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[Булгаков]

Hello all,

As I (and others) have expressed frustration because of inaccuracy of range estimates, % battery remaining display, etc when driving on road trips, I decided to finally install a voltmeter. Three times now I had either 20-30 miles of range or 10-25% estimated battery remaining, only to have it very quickly die, and have the battery show 0% or 2% when I turned it back on, and have to push the bike a couple of miles until I could arrive where there is electricity. I wonder if heat makes these measurements less accurate?

Or I have seen 96 volts with my voltmeter and the console still thinks many miles remain. (And yes, I checked, cell balance is <5mV)

So, I purchased a DROK waterproof 150VDC voltmeter, project box, small fuse holder, crimp rings, etc, and added a voltmeter to my handlebars. It is very bright at night, and still visible daytime. When riding, voltage appears to lower only 1-2volts versus resting (no-throttle) voltage. I have used it now only a few days, but very pleased so far, as it has already once saved me from a mistake (and possibly pushing the bike again). Until there are charging stations absolutely everywhere, I feel that a voltmeter is absolute requirement if wanting to ever explore on the motorcycle.

Steps: Used dremel to drill drain holes in corners of project box case, cut rectangle in lid for voltmeter, snapped voltmeter in, secured with hot glue gun, cut slits in project case for pipe clamp steel band.
Crimped ring connectors onto spare 14AWG wire and small fuseholder, added heat shrink and dielectric grease and wire protector sleaves, pull wire under tank, bolt wire rings onto DC side of motor controller under seat (be extra sure that there is no voltage between B+ and B-), zip ties to secure all.
Wrapped handlebar in cut pieces of bicycle inner tube rubber, attached project box, connected wires to voltmeter, again used dielectric grease on connections.

Warning: voltmeter has no protection against reverse polarity. Be sure to double check +/- .

The project box has several holes where moisture can enter (and drip out), but both the wires and the voltmeter should be ok. We will see how long it lasts. It is not pretty, but it was inexpensive and quick.

Does anyone have available a chart to correlate % State of Charge with voltage? I have my own numbers, but I want to see if this is accurate.

[NEW2elec]

Terry listed some of the voltage to SOC numbers in a recent thread.

[Булгаков]

Terry listed some of the voltage to SOC numbers in a recent thread.

Thank you. I searched a little, but I did not see that. Do you remember which one?

[NEW2elec]

well it's some of what you wanted any way.  It was a post by Electric Terry on May 25 2017 under the post " Limp mode at 25% "
I just searched "volt meter"

[togo]

I use these to estimate:

10% 96v
20% 97v
...
80% 108v
90% 112v

Voltage sags under load, and runs high during charging.

The middle section is a little too flat to be a good indicator, but voltage is pretty good indicator of SoC at the top and bottom.

[DonTom]

The percent of charge shown on the LCD display on the stock bikes. How is that figured, if not from voltage?

-Don-  Reno, NV

[Shadow]

The percent of charge shown on the LCD display on the stock bikes. How is that figured, if not from voltage?

The percent is given to the display by the bike's Main Bike Board (MBB) firmware code. The code it is a "black box" intellectual property and proprietary to Zero. From what I hear the percent is based on counting electrons (A) with a current sensor and also a lookup table of values in the code. The figure is affected by configurable pessimism value and what the firmware is told what battery (Ah) configuration the bike has. The current sensor used in 2017 and newer bikes is accurate over a wider range of operation for example and so those bikes have a more accurate state of charge indication.

[togo]

http://zeromanual.com/index.php/Common_Problems#Low_SoC

http://zeromanual.com/index.php/Unofficial_Service_Manual#State_of_Charge

Current sensors appear to be especially bad on 2014 SR, a number of us have recurring 6%-12% drop to zero.  Partial charge/ride cycles seem to exacerbate the issue, ratcheting up the inaccuracy, I personally have had 52% SoC indicated when actually empty, on the way home from laguna seca, and seen my purported capacity showing like 19kwh after the following charge.  It seems the Zero firmware resets SoC only on top off.

Булгаков and Mr. Wilson and I have all added physical voltmeters, Anton has made an android bluetooth app to show voltage for those with diginow dongles/reaper devices, and I believe Luke and Terry run have Cycle Analyst installed, which show voltage as well.

There's a lot of discussion of the issue if you want to look in the archives, DonTom.

[Булгаков]

New2Elec, thank you for pointing that one out,

and togo --  thanks for the numbers. That is close to what I have seen as well.

[Keith]

Here's a link to the voltage data that I collected. The effect of temperature is significant, voltage rises with temperature. It also changes over time in mysterious ways. But it does tell you something about the state of charge. http://electricmotorcycleforum.com/boards/index.php?topic=7116.msg59121#msg59121

[Булгаков]

Oh very cool! Thanks for the link.

[DonTom]

The current sensor used in 2017 and newer bikes is accurate over a wider range of operation for example and so those bikes have a more accurate state of charge indication.

Since both of my Zero bikes are 2017 (Zero SR 13 w/pwr tank & Zero DS ZF 6.5), does that mean I don't have to be concerned with the voltage measurement?

What should I expect when I get near or down to zero on the display?

CU tomorrow!

-Don-  Cold Springs Valley, NV