Tesla Model 3 & Implications for Wheels

[Jason McNeil]

Did anyone stay up to watch the Model 3 release last night? While a bit short on actual specifics, Musk made the statement of "...will also be producing the most advanced cell & battery in the world". There's rumours claiming over a 30% improvement in the energy density of the Model S, which is 3Ah/cell. If true, this means we're going to start seeing 4Ah (14.4Wh) batteries in the next couple months!

"...One of the most scintillating bits of talk comes from Sanford C. Bernstein’s Mark Newman, described a significant advance in battery technology that would make the Model 3’s batteries far more energetic and cheaper According to Newman, the Model 3 battery will achieve energy density of 300 watt hours per kilogram, and cost $200 per kilowatt-hour. If so, both of those are industry-leading."
"Model 3 batteries, made by Panasonic, start with a negative electrode—an anode—made up of 10% silicon. This achievement will cause eyes to glaze over outside the field, but experts say it is a serious breakthrough."

http://qz.com/651391/teslas-model-3-debut-how-to-watch-it-what-we-know-about-it-and-why-scientists-are-excited-by-it/ 

[Jag_Rip]

I didnt watch it, but just read your linked article and I am intrigued to know more. Especially since Musk has the tendency to share his archievements. Meaning other manufacturers might get to build on the tech as well, advancing it faster.

[Keith]

Significant improvements in battery capacity and cost plus, way more importantly, a real and pressing need for those improvements, are certainly excellent news for  personal electric vehicles ( as well as my other passion of radio controlled aircraft). I just wish I could believe that electric cars really did make sense!

The one question that nobody seems to ask, or answer, where electric cars are concerned, is how long, in the real world, the batteries are going to last and how much replacing them is going to cost.

Over the 15 years or so I've been flying electric model aircraft I have found, regardless of the number of cycles, a LiPo battery will rapidly degrade to the point of uselessness in either the 2nd or, if lucky, 3rd winter. I've had batteries with as few as 20 cycles (I record every charge on each battery). Fail at least one cell in 3 years or less.

Cars get parked outside or in unheated garages, their batteries will be subject to greater cooling and greater winter use, than my model aircraft batteries. 

Unless the focus is way more on longevity, particularly very low cycle depreciation and excellent cold weather performance, then I personally believe current electric car batteries in countries with freezing winter temperatures will last 3 years at most and, I suspect, cost so much to replace that scrapping the car is the most likely outcome. How on earth is that a green solution.

Is it not hilarious that one person commuting in a ton of car burning 3 figure kilowatts of electricity and which will be a big lump of scrap in a very few years is seen as a desirable green outcome, yet one person on a truly electrically efficient electric Unicycle burning a few hundred watts is seen as breaking the law in most countries that have signed emission reduction treaties.

[jer]

I don't see why electric cars won't go for several hundreds of thousands of miles, albeit with battery replacements  every now and then. My leaf is getting quite ancient and is still going strong on the original battery 36,000 miles since 2011, I would hope it would get to 100,000 on the original battery.  I would hope that the battery would then be replaced and it would just keep going.   Aside from fuel and tax savings, servicing costs are tiny compared to  fossil fuel cars.  The one disadvantage is you have to drive like a snail and you need to wrap up in winter, however this means the tyres last forever.  Electric cars make sense to me, fossil fuel cars don't

As for the model 3 I could see disk brakes in the wheels rather than motors, oh well they will learn from EU technology where to put them.

 

Jer

 

[dmethvin]

I have a 2001 Toyota Prius on its original battery. Both the first and second gen Prius use NiMH chemistry so it's tricky to compare, but the main problem the Prius batteries have had is corrosion at the terminals due to electrolyte leakage. Eventually the corrosion can become enough to bridge to the metal protective cover and short a cell to ground. But the batteries are in general very long lived and stable without being babied, unlike Lithium-based batteries.

The Teslas are being designed so that the battery packs can be dropped and replaced, the primary reason being so that you could swap packs rather than stopping for a long time to recharge. However, making the packs easy to replace would also help the short-lifetime issue as well. People could just "rent" the packs as a service from Tesla and not actually own a particular pack. 

[electric_vehicle_lover]

My electric Smart car have now 3 years old and 50000 kms and battery seems to be new.

I didn't heard any review of electric car owners about battery dead over the time and yet I think Nissan Leaf may have now about 6 years in the market.

Tesla model 3 is a super car for the price of usual car - and also a "green" car.

[MarkoMarjamaa]

One writer, not owner of electric car, writes about rc airplane batteries and says eletric cars batteries will not last but still, does not own electric car = 3 likes

Three writers, owners of electric cars, IRL, write that battery longevity has not been an issue = get 2 likes combined.

 

[Dr Bob]

[Gimlet]

I'm pretty sure that car batteries tend to have a lot more controls built into them to ensure their longevity. Tesla wouldn't guarantee their batteries for 8 years if they thought they would have to swap them out in that time.

The recommendations that come with the Tesla are to only charge to 100% on odd occasions that you think you're really going to need the extra range and then to only do so immediately before setting off so that the batteries are at maximum charge for the smallest time possible. I believe even the  they arent actually taken to 100% capacity. They are also heated or cooled to keep them at their optimum temperature whilst working or charging.

I daresay that with radio controlled model batteries they are taken to maximum charge on just about every cycle which will add hugely to their degradation.

If it hadn't been for the eight year warranty and my research on how the batteries on my Tesla are looked after I certainly wouldn't have bought one.

[dmethvin]

4 hours ago, Gimlet said:

The recommendations that come with the Tesla are to only charge to 100% on odd occasions that you think you're really going to need the extra range and then to only do so immediately before setting off so that the batteries are at maximum charge for the smallest time possible.

That is true for the Prius as well, it tries to maintain an 80% charge on the battery. Of course it has the advantage of a gas engine that charges the battery so they are treating the battery mostly like an energy buffer to maximize the efficiency of the gas engine.

I use a similar strategy for my EUC, I only do a full charge shortly before I go for a ride so that the batteries are only at full charge for an hour at most. 

[AlanR]

On 04/04/2016 at 8:28 PM, dmethvin said:

That is true for the Prius as well, it tries to maintain an 80% charge on the battery. Of course it has the advantage of a gas engine that charges the battery so they are treating the battery mostly like an energy buffer to maximize the efficiency of the gas engine.

I use a similar strategy for my EUC, I only do a full charge shortly before I go for a ride so that the batteries are only at full charge for an hour at most. 

So, how would an EUC user limit charging to say 80 / 90% - I try to keep a check on the charging toward a guessed 'full' level by setting  a timer for 10 min intervals - so that over-charging is limited to 10 mins at worst. What do others do to reduce over-charging?  Are there clever battery level indicators available?

[esaj]

Just now, AlanR said:

So, how would an EUC user limit charging to say 80 / 90% - I try to keep a check on the charging toward a guessed 'full' level by setting  a timer for 10 min intervals - so that over-charging is limited to 10 mins at worst. What do others do to reduce over-charging?  Are there clever battery level indicators available?

Jason sells a charger that has a switch to select between full charge (67.2V) and around 65V (if memory serves).

[sbouju]

33 minutes ago, AlanR said:

So, how would an EUC user limit charging to say 80 / 90% - I try to keep a check on the charging toward a guessed 'full' level by setting  a timer for 10 min intervals - so that over-charging is limited to 10 mins at worst. What do others do to reduce over-charging?  Are there clever battery level indicators available?

For me (and some other users), the new version of Charge Doctor is perfect for that!

[Mono]

On 6/9/2016 at 1:36 PM, AlanR said:

So, how would an EUC user limit charging to say 80 / 90% - I try to keep a check on the charging toward a guessed 'full' level by setting  a timer for 10 min intervals - so that over-charging is limited to 10 mins at worst. What do others do to reduce over-charging?  Are there clever battery level indicators available?

 

On 6/9/2016 at 2:14 PM, sbouju said:

For me (and some other users), the new version of Charge Doctor is perfect for that!

I can confirm this. I let the Doctor stop charging at 1.7A current which leads to 65V final voltage, which increase the number of possible (full) cycles by a factor of almost three.

http://www.batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries 

 

[AlanR]

Thank you @esaj, @sbouju and @Niko much appreciated for the leads. BTW, @Niko the webpage 'batteryuniversity.....' wouldn't open!?

I am impressed with the  "increase the number of possible (full) cycles by a factor of almost three".       Certainly well worth adopting.

Which Charge doctor do I need – the Charge Doctor for Ninebot   or  the Charge Doctor V2 – 10 amps?  Seems 10 amps is way over capacity if the limit required is 1.7amps?

What does the 'Dongle for PC link' do?

 

[esaj]

1 hour ago, AlanR said:

Thank you @esaj, @sbouju and @Niko much appreciated for the leads. BTW, @Niko the webpage 'batteryuniversity.....' wouldn't open!?

There's an "s" missing from the end of the link, try this:  http://www.batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

 

1 hour ago, AlanR said:

I am impressed with the  "increase the number of possible (full) cycles by a factor of almost three".       Certainly well worth adopting.

Charge level(V/cell)	Discharge cycles	Capacity at full charge	Table 4: Discharge cycles and capacity as a function of charge voltage limit. Every 0.10V drop below 4.20V/cell doubles the cycle but holds less capacity. Raising the voltage above 4.20V/cell would shorten the life. Guideline: Every 70mV drop in charge voltage lowers the usable capacity by 10%.
[4.30] 4.20 4.10 4.00 3.92	[150 – 250] 300 – 500 600 – 1,000 1,200 – 2,000 2,400 – 4,000	~[114%] 100% ~86% ~72% ~58%

 

1 hour ago, AlanR said:

Which Charge doctor do I need – the Charge Doctor for Ninebot   or  the Charge Doctor V2 – 10 amps?  Seems 10 amps is way over capacity if the limit required is 1.7amps?

If you use Ninebot, get the Ninebot-version, as Ninebot uses other connector ("LEMO-plug") than other wheels (GX16-3). "Extra" current handling capacity won't hurt. The current comes from your charger, it's not like the Charge Doctor "amplifies" it or anything.

 

1 hour ago, AlanR said:

What does the 'Dongle for PC link' do?

You can log the charging with it and then draw pretty graphs from it later on

 

[Mono]

3 hours ago, AlanR said:

Which Charge doctor do I need – the Charge Doctor for Ninebot   or  the Charge Doctor V2 – 10 amps?  Seems 10 amps is way over capacity if the limit required is 1.7amps?

You need in any case the version 2, which is the 10 amp version. Version 1 does not have the configurable switch off. 10 amp is only the maximum current it can tolerate, that is, your charger must have <=10A, otherwise you will burn the charge doctor. Whether you need the Ninebot version, I guess, depends on whether you want to use it with a Ninebot.  

[AlanR]

@esaj and @Niko   thanks for the clarification and comprehensive information - I have ordered the Ninebot 10 amp!  Quite reasonably priced!

I usually play around the river doing at most 14 km, so I could set at 4 V/cell  !?

 

[Mono]

20 hours ago, AlanR said:

@esaj and @Niko   thanks for the clarification and comprehensive information - I have ordered the Ninebot 10 amp!  Quite reasonably priced!

I usually play around the river doing at most 14 km, so I could set at 4 V/cell  !?

AFAIK you can only set the current, not the voltage. From the above graph we can see that this means you can only manage when to stop charging close to the end, because the current does not change in the beginning. It would be the other way around for the voltage, which remains constant in the end. (It seems to make more sense to use current, because the last percents are the critical for battery life). If you want to stop as early as possible set the current close to the max current. I don't know if it will sometimes stop very early by chance, if you chose, say 1.9A for a 2.0A charger.

FTR: the other relevant how-to-charge aspect: charge rather before you leave home instead of after you get home (unless the charge state is <40%), or rather after you wake up than before you go to sleep. It is preferable to have high charge levels only for short periods of time. This again can increase life time by a factor of three or so.

[esaj]

The instructions for Charge Doctor V2 are here: http://hobby16.neowp.fr/2016/02/06/charge-doctor-v2-10a-3/  The "early" termination of charging is indeed current-based. Got mine yesterday, but haven't yet tried it (as I'm still working on the Firewheel shell to get the batteries in).