Dr. Billy Wu: How Charging Routines affect Degradation | Battery Podcast

Before purchasing a second-hand #battery-#electric #vehicle, every buyer and seller asks themselves how the battery state of health (#SoH) can be determined as precisely as possible.

First services, such as the "Aviloo Device", are already being offered in order to externally check the condition of the battery. But wouldn't it be much more interesting if there was a kind of "digital twin" of this exact battery that automatically saves all the information needed? A kind of "universal protocol" that provides the SoH - regardless of the #manufacturer?

Here is the kicker: Such a "Battery #Twin #Model" could not only store all the important information, but also provides useful tips on how to handle this individual battery in real-time and/or in the future. (1) How to charge, (2) How to use the battery better and even (3) Predict its own service life under certain conditions. Brilliant, if such a thing existed!

Meanwhile, there are countless tips on the internet about the Do's and Don't of battery charging. But even research has not yet been able to provide a universal model that applies to every #cell #chemistry, every cell #format, every #charging #profile, #cooling system and #type of use.

Our guest for today is Dr. Billy Wu. He is a Reader (Associate #Professor) and Director of Research in the #Dyson School of Design Engineering at #Imperial College London. He works in the area of #electrochemical design #engineering.

Music:
“Fuzz Buzz” licensed via Music Vine: ZNUNZWRN01IAVWZL

[bellshooter]

Great discussion here, as always the devil is in the detail. But intelligent design of cooled cables can help reduce cable size and heft, Tesla has a patent on cooling individual cores that makes their cables lighter.
I disagree a little with Dr Wu about his reply to the question on charging degraded batteries, the vehicle BMS/Thermal Management will know the status and tell the charger what to do. Smart charging is more often done with lower power home charging where a charge to time/state can be specified, better not to conflate the two purposes.

[EfficientRVer]

Great guest. He didn't stumble, need to BS, or get anything wrong but more importantly, always saw the bigger picture and perspective, and was able to come up with a way to convey it to laymen. So, a great engineering mind, plus a great ability to understand how to explain things to people who are not.

[Turbo]

This is interesting for sure, there are many that hate EV and there are those that love EV and I find that those that hate EV does not understand how a battery works. Understanding is the key in which the tech is getting better by the day so don’t give up and keep an open mind.

[aussietaipan]

Use a glass to catch water, the faster the flow and the more volume of flow will make the glass spill over. You can fill it fast but then slow down the rate as the water reaches the top. Batteries work exactly the same way. My 9 year old model S battery is still in excellent condition as it has never been super charged. The max charge rate it has ever used was a public 48kW, otherwise it has only been home charged at 7kW or 3kW and only to 70% for daily use, 50% if parked for longer periods and 90% for longer road trips over 300km.

[batterygeneration]

Thank you so much, Dr. Billy Wu! It was a pleasure talking to you!

[jounisaari]

I have over 10 years old laptop with over 95% SOH battery. I have limited charging to 60%, and starting of charging to 50% unless I need hours of working time.

When battery was new, it was bit under 30Wh, and now it's over 27 Wh. I perform couple of times a year a balancing and capacity measurement cycle. Most of time the battery is idling between 50 and 60%. That 10% is enough to move with power on in energy saving mode or work for a while without plugging in. It sometimes goes to under 40%, but charges then only to 60%. The battery experiences full cycle or nearly empty only couple of times a year. Otherwise it's between 40 and 60% soc.

[gregbailey]

It's so obvious to me that the vehicle needs to develop it's own version of the 'digital twin' of the battery, which could also easily be stored in the battery.
This sort of technology has been available for years already, if not decades!
All that has to be done is to legislate that the battery's history be stored in a defined form INSIDE each battery.

[ericverlaet]

Yes I agree with you, the battery of my car, 9 years old, 420.0000 km and 1900 cycles, have a capacity degradation of 12 %, 20 % increase of internal resistance.
But with my New victory smart solar charging at home the charging power varying from 1200 to 3500w
So I gain 1 % capacity and lower impedance.
120 KW at 5 % soc 7 years ago, now 83 KW at same soc....the BMS do his
45% SUC 55 % slow at home.
Thanks tesla.
Have a nice day🌞

[flashsushi]

Excellent take aways.

State of health (driving range/original range) is not a good predicttor of remaining life.

Keeping SOC low helps with battery longevity.

Fast charging is never a good thing, though convenient.

There's more sensors required aside from voltage, current and temperature to fully assess the state of the battery cells.

One of the few discussions where almost everything stated is factual.

[a.rostamifard]

Great interview, informative and useful. Thanks a lot.

[typxxilps]

Might be time to define a rule of the sweet spot cause if 250 kW is a kind of hard limit (which requires active cable cooling) and usually 350 kW is only possible for short times and big batteries then it makes not much sense to go above 250 kW.
But then a bit bigger batteries becomes more important and less high fast charging over a longer time for example 250 kW from 1% to 70% or so for a lower price.
Right now the progress is decreasing cause the most recent gaines were cell to pack / battery and then the battery as integral part of the car structure which lowers weight and gains range by saving 80 kg or so and gaining volume which then could be used by a few kWh more.

[cetocoquinto]

You know this topic is great! Im from the solar installation industry nice insights keep it up! Cheers from philippines.

[andywurst]

Around 24:30 Dr Wu suggested a choice between accuracy and simplicity. I think that is a false choice. Logs over the life of the battery charging and discharging environment can certainly be maintained. Effort of creating such a system and at what cost is likely the real problem. OEMs don't care once they sell a product. Also, they may be creating a system that could be used against them when it comes to warranty issues.

a graph of SoC would be useful to the 2nd hand market. I personally would avoid an EV with high annual mileages. The chances of poor charging habits might increase. Wouldn't a graph showing 20-80% charging and little degradation be more valuable that someone that drives little but charges to 100% frequently?

Finally, the unspoken truth -- data is being harvested from every car without the owner's knowledge. So why couldn't more information be available as to a batteries care over it's lifetime?

[jimgraham]

Operating, charging/refuelling an EV is a different paradigm to ICE vehicles. In my experience fast charging is to a large degree irrelevant as it is something I have rarely found a need to do.

[jeffg]

Interesting facts that give a better understanding of how to look after your battery,
I've always thought that the reason the charging slows down as the battery gets more charge was because the Potential difference between the power source and the battery was getting closer so it becomes harder to push charge when the Voltage equals out.

[blueangel]

Is 100% battery always full on battery? I have scooter it says 100% full but when I test it on multimeter it says 82, 5 something, if 82, 5÷20 (it's 20 series system) it gets 4, 1 volts the lithium can be full at 4, 2 volts?? 2nd another my scooter it's says 97v (23 series system) after got charged at 97v full, it's drop to 96, 5 it's 4, 19 each it is save for long run? It's already 4 years now and I feel like nothing changed on range it's like brand new

[snodgee]

I know it’s a bit different but I had a iPhone that one day stated 98% battery health to not charging with in a few days

[cybergigafactory]

Great episode, thanks!

I would love to know how the different cell chemistries should be charged for best cycle life.

NMC/NCA should be between 20-80% to prolong the battery life.

LFP should be charged to 100% once a week or so.

But does it help also to hold it between a specific percentage to prolonged its life or does it not matter as much?

[Tore_Lund]

Big unwieldy cables are not the problem. It is just unfeasible with the way people charge now. We could easily have another high power charging standard, with say a Pantograph that comes out of the ground under the car, that would require no user interaction at all.

[ToyotaKTM]

With a laptop, would it be better to always have it plugged in, when in use and charged 100% but have no charge cycles or to let it run off the battery and have a charge cycle everyday?