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[Crissa]

@NEW2elec That's my experience with pretty much all rechargables.  Use it or lose it.

-Crissa

[heroto]

I know a lot less than other posters on this thread, but I do see 100% incompatible responses that have have not been sorted out.
Cell balancing seems to be a good thing. Lots of explanations why and some explanations about how when are on this thread.
But I don't understand the where or when details.

Specifically: If cell balancing on the latest gen Zeros is not occurring during that long slow taper then when.? If no then the when?

[Crissa]

If there's no cell balancing being needed, it's not going to do it.  Also, power meters may or may not catch the extra extra blips of power used for balancing.  It's not going to be a high level of power needed.

Zero's own instructions say that it's not needed all the time, either.

I don't see anyone saying anything incompatible, either.

-Crissa

[valnar]

I do have a working theory that "using" these bikes helps keep the battery in better health than sitting.

Unfortunately that will be me.  I'll be a fair weather rider in Northern Ohio.  I wish there was a way to exercise the battery on the occasional snow or rainy day in the garage without the obvious dangerous method of running the throttle while it's on a stand.

[Richard230]

I know a lot less than other posters on this thread, but I do see 100% incompatible responses that have have not been sorted out.
Cell balancing seems to be a good thing. Lots of explanations why and some explanations about how are on this thread.
But I don't understand the where or when details.

Specifically: If cell balancing on the latest gen Zeros is not occurring during that long slow taper then when.? If no then the when?

It is possible that the newer Zero models do not taper the charge to balance the cells every time the battery pack is being recharged by the onboard charger.  Perhaps it is only done after a certain number of recharges have occurred? Recharging at maximum charger power right to 100% SOC and then shutting down will cut the overall time to recharge, which is a good thing for the owner.  In any case, my cell balancing remains between 2 and 3 mV, so balancing seems to be OK.   

[Doug S]

I can't speak definitively for the Zeros, but for maximum charging speed, a "constant current/constant voltage" (CC-CV) scheme is usually used, which looks like this:

1) If the battery is highly depleted (below say 20%), a fairly low constant current is applied to the battery until it exceeds the threshold -- maybe 1/5th of the highest charging current or so. Batteries are fairly delicate when at low SoC and can't handle high charging currents.

2) Full charging current is now applied. Typically no more than 1C, but some batteries can tolerate more (especially if they're well cooled). This is the "bulk charging" phase and it's where you want to operate if you're trying to charge fast on a road trip. For obvious reasons it's also referred to as the "constant current" (CC) phase. Voltage slowly rises as the battery charges.

3) When a certain voltage threshold is reached (116V for the battery in my SR), the charger holds that voltage. The current will then ramp down as the battery approaches "full charge". This is (obviously) called the "constant voltage" (CV) phase.

4) When current drops dramatically, any individual cells that aren't yet at their "full charge" voltage are given a tiny current individually until they do achieve that voltage. This is what's referred to as "cell balancing". It's usually a very, very small current, a couple of orders of magnitude smaller than the charging current. Charge current is usually reported as 0 during cell balancing.

So cell balancing doesn't even start until "charging current" registers as 0. That's why you may not want to do it all the time -- you have to get to 100% charge before it even starts, and it is true that constantly 100% charging your battery isn't ideal for battery life.

That's why I presented it as a compromise between periodic cell balancing and 100% charging in my post above.

[TheRan]

I don't know whether Zero does it but it's possible to balance cells without them being connected to a charger. Some battery packs have built in balancing boards (or it could be a separate component on the bike I suppose) that shuttle charge from the higher voltage cells to the lower ones and keeps doing so until they're all close. Doing so would mean the SOC of the whole pack would drop a little, more so if the cells are really out of balance.

Reading through the 2019 manual last night and the charging recommendation notice on the Zero site (for 2013 and newer I think) Zero says it's okay to leave the bike plugged in at 100% but recommends that it is unplugged to extend battery life. If it is left plugged in it will discharge to 90% and then charge back to 100% and continue this cycle until unplugged, I suppose in an effort to not leave it at 100% but also give you a higher chance that it's close to that when you do unplug it (so you're not left at 90% if you forget to unplug it). I don't know what the time frame is for this 90-100% cycle, whether it's hours or days or even less. I imagine that leaving the bike still plugged in for an hour or two is probably fine and they're more worried about people leaving them plugged in for days at a time ready for riding at the weekend.

[DonTom]

On the subject of balancing, I have a question. If a cell or section of cells is a dead short inside the battery pack, will that show up as a serious imbalance on the app?

The reason I am asking is because the way my Zero DS behaves. Half the range it should have and charges twice as fast as it should, just as if my 6.5KWH  battery pack was only 3.2 KWH. As if half the cells are shorted out or whatever.

But the Zero app shows my battery imbalance as only a couple of MVs.

IAC, I may soon be looking for a warranty replacement. IIRC, the battery is warranted for  five years.


-Don-  Reno, NV

[Richard230]

On the subject of balancing, I have a question. If a cell or section of cells is a dead short inside the battery pack, will that show up as a serious imbalance on the app?

The reason I am asking is because the way my Zero DS behaves. Half the range it should have and charges twice as fast as it should, just as if my 6.5KWH  battery pack was only 3.2 KWH. As if half the cells are shorted out or whatever.

But the Zero app shows my battery imbalance as only a couple of MVs.

IAC, I may soon be looking for a warranty replacement. IIRC, the battery is warranted for  five years.


-Don-  Reno, NV

That is what happened with my 2010 Electric Motorsport GPR-S when its batteries started going south after 1000 miles.  But then you can hardly compare a GPR-S with any Zero.   

[BrianTRice@gmail.com]

A dead short in the pack in a cell or series of cells would be highly detectable; both the pack voltage would be noticeably capped by the amount of voltage decrease from that layer of cells (~3V), and there would be a massive, shutdown-inducing cell imbalance.

I believe that the cells inside a Zero pack are also separately fused.

Basically, stop speculating like this and extract your BMS logs and read them, instead.

[DonTom]

Basically, stop speculating like this and extract your BMS logs and read them, instead.

Will do, but what will I be looking for? I had no idea such info. would be in there.

-Don-  Reno, NV

[BrianTRice@gmail.com]

Basically, stop speculating like this and extract your BMS logs and read them, instead.

Will do, but what will I be looking for? I had no idea such info. would be in there.

I don't know, but for each BMS, 28 cell voltages will be listed out explicitly in a single log status event, and over time you'll see what voltage range that covers.

[Doug S]

Or, if you suspect your battery is really down to half capacity, just freakin' take it to the shop. You're asking opinions of people on this forum, from people who are generally well-informed but not knowledgeable of the details of the Zero construction. Those that ARE knowledgeable of those details work for Zero and aren't allowed to reveal that sort of information here. You're really not going to find your answers here.

Take it in and quit wasting bandwidth.

[DonTom]

Or, if you suspect your battery is really down to half capacity, just freakin' take it to the shop.

I will when I can, but I am 100 miles away from the bike right now and it will be a few weeks before I can take it anywhere.

IMO, some of the people here often know more than some of the people in the shops that service Zeros. It's sometimes best for me to know what could be happening before I bring the bike in.

-Don-  Reno, NV