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[princec]

No, not really dense at all, I'm just wondering what about the protocol and its abilities stops it from delivering just a couple of amps if asked, or whatever fairly small current is needed for balancing on the Energica. Because it strikes me that the Energica should never end up in this state if the only charging you have available is DCFC.

Cas

[DonTom]

Hm so ... how come DCFC is not capable of a balance?

Cas

The speed of the charge. Balancing takes time. The more time, the better balancing.


IOW, DCFC does  balance a little. But very little.   But a 120 VAC level one charge would be a lot better as then there is a lot more time to balance.


If you want a real good balance, use the lowest power you can get aways with and be very patient.


-Don-  Auburn, CA

[DonTom]

Because it strikes me that the Energica should never end up in this state if the only charging you have available is DCFC.Cas

Do your balancing at home with the AC input charger that is on the bike.


You do NOT need to balance every charge. Your home charges should take care of it so you do not need to worry about it when on the road.


-Don- Auburn, CA

[princec]

Obviously I know all this ... I want to know why DC charging can't also be slow when it needs to be. You know, when the bike's about to brick. Usability fail. This is why EVs aren't catching on as fast as they should be. This should be a no-brainer, and most importantly, it should fail-safe, not just keep charging your bike at 20kW until the battery's fucked.

Cas

[T.S. Zarathustra]

DC charging (or charging control circuit in the charging station, not in the vehicle) can charge at lower power. The rating for DC station is max what it's capable off. It needs to communicate with the vehicle what are the safe charging parameters before it starts charging (current, type of battery, cut-off voltage, etc). The AC chargers (with the control circuit built into the charger in the vehicle) are specifically for that batterypack with those parameters hardcoded.
The BMS (also built into the vehicle) is in charge of balancing the cells. It depends on the BMS design if it can balance the pack when it's half charged. Usually there is no need. As long as all cells have some charge they don't "need" balancing. By design BMS (usually) only balances the cells when they are fully charged. It does not matter if there is imbalance when discharging. If one cell goes critically low, the BMS shuts off the whole pack, it does not discharge the other cells to match when that is not needed.

[Specter]

T.S.   It can charge at lower rates but is not very good at it. it's designed to push sometimes hundreds of amps through the battery to get it back up and on the road, not to pump half an amp through it so it can balance for 3 hours.  They don't do very well regulating small currents like that, and when the batteries are at their top end, voltage swings are very easily caused with just a few amps, enough to push the top battery into 'im done' stopping the charge,  or worse over charge them.

By the nature of how a balance takes place, even on active balancing systems, it takes a while to shuffle the charge around or bleed off through the small bleed resistors, the fast charger would overwhelm the circuitry's ability to do it properly.  An AC charger that can readily go down to an amp or two (which would potentially equate to fractions of an amp on the high side), does a much better job for that fine tuning charge.

DC FAST chargers were not built for fine balancing.  They are built for speed.  They don't want you sitting there for 2 hours, they want you in and out so the next guy can charge.

besides, here's another way to look at it.

for all you gas car users who smugly claim oh i gas up in 5 minutes and im back on the road.  How would you like it if I was in front of you, filled my car but then decided, you know what, i need to wash it too.  im parked, so might as well do it here at the pump!!  I'll go inside grab a quick snack, a bucket of water then after i eat, ill come out and wash my car.  Then proceed to spend the next 2 hours fiddling around with something i could easily and should do while i am at home, all while you are behind me, waiting for your 5 minute block of time to fill your car.   THIS is about what using a fast charger to balance fully would be like.

how would you like it if i pulled up to the charger, charged my car, then let it set there an additional 3 hours so i could squeeze that last 2 percent out of it and fully balance it?  You wouldn't mind sitting there waiting your turn while i balance would you?  Of course you wouldn't, because the kids today are just soooo patient, they don't want everything now now NOW!!!  they can wait until... whenever and will be happy about it!!

Many DC stations will also charge you for idle time too... this is so the entitled jackasses who think they CAN just park there, and go shopping, and fuck over everyone else needing power, are paying for that parking, because it costs the company money too in lost revenue.

DC fast charge is not designed to fine balance, and they don't want you there, sitting there, balancing for hours.

Aaron

[T.S. Zarathustra]

DC fast charging is designed for speed, but that doesn’t mean it’s not accurate. DC chargers don’t just blast “hundreds of amps” blindly into a pack. They follow the vehicle’s BMS commands down to very fine resolution. As the pack approaches full, the vehicle automatically tapers the current, often down to single digit amps, precisely because the BMS regulates it at the millisecond level. This is why many EVs finish their last few % at well below 10 kW on DC, not 250 kW.

EV charging isn’t a single sequential line. If one station out of eight is occupied, you don’t line up behind that one. You plug into another.

[princec]

I'm aware of all of this too. I think my question boils down to, would you rather upset someone mildly by making them wait another 30 minutes for a charge (first come first served buddy, my SOC is none of anyone else's business) and not ruin your £20k motorcycle, or meekly throw your hands in the air and move on swiftly, to end up with a two wheeled brick a week later because you're so polite?

I mean if we're on the subject of fast, it's downright rude to be charging at a mere 20kW for an hour isn't it when the next guy could be drawing 350kW and be on his way in 15 minutes. So you see the flaw with that line of thinking.

Cas

[Specter]

Things are designed for real world practicality and profitability, not your hurt feelings.

Aaron

[PWM]

The only way to fill a cell to capacity is to slow down the charge, the terminal voltage will drop proportionally so it matters significantly when SOC rises otherwise capacity falls short...balance starts when the first cell hits 4.2V and as was stated, this is a BMS function inclusive of dissipating the excess by discharging the cell(s) that have reached full capacity. DC charge stations exist to make money on the basis of energy delivery not time connected...leave the burden of balance to BMS it will select the correct charge rate which in our case is fixed at 4-amps when one charges by AC.

[Specter]

pwm, in the case of the energica, the discharge resistor is not very big.  so at the beginning, when it is only discharging maybe a few cells, it can cycle this a few times, but after it goes on for a bit, lets say now you have 20 cells that are topped off, it can't dissipate them in the time allotted (which is about an hour) down low enough to trigger another charge/balance cycle so it shuts off the charge session, terminates it.  in a badly unbalanced pack you may still have half your cells that are not up to par, but the cycle terminated.  This is why having an external timer to physically cycle power going TO the bike on and off WILL work.  See if you are in a charge session and power is cut to the bike, after, i want to say 15 or 20 seconds, it times out, shuts down the charge session.  So this manual cycle, once power is re applied, forces a restart of the charge cycle again at whatever the batteries are currently at, until it hits peak again.  Sometimes it can take a day or two, especially if you got cells that are 200 mv / half a volt out but this can and will walk up a badly unbalanced pack unless there is physical degradation that is preventing it from reaching there.

Aaron

[PWM]

Hi Aaron, I understand what you are saying and functionally you're correct but typically there's a discrete discharge shunt (not necessarily a resistor but can be semiconductor) assigned to each BMS channel...in the Energica case each channel connects to (2) cells in parallel as best as I can tell from module images posted on a different thread in this forum.

Anyway, the charge / balance cycle time-out is somewhat of a mystery to me too and I'm guessing it's safety compliance for software to terminate orderly...like a watchdog requirement?

BTW Aaron...don't you possess a 21.5k_Whr pack that was salvaged and available to experiment / explore?

Be interesting to know what BMS controller chip is used or the pat number...advance apologies if confused...

[Specter]

i think the timeout is in case it hangs or maybe locks up somewhere so it eventually terminates.  i do know that occasionally a charge can get goofy on the shut down, something glitches software wise and it has to turn off basically throwing the knife to get it to shut down ,it's locked up.

i know some chargers remember stuff too and can throw and save their own faults, and need a p.o.o.r to get going again.

i just said resistor, it can be semi, a lot of balancers are ,but it's basically something to bleed / eat down power.  Basically it's shave down the high , charge entire pack, shave down high ,charge whole pack, etc until they all finally fall into the proper range.  Now you can see how when you get towards the end and you got 100 batteries trying to seep down thru a circuit that was designed to handle, what 10 watts, it's going to take some time.  Too had they didn't use active but that's of course more expensive bla bla.

i dohave a pack but have not had time to bust into it really yet.  been so busy with everything else going on, and milking my bum arm here etc. im hoping, probably around may when the track shuts down for a few months ill get to it then. worse case ill bypass some stuff and use it for solar storage along with the rest of the frankenwatt mobile.

Aaron

[PWM]

In today's Mark Travels segment, Mark went skiing, the only Experia content was Mark's renewed awareness towards balancing pack thru AC charging and some sort of issue with flakey range estimate being displayed.

Wondering if other Energica riders are having same issue...this has never been a problem with my '21 Ribelle e.g. range estimates based on current ride mode are typically accurate @ 1.0-1.5% SOC / mile...I will get 100-miles worse case (typical highway mode does not exceed 70_mph_gps) versus 150-miles best case (typical city mode which is 35-40mph inclusive of some stop-n-go).

[Specter]

Every motorcycle manu on the planet should do themselves a favor and get rid of range estimates.
You tell people over and over how it works, it's not accurate since YOU are not consistent on how you ride, bla bla, but hey, it makes for great drama when they are click whooring for pootube pennies per hour from people watching the same crap play out for the 10001 time.

it's like these cheap 'reality shows' that are 'shot live' and it's episode 5 now and the cops still have not figured out that the moonshine pit is right behind their police station and once again just miss porksword and cleetus turning off into the punkin patch   

What they should call it is,  based on the way you have been driving the past mile, if you keep it up, you  got XX more miles left.

once people understand it for what it is, and quit pretending it's what they want it to be, it works just as intended.  But the drama he can create with it should be good for at least another 100 page clicks and pearl clutches.  Cha Ching $$$

aaron.,