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[DerKrawallkeks]

Hey,
thanks Zelidar for linking the papers! Luckily they're both free, I just found them on the internet.

@MVetter, sure when the voltage goes down, the battery amps must go up to maintain the same power. But what I think counts for all bikes, both the livewire, Zeros and all the other ones:

No matter the overall voltage and overall amps (livewire having lower amps due to higher voltage), the decision really is wether you design the bike to be able to handle some extra current or not.

To maintain full power: On the zeros, let's say it must handle 700A when full, but it would have to handle 800A when empty. On the livewire, it might be 300A when full and 350A when empty.
It's just a decision wether you spend the extra money to design the components to handle the extra load or not, no matter the absolut currents we're talking about.

What do you think of that thought?

[TheRan]

Oh of course, it's just presumably easier to have a drive train that handles higher voltage than higher current. Zero say the SR/F/S actually have a 900A controller so in theory it can supply the full 83kW down to 91V and 0% SoC is like 95V, so the limit must be the battery (or voltage sag drops it below 91V at a low SoC).

[valnar]

A: Ph.D. thesis “Aging of Lithium-Ion batteries in electric vehicles” – Dipl.-Ing. Univ. Peter Keil
https://mediatum.ub.tum.de/doc/1355829/file.pdf

This PDF is very enlightening.  I read most of it.  Everyone should read page 141 onward.

So basically keep the battery between 40-80% while riding (if that is enough range for you), and store at 50%.  At least that's how I read it.  The only part that concerns me is the storage of the battery below freezing, which mine is doing right now.

[Crissa]

Just don't charge it while freezing!

-Crissa

[JaimeC]

Just don't charge it while freezing!

-Crissa

I discovered last year that if the battery is too cold, it won't charge at all.  You have to take it out for a ride so it heats up and THEN you can charge it.  The takeaway for me was make sure I put it away in cold weather with enough of a charge that I can actually take it for a ride before recharging it.  30% seems to be as low as you'd ever want to park it for a variety of reasons.

[DerKrawallkeks]

@Valnar,
Don't worry about freezing temperatures, the Farasis Cells are rated down to -20°C in the official datasheet, so no problem.
Also (that goes for any lithium battery) the electrolyte is not water, but an organic solution. So it does not freeze at 0°C. Storing it around freezing temperatures is the best you can do! It's perfect.

What Crissa said is probably smart, don't charge at low temp if possible, or at least charge slowly.

[Crissa]

Bring you Zero indoors to snuggle warm to charge in cold weather!  The electrolyte gets sluggish when cold and works best above body temperature.

-Crissa

[DonTom]

Bring you Zero indoors to snuggle warm to charge in cold weather!  The electrolyte gets sluggish when cold and works best above body temperature.

-Crissa

Old thread, but isn't storage different? IOW, you want the batteries a bit cold for long storage, but warm  for use.


-Don- Reno, NV

[DerKrawallkeks]

Hey Don,
I'd say that's right, that's what I concluded in my first post of this thread, after reading the papers.
Just like you said, warm for use cold for storage. With very slow charging, it doesn't matter much I think

[DonTom]

Hey Don,
I'd say that's right, that's what I concluded in my first post of this thread, after reading the papers.
Just like you said, warm for use cold for storage. With very slow charging, it doesn't matter much I think

Yeah, the way I think of it is that cold turns the battery more "off". That way, longer storage, less drain.


A warm battery is more "on" and ready for performance, but more drain when not in use.


-Don-  Reno, NV

[Crissa]

Bring you Zero indoors to snuggle warm to charge in cold weather!  The electrolyte gets sluggish when cold and works best above body temperature.

Old thread, but isn't storage different? IOW, you want the batteries a bit cold for long storage, but warm  for use.

Yes, that doesn't contradict what I said.

If you're storing a battery, you're not charging/discharging it.

-Crissa

[DerKrawallkeks]

Yup. Like you said Crissa, the electrolyte looses its ability to move ions, the colder it gets. Also they can't move as well inside the anode/cathode material.
So for quick charging, it makes sense to have it warm. for slow charging (0,1C) with the onboard charger, it probably doesn't matter

[Crissa]

Well, it needs to be above freezing.  You need the ions to move to charge, and if they don't move at all, well, that's bad, too.

-Crissa

[DerKrawallkeks]

Yes, but the electrolyte doesn't freeze. It's not like at exactly 0, charging or use becomes impossible. The electrolyte is organic:)

[Crissa]

Yeah, it's worse:  it doesn't freeze evenly.

-Crissa