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[Richard230]

After 3.5 years of faultless running and charging and no firmware updates, my 2014S with PT charging system is starting to operate a little oddly.  Last month the charger started turning off at an indicated 92% (whatever the dash display says the app just repeats) and 115 volts on the app.  If you pull the charger plug and plug it back in the charger will pick up again at 12 amps and then taper off to .08 amps almost immediately.  But if you leave the charger plugged in, it will wake up 24 hours later and start charging again at 12 amps and then slowly start tapering the charge every few minutes until it is charging at 1 or 2 amps, before finally returning to .08 amps, having added about 250 Wh to the battery pack. Each day it will add about 2% to the indicated charge on the display. After about 4 or 5 days, it will finally show 99 or 100%.

While I can live with these sort of antics, since I don't take really long trips where I need the maximum capacity of my battery pack, it does give me something to think and worry about.  My first guess was that the charger might be getting goofy, but you would think that it would just expire, rather than turn itself on and off like that.  So then I thought that the BMS system might have a bug, but nothing has changed to the firmware and it was operating perfectly until last month. So unless a cosmic ray happened to hit one of its little transistors and altered the programming, a random malfunction to the BMS doesn't seem likely. The only explanation that makes any sense to me for this weird charging is that perhaps one of the battery packs is fading a bit and that is causing the charger to cut off for a day at a time. My money would be on the Power Tank, as all of the other internal battery packs show a balance of 0.3 or 0.2 mV when fully charged, but it appears that the voltage of the Power Tank may not be checked by the app as there was never any indication that the app was showing more than three balancing voltages as it rotated through the display. 

Perhaps I am trying to overthink this issue, but I can imagine that my batteries are slowing starting to show their age and perhaps that is what is causing the bulk charging cutoff.    I can live with that sort of explanation, rather than a charger failure that would require the purchase of a new component and a visit to the nearest dealer - which has never happened before. 

One other example of why it might be a fading battery pack is that I am seeing slightly lower percentage readings on my display after riding the same distance and same route, in the same temperatures, compared to previous results.  One 10-mile trip that used to use 5% of the battery pack capacity, now shows 93% and the 37-mile ride to my daughter's home that originally used 30% now shows that I used 33-35% of the battery's capacity.

Zero originally estimated that the battery pack with the PT would last for about 350,000 miles before fading to 80%, but I never really believed that estimate. (To date I have recharged the pack something 470 times, according to the app and up until recently I have always kept the charger plugged in 24/7, since I ride my Zero at least once a week.)

Other than the slow and sporadic charging to 100%, my Zero continues to function perfectly, I might add.

[togo]

I would caution you not to take percent of charge very seriously
on your 2014, I've seen mine indicate 56% full when empty.

Voltage of the batteries should be checked and reported, not just SoC.

[Richard230]

I would caution you not to take percent of charge very seriously
on your 2014, I've seen mine indicate 56% full when empty.

Voltage of the batteries should be checked and reported, not just SoC.

Well, up until now, the % display has been very accurate.  I once ran the bike down to 0% and it shut off just as the "0" showed on the screen. Right now 92% shows 115 volts.  The next time it hits 100% I'll check the voltage again.  In the past (two months ago) at 100%, the app was showing 117 volts and 13.32 kWh.    What I can't figure out is why things would suddenly change.    I don't like change. 

[togo]

I must have a knack.  I rented a Tesla ten days ago, and it jumped from 16 miles remaining to zero suddenly too, just like my 2014 Zero SR.

[evdjerome]

Richard, do you have access to another external charger you could run through the auxiliary charging connector? Maybe you could borrow one and try just charging through it to see if you experience the same symptoms.

[Richard230]

Richard, do you have access to another external charger you could run through the auxiliary charging connector? Maybe you could borrow one and try just charging through it to see if you experience the same symptoms.

Thanks for the suggestion evdjerome.  But I don't have another charger that would work on my Zero.  In any case, right now I am more interesting in trying to understand what is going on rather than trying to fully charge the battery pack to 100%. Other than the weird charging, the bike is running perfectly and the battery display seems to be functioning properly, except when attempting to install a completely full charge in just one day. I'll be buying a 2018 Zero before the end of the year and that will solve any concerns about range.