a spreadsheet.

There is a limited range of motors modelled by ebikes.ca, but for the other variables you can input your own parameters. Their controllers model current limits only, but I thought it might be necessary to have a power limit also built into the controller to avoid exceeding the 250w legal continuous power rating. (Maybe I am being too strictly legal here, and you are allowed to exceed 250 watts continuously on a hill of appropriate gradient, provided the motor has a label on it saying 250 watts. (I find the business of maximum legal power very obscure and rather murky).

My spreadsheet results which I showed here, give some what different shape plots from when I try and put in the same parameters on an arbitrarily chosen motor on the ebike.ca site. Compare this:

with my spreadsheet results:

I had assumed the difference is due to the modelling of motor inductance which is included in the version2 ebike.ca simulator. It also mentions cogging torque. I have not yet worked out how to model these. But I now see that the ebikes.ca site still has the simple version model, which is not much different to their inductance model. So I shall have to look more closely at my model and see why it does not produce similar shaped curves.

Before I lost access to the German pedelec site I was trying to read their discussion of EPACSIM which does include inductance to see how their model was constructed.

At the moment I am limited because I lack a motor to start to try and measure. It is interesting that both sites have had to obtain motor parameters empirically. Presumably because no manufacture actually tells you the parameters of his motor which you need for modelling.

 

[flecc]

I generally take the view that the 250 Watts limit is a bit of a nonsense in practice. Most hub motor e-bikes can climb continuously at the speed where maximum power starts to coincide with the early drop in torque with gross and net power at well over the limit.

I did an experiment with an SB motored eZee Torq 1 once to check this out. The motor being overgeared makes it a poor climber on motor only, so I set out a North Downs route with a almost continuous gentle climb for over three miles, a sudden steep drop into a valley that takes only seconds and then the climb resumed to complete well over 8 miles in all.

Riding to the start point on a hot summer's day to get the motor warmed up, I checked the motor shell temperature with a thermocouple. I then did the route on motor only, slogging at around the point of maximum consumption/power. It took over three quarters of an hour, the motor temperature checked at the end was one degree lower, so it was effectively the continuous power capability. Consumption rate wobbled between 700 and 800 watts so at 75% efficiency the net motor output would have been around 550 watts continuous.

This made the legal 250 watt rating nonsense, but of course in normal use on journeys the average consumption and power out would be very much lower at 15/16 mph average. I think that's possibly how the e-bike motor makers look upon this, the average in practice. I remember the early days of the 1980s when English made e-bikes really did have maximum power at the legal 200 watt point and they were pathetically weak to the point of uselessness.
.

 

[Miles]

Here are a couple of links that may be of interest:

Drive Calculator

Endless-sphere.com • View topic - New Open Source E-Bike/E-vehicle calculator & simulator

Miles

 

[didi28]

As mod (also didi28) in the german pedelecforum and main writer of the german Pedelec-Wiki (start [Wiki Pedelec-Forum]) I shortly want to promote EPACSim.

EPACSim was developed by Christian (also mod in the pedelecforum) to compare all pedelec-motors by using the data, everybody can create by measuring his own motor:

EPACSim - Dokumentation

and upload the own data to the data-pool. So we are not further depending on doubtly data from the producers, but can build up our own data-basis and simulate the power of the motors. It is astonishing near at reality!

These are the EPACSim-Links:

Download: EPACSim - Download
Dokumentation: EPACSim - Dokumentation
Diskussion: EPACSim - Diskussion
Messdaten: EPACSim - Messdaten

 

[10mph]

didi28: Many thanks indeed for links. But for the last 20 hours or so I have not been able to reach any of the pages at Pedelec-Forum

It was working for me yesterday morning when I was reading your pages with the aid of the google translator. I was so enthusiastic about your forum, the wiki and the EPACSIM that I successfully registered for the forum - as 16km/h.
However since then I have not been able to surf your pages. I have tried another computer and a different IP address here without success. Have you any idea what I am doing wrong? Is there some problem with your website. I have a suspicion it may be partly due to images not being available , but even when I switch off image download, I am still not getting the website. I have also noted that an image from your website which is linked on this forum does not display.

Miles Hellon - Thanks for the links. More to study which will take some time I think.

Flecc: You have described the situation very clearly. Thank you.

So manufacturers, how on earth do you decide what is a 250 watt bike? Two months ago Banbury Frank pointed us towards the European Standard NF EN 15194. I find that to be an extraordinarily unsatisfactory standard.

 

[didi28]

I was so enthusiastic about your forum, the wiki and the EPACSIM that I successfully registered for the forum - as 16km/h.
However since then I have not been able to surf your pages. I have tried another computer and a different IP address here without success. Have you any idea what I am doing wrong? Is there some problem with your website. I have a suspicion it may be partly due to images not being available , but even when I switch off image download, I am still not getting the website. I have also noted that an image from your website which is linked on this forum does not display.

I don`t know of any problems of this kind. What do you see, if you klick on Pedelec-Forum or start [Wiki Pedelec-Forum] ?

 

[10mph]

I don`t know of any problems of this kind. What do you see, if you klick on Pedelec-Forum or start [Wiki Pedelec-Forum] ?

the browser (firefox) times out.

The connection has timed out
The server at Pedelec-Forum is taking too long to respond.

I suspect there may be some sort of wider internet problem. Although many of my favourite sites are reachable OK. I have just noted that en.wikipedia.org seems to be serving a cut down page without css from a server bits.wikimedia.org Something which I have never seen before. Also the website The Register: Sci/Tech News for the World which I usually go to to see there is news of internet problems times out. but curiuosly I can see that this forums webserver has picked up the page title I have just typed the link for so I am finding it hard to pinpoint where the connection problem is.

Possibly this is something which is affecting my ISP providers links to the wider network. It is odd it is only affecting a few of the websites I am trying today.

 

[10mph]

BT network problem

I googled and eventually found a thread at Cannot access certain US sites since this morning ... - Page 7 - BTCare Community Forums
It appears to be some sort of BT network problem (my ISP) and has been in progress since yesterday afternoon, when I picked up the problem first here.

Didi28 I will wait till the problem is cleared by BT then let you know if access to yourwebsite is back to normal for me

 

[didi28]

I will ask the admin (Reinhard) of the Pedelecforum, if he knows anything.

 

[didi28]

Reinhard just told me, that his provider had problems with a broken core-switch from midnight `til about 10:00 A.M. yesterday. Maybe therefore was no access from GB possible.

 

[10mph]

pedelecforum.de reachable again

I did a couple of traceroutes earlier this afternoon. One from my computer and one from a computer in the USA. They ended up in Frankfurt, one hop away from the pedelecforum.de server.

Another just done, now gets through and the site is back up on my browser. Thanks Didi28 for getting your admin to sort it out.

Really intriguingly this has now brought the wikipedia page back to its normal image-laden self. I have been trying to follow the nuclear accident. A bit of a coincidence really, for on Thursday I went to a general interest talk given by a nuclear industry expert and was saying about how safe the latest power reactors were - multiple redundancy etc etc. He also said how much Three Mile Island and then Chenobyl set back the industry coupled with the dash to gas. I told him of my plans to run an ebike, and we agreed that using nuclear generated electricity this would actually save carbon, and more especially if car journeys are replaced with ebike journeys.

 

[didi28]

Nice to hear that the problem is somehow solved.

As a retired physicist you would be the perfect contact person of EPACSim (Electric Power Assist Cycle Simulator) in this nice forum here. If you have any questions, ask me.

EPACSim is a powerful program from pedelec-users for pedelec-users.

For example motor power at several speeds, wheel-size, gradients, ampere can be shown, battery-range considering motor- and human power can be calculated.

The own motor and battery (if they aren`t already in the data-base) can be calculated if some measurements are made, which can be done by every slightly capable hobby-technician.

And the own data can/should be uploaded for other pedelec-fans and/or prospects. This can be a great help, which conversion kit to choose.

 

[flecc]

I have been trying to follow the nuclear accident. A bit of a coincidence really, for on Thursday I went to
a general interest talk given by a nuclear industry expert and was saying about how safe the latest power
reactors were - multiple redundancy etc etc.

Please forgive me being pernickety 10mph, but as a strongly pro-nuclear power person I point out that the
current incident is not a nuclear accident, it's an earthquake accident, e.g. when a car hits a building it's not
a building accident, it's a car accident.

I know you'll appreciate that a largely uninformed but emotionally anti-nuclear public like to seize on anything
to justify their stance.
.

 

[10mph]

Guilty as charged. But at least I do use punctuation. Perhaps I should used an emoticon here, but I have always hated them.

 

[flecc]

Guilty as charged. But at least I do use punctuation. Perhaps I should used an emoticon here, but I have
always hated them.

I tend to feel that way about emoticons too, but still try with difficulty to conform to their common usage.

Puzzled about the punctuation remark though, since I can't see where I've failed to use it appropriately? Please
advise if you know different though.
.

 

[10mph]

Puzzled about the punctuation remark though, since I can't see where I've failed to use it appropriately? Please
advise if you know different though.

This was an off-the-cuff remark, and not in fact referring to you. I hope I wont be too flippant in future and not post without careful review.

Now I must get back to my spreadsheet and see if I can pinpoint why my e-bike simulation curves are of a different shape to other people's.

 

[mechaniker]

Now I must get back to my spreadsheet and see if I can pinpoint why my e-bike simulation curves are of a different shape to other people's.

hi,
if you something dont understand on epacsim you can ask in german pedelecforum how to do. You can write in english and you receive english answer;-) you would be not the first british who write in english to the german forum ;-) and the most people can talk better english as me.

i can help in many point´s but unforgenatly not in epacsim, i have never use this programm but i know the guy who has written this programm, he know what he do.

regards
frank

 

[10mph]

Frank: Thanks for making an English only poster welcome. I will post there when sorted out a question to ask.

I really respect the knowledge of English that many German speakers have. 10 years or more ago I greatly enjoyed the company of a man from near Munich, who it seemed knew more about English literature - from Shakespeare onwards - than I did. My excuse about my imperfect knowledge of English literature was that at school I took to the precision of Science subjects rather than Arts subjects. My German friend was also a scientist, so I respected his knowledge of English literature even more.