Ways to tell you should start to think about going home (voltage monitoring)

One of my boards actually has a primary and a secondary pack. So once the primary is out you know you shpuld have enough juice to get you at least most of the way home.

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When I ride, I just use endomondo… when I reach 25/27km I know that’s gonna be the end soon. In fact you need to be consistant at riding, know your board and how to maximize the miles coverage when having a blast in the streets! cause that’s the most important !!!

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It’s the cold season here so once again I dont have many chances to take the board out (uh).

I wont be really able to tell average power consumtion, as im running car esc with just a coulometer/wattemeter installed. From the few ‘‘loose’’ tests I did, it looked like board consumes about 20wh per km or close to 900mah/km (at ~8000mah 6s4p li-ion, 4.1v-24.6v when fully charged).

I still need to take a test at constant speed and just straight road, I was willing to this but the next day the snow came, so I had to leave this for later.


As of now, when voltage is around 3.8-3.9v per cell I assume it is somewhere in the middle!

I would like to have percentage display I think, so perhaps I will just look into getting one of these coulometers ppl are using! But I was concerned about the reliability of these percetanges… as I was not entirely sure does 5-10% percent stand for the same distance in all scenarios (voltage levels).

I know that my turnigy charger shows up around 10% charge level, when the cells are at ~3.5v no load voltage. Though, its max charge voltage is set to 4.1v per cell, so I assume it calculates the percentage level using these 0.6-0.7v of range. Not sure what counts 0% for it, have not ridden the board so far yet :slight_smile:

So far I usually just assume that I can do a distance of 8-10km, and so far the longest recorded one was about 6-7km. But this takes into consideration that you need to log the kilometers with a phone app which is not always so conveniant, if you want to go somewhere in a hurry without looking at the phone every 5-10min /2-3km to check the distance :smiley:


This is the deepest I’ve discharged my battery, unfortunately I did not do a full discharge test on these batteries but I might do a seperate test on just one battery at ~3A load, to see what capacity it has… From the manufacturer, it states these batteries have 2100mah capacity, or around 2000mah when discharged at 5+ A per cell.

As im not pushing them till 4.2 and I also stop at around 3.5v I assume 7.600mah is pretty fair.

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@PXSS I did not mean to kill the conversation with my lenghty text / detailed description…

As I was not able to tell you average watts consumed I tried to answer in different terms.

So far I only know that I reach a peak of 800-1200w very easly but Im not sure how much is spent on a regular ride on average. As I said, I will need to pump the tires even more(as they are not max inflated) and just do a few tests at different constant speeds to see what wh consumtion/ mileage I get :slight_smile:

Though, this is maybe a side topic, as I opened this discussion to dwell upon ideas on how I could see the energy left in batteries in a better way to determine the distance.

And so before I know what distance at which speed can I do, I do like to look at the possible options of showing voltage / percentage / estimated capacity left etc :slight_smile: (which was already done in the topic anyways :wink: )

No worries. It’s 8am. Thats why I didn’t reply! I will write a response later :slight_smile:

On a side note - I remembered that this app ‘‘Runkeeper’’ had the option to tell with sound/voice when you have made 1km/1mile, so if you can trust the gps/app accuracy, this might also be a great way to tell when to go back…

(Endomondo might also offer this feature but last time I used it, it did not call out the distance out load, might perhaps search for this option, as I installed it only recently and have not checked all of it)

Though this will probably only work if the power consumtion is constant…but at least it should give a somewhat accurate estimate on how much has been traveled versus max possible distance and then looking at the voltage display (or coulometer), determine about how much more it is possible to do based on that.

On a side note… vesc monitor app still would be the best, no need to turn on logging apps on phone (since they tend to get stuck for me or not always easy to activate them before the ride)


Why not use a bluetooth chip that sends data to your phone? I know theres a bunch out there now with apps. Im sure there is a setting to alert your phone when you reach your pre set volatge

Would you guys be interested in smart display? You need a Arduino Nano for it and a SSD1306 display. Here is a example of what i mean. It can show way more information then only the range. It could be attached to the slave VESC so that the master has the Bluetooth connection and this one the connection for the display. Originally that display was planned from me to add it in a remote so that via the remote the drive modes could be changed. But then i didn’t find a propper way to add all the components. Maybe i find the time again in the future to finalize that. But it could be modified to add the display at the front truck mount when it is a dropthrough or in the enclosure. Could give a lot of information. And with attached buttons the drive modes could be changed.

But as i already told, maybe in the future.

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I like the idea @Ackmaniac .

But could somebody tell, is it possible to feed the battery pack’s voltage into the arduino? I assume there needs to be some sort of voltage step down module or a shunt module, which is able to measure the voltage/current.

With voltage step down, I assume some resistor - voltage dividers might work, at least that is how I understand a higher voltage is measured on an arduino, it will just miss the most precise measurements this way, if it in 1024 bit / step in or whatver system converted.

Not so smart about shunts, so if someone has experience with them, that would be great!

Shunt would be best, because it could measure capacity / amp hours, too, but for the start, simple volt meter would also suffice… It would be great, if it was possible to make a custom percentage display based on voltage left :slight_smile: perhaps with additional sound signal or flashing display at set levels…

Sadly in the video the battery percent value didn’t work because i adjusted it to a 12S battery. But it was comnnected to a 10S. So it shows 0%. Value in the upper right corner. Adn because of that the Range (value R) also was calculated to 0. And this display works with the VESC. So there is no need for any resistors because the arduino can be connected directly.

I know. Still not owing a vesc, so I will have to pass this… (unless someone ‘‘donates it’’ for ‘‘scientific purposes’’ haha)

I will create a seperate - arduino only - thread about this. It will / should work for 25v max at first, so ideal for 6s Li-ion 4.1v x 6cells users!

Anyways, nice idea / job @Ackmaniac I believe other ppl will also find it useful, just tell them about it, create a seperate thread or post this info into the topics about remote controllers, / vesc monitor app, I believe it might catch up, who knows…

Will add these little guys to the discussion:

http://www.ebay.com/itm/Lithium-Battery-Capacity-Indicator-Module-Blue-Display-Electric-Vehicle-Tester-/122299410400?var=&hash=item1c799ce7e0:m:mPITzCDzV3Wbf-mBUXYWZlw


http://www.ebay.com/itm/Waterproof-12v-24V-48v-72v-Acid-lead-Battery-indicator-capacity-Tester-voltmeter/232099381203?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D40778%26meid%3D4d563d892e994567a7a773fb84743d8c%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D221797490150

For this one price not that great, I hope to find cheaper units for these, though, the principle with bars/percentage or volts included, looks really nice!


http://www.ebay.com/itm/12V-24V-36V-48V-LCD-Battery-Capacity-Tester-Indicator-car-Lead-acid-Lithium-Cell/222293145050?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D40778%26meid%3Dbe8753b7419541bd95d80d5f45b006f4%26pid%3D100005%26rk%3D2%26rkt%3D6%26sd%3D172143986261

Did not know these can be so cheap… They only got 5 bars of voltage indication (some more perhaps, would have been welcome) but non the less in overall this display looks really good.

Hi,

This thread is awesome, it’s exactly what I’ve looked for. I’m on a halt right know because I try to figure out how to make my own battery indicator with 4 or 5 LEDs. I found a lot of these voltage indicators which @Okami already posted but I don’t like the look and would love to have something like the old MacBooks had. I already read about Zener Diodes and op amps and so on… Fact is I’m to damn stupid for that :smiley: Maybe someone of you could help me out. When I have results I would love to share these with all of you.

Thanks a lot!

I would advise to you to get ‘‘acrylic panel’’… Then you mount some leds, perhaps SMD preferabbly onto that panel… You could buy ‘‘individually controllable’’ Led stip… you wouldnt need a lot of it…

Then hook that up to arduino… get a voltage reading for just one cell from your balance connector… then make the arduino display it on your individually addresable led strip…

So you mean instead of meassuring al 8 cells in series (about 33,6V - 25,6V) just meassure one(4,2V - 3,2V) and apply that to all the other cells?

yeah, if you look up what I wrote elsewhere there was one user who already did this… you get ‘‘better resolution’’ this way… as arduino can only measure ‘‘1023 steps’’ of voltage, I believe… It has a range of 0-5v… and you have ‘‘bring down the voltage’’ anyways… for the arduino to be able to read it…

At least this is how I understand it… I havent yet hooked up mine… been busy doing other things… but non the less, it just seems easier to base everything on single cell, especially if your cells stay ‘‘in shape’’ more or less… all the time

If you got lipo pack… u might as well go for full voltage… then you would have to downgrade it with some resistors…


I think you should strive for achieving / getting something like that

Here are some of the ‘‘options’’ I think you should go after:

Click the last item - 8bit led strip

If you want something from usa… for a bit more money, you can look up ‘‘NeoPixel Ring’’…

Though you will have to look up some tutorials on how to do this…

The leds inside of these are called WS2812… there should be some tutorials around the net on how to control them… you can basically choose any color you want for them, if you know how to adjust it…


Here’s some resources on how to do that ‘‘voltage divide’’ thing:

https://startingelectronics.org/articles/arduino/measuring-voltage-with-arduino/

https://learn.sparkfun.com/tutorials/voltage-dividers

There’s a calculator on the 2nd site on how to calculate what resistors you need, I believe.

As said… if your voltage stay all the same more or less, I think this step can be left out… but if you want it somewhat more reliable… to see the total voltage, then go for ‘‘voltage dividers’’ option…

Hi @Okami,

I am completely into Arduino, so this won’t be a problem for me. I’m just really bad in calculating electronics because I never really learned it :wink: I already have a Neopixel ring but will use a strip for this project. Thank you very much for this idea of just measuring one cell instead of all 8S.

When I’m ready I will upload the code an some pictures but that could take a little while :slight_smile:

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@mrplaygood Found today this nice ‘‘solution’’

You would probably need to modify that button, so you can permantely turn it on / off…

Will add this one to the list:

Seems to be quite good, also 3 mode screens…

~20usd at banggood…

(though for similar price, coulometer could be bought too… but hey, the screen looks somewhat good and monitors up to 8s battery)

One more screen, showing voltage sag:

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