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[rider7]

I found this sweet place with some real nice curves in the road.  Since I'm in Florida, curves are hard to come by.  It was so far from home, that I only went around it 1 1/2 times before I hit 50% on the battery and turned around for the ride home.  4 miles from home, I was at 12%, but speed cut down to 27 mph.  I was about a full mile from home with 9% when it went straight to 0% and simply stopped.  I pushed it the rest of the way home.   

Fivespeed, you got yours out of the way, huh?

Does the old saying about riding bikes, "It's not if you go down, it's when you go down" apply to EVs?
"It's not if you have to push your bike home, it's when you have to"
I sure hope I can dodge this bullet.

By the way, I don't really like GPS etc... but I realized that it is essential on an electric bike.
The other day, I could pick between two on-ramps, one north (the right one) and one south (the wrong one).
I picked the wrong one and it could have put me out there with no charge left.
I was lucky that there happened to be an exit fairly close, but that's not always the case, especially on a toll road here in Texas.

Thanks for sharing, it makes me pay very close attention now as an EV beginner.

Thanks for your input too KrazyEd. You have a lot of experience.

Rider7

[mrwilsn]

I think we have to get a detailed than just year and model in our experience reporting for this behavior.

Some are reporting stability getting down in the low single digits SOC while others are reporting erratic drops.

Board and firmware?    http://home.hasslers.net/zerologparser/logs/

I've not been below 17% on my Zero (which is zero bars) So I'm nowhere near experienced on this subject of low SOC behavior.
03160   2013   Zero   SS   2013 rev1   7

Though I've pushed my 79 Sportster hilly 1.5 miles (i mapped it to be sure) and would much rather push my Zero.

I don't think it's a firmware thing.  The most recent time this happened to me I had just been at the dealer getting the firmware updated less than a month before it happened.  It was October 2016.  I was actually out deliberately trying to see if I could induce the error hoping the firmware update might have fixed it.  I think this issue was actually fixed in the 2015 model year with the ZF12.5 battery but we can see if anyone that has a 2015 or newer posts about having the problem.  It would also be interesting to see if anyone that has a 2014 or older but with an upgraded ZF12.5 or ZF13 has seen the problem.

I just bought a 2017 Zero SR but the weather has been bad around STL so I have been riding my 2014 Zero S and haven't been able to do all the different tests I want to run on the 2017....it only has 150 miles on the ODO even though I have had it for almost 2 months now....for comparison I put 1500 miles on the ODO of my 2014 Zero S the first month I owned it and have averaged 600 miles a month since.

[mrwilsn]

But not being able to trust the bike on longer trips was one of the primary reasons I got rid of it. As far as I know the guy who bought it has never had a problem but have no idea how he rides.

I agree....I have pretty much lost confidence in my 2014 Zero S for longer trips.  I will only take it to really low SOC if I have been riding at low discharge rates for my whole ride and once it gets really low I am super careful not to give it too much throttle.

[odedmaz]

My 2.8 FX drops from 17â„… to 0 as well. Since I am aware of that, i rode the bike slowly (10 kmh) , to prevent voltage drop  did not help...
I'll try to update the fw.

Sent from my XT1585 using Tapatalk

[KrazyEd]

   Stealing power would be going to a non public area, or area with prohibitive signs
and plugging in. If an outlet is in the public area, ( business complex, strip mall ) and
I am patronizing a business in that complex, I feel no moral problem using publicly
accessible outlets. If I were to feel the need to charge to make it to next known
charging area, and the only possible outlet would be  residence I would knock
on doors and plead my case. Offer some money, see what happened.
Worst case would be to call for tow truck ( I have roadside assistance ), or,
take public transportation home and come back with tow vehicle. Have
only had to do that once when a battery in my Electric Paseo lost a cell
and I didn't have the tools with me to diagnose.

[Justin Andrews]

Asking nicely often works rather well.

I once was getting rather low, and explaining my situation I asked a gentlemen working in his garage if I could charge. A couple of cups of coffee and a nice chat later I was on my way. (the Elcon helped here)

[Ndm]

Mrwilson, excellent description of the cell behavior, I have a 2013 with the 13kw upgraded battery and as I was reading your post it dawned on me that the very few times I have taken the battery past 15% I have done it while riding quite gingerly (80 kmhr) I have had it all the way down to 3% and gone 2km more at 60 kmhr, I have never experienced the power cut and was wondering why I so often see it mentioned on forums etc, I now believe that the cells remain in better balance due to the fact that I try and ride economically when pushing my range limits, it sounds a little like the voltage sag experience in my lead acid solar batteries (hard use only leads to faster depletion of the pack obviously)

[Low On Cash]

It's pretty scary stuff to lose your motor when the % gauge is showing you have range left.

Maybe its just old school thinking - but remember the old days when we had reserve tanks - it would be pretty neat if we had just a small 2 mile or so reserve to switch over. This way if the motor stops at 10% 5% or 0% you would have a small reserve to get off the highway or a 110v plug.

Regards!

[BrianTRice@gmail.com]

Mrwilson, excellent description of the cell behavior, I have a 2013 with the 13kw upgraded battery and as I was reading your post it dawned on me that the very few times I have taken the battery past 15% I have done it while riding quite gingerly (80 kmhr) I have had it all the way down to 3% and gone 2km more at 60 kmhr, I have never experienced the power cut and was wondering why I so often see it mentioned on forums etc, I now believe that the cells remain in better balance due to the fact that I try and ride economically when pushing my range limits, it sounds a little like the voltage sag experience in my lead acid solar batteries (hard use only leads to faster depletion of the pack obviously)

Thankfully, the upgraded battery (2016 era) does not degrade at low % SoC like 2013-2014 batteries did. (Terry and others have explained how the cell upgrades helped this.)

It's still a good idea to leave yourself some indicated reserve of 15%, but the 2016 will usually run right down to 0% and then take you several more miles at low speed and low torque/power.

Battery chemistry unfortunately doesn't always offer a quantifiable reserve like a physical amount of gasoline would. State of charge is a software abstraction over things like cell voltages and temperatures, so when it "drops", it's an estimation update rather than a physical drop.

[Richard230]

It's pretty scary stuff to lose your motor when the % gauge is showing you have range left.

Maybe its just old school thinking - but remember the old days when we had reserve tanks - it would be pretty neat if we had just a small 2 mile or so reserve to switch over. This way if the motor stops at 10% 5% or 0% you would have a small reserve to get off the highway or a 110v plug.

Regards!

My 2012 S had a 10% reserve after the power level bars disappeared. But it wasn't advertised and you wouldn't know about it without people on this board encountering the "reserve" and mentioning it.   

[KrazyEd]

I think that the "reserve" is probably still there, just with the newer
gauges and apps, we are just using it as power and ignoring the
bars on the dash

[Electric Terry]

My iPhone 6sPlus died today at 24%

I was at home and it was warm, then went out to ride and the phone got colder than it was quickly.  My dog Charger was playing with another dog and I went to take a video and the phone stalled, I remember seeing 24% battery, next thing I know the screen went blank.  Tried to power it on and the screen showing I needed to plug it in came on.  3 hours later I made it home and plugged it in, and after about a minute it came on and said 16%.

Some might think Apple is a big company with a lot of resources.  At least compared to Zero.  And Apple doesn't have it figured out yet.   Calculating battery energy completely accurately is incredibly difficult.   Other times my phone has been at 1% for like 2 hours of talking on the phone while I keep telling the person my phone will shut off at any moment and it never does.

The Zero battery is very similar.  Sometimes it might say 20% but really be almost empty at any minute.  Other times it might say 20% but have 35% left.  The 2015's and up seemed to deal with this much much better than the 2014's but we've seen it's not perfect still.  I've heard the 2017's have 2 completely separate current sensors, so this should be solved on the 2017 bikes to where you can depend on the SOC more than a 10% margin,

Remember when in doubt, check the phone app while stopped and check the battery page.  If the resting voltage is 98 or below, start looking for a place to plug in.  88-90 volts is the lowest you will see where 93 volts might get you one mile at very slow speed.  97 volts and below it will start dropping faster and faster and will reduce power more and more.

Having some sort of fast charger with you means if this ever happens where you ride to the bottom of the range and it cuts power back you can simply find the closest place to plug in to high power and boost charge real quick to either get home or to find a charging spot where you can grab a bite to eat and use the bathroom if you are on a long road trip.

Phones and electric devices were almost better when there was just a battery icon in the upper right with 3 diagonal pieces that would fill it.  With 3 pieces it was considered full.  With 2 pieces, all we knew is it wasn't full.  With 1 piece it let us know it could be empty at any time.  When there were 0 pieces left it usually would flash or something letting us know not to expect too much.  But this was the 25% mark.  it could last a while, just no guarantees.

We all think the 2014 had the worst current sensing, but the 2013 had a bar gauge that wasn't a precision reporting meter to us, so we didn't expect to get it down to the bottom accurately.  If you know how batteries work than you know not to expect anything under 20% that will ruin your day if it comes up short.  Always have a backup plan, preferably with a fast charger.

Zero could hide 25% of the capacity from the user, and have it ramp down to 0% quicker, but you could have 25 miles left then and not know at all where you stand.  it's pretty good the way it is, and the 2017 bikes with dual current sensors should make it pretty much perfect accuracy now. 

[KrazyEd]

   When I first got my DigiNow Dongle, while looking at different settings, I recall seeing something
about battery reserve. If I recall, there was the ability ( using the dongle ) to change what was
called reserve battery. It may have been at what point the gauge read 0%. Not sure, that was
a while ago. Will probably play with settings on the SR with the dongle to see what offerings
there are with the 2016 VS the 2013 FX.
   Going back to the iPhone reference, In one of the earlier models there was a big uproar
about signal strength. Everyone was complaining about how many ( of few ) bars they had
in comparison to other brands in the same service area. Apple provided an update and now the
iPhones were all getting better signal. They weren't, they just adjusted what the phone
saw as signal to "show" greater signal strength. It's possible that Zero did this with the
battery bars. I doubt that would be the case though as they would want people to be
more careful at low SOC rather than have them get stranded because they THOUGHT
they had more battery.

[Electric Terry]

Apple provided an update and now the
iPhones were all getting better signal. They weren't, they just adjusted what the phone
saw as signal to "show" greater signal strength. It's possible that Zero did this with the
battery bars. I doubt that would be the case though as they would want people to be
more careful at low SOC rather than have them get stranded because they THOUGHT
they had more battery.

Right Ed, there are pros and cons to each.  if you hide 50% of capacity for instance, then people would complain their new motorcycle only goes 40 miles on a charge, to which they would be asked did it stop running, and they would say, no but it was at 10% and so I figured it was empty when really they had 60 miles left.

The best case scenario is to report battery almost completely accurately to the user and let them decide the risk they wish to take.  Maybe hide 5% or offer 5% pessimism on the display.  The key is people have to just know not to rely on anything under say 20%.  Although half the time they could ride to 0% and perhaps a few miles more, but the other half it might run out a few miles before 0%. 

Like I said above, Zero I think fixed this issue completely with the addition of a second current sensor calibrated for a different range from the first so it should be highly highly accurate now in the 2017 models.

[Doug S]

The best case scenario is to report battery almost completely accurately to the user and let them decide the risk they wish to take.  Maybe hide 5% or offer 5% pessimism on the display.

I agree completely, but the ICE vehicle manufacturers haven't done it this way for at least as long as I've been driving -- everybody knows when the needle hits "E", you've still got plenty of gas in the tank. It makes me crazy. If people are too stupid to refill before the needle gets to the "E", they deserve to be stuck on the side of the road! You have to manage your affairs better than that.

The reason I'd agree with reserving 5% or so is just because of the uncertainty factor. In spite of the best-laid plans, it is possible for the algorithm to think there's 5% charge left when actually the battery is done.