Battery myth or fact? Drain new battery to zero?

[jazzmanmonty]

So it's always encouraged when you buy a phone or anything w/ lithium ion battery to drain it down to zero, charge to 100, rinse and repeat a couple times for improved battery life or something...not sure what it really helps, but if true, should we do the same conditioning with new ev batteries? Not an electrical engineer here so pardon my lack of electrical knowledge.

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[MostlySafeBear]

So it's always encouraged when you buy a phone or anything w/ lithium ion battery to drain it down to zero, charge to 100, rinse and repeat a couple times for improved battery life or something...not sure what it really helps, but if true, should we do the same conditioning with new ev batteries? Not an electrical engineer here so pardon my lack of electrical knowledge.

110% myth. Running a new modern lithium-based battery down to 0% at all is outdated knowledge that originated from much older rechargeable battery technologies, such as Ni-Cad and NiMH.

Those older technologies had somewhat of a "memory" effect, and would operate at less than their full capacity unless they were fully drained and fully recharged. This also aided in calibrating battery charge meters of the day.

Nowadays, devices are pre-programmed with their available battery capacity, and there is no need to calibrate them.

Note that what the truck refers to on your displays as 0% and 100% are not truly 0 and 100, but are safe values to prevent damaging the battery. The truck always holds a small amount of energy back at both ends to limit battery aging. This is a good thing, and you should never run it to truly dead where it actually forcibly powers itself off, as that will accelerate battery wear.

 

[RonTCat]

So it's always encouraged when you buy a phone or anything w/ lithium ion battery to drain it down to zero, charge to 100, rinse and repeat a couple times for improved battery life or something...not sure what it really helps, but if true, should we do the same conditioning with new ev batteries? Not an electrical engineer here so pardon my lack of electrical knowledge.

Do this if you want DECREASED battery life.

 

[Amps]

Do this if you want DECREASED battery life.

BOLO for those very low VIN number launch tester/demo trucks. I'm glad somebody is doing it to some trucks just as much as I'm glad it's not my truck they're doing it to.

 

[hturnerfamily]

right, when the 'miles' show 0, you're likely not yet fully depleted, or at the 'real' 0. EV manufacturers build in a 'buffer', an amount of battery power, that will be your 'emergency' power, just in case, such as to be able to continue to keep the truck 'on', and even a few more 'miles' to get to some charging option, or to at least get off the highway, etc.
You'll see in most any videos where they 'try' to run it down to 'turning itself off', the truck is still moving WELL AFTER the 'miles' have fallen to 0.

Also, while we consider the SR to be a 98kwh size, it's actually larger than that. Ford doesn't show anything but 98kwh since that's the 'usable' battery power, while holding the rest as the 'buffer'.

 

[Maquis]

1. Discharging a lithium battery to zero degrades, not improves it.
2. Ford has a reserve at the low end, so it won’t even be possible to discharge totally to zero.

 

[RickLightning]

So it's always encouraged when you buy a phone or anything w/ lithium ion battery to drain it down to zero, charge to 100, rinse and repeat a couple times for improved battery life or something...not sure what it really helps, but if true, should we do the same conditioning with new ev batteries? Not an electrical engineer here so pardon my lack of electrical knowledge.

Ignore myths, rumors, and the internet in general. Follow your manual. Charge to 90% at home. Charge to 100% for a trip. DC fast charge on trips.

 

[metroshot]

I charge to 100% every day.

What I think is "100%" is actually less due to SOC buffer that limits maximum charge.
In reality the cells receive about 85% maximum charge due to the limit placed by the onboard charger's SOC programming for safety and longevity.

Same as the depletion - EVs will not allow 0% - there is always a charge left.

SOC buffers exist on all EVs.

Don't buy into the GM EV battery fires where they warned owners not to charge over 80% or under 20% depletion. That was a problem for certain poorly manufactured EV battery packs.

 

[greenne]

I charge to 100% every day.

What I think is "100%" is actually less due to SOC buffer that limits maximum charge.
In reality the cells receive about 85% maximum charge due to the limit placed by the onboard charger's SOC programming for safety and longevity.

Same as the depletion - EVs will not allow 0% - there is always a charge left.

SOC buffers exist on all EVs.

Don't buy into the GM EV battery fires where they warned owners not to charge over 80% or under 20% depletion. That was a problem for certain poorly manufactured EV battery packs.

FWIW...Kyle from out of spec ran the battery down to 0% on the display(and beyond), however the truck completely shut down at 2KwH left in the battery(buffer).

 

[sotek2345]

FWIW...Kyle from out of spec ran the battery down to 0% on the display(and beyond), however the truck completely shut down at 2KwH left in the battery(buffer).

Yup - from that video it looks like the ER battery has a ~5% buffer on the top end and a ~3% buffer on the bottom end (that you can dig into a little bit beyond 0% indicated).

 

[jefro]

You are mixing up NiCad with modern Lithium batteries. Even the LiFePo4 batteries should not be depleted to zero. They can be but for longer lasting you should charge to a range between maybe 30% and 70% if you can on a normal day use.

I had a BMW i3 that depleted the battery every day I used it. At 70K miles the battery was very degraded. That and fast charging takes a toll.

 

[PV2EV]

Let me answer a few of these questions.
0% SOV means minimum Voltage (Vmin) and 100% SOC means maximum Voltage (Vmax).
0 miles on an EV is NOT Vmin. If you drive past that to the point it shuts down, you are still not at Vmin.

Discharging to zero implies going to 0 V. The more you go past Vmin, the more damage you are doing. We had a pack/module/cell under test last year, and once it hit a certain Voltage (halfway from Vmin and 0 V) it would actually catch fire. We had a module and a pack catch fire.

The more you go over Vmax, the more damage you do to the cell. Most cells I have tested over the last 12 years will catch fire at 120%-150% SOC. The SAE J2462 test standard says to overcharge to 200%, and only a couple of cells have actually passed, mainly from the Current Interrupter Device (CID) or PTC (deals with temperature) activating.

As far as cycling from Vmax to Vmin on a new battery, it doesn't hurt the device at normal charging currents. It is a myth that it helps. However, this is something I have to do when we have a new lot of cells before I bin them for certain tests. I will actually see an increase in the discharge capacity when I first start cycling. I cycle them until the capacity increase is below 20 mAh or 7 cycles. We then bin based on DC resistance, discharge capacity, charge time constant, and discharge time constant. We want the tightest grouping of cells for our cycle/calendar life matrix, followed by characterization cells, followed by the safety (all the things the manufacturers tell you not to do)

Our calendar life graphs show a dramatic difference in cell degradation based on storage temperature and storage SOC. These DO matter.

Cycle life graphs show a dramatic difference in cell degradation based on current levels, delta SOC, and temperature. Max charge/discharge currents at the best temperature are the second-worst case. The worst case is high temperature, max delta SOC, and max charge current.

TL;DR I have posted before about how to make your battery last almost forever, none of which I plan on doing

In summer, what would you recommend for a safe SOC?

Any tips for winter (stored outside) beyond conditioning prior to use?

 

[vbaker4444]

This was a practice that the techs from Tesla used to have me do to recalibrate the battery on my old Model S. It never made a difference on my range estimates though. I’d say skip it and just keep it under 80%

 

[FlasherZ]

This was a practice that the techs from Tesla used to have me do to recalibrate the battery on my old Model S. It never made a difference on my range estimates though. I’d say skip it and just keep it under 80%

Came here to say this too... some people have found that the range calculations are more accurate when you occasionally take it down to low levels and allow it to charge back up because it helps the BMS understand the range of the battery. It typically doesn't make much of a difference. From a battery life standpoint, it's harmful.

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