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[NEW2elec]

Brian  (quote)  Visit the bike monthly and check on the state of charge; if below 40%, say, initiate a charge to a high end of the range; if there's cell imbalance, ensure cel balance is restored and then discharge the battery to 70-80%, say, before leaving it unplugged and unattended for another month.
This is where I get frustrated with the contradiction of "leave it plugged in for 72 hours to ensure the cells balance" and "100% SOC can hurt the batteries in the long term", with both statements being true but regarding different issues.
First how do I know if they are unbalanced?
Next could it ever be set up to balance at a set SOC like 70% and shut off charging from the app or will a BMS only balance as full SOC cells bleed off a little voltage at a time and let the others catch up?
How long would it take to be at 100% SOC to start to really stress out the cells? A few days, a week, a few months?
I realize this is not a critical issue just like changing the oil in a car at 3500 miles won't cause a seized engine but some good rules of thumb would be great to start to ingrain into new EV owners heads.
Thanks as always for every ones input and knowledge on these matters.

[BrianTRice@gmail.com]

Visit the bike monthly and check on the state of charge; if below 40%, say, initiate a charge to a high end of the range; if there's cell imbalance, ensure cel balance is restored and then discharge the battery to 70-80%, say, before leaving it unplugged and unattended for another month.

This is where I get frustrated with the contradiction of "leave it plugged in for 72 hours to ensure the cells balance" and "100% SOC can hurt the batteries in the long term", with both statements being true but regarding different issues.

72 hours is longer than I know about - 24-48 seems like it usually works. In any case, 72 hours is not long term compared to leaving the bike unattended for a month or more.

First how do I know if they are unbalanced?

Use the mobile app's battery screen or a DigiNow dongle to extract the data.

Next could it ever be set up to balance at a set SOC like 70% and shut off charging from the app or will a BMS only balance as full SOC cells bleed off a little voltage at a time and let the others catch up?

Right now, you can't get the BMS to rebalance cells without using the onboard charger, and usually to use it at/to 100% SoC.

While I hope that Zero is not so fickle as to rely on us jabbering on the forum anxiously when designing BMS features, I do hope they've already considered this sort of thing for new firmware updates, if the leaks are to be believed, maybe by using the app to direct the bike to use a "storage mode".

Maybe you could game the current software by unplugging the bike at a low level of charge, waiting a while, then plugging it back in, but someone would have to really monitor the balancing by the app to see whether it would even respond to such trickery.

How long would it take to be at 100% SOC to start to really stress out the cells? A few days, a week, a few months?

See, this is where some very clear language (that we lack) makes a big difference. It seems that the experts are talking about battery-lifetime-level factors, and that the risk is chemical around dendrite formation around the lithium anodes, and my understanding is that this process is fine if it's short term, because regular usage sort of clears it up, whereas longer periods eventually accumulates in a more permanent sense.

What the parameters are of those curves are, I'm not entirely clear on aside from some engineering summaries published online.

We still have the captured advice of a Farasis engineer about the matter, which generally rounded it to "more than a few days" and "Zero seems to have factored in plugging it in all the time into their battery lifetime estimates":
http://zeromanual.com/index.php/Unofficial_Service_Manual#Battery_Storage_and_Capacity_with_Age

I tried to distill it further here, partly based on concerns raised in this thread, mediated by the engineering background put into the battery article above:
http://zeromanual.com/index.php/Usage#Storage

I realize this is not a critical issue just like changing the oil in a car at 3500 miles won't cause a seized engine but some good rules of thumb would be great to start to ingrain into new EV owners heads.
Thanks as always for every ones input and knowledge on these matters.

I'm just trying to make sense of everything I've heard like you are. In this case, I've become local to some relevant people and aggressively curious enough to keep prodding them until I get a bunch of answers that seem consistent internally and externally.

I think what we're talking about has a bit of a risk curve that's worth exploring, but getting worked up about and dramatizing the negatives is unhealthy. I'm hopeful that with a basic maintenance discipline and the app both coaching the user and customizing the software mode, we could get 100k miles out of a battery with minimal risk. That's why I take even unhealthy discussions as lessons on what to put on the wiki.

[NEW2elec]

Thanks for breaking down my questions Brian.  I looked up the 2013 Zero manual and found two bits of information on this from Zero.  One was where I got the 72 hour advice but it is only for an "unbalance error". It's in section 6.6 here.
http://media.zeromotorcycles.com/resources/owners-manuals/2013/2013-Zero-Owners-Manual-S-DS.pdf#page=99&zoom=auto,478,100

But the section that covers this best regarding over charging is:
During an ordinary charging cycle, when the cells are
balanced, the charger (not t
he BMS) senses that the
power pack is full and terminat
es the charging cycle with a
“green light.” The BMS does have a redundant back-up
mechanism to prevent overcharging of the power pack. If
the charger fails to terminat
e a charging-cycle when the
power pack is full, the BMS will terminate charging itself to
prevent damage.

So the BMS backs up the charger not the other way around so if there is a third safety back up would be the only question at this point.  Either way before my battery replacement recall mine showed errors and kept any real problems from happening so I'm ok with it so far.

I'm posting this just to get info out there as I am curious as well to know as much about these bikes as I can (without getting an EE degree) thanks again for all the posts and seeking positive approaches to issues big and small.

[Low On Cash]

All of us plug in our Zero's and leave the room, the whole basis for my cautions is "Long term Storage" and  leaving the bike on charge for months which has to be one of the most ridiculous recommendations I've seen yet from a manufacture.

Take my word, Zero is 100% incorrect on this one and don't be shocked to see a revision in future manuals since they have been notified form me concerning this dangerous practice. 

Please do exactly what you want to do. If you're ok with risking your home to a $19.00 battery management board then fine, its your home and family.  No matter how you guys attempt to twist the facts around, any BMS that does not terminate its charge on a lithium battery will result fire.

Period. . . . .

[NEW2elec]

Mike I'm not against you.  I don't think anyone is twisting facts.  ANY safety feature on any product CAN fail with very bad results.  There is a fire risk with anything flammable near a heat source.  Zero's CAN catch fire but a lot of things have to fail first.  I'm not saying it can never happen but I don't believe it is at all likely in an undamaged state.  I feel it's less risky than a gas leak from an ICE bike or car or a natural gas leak or cooking fire or fireplace fire that have no real means of stopping those fires.
I never followed the "leave it plugged in all the time" suggestion myself because of the storms here in GA, I didn't want the chargers fried so I plug it in at night and unplug it in the morning.

I think it is in the manual from the 2010 and 2011 bikes which would canabelize battery cells as they tried to keep a certain SOC killing the bike. (look up EV Jedi on You Tube)  Which at that time was the most pressing problem so the "just leave it plugged in" came to be.  I think it could very well be removed soon and I hope "we" (non battery experts like myself) get a bit more of "why" things need to be done and not just a "rule" to follow.

Frankly what got me more was no mention of 100% SOC stressing a battery.  I never knew that at all until I saw it on here regarding all Li-on batteries.  I assumed a full battery was a happy battery.  Then I understood the "voltage is pressure" concept and now see how that would be stressful.

[BrianTRice@gmail.com]

It's so clearly not a $19 BMS board, more like several hundred dollars just from a casual BOM reverse engineering and asking around, and the way charging protections are arranged (see above about how the contactor is activated and how it fails, which has been repeatedly verified with lots of charger testing by myself and others) flatly contradicts your assertions.

The only BMS deficiency is lacking a long-term storage mode, which can be compensated for by the recommendations we've compiled until Zero figures out what they'd like to do about this.

This argument smells more like defamation than professional advice given in good faith, particularly since you claim to be a professional but haven't bothered to square any of your claims about Zero's systems with others' knowledge here.

[JaimeC]

The big disconnect for me here is trying to compare a $14,000 motorcycle to a $1,000 toy aircraft...

[Low On Cash]

The big disconnect for me here is trying to compare a $14,000 motorcycle to a $1,000 toy aircraft...

Jamie thanks for your reply, however it only shows your lack of understanding of the scope in which I work.

The Remote Piloted Vehicles RPV military drones both fixed wing and Rotory in which I design and work on for defense contractors such as Martin Merietta Aerospace and others are priced from $250,000 to well over a million. I hope this clarifies your negative remark on such an important safety matter. 

Regards - Mike

[mrwilsn]

The big disconnect for me here is trying to compare a $14,000 motorcycle to a $1,000 toy aircraft...

Jamie thanks for your reply, however it only shows your lack of understanding of the scope in which I work.

The Remote Piloted Vehicles RPV military drones both fixed wing and Rotory in which I design and work on for defense contractors such as Martin Merietta Aerospace and others are priced from $250,000 to well over a million. I hope this clarifies your negative remark on such an important safety matter. 

Regards - Mike

Then you must understand the difference between a battery pack, BMS and charger designed to charge each cell to 4.4V or even 4.5V and one that only charges to 4.15V per cell.  If you have the experience you claim you would know by doing simple math that Zero only charges to 4.15V per cell and you would know that this is a much safer voltage than 4.4V for lithium chemistries.  That difference is the reason the Zero pack can be 'fully charged' and still provide at least 80% original capacity after hundreds of thousands of miles (1800 cycles or more) whereas your cell phone, hobby drone or overpriced military drone only last 400-800 cycles.

The Zero charger would have to charge the bike to over 120V before you would be in the danger zone and the stock charger isn't capable of going that high.

Sent from my Nexus 6P using Tapatalk

[Low On Cash]

The big disconnect for me here is trying to compare a $14,000 motorcycle to a $1,000 toy aircraft...

Jamie thanks for your reply, however it only shows your lack of understanding of the scope in which I work.

The Remote Piloted Vehicles RPV military drones both fixed wing and Rotory in which I design and work on for defense contractors such as Martin Merietta Aerospace and others are priced from $250,000 to well over a million. I hope this clarifies your negative remark on such an important safety matter. 

Regards - Mike

Then you must understand the difference between a battery pack, BMS and charger designed to charge each cell to 4.4V or even 4.5V and one that only charges to 4.15V per cell.  If you have the experience you claim you would know by doing simple math that Zero only charges to 4.15V per cell and you would know that this is a much safer voltage than 4.4V for lithium chemistries.  That difference is the reason the Zero pack can be 'fully charged' and still provide at least 80% original capacity after hundreds of thousands of miles (1800 cycles or more) whereas your cell phone, hobby drone or overpriced military drone only last 400-800 cycles.

The Zero charger would have to charge the bike to over 120V before you would be in the danger zone and the stock charger isn't capable of going that high.

Sent from my Nexus 6P using Tapatalk

Thanks for the reply - all your assumptions are correct only if the BMS is operating as intended. Evidently most of you guys replying here are not reading the original post or my following reply's.  My comments have 0% to do with the Zero's charging protocol and 100% to do only with the unsafe recommendations from Zero regarding un-attended charging for months and months at a time.

Facts are Facts; In the event of a BMS failure to terminate a charge or a simple lightning spike that freezes the processor it "Will Result In A Fire" there is no question about it.

Anyone who knows anything about lithium cells would question why Zero would recommend leaving the bike plugged in and at full charge knowing it was not in the best interest of the batteries health. The answer is simple; the lost health of the cells being stored at full charge will not be a factor in Zero's warranty period.

Zero cannot control the charge level when the owner stores his bike, which may be depleted, or say at 10-20%, so their biggest fear is the cells self-discharging themselves to a critical level during storage and cell deterioration, so their simple remedy is to keep it plugged in.

My recommendation of storage is 100% safe - Lithium cells only self-discharge at a rate of 2% to 3% per month, so if we stored the bike at 50% SOC, in 6 months it would only lose an average of 15% and therefore the pack would remain at a safe 35% SOC.  Zero’s biggest fear is the cells self-discharging to a critical level and the need of replacement under warranty. With this in mind, they figure as long as the charger is plugged in and working everything will be in order. However, Zero's procedure fails to consider the owners safety and fire risk in the event of the a BMS failure or a spike causing a the processor to freeze and not terminate the charge.

The Zero's BMS is of a "simple low cost" design and prone to failure - there are hundreds of threads and Google searches to validate that owners have constant failures - so why would anyone lock up their house for months at a time and leave the bike plugged in? Its a senseless decision when storing the bike as I recommended will better protect the health of the battery and most important remove the risk of the owner losing their home or even possible death from a lithium fire.

You guys have to ask yourself the question of why would anyone trust the advise of a company that does not even have the know how to get a simple App to work ?

Is any of this starting to make sense now?

Regards

   

[manitou]

Let's say a bike was left unplugged in enclosed storage for like.. 4 months? a year?  I suppose the best thing to do would be to plug it in right away before attempting to turn it back on?

[Low On Cash]

Let's say a bike was left unplugged in enclosed storage for like.. a year.  I suppose the best thing to do would be to plug it in right away before attempting to turn it back on?

Thanks for the reply - it won't matter if you turn it on or charge it - but storing it for 12 months you would want the SOC charge state to be at 80-85% since self-discharging will drop the battery around 30% for 12 months.

[manitou]

I would want the SOC state to be that?  You mean, that's what you would expect it to have dropped?  Will it charge back up to 100% ok, or will the battery capacity be permanetly lowered? 

[wontuan]

User Low On Cash is mostly right. Cells don't like being stored at full SOC, it shortens the cycle life. But there is a reason why Zero recommends leaving the charger plugged in.

I am not sure where this idea that there is a 2-3% self discharge every month came from but it isn't true with Farasis's cells. The self discharge rate is heavily dependent on chemistry, temperature, and SOC. After extensive testing with these cells, at higher SOC (70-90) Farasis's cells will self discharge maybe around 1-1.5% a month while at lower SOC its much less. So much less that the amount of current the BMS draws is more important than the self discharge rate.

Other people have already said it but Zero only charges the battery to 4.15V which is not full capacity of the battery. The area that hurts cycle life the most is between 4.15V and 4.2V, any thing higher than 4.2V it is considered dangerous (I can explain why if people are curious).

I store my bike around 40-60%, this is what Farasis stores their batteries at. While leaving the bike on charge isn't the best for it's cycle life it shouldn't cause any fire. In the event the BMS locks up it can't do anything but open or close the contactors. There is also the MBB on the bike that can protect the bike in the event of a non-responding BMS. If the charger dies due to surge or something then the BMS will open the contactors due to a non responding charger.

The ways to get a battery fire is to put it in a super hot environment, or over discharge the battery then try to charge it back up, or over charge the battery. Leaving the bike on charge can't cause either of those scenarios. Leaving the bike plugged in won't allow for an over discharge, and since the charger won't go higher than 116V you can't over charge your battery plus the BMS and MBB are there to oversee things. In the event of the BMS and the MBB not responding and the contactor is welded and the charger some how outputs more than 117.6V then yes there is a risk of fire. This is probably why Zero ask you to check on it every 72 hours to make sure the bike is still responding and the BMS is still alive. Also just to clear things up there has never been a fire with a production Zero bike that uses Farasis cells (this doesn't count prototypes and test bikes).

I think someone said that Zero’s BMS is like $20-30. Not true, the parts on there alone are like $40 not counting the PCB, potting, and assembly cost. Their BMS is not perfect and has some known flaws but they are making them better each year. But when it comes to protecting the battery the BMS does a really good job and won’t close the contactor if there is anything out of the ordinary. I think the Zero BMS uses some of the same parts in the Tesla Model S BMS.

So the reason Zero says to leave the bike plugged in is that it prevents over discharge and there shouldn't be any over charging because they left some margin and there are many things that needs to fail to over charge. This does hurt cycle life on the cells, but its better then having either an over discharge or over charge situation.

Also something else that people might not know. Without saying too much there are a few magic secret things in those battery pack and cell pouches that in the event of thermal runaway or fire they will limit the current flow and suppress any damages. There is a reason why Zero pay a premium for these pouch cells and not cylinder cells like other people

Sometimes it may not be clear why engineers including those at Zero and Farasis do what they do but I assure you that they are concern with safety and they always have to evaluate the risks. I am sure someone will say that I am wrong but I think I will leave at that.

[BrianTRice@gmail.com]

I am not sure where this idea that there is a 2-3% self discharge every month came from but it isn't true with Farasis's cells. The self discharge rate is heavily dependent on chemistry, temperature, and SOC. After extensive testing with these cells, at higher SOC (70-90) Farasis's cells will self discharge maybe around 1-1.5% a month while at lower SOC its much less. So much less that the amount of current the BMS draws is more important than the self discharge rate.

...

I store my bike around 40-60%, this is what Farasis stores their batteries at. While leaving the bike on charge isn't the best for it's cycle life it shouldn't cause any fire. In the event the BMS locks up it can't do anything but open or close the contactors. There is also the MBB on the bike that can protect the bike in the event of a non-responding BMS. If the charger dies due to surge or something then the BMS will open the contactors due to a non responding charger.

The ways to get a battery fire is to put it in a super hot environment, or over discharge the battery then try to charge it back up, or over charge the battery. Leaving the bike on charge can't cause either of those scenarios. Leaving the bike plugged in won't allow for an over discharge, and since the charger won't go higher than 116V you can't over charge your battery plus the BMS and MBB are there to oversee things. In the event of the BMS and the MBB not responding and the contactor is welded and the charger some how outputs more than 117.6V then yes there is a risk of fire. This is probably why Zero ask you to check on it every 72 hours to make sure the bike is still responding and the BMS is still alive. Also just to clear things up there has never been a fire with a production Zero bike that uses Farasis cells (this doesn't count prototypes and test bikes).

I think someone said that Zero’s BMS is like $20-30. Not true, the parts on there alone are like $40 not counting the PCB, potting, and assembly cost. Their BMS is not perfect and has some known flaws but they are making them better each year. But when it comes to protecting the battery the BMS does a really good job and won’t close the contactor if there is anything out of the ordinary. I think the Zero BMS uses some of the same parts in the Tesla Model S BMS.

So the reason Zero says to leave the bike plugged in is that it prevents over discharge and there shouldn't be any over charging because they left some margin and there are many things that needs to fail to over charge. This does hurt cycle life on the cells, but its better then having either an over discharge or over charge situation.

Also something else that people might not know. Without saying too much there are a few magic secret things in those battery pack and cell pouches that in the event of thermal runaway or fire they will limit the current flow and suppress any damages. There is a reason why Zero pay a premium for these pouch cells and not cylinder cells like other people

Sometimes it may not be clear why engineers including those at Zero and Farasis do what they do but I assure you that they are concern with safety and they always have to evaluate the risks. I am sure someone will say that I am wrong but I think I will leave at that.

Higher discharge rate is quoted as a conservative estimate in case there is a battery defect or a board / systems defect. The idea is predicting a safe visit / check frequency from some basic assumptions to maybe corroborate the official recommendations or provide a reasonable fallback.

Thanks for clarifying everything else. It's been clear since the first battery engineer posted about Farasis here on the forum that being left plugged in unattended was considered a reasonable but not optimal recommendation. I'm pretty sure we've already nailed a better set for recommendations but your feedback is worth incorporating for better depth of understanding.

Not to pry, but how do you know Farasis' practices and accident statistics?