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Estimated charge time way off

I have had my model 3 for a week now.

Currently using the mobile charger until my wall charger is installed in a few weeks.

I plug my car in every afternoon and set the charging start time to 730. At 730 when the charging starts the estimated time to complete is way off. I have the max charge set to 80%

For example, last night it needed to charge about 15% of the battery or about 75KM. The app was showing the estimated time as over 1 day. The charger was operating at 7KM/H so it should have been about 11 hours which is how long the actual charge took. As the charging time goes the estimated time comes down quickly but always seems to be 2-3 times longer than what is actually needed.

I am curious if anyone else has this issue or if there is a known way to fix it

Thanks!
 
I have had my model 3 for a week now.

Currently using the mobile charger until my wall charger is installed in a few weeks.

I plug my car in every afternoon and set the charging start time to 730. At 730 when the charging starts the estimated time to complete is way off. I have the max charge set to 80%

For example, last night it needed to charge about 15% of the battery or about 75KM. The app was showing the estimated time as over 1 day. The charger was operating at 7KM/H so it should have been about 11 hours which is how long the actual charge took. As the charging time goes the estimated time comes down quickly but always seems to be 2-3 times longer than what is actually needed.

I am curious if anyone else has this issue or if there is a known way to fix it

Thanks!
I am not totally sure but it sounds like your battery might be cold coaked and not be able to take full charge.

Once it is plugged in for an hour or 2, does the estimate become accurate?

What is the charge rate shown in the car when it first starts charging, and the estimate is inaccurate?
 
I think the problem is you're using a 120V 12A plug. That only provides the car with 1.44kW, or which at least 200-250w are used for the car's systems (computer, pumps etc). If the battery ever drops under 10C or so, the car will want to heat it before continuing to charge. 1.2kW is so little energy to heat that it might never get to the target temperature. It all depends on external factors (temperature). If I were the car, I wouldn't even venture a guesstimate of completion time given that power :D
Give the car more power through a 240V collection of some sort and your problem will go away. Alternatively, charge at 120V in a heated garage maybe?
 
I get what you are saying But the charge time still is correct. It’s just the estimate that’s wrong

Are you saying it can’t figure the estimate because there’s too many factors that could slow down such a low speed charge? Such as cold

I can put a heater in the garage and test out what happens if it’s a bit warmer in there
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
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Nov 28, 2018
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Riverside Co. CA
Are you saying it can’t figure the estimate because there’s too many factors that could slow down such a low speed charge? Such as cold

That would be my estimation. Its an estimate, and its not able to estimate it accurately due to the slow charging speed and cold battery etc would be my guess. The charge speed you are using is slow enough to be completely absorbed by battery heating, and still lose range.
 
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Keep in mind though that the charge is still happening. I am getting 7km/h of charge.

Maybe I will try heating the garage and see what happens.

I didn’t have the issue in my first charge but it was similarity cold. Only difference was I hadn’t set it up charge at a specific time
 

Big Earl

bnkwupt
Supporting Member
Jul 12, 2017
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Springfield, VA
I get what you are saying But the charge time still is correct. It’s just the estimate that’s wrong

Are you saying it can’t figure the estimate because there’s too many factors that could slow down such a low speed charge? Such as cold

I can put a heater in the garage and test out what happens if it’s a bit warmer in there

Exactly. The estimation is off because of the cold temperature combined with other factors like low charge rate and the need to maybe heat the battery. This won’t be a concern when you install faster charging and you should find that the car’s estimates are very accurate.

If you have limited power available, your best bet is to charge immediately after driving while the battery is still warm. Of course, this won’t help you if the trip was too short to warm up the battery.
 
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Exactly. The estimation is off because of the cold temperature combined with other factors like low charge rate and the need to maybe heat the battery. This won’t be a concern when you install faster charging and you should find that the car’s estimates are very accurate.

If you have limited power available, your best bet is to charge immediately after driving while the battery is still warm. Of course, this won’t help you if the trip was too short to warm up the battery.
This makes sense as the first day my estimates were fine and I charged right after driving.
 
I’ve noticed this in cold temps even charging at 240V 16A. The charge time estimate is often too high by maybe 30-50%.

To be clear, just like the OP said, the estimate is wrong even when the battery is warm enough to accept the max charge rate, so there’s so good reason for it to be so wrong.

I don’t recall the estimate being so bad my first couple winters, so I wonder if something changed in the software. (Either that, or it was always this way and I’m just misremembering.)
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
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Nov 28, 2018
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Riverside Co. CA
This makes sense as the first day my estimates were fine and I charged right after driving.

Note that it may take a lot longer to "warm up the battery" by driving, than you might think it would take. You wont be able to go drive for 5 minutes and then come back home thinking the battery is warm, for example.

Just pointing this out because, while I also agree with @Big Earl, the next thing a person might do is say "well I did drive (to the grocery store and back) " and the estimate is still off, so what gives?
 
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Rocky_H

Well-Known Member
Feb 19, 2015
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Boise, ID
Yeah, we know why the estimate is wrong. It's because it's cold, so it is diverting all of the incoming power to heating up the battery first before charging, so the charging speed is literally nothing---0 mph. So what is it going to show for an estimate? How long at 0 mph will it take to recharge? There's no good way to guess that. Doing the math would say you're dividing by zero, and the answer would be infinity amount of time. And how long will it take to warm up before it can begin charging? That's also hard to tell, because it depends on how cold it is outside, whether it's inside or outside, etc. So the time estimation is a little simplistic and really confused when it's heating the battery and hasn't begun actual charging yet.

Maybe I will try heating the garage and see what happens.
Don't do that. That's just a huge waste of energy. The car does eventually charge; it's just that the estimate is not accurate or useful from a really low power source like that. And really, if you are using a basic 120V connection, you don't really need a specific estimate, because the answer is: "a really long-ass time", and you should just have it plugged in for as long as you possibly can.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
14,608
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Riverside Co. CA
I will drive it for a while to heat it up and drain some charge

I was virtually positive you were going to say this, which is why I specifically said:

Note that it may take a lot longer to "warm up the battery" by driving, than you might think it would take. You wont be able to go drive for 5 minutes and then come back home thinking the battery is warm, for example.

I live in southern california. My car is parked in an fully enclosed, drywalled garage, with insulated garage doors. It never (ever) gets colder than 45 degrees or hotter than 90 degrees in my garage at any point during the year, even though some times in the winter it gets down to "low 30s" where I live.

Point is, my car never gets "that" cold.

My commute into the office is 40 miles each way, with the majority of it on a freeway where average speeds, if no traffic, are 80MPH. I can drive approximately 25-30 miles at those speeds and still have "regen dots" showing on my car, showing limited regen.

The TL ; DR version is, you will not be able to "drive for a bit and warm up your battery" as I said, because its likely colder where you are than where I am, and I doubt you are going to go drive 25 miles at 80MPH to "warm up your battery".

"driving for a bit to warm up your batter" is not going to tell you anything because it wont be warm.
 
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Unless you only need a couple percent of charge, the car will probably assume that between the start and end of the charge, the battery will cool down and eventually need heating. At that point, all bets are off.

What you should take away from this discussion is:
- It's just an estimate, actual charging might be different
- On 120V 12A, if it's significantly under freezing, you might never add any charge once the battery cools down.
- 120V 12A charging itself doesn't generate enough heat to keep the battery warm in cold climates.
- Driving a bit doesn't generate nearly as much heat as you think it does. Everything's pretty efficient under there.

As someone already put it, the estimate is "it's gonna take freakin forever" at that charging power. Plus or minus a few hours doesn't matter.
 

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