And you should have seen where I was, in the middle of a retirement village. The only way I could have charged my bike would have been to steal electricity. In addition, after an hour it was at 10% and still wouldn't operate properly. The dashboard would turn on but the red warning light flashed like the kickstand sensor was faulty and the throttle was useless.
It wasn't until it was in the mid 40's when I tried again and it worked fine.
Or you could just knock on someone's door and ask to plug in....it's pretty embarrassing but sometimes you've gotta do what you've gotta do. I have had very similar behavior on my 2014 Zero S twice and several other times I have just taken it all the way down to 0% (no sudden drops) before reaching my destination. The first time SOC suddenly dropped to 0% I pushed about a mile past many houses to get to a parking garage that had an outlet. The second time I just sucked it up and knocked on someone's door that had their garage open.
Yes, it was awkward but the old man that lived at the house was very friendly. I tried to give him a few bucks but he wouldn't take it. You might be surprised how many people would have your back if you just have the courage to ask.
Some tips on the Zero behavior...
The BMS controlled cell balancing takes place when the batteries are almost fully charged. When you check cell balance at 100% it should be very low. As ultrarnr said, 3-4 mV is normal. I have seen my pack as low as 1 mV many times but I have also seen it over 100 mV many times. Here are some screen shots of some times when I have had low SOC and high cell balance as well as a couple times when I was fully charged and cell balance was just 1 mV. Note that in the one instance pack voltage was actually at 117 V with cell balance at 1 mV.
As you drain the battery the cells will slowly get out of balance due the small differences in internal resistance within the cells. The lower the SOC the more out of balance they will get. As soon as you start charging they will naturally start to rebalance themselves. Once the pack is fully charged but before the BMS controlled cell balancing starts the cell balance should already be pretty good. Then the BMS will kick in and start to balance the pack attempting to get every cell to exactly 4.15 V.
The cell balance is measured between the cell with the highest voltage and the cell with the lowest voltage. Thus, when the pack is out of balance it's possible that most cells are very close and only one or a couple is actually much lower or higher than the others.
Higher rates of discharge are more likely to get the cells far out of balance than slower rates of discharge. Also, if you unplug before the BMS can balance the cells at full charge then you may see higher cell balance when you get to low SOC. If you just do this once you will be fine but if you go long periods of time without letting the BMS balance the pack then you will be at higher risk for seeing large cell balance at low SOC.
When you were ridding at 12%, your cells were likely too far out of balance. I think what happens is that when the cells are far out of balance, SOC is low and you try to give it too much throttle then the voltage sags too much and the bike drops to 0% even though the voltage rises back up when you let off the throttle. It could also be that the cell balance was worse than shown in the app but recovered before I was able to get connected and check it. I haven't been able to confirm this because voltage and cell balance are not options on the riding screen in the app. Notice that in the following picture I had just experienced the same problem as you with a sudden drop to 0%. However, cell balance and voltage are similar to the previous pics where I was at 8-11%.
After plugging in, if you just let it go for a while and then unplug and try to ride you may see the behavior you described....still won't let you ride away until you got to 40%. If it happens again do the following...
Plug in the bike.
Connect phone to the bike and check the balance (just for the data point).
After about 45 minutes - 1 hour unplug the bike and turn it on.
Turn the bike off.
Reset the BMS using the reset switch on the front of the battery (instructions on the unofficial zero manual)
Wait about 20 seconds and then turn the bike on.
You should have a few percent and you should be able to ride away but with such a low SOC it would be risky that you might have the sudden drop again before getting home. But now you can at least plug back in and charge until you decide you have enough that you feel comfortable making a break for home (or wherever you plan to fully charge). Make sure you fully charge the bike and let the BMS balance the cells when you do get home. I think I waited until I was at about 20% before I rode home....actually, the first time it happened I rode home but the second time (pictured above) I gave myself just enough charge to make it to a charge point that was 2-3 miles away and then super charged for about 30 minutes to get the bike to 40-50% before riding home.
One other tip....when at 0% I have been able to push my bike with it keyed on for a block or two then turn the bike off and then turn back on and the regen was enough that I was able to do an assisted walk using the throttle while walking next to it. It didn't work the second time my bike suddenly dropped to 0% (even after trying a BMS reset)...but I have been able to do it successfully more than once.
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Topic: I had to push it home for the first time today (Read 2222 times)