Delayed/Scheduled charging enhancement (software only?)

Toyota Rav4 EV Forum

Help Support Toyota Rav4 EV Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

AgingHippie

Well-known member
Joined
Oct 2, 2017
Messages
46
I'd like to see an enhancement to the delayed/scheduled charging function, to extend battery life by reducing charging amperage.

Here's how I envision it working.

You plug your car into the charger at 10 PM, with the charge level at about 3/4. The car is configured to charge itself to full by 6 AM the next morning, so it has 8 hours to charge. At 40A, it could charge the battery to full in 2 hours. Currently, that's what it does, it waits until 4 AM, then starts pumping 40A. But it could also take the entire 8 hours to charge the car at 16A, causing much less wear on the battery, and reducing the load on the house to reduce the possibility of popping a breaker. Also, if I change my mind and go somewhere at 4 AM, the car is at least partially charged, where currently it would have had no additional charging.

We know that the car can charge at variable amperage, otherwise it would pop the breaker on every commercial charger you plug it into. We know that the car knows how long it will take to charge at either 120 or 240, because it displays that information when you turn it off. So there should be no hardware change required to do this, just software to select the lowest amperage that will get the job done in the time allowed.

Ideally, you'd be able to choose from the charge scheduling menu whether to charge at full power as it does now, or charge at the lowest amperage that will charge to full by the departure time. But I'm not sure of the purpose of continuing to use the current full power charge functionality with the scheduling menu - if you're always going to charge at full power, why not just leave "charge immediately" on, and set the home charger to turn on when you want it available?
 
davewill said:
Honestly there isn't any real difference in "wear" between 16a and 40a. They're both a fairly slow charge

Where did you get these 2 contentions? I've looked everywhere for specifics on amps or charging rate vs. battery life and found no specifics, only "the faster you charge it, the sooner it dies permanently". And 40A is the maximum rate it can take, so how is that a slow charge? And if the feature is worthless, why has Tesla implemented it on all their cars?
 
AgingHippie said:
davewill said:
Honestly there isn't any real difference in "wear" between 16a and 40a. They're both a fairly slow charge

Where did you get these 2 contentions? I've looked everywhere for specifics on amps or charging rate vs. battery life and found no specifics, only "the faster you charge it, the sooner it dies permanently". And 40A is the maximum rate it can take, so how is that a slow charge? And if the feature is worthless, why has Tesla implemented it on all their cars?
The 40A charge rate can only charge the battery from completely empty to completely full in 4 hours. In industry parlance, that's 1/4C. 10kW / 40kWh = 1/4 of the capacity per hour. There's not much wear on the battery until you get to something faster than 1/2C or more. Tesla provides the variable current feature so that you can safely plug into different circuits without having an adjustable EVSE. For example, you often can't charge at 40 amps at RV parks because of the age of the equipment. Turning down the current allows you to safely charge without tripping breakers and such.
 
1) There will never be another firmware change unless there is a lawsuit or a government recall.

2) The premise that anybody might be extending the life of the battery by charging at 16 amps instead of 40 amps AC @ 240 volts (about 25 amps DC @ 300 to 386 volts) is completely wasting their time and effort.

Do you really want to save your battery?

A- keep the battery as close to 50% as possible. Never charge above 75% and never let the battery go below 15%.

B- keep the battery cool. If it’s brtually hot out (like over 100F), turn the car to READY and turn the cabin climate control to AUTO... not ECO-Lo or ECO-Hi... just AUTO. You can lock the door with the mechanical key. Don’t leave the fob inside the car!!!
 
AgingHippie said:
davewill said:
Honestly there isn't any real difference in "wear" between 16a and 40a. They're both a fairly slow charge

Where did you get these 2 contentions? I've looked everywhere for specifics on amps or charging rate vs. battery life and found no specifics, only "the faster you charge it, the sooner it dies permanently". And 40A is the maximum rate it can take, so how is that a slow charge? And if the feature is worthless, why has Tesla implemented it on all their cars?

I would love to be able to dial down my charge rate, but not to save wear on my battery. Look, 40a is 9.6kW. The LEAF can charge it's much smaller battery at almost 50kW using CHAdeMO. Teslas routinely charge at 11.5kW and supercharge at 100+kW. I really can't be concerned with the difference between 40a and 16a from a wear POV. It would be great to use to adapt to questionable circuits, though.
 
davewill said:
I would love to be able to dial down my charge rate, but not to save wear on my battery. Look, 40a is 9.6kW. The LEAF can charge it's much smaller battery at almost 50kW using CHAdeMO. Teslas routinely charge at 11.5kW and supercharge at 100+kW. I really can't be concerned with the difference between 40a and 16a from a wear POV. It would be great to use to adapt to questionable circuits, though.

I guess I'm thinking that when your Leaf battery fails, or your Tesla battery fails, you can get another. But when your RAV4 EV battery fails, it's a parts car for somebody who was luckier than you. So I'm trying to come up with anything and everything to keep the battery healthy, especially since none of the "indicators" really tell you anything about the health of your battery.
 
I use a JuicePlug for charging energy monitoring and the possibility of getting some benefit from demand management payments. I have the JuicePlug current set for 32 amps even though it's connected to a 40A leviton EVSE. You can set it through their app. Selections are 6 / 12 / 16 / 24 / 32 / 40 / 48 / 80 amps. The JuicePlug is not that cheap, not that well built, and it's not always available for purchase. I got a discount for enrolling in the demand management stuff.
 
If you want to reduce charge rate:

1) Use the appropriate interchangeable plug with JESLA or JESLA JR for 12, 16, 24, 32 or 40 amps

2) Use the J-Wall at all the same above settings with a simple rotary switch

3) Use Go-Cable at 16 amps

4) Use the original blue handled charge cable at 120 / 12 amps
 
TonyWilliams said:
If you want to reduce charge rate:

1) Use the appropriate interchangeable plug with JESLA or JESLA JR for 12, 16, 24, 32 or 40 amps

2) Use the J-Wall at all the same above settings with a simple rotary switch

3) Use Go-Cable at 16 amps

4) Use the original blue handled charge cable at 120 / 12 amps

I was sort of hoping for a way to do it automatically, let the car or charger figure it out. I've got a Juicenet 40 Pro, and it's set to stay off until 10 PM, so I avoid peak rates. But since I know the car can charge from a 32A charger or a 24A charger, I thought there might be some way to make it do that. From what I'm hearing, it wouldn't meaningfully extend the battery life anyway. I just have to hope I'm one of the lucky ones.
 
AgingHippie said:
TonyWilliams said:
If you want to reduce charge rate:

1) Use the appropriate interchangeable plug with JESLA or JESLA JR for 12, 16, 24, 32 or 40 amps

2) Use the J-Wall at all the same above settings with a simple rotary switch

3) Use Go-Cable at 16 amps

4) Use the original blue handled charge cable at 120 / 12 amps

I was sort of hoping for a way to do it automatically, let the car or charger figure it out. I've got a Juicenet 40 Pro, and it's set to stay off until 10 PM, so I avoid peak rates. But since I know the car can charge from a 32A charger or a 24A charger, I thought there might be some way to make it do that. From what I'm hearing, it wouldn't meaningfully extend the battery life anyway. I just have to hope I'm one of the lucky ones.
If you have a JuiceBox Pro, then you should have the same current settings in the app that I do with the JuicePlug. Have you tried it?

This is the settings screen where you set the maximum current.

EV_Juice_Net_2018_04_02_15_48_22_000.jpg
 
I can manually limit the EVSE output, but I don't have that "Efficiency" setting you have, don't know what it does. When something says "smart" charging, I kind of expect that it will say ok I have 240v and I have 4 1/2 hours to add 27 miles of range, so that means I need to set my own amperage at X to finish charging. But if it doesn't make any difference in battery life, then it's not worth worrying about.
 
AgingHippie said:
I can manually limit the EVSE output, but I don't have that "Efficiency" setting you have, don't know what it does. When something says "smart" charging, I kind of expect that it will say ok I have 240v and I have 4 1/2 hours to add 27 miles of range, so that means I need to set my own amperage at X to finish charging. But if it doesn't make any difference in battery life, then it's not worth worrying about.
Only a car can do that. The EVSE doesn't know how much energy is required to fill the car or even what the desired level is. Also, in the case of cars with Tesla battery packs, the efficiency will be lower (more power from the wall for the same energy into the battery pack) if you charge a lot slower since the cooling loops for the battery and charger require power whenever they are actively charging. Those overhead losses add up to a higher percentage of the total when you charge slowly.
 
Back
Top