[john61ct]

The definition of "Full" is arbitrary.

Mine for LFP longevity purposes is:

3.45Vpc at well <.5C, until charge acceptance drops to .01C

That is likely quite a few percentage points below the AH capacity your BMSs achieve.

But when new, right around their rated 20-hour capacity.

 

[Sunking]

THX but I am not talking about LFP batteries or DIY vehicles.

 

[john61ct]

Yes, just giving an example to illustrate the principle.

Being gentle is opposed to max capacity. Allowing higher pc voltage and/or a lower amp cutoff, gives a higher definition of Full.

To the extent different mfg have different chemistries, their BMS settings aren't really comparable.

I guess it would be interesting to gather the specs together in one place for reference though. . .

 

[rmay635703]

THX but I am not talking about LFP batteries or DIY vehicles.

Volt uses 10.5 kw if a 16kwhr battery

So yeah they do that

 

[Duncan]

I believe that the Tesla has a "normal" Full charge and a "Road Trip" full charge

 

[iainventor]

I recall reading sometime ago commercial EV manufactures limit the SOC they allow customers to reach. I know they limit the discharge side so a customer cannot over discharge, but my question pertains to the Charge side. I recall they do not allow customers to fully charge the batteries.

Seems to make sense as that would be required in order to offer such long warranties. Anyone know about any particular model like Leaf, Tesla, or Volt?

this what I have learned from my Ford Focus E-hatch. with commercial ev around 80% Lithium Ion charge limit is it. The reason I have found out is thermal runaway issues can start a little above that.

 

[pdove]

First thing you must discover is that all these charging rules are not rules. They are typically based on experimentation and observation by researchers. Li ion batteries can be charged many different ways. experimenters were trying to find out how to get maximum capacity with the least amount of damage since damage is caused every time you charge no matter how you do it.

Capacity is also based on how you charge them. Different charge methods result in different capacities. this can all be found in scientific papers online.

The manufacturer usually gives a recommended charge cycle in order to achieve the number of charge cycles they claim the batteries will last.

Second thing is all Li ion batteries are not equal. They have different voltages, currents and capacities.

So, assuming one knows what chemistry a manufacturer is using, and assuming you know how their charger works, and assuming you know the charge cycle the battery manufacturer recommends then one could assertion the answer to your question.

I suspect it's different depending on the car manufacturer.

More than likely one will never know all of these facts to ascertain what they are doing...... though with these phone apps one might be able to see the charge cycle and recreate it from the data. As to knowing the exact chemistry used in their cells.... doubtful.

My advice is follow the battery manufacturers guidelines on charging and ignore everyone else.

 

[AntronX]

Nissan Leaf limits max charge to 90% true SOC or 4.13V per cell. But their 80% setting is actually 80% SOC. In 2013+ models they updated their BMS to report 90% SOC as 100%. They discharge down to 2.5% SOC, or 3V per cell. Low battery warning come on at 20% with 8-10 miles remaining and very low batt warning or 0 miles remaining comes on at <15% SOC.

 

[Duncan]

Hi Antrox
Sounds like you know about Leafs
I am curious - when you get a Leaf and it loses battery bars what is happening?

Is it some cells or modules that have lost capacity and the whole pack is then de-rated or is it all or most of the cells?

 

[AntronX]

..I am curious - when you get a Leaf and it loses battery bars what is happening?...

My leaf is at 85% with all 12 bars remaining but is about to drop one any day now. All cell voltages are within 10-30 mV. There is one cell that starts to drop before others below 10% SOC. I rarely discharge that deep. Most of my trips end at 15-20%. It appears that bar loss is due to overall battery degradation, with battery temperature (above 90F) being main driver of capacity loss.