Does volts / mile really indicate anything?

[Gionnirocket]

3v seems to be the default, and it's bothered me since day one... No wonder it's of Luna origin
In the end I find charts good for a baseline and some background info, but there can be so many variables when riding that experience with your particular ride and your ability will be a much greater asset.

 

[m@Robertson]

It didn't come from Luna. That chart is their follow-on. Their original used different assumptions and they had to pull them and go with the 'standard' that you see earlier in the thread.

I remember the charts they used before that one came out. Here's their original 52v and 48v charts. Long gone from the interwebs but I still have copies. I was told by someone on their tech support side that they were meant to include some fudge to keep people from blowing stuff up. But it didn't go over well. You can see they left rather a lot on the table at the upper end. Once I realized this I ended up making my own charts for my own use, and you can see what that ended up becoming.

 

[m@Robertson]

For giggles, I ran a program that tells us the 'true' calculation for a Samsung 25R that goes down to 2.5v. Its pretty rough as I'm just showing raw computer output. The increment from 1 percentage point to another increases to 0.017v. Using the cell's individual specs, an 80% charge is now 54.04v instead of (the universally recognized) 55.4v. Going down to 2.5v now means a 0% charge is 35v.

But here's the thing: Is this useful in the normal world? What controller (other than some seriously custom DIY stuff) is going to allow you to do an LVC down to lets say 36v on a 14S/52v pack? And if we can get the controller to play ball, what BMS is going to go that low before it shuts down? You'll have to build that pack yourself with a BMS that you can specify all the parameters for. This is why you see 3v as a quasi-standard.

 

[Gionnirocket]

That's very true... a better determination of 0% (or a more practical) would be the LVC on the BMS or on the controller if not adjustable and was also a higher value.
I did say that I was being anal and splitting hairs

 

[tomjasz]

FFS it's so easy to sort. Ride until it hits LVC and don't exceed that limit This trend to use pretty color screens and obsessing about mileage is, well, boring. I know how far every one of my bikes will carry me. I don't need a pretty color screen to sort it for me. Much adieu about nothing.

 

[harryS]

There was nothing wrong with what the OP was doing. Knowing the voltage is a lot more accurate than looking to see how many bars are left. If someone wants to convert the voltage into a percent capacity for the battery, it's just another way of looking at the same thing. Most of my ebikes have voltmeters, and I use them in the same fashion. I also track watthours on my different bikes, and know the useable AH capacity of all my batteries.

 

[Denny]

I am talking about is how to use the information that my bike display gives me during my ride. Specifically my display show voltage remaining.

So my comment was about using that information to determine mileage remaining. Thought that was pretty clear

I like your assessment of 4 MI / V seemed to work out for me over the course of 250 miles and 8 charge cycles. The lowest I have run my battery down was 44 volts but after letting it rest for about a half-hour its back up to 46 V. I'm a large man 6'4 215lbs.