Lowering Amps to Improve Battery Life

[Canuck]

For one, it ignores depth of discharge effects on degradation. For example, if your charging habit of 50% leads you down to 15% sometimes day due to unexpected traffic, detour, a few unplanned errands, etc, that is worse for lithium batteries than running it down from 90% to 55%.

Where do you get this information from? Charging to 50% can never be ideal since you need to cycle around 50%. That's why the daily charger slider starts at 60%! You need to set the slider so you cycle around 50% as the optimum way of slowing degradation. That's why the slider has different settings within the daily driving range, since we all have different commutes.

Moreover, running a lithium ion battery down to zero, or conversely, charging it to 100%, is not that hard on the battery unless you keep it there after doing so. That's why you are told to drive it as soon after it hits 100% as possible, and charge it as soon as possible after it discharging it real low. What is hard on lithium ions batteries is charging them high and keeping them there, or discharging them low and keeping them there.

So you are much better off to go down to the unexpected low on occasion than to keep your battery at an unnecessarily high state of charge on a regular basis.

Again, there's probably nothing all that bad with you keeping your battery at 90% if that makes you feel good. (If you arrive home every day with 10% left then it's your ideal state of charge -- but that's a long commute!) In fact, it's probably better to look after your own health than that of the battery, and if you like to charge to 90% daily, go for it, but I can't leave this misinformation out there, even though I previously said I was done here.

Trust the smart scientists and engineers at Tesla to handle it properly.

I am. You are not. Take a look at the daily driving range on your slider. Those smart engineers made it and I've set mine right at the middle unless I need more. It makes no sense to me that they made it this way for me pick their extreme end, unless I need that extreme range. That's not how engineers design things.

They also have been warning me. It's only been lately that they toned it way down, strangely right around the Nissan EPA fiasco. "Politics" you say? I highly doubt it looking at the science and the timing of when they toned it down.

 

[tinm]

Just a data point... for months my 2013 S85 was gettin 227mi at 90% using my 240V 40A HPWC at home. A few weeks ago I dropped the amps to 28. Takes longer to charge but still works out fine in terms of being back to 90% in the morning.

But here's the thing: ever since I dropped to 28A I'm consistently getting 229mi at 90%.

 

[TexasEV]

Just a data point... for months my 2013 S85 was gettin 227mi at 90% using my 240V 40A HPWC at home. A few weeks ago I dropped the amps to 28. Takes longer to charge but still works out fine in terms of being back to 90% in the morning.

But here's the thing: ever since I dropped to 28A I'm consistently getting 229mi at 90%.

The estimate of rated range is not that accurate. There is no meaningful difference between a display of 227 and 229 miles.

 

[Rocky_H]

I'm going to need more popcorn while I see who is going to say "I'm leaving now." more times before actually stopping. This one might go into extra innings.

 

[jelloslug]

Charge as often and as fast as possible. The battery management computer with handle the details.

 

[tinm]

The estimate of rated range is not that accurate. There is no meaningful difference between a display of 227 and 229 miles.

So say you. But when I see 229 instead of 227 I let out a little cheer every morning.

Clearly, your mileage may vary.

 

[Saghost]

Just a data point... for months my 2013 S85 was gettin 227mi at 90% using my 240V 40A HPWC at home. A few weeks ago I dropped the amps to 28. Takes longer to charge but still works out fine in terms of being back to 90% in the morning.

But here's the thing: ever since I dropped to 28A I'm consistently getting 229mi at 90%.

A slower charging rate means both a warmer battery in the morning and less time after the charge ends for vampire drain to reduce the range. Of course, if you're only replenishing 10 or 15 miles and plugging in eight hours before you leave, the difference would be insignificant for you, and in any case it'll be relatively small.

 

[tinm]

I always time things so the car finishes charging within 5-10min of my leaving in the morning. Have gotten quite good at that

 

[Blissedout]

According to the Owners Manual COMPANION (not the Owners Manual)Owner's Manual Companion | Tesla Motors

To add just a little more confusion to this topic you should be aware that when asked, Elon Musk and JB Straubel said that the "most comfortable" SOC for the Tesla battery is between 50% and 62%. So, if you need to keep your car plugged in for a couple on months at a time for vacation or travel set the charge level to 60%. This way Vampire Loss might take it down to 55% before recharging.