Electric car battery life question
- Thread starter joesxm3
- Start date
Old Microbiologist
Recycles dryer sheets
I don't have a Tesla but I do have a Mercedes EQS with a 108kWh battery. I have studied this quite a bit and there are a lot of issues that seem not well understood. Basically, it somewhat depends on what chemistry was used in the battery. LiFePO4 batteries last the longest and are the most resistant to catching fire when they produce hydrogen gas. The LiMn are higher capacity. I am unsure what is in Tesla as they keep changing it.
However, in general, there are some rules to keep in mind. All Li-Ion batteries use a battery balancing system that keeps all cells more or less the same. I used to have a Honda 2002 Civic Hybrid and a 2008 Toyota Prius and both of these used NiMh batteries and both have serious problems with balancing batteries to the extent I learned how to pull the packs and manually rebalance the strings and toss bad cells. Both Toytota and Honda built in that at 0 charge they were really 20% and at 100% charge they were really 80%. So, this is a good place to start. Never charge to 100% unless you plan to use the full capacity the next day. Every time you charge it high it shortens its life. DC rapid charging should also be limited. Again, it is too much all at once and shortens life. It is best to charge to 80% and then use it down to 20% before recharging. Use a home charger at the lowest rate you can tolerate. I have a three-phase 400V system but unless I am in a hurry I run it at 12 Amps. My maximum charge rate on my home charger is 11.7 kW/h but I generally use it at 9 kW/h which won't overheat the battery. The rapid charger for my car can put in 200 kW/h maximum but I have never seen it go above 175 kW/h and it drops as it reaches the maximum state of charge and at 80% drops down to 20 kW/h or so. This is deliberate and helps prolong the life of the battery. Ramping it up to 100% at a fast charging station (or SuperCharger) is a bad idea unless you absolutely have to do it. I believe they still have a buffer in the BMS but it isn't 20/80 as we had in the past. It looks more like 2.5% and 97.5%. My 108 kWh is in usage more or less 100 kWh. The gauges pretty much lie about it and are an estimate. The other thing is that at zero state of charge there is still 2% or so left. Every car handles that differently. If I am on the road the EQS will force a diversion to a charger with sufficient charge to actually get there. It also will warn about the availability of chargers on a given route and will automatically add a charging stop at the best rate available. Here in Europe and in particular Eastern Europe chargers are few and far between. It is improving and I haven't had any issues other than rapid chargers being damaged or non-functional. When I run into that I can shift to the less capable 50 kWh charger that seems to be everywhere now and worst case a 2 kW/h regular 1 phase charger like you will find in parking lots of hotels using a Schucko plug adapter.
I can also say categorically consumption goes way up in the cold which affects range. Pre-heating the battery will make it more gentle to charge and a faster charge rate.
However, in general, there are some rules to keep in mind. All Li-Ion batteries use a battery balancing system that keeps all cells more or less the same. I used to have a Honda 2002 Civic Hybrid and a 2008 Toyota Prius and both of these used NiMh batteries and both have serious problems with balancing batteries to the extent I learned how to pull the packs and manually rebalance the strings and toss bad cells. Both Toytota and Honda built in that at 0 charge they were really 20% and at 100% charge they were really 80%. So, this is a good place to start. Never charge to 100% unless you plan to use the full capacity the next day. Every time you charge it high it shortens its life. DC rapid charging should also be limited. Again, it is too much all at once and shortens life. It is best to charge to 80% and then use it down to 20% before recharging. Use a home charger at the lowest rate you can tolerate. I have a three-phase 400V system but unless I am in a hurry I run it at 12 Amps. My maximum charge rate on my home charger is 11.7 kW/h but I generally use it at 9 kW/h which won't overheat the battery. The rapid charger for my car can put in 200 kW/h maximum but I have never seen it go above 175 kW/h and it drops as it reaches the maximum state of charge and at 80% drops down to 20 kW/h or so. This is deliberate and helps prolong the life of the battery. Ramping it up to 100% at a fast charging station (or SuperCharger) is a bad idea unless you absolutely have to do it. I believe they still have a buffer in the BMS but it isn't 20/80 as we had in the past. It looks more like 2.5% and 97.5%. My 108 kWh is in usage more or less 100 kWh. The gauges pretty much lie about it and are an estimate. The other thing is that at zero state of charge there is still 2% or so left. Every car handles that differently. If I am on the road the EQS will force a diversion to a charger with sufficient charge to actually get there. It also will warn about the availability of chargers on a given route and will automatically add a charging stop at the best rate available. Here in Europe and in particular Eastern Europe chargers are few and far between. It is improving and I haven't had any issues other than rapid chargers being damaged or non-functional. When I run into that I can shift to the less capable 50 kWh charger that seems to be everywhere now and worst case a 2 kW/h regular 1 phase charger like you will find in parking lots of hotels using a Schucko plug adapter.
I can also say categorically consumption goes way up in the cold which affects range. Pre-heating the battery will make it more gentle to charge and a faster charge rate.
The current max capacity (health) of the battery is easily seen on my cars so I assume it is the same on every EV, just like I can see the health of the battery on my iPhone. I would think the resale or trade-in value of the car will be lower if you have a poorer than expected battery. (The driving range per charge will be much lower)
Christine
Full time employment: Posting here.
- Joined
- Dec 31, 2014
- Messages
- 670
I have my Tesla limited to 70% and always plug it in. I trust the car to handle charging and discharging. This is also what Tesla recommends. I use the app to increase this when planning a longer trip.
If my EV had a battery made with pouch cells I would be more careful and not charging it all up. My Tesla has cylindrical cells resembling AA batteries. But many other EVs use pouch cells. Which unfortunately expand and shrink with high charge. Potentially creating a fire risk.
More background:
https://insideevs.com/news/532693/tesla-pouch-battery-cells-risk/
If my EV had a battery made with pouch cells I would be more careful and not charging it all up. My Tesla has cylindrical cells resembling AA batteries. But many other EVs use pouch cells. Which unfortunately expand and shrink with high charge. Potentially creating a fire risk.
More background:
https://insideevs.com/news/532693/tesla-pouch-battery-cells-risk/
Old Microbiologist
Recycles dryer sheets
Battery Health
The data from the car (or OBDII app) is a good indication. It can be finagled though by resetting the car computer. But the voltage per cell is the best but usually only available using an OBDII monitor and associated software. Some battery degradation is expected and roughly 10% at 5 years is normal. In general 1-2% per year loss is normal. The voltage per cell is a good measurement and what is used for warranty replacement. The same for capacity and voltage at full charge.
A more useful test is to fill it up drive it under "normal" conditions and see what your range is. I am particularly anal about this being a retired scientist and record and evaluating everything I can measure. I am particularly interested in kWh/100km data which so far is the most sensitive measurement but is wildly affected by road conditions, vehicle speed, temperature, etc. I determine the kWh/100km after each charge and can see if something is out of whack. I am averaging 21.5 kWh/100km but in winter this has gone to 32.2 kWh/100km at each charge as we are only driving in the city at slow speeds. However, the distances are also low so won't dramatically affect the overall average. The EQS sucks at slow speeds being 2.5 tons in weight. However, at 120 kph it does well (even better at 90 kph). I can easily get ±15 kWh/100km at a constant 90 kph at 20 degrees C. If I drift up the 140 kph (10 above the speed limit of 130 kph which is within the 10% rule) it gets worse at around 25 kWh/100km. So, driving can affect measurements. The EQS is very sparse on what you can read regarding the battery but an OBDII dongle yields a lot more information.
The data from the car (or OBDII app) is a good indication. It can be finagled though by resetting the car computer. But the voltage per cell is the best but usually only available using an OBDII monitor and associated software. Some battery degradation is expected and roughly 10% at 5 years is normal. In general 1-2% per year loss is normal. The voltage per cell is a good measurement and what is used for warranty replacement. The same for capacity and voltage at full charge.
A more useful test is to fill it up drive it under "normal" conditions and see what your range is. I am particularly anal about this being a retired scientist and record and evaluating everything I can measure. I am particularly interested in kWh/100km data which so far is the most sensitive measurement but is wildly affected by road conditions, vehicle speed, temperature, etc. I determine the kWh/100km after each charge and can see if something is out of whack. I am averaging 21.5 kWh/100km but in winter this has gone to 32.2 kWh/100km at each charge as we are only driving in the city at slow speeds. However, the distances are also low so won't dramatically affect the overall average. The EQS sucks at slow speeds being 2.5 tons in weight. However, at 120 kph it does well (even better at 90 kph). I can easily get ±15 kWh/100km at a constant 90 kph at 20 degrees C. If I drift up the 140 kph (10 above the speed limit of 130 kph which is within the 10% rule) it gets worse at around 25 kWh/100km. So, driving can affect measurements. The EQS is very sparse on what you can read regarding the battery but an OBDII dongle yields a lot more information.
dixonge
Thinks s/he gets paid by the post
According to this article, a Tesla battery will degrade approx. 10% after 200,000 miles.
https://electrek.co/2021/08/12/tesla-claims-battery-packs-lose-only-capacity-200000-miles/
https://electrek.co/2021/08/12/tesla-claims-battery-packs-lose-only-capacity-200000-miles/
audreyh1
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
It takes a lot longer to charge to 100%. I only do so if I need max range for some reason. I rarely do.
Last edited:
When you say kWh per x miles, is that the same kWh you pay the power company for or is there some lost in the charging process so kWh paid for is more than kWh in the battery pack?
With the Tesla mobile connector on a 50 amp circuit, can you control the charge rate or does it just use the max 40 amps provided by the circuit?
Tesla recommends 6 gauge wire for the circuit. Any benefit to using 4 gauge wire? Big cost icrease?
With the Tesla mobile connector on a 50 amp circuit, can you control the charge rate or does it just use the max 40 amps provided by the circuit?
Tesla recommends 6 gauge wire for the circuit. Any benefit to using 4 gauge wire? Big cost icrease?
DayDreaming
Full time employment: Posting here.
- Joined
- Jan 19, 2008
- Messages
- 850
New Jersey Manufacturers for auto insurance. I occasionally shop around, but NJM is always the cheapest for me.
audreyh1
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
I believe the power draw in kWh is for what you will pay the power company directly, but yes there is some power loss in charging so it won't directly match the kWh in your battery.
We use the Tesla mobile connector on our RV 50 amp circuit, and it defaulted to draw 32A. However you can control the current draw via the app or car charging UI. We did that once when using the 115 outlet at my sister's house - lowered the current a bit. And it remembered the setting.
We haven't yet had our Tesla wall connector installed so I don't know about the wire gage.
I ordered the wall connector in a rush and it has shipped, but now I realize that for me the mobile connector is better. I will return the wall connector. However, the mobile connector has not yet shipped. I bet there is a rush on them. Maybe I will end up with a car and no charger. One family from my church has two model Y and charges at their business from solar. I hope in a pinch I can borrow one from them.
Thanks for the info.
Thanks for the info.
Koolau
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
So true. If they were, we'd all mostly buy late model used cars - and then their prices would sky rocket!
Koolau
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
ken830
Recycles dryer sheets
Wh/mile that the car reads out is what's being used from the battery. Charging losses aren't in that calculation, but you pay for it on your electric bill. It's not much, though. I don't notice a difference enough to care.
If you will charge at 40A, then you need a 50A circuit, because by code, you are only allowed to continuously draw 80% of the max peak rating. And charging a car is considered a continuous load.
BTW, I ordered my first Tesla almost 11 years ago and have bought a few more since. That first car, I just sold to my long-time friend. After 10+ years and 160k miles, It still had about 88-89% of its original capacity. He's still using it daily and started to do a lot of road trips because it has lifetime free Supercharging.
Oh, and I switched Insurance from AAA to Tesla Insurance and saved more than 50%. I couldn't believe it. Equivalent coverage levels. Tesla really makes the full cost (and experience) of ownership great!
Thanks for the info. I wish I could get Tesla on insurance but it is not offered in my state. In fact they don't even allow Tesla to be sold. Tes!a tried to open a service center in the city near me but got sued by the large dealer franchise and the zoning canceled the permit.
With the order rush for Model Y, I am considering getting a model 3 RWD from inventory so I can take delivery before March and guarantee getting the $7500 tax credit.
Aside from the loss of AWD and cargo space, which by itself may be enough to keep me from dong it, I have a worry about the rear seat in the model Y.
I have to transport my 91 year old stepfather in the rear seat and have read comments that the model 3 rear seat is very low and does not have much room.
I am trying to figure out if the rear seat in a model 3 is worse than the rear seat in my Acura TSX.
Unfortunately the closest Tesla showroom is pretty far away. I may try to ambush a model 3 owner if I see one parked and ask to see the rear seat, but I am hoping someone familiar with the model 3 can comment.
Also, opinions regarding the loss of AWD and cargo would be appreciated. I ran the numbers and factoring an extra $2500 credit and 1.4% lower sales tax for model 3 it seems to come in about $10K less since most inventory has color and 19 inch wheels. Aside from the general tight wad factor, I can handle the $10K difference.
Thanks.
Aside from the loss of AWD and cargo space, which by itself may be enough to keep me from dong it, I have a worry about the rear seat in the model Y.
I have to transport my 91 year old stepfather in the rear seat and have read comments that the model 3 rear seat is very low and does not have much room.
I am trying to figure out if the rear seat in a model 3 is worse than the rear seat in my Acura TSX.
Unfortunately the closest Tesla showroom is pretty far away. I may try to ambush a model 3 owner if I see one parked and ask to see the rear seat, but I am hoping someone familiar with the model 3 can comment.
Also, opinions regarding the loss of AWD and cargo would be appreciated. I ran the numbers and factoring an extra $2500 credit and 1.4% lower sales tax for model 3 it seems to come in about $10K less since most inventory has color and 19 inch wheels. Aside from the general tight wad factor, I can handle the $10K difference.
Thanks.
ken830
Recycles dryer sheets
There are a variety of car comparison websites. For example, cars.com shows the Model 3 had slightly more head and leg room for the second row, but slightly less hip room. Model 3 trunk volume is much larger than the TSX. Plus it has a frunk.
You should see it in person though. Many Tesla owners would be ecstatic to show you their vehicle. And there are many Tesla owners clubs around the world. The easiest is to make a post on one of the Teslamotorsclub regional forums. Here's the link to the regional forums in the Americas: https://teslamotorsclub.com/tmc/forums/americas.97/
You should see it in person though. Many Tesla owners would be ecstatic to show you their vehicle. And there are many Tesla owners clubs around the world. The easiest is to make a post on one of the Teslamotorsclub regional forums. Here's the link to the regional forums in the Americas: https://teslamotorsclub.com/tmc/forums/americas.97/
Similar threads
