daily battery charge rate recommended

[Elbert_gone]

Hello i m trying to find the recommended charge rate for model Y.
Does 48A as every day charging will affect my battery over time?

At how many amps should i charge my battery to avoid lossing range on the long run?
Does 48A will damage model y battery as every day charging at home?

 

[jcanoe]

By not plugging in daily you will have a bigger swing in the battery SOC and your vehicle will use the battery more often (both 12v and HV batteries).

The 12V battery will not be used more often if you don't charge every day. Even when plugged in, when the Tesla Model Y is not powered on the 12V battery is powering things like the door locks, Bluetooth, car alarm (not Sentry Mode) and the LTE modem. Plugging in does not cause the Tesla Model Y to maintain or charge the 12V battery any differently; the 12V battery is maintained whenever the Tesla Model Y is powered on, i.e. awake or when the Tesla vehicle determines that the 12V battery needs to be charged, i.e. the voltage has dropped below a set threshold, i.e. probably at or close to 12.0V. To full time maintain the state of charge of the 12V battery you would have to connect the 12V battery to an external 12V battery tender/trickle charger whenever the Tesla Model Y was parked.

 

[cgell]

The 12V battery will not be used more often if you don't charge every day. Even when plugged in, when the Tesla Model Y is not powered on the 12V battery is powering things like the door locks, Bluetooth, car alarm (not Sentry Mode) and the LTE modem. Plugging in does not cause the Tesla Model Y to maintain or charge the 12V battery any differently; the 12V battery is maintained whenever the Tesla Model Y is powered on, i.e. awake or when the Tesla vehicle determines that the 12V battery needs to be charged, i.e. the voltage has dropped below a set threshold, i.e. probably at or close to 12.0V. To full time maintain the state of charge of the 12V battery you would have to connect the 12V battery to an external 12V battery tender/trickle charger whenever the Tesla Model Y was parked.

I was basing my statement on the following from the owner's manual: "Whenever Model Y is plugged in but not actively charging, it draws energy from the wall outlet instead of using energy stored in the Battery. For example, if you are sitting in Model Y and using the touchscreen while parked and plugged in, Model Y draws energy from the wall outlet instead of the Battery." I assumed that the screen is powered by the 12v. Is that not correct? I figured that sometimes we wake the car for various things, so there would be some additional battery use.

 

[DanDi58]

I don't understand why people don't just follow the owners manual..... Emphasis in the original.

About the High Voltage Battery​

Model Y has one of the most sophisticated battery systems in the world. The most important way to preserve the high voltage Battery is to LEAVE YOUR VEHICLE PLUGGED IN when you are not using it. This is particularly important if you are not planning to drive Model Y for several weeks.

There is no advantage to waiting until the Battery’s level is low before charging. In fact, the Battery performs best when charged regularly.

 

[JSolar]

I first charged to 80% with the tesla wall charger at 48 amps. Then the pandemic hit so I switched to 50% charge every day. On the days I new I would be driving more than 100 miles, I set the overnight charge to 75%. 99% of my driving is less than 25 miles a day.

 

[Darmie]

The difference between 48 amps and anything lower is nothing to the battery. Anything at that level is a very safe charge rate for the battery.

The only reason it may be worth reducing the level is to prolong the life of the supply equipment (such as wall connector) since longevity is reduced by heat. That being said, your equipment can handle the full rate and will last a long time either way. It just may last longer at lower charge rates. The only downside to lowering the rate (besides charge speed) is that charging at lower rates may be less efficient.

That's my regiment. If I'm charging overnight, I'll reduce this down to 25amps or so just to keep things from getting too warm.

Hello, I am new to the EV world and have a Tesla home charger that charges my 2022 Tesla model S at 48 amps. My question is; should I really charge my model S every night, even if I only drive 5-10 miles a day or sometimes none at all. Is it better to charge my car every night or will my battery health be the same if, say, I charge my battery three times a week and on the weekend?

I believe it's still in the manual to always be charging. You can set your SOC to a lower number, and just hover the 50pct range.

if reduce from 32A to 20A or lower , charging efficiency goes down or up ?

Efficiency goes down with kW. That's not to say it's a bad thing. There is phantom drain from the vehicle. Longer charge time, the less over time power will reach the battery.

 

[jcanoe]

I was basing my statement on the following from the owner's manual: "Whenever Model Y is plugged in but not actively charging, it draws energy from the wall outlet instead of using energy stored in the Battery. For example, if you are sitting in Model Y and using the touchscreen while parked and plugged in, Model Y draws energy from the wall outlet instead of the Battery." I assumed that the screen is powered by the 12v. Is that not correct? I figured that sometimes we wake the car for various things, so there would be some additional battery use.

That statement from the Owner's Manual is an over simplification. When powered on, with the climate control running, the power used will exceed 1.5kW, even up to 8kW when preconditioning. This is well beyond the power that can be delivered to the Tesla Model Y when plugged into a 120V receptacle. When using a 15A circuit the maximum power is just 1.4kW. In this example the only available source for this level of power is the high voltage battery.

The other point is that there is a low voltage side and a high voltage side to the Model Y's electrical system. The AC compressor runs on high voltage, i.e. 360V. The only cabling to provide the high voltage power that the AC compressor requires is from the high voltage battery.

The on-board charger can operate at up to 11.5kW (requires a 240V, 60A circuit.) There would be conversion losses and excess heat generated by the on-board charger if this was used to provide power for the AC compressor. There would have to be additional high voltage wiring from the on-board charger to the AC compressor. This would increase weight, complexity and cost of the wiring in the Tesla Model Y, i.e. it would not be a good solution. Better to draw all power from the high voltage battery, run the AC compressor directly off the high voltage battery. Use the power conversion system (PCS) to step down 360V from the high voltage battery to the needed 13V to 15.5V DC for up to ~2kW to run the 12V accessories including the infotainment screen, computers, HVAC blower, lights, wipers, doors and windows. The PCS maintains the 12V battery whenever the Tesla Model Y is powered on. The Tesla Model Y will detects the voltage drop in the 12V system when parked, then the Tesla Model Y will power on so the PCS can charge, top up the 12V battery.

A different approach to maintaining the 12V battery was taken GM. The GM Chevrolet Volt has a dedicated charging circuit that periodically will use power from the charging station (either 120V or 240V) to charge, top up the 12V battery in the Chevy Volt when the Volt is plugged in. When the Chevy Volt is powered on all power comes from the high voltage battery and the accessory power system (APC) the GM version of the Tesla PCS.) The Volt can be actively charging at either Level 1 or Level 2 while powered on. If power is being drawn from the high voltage battery faster than it can be put back into the battery while charging then the battery would not be able to be fully recharged until the preconditioning cycle has completed. Charging could continue for an additional 20 or 30 minutes after preconditioning completes to put back the all of the energy that was consumed during preconditioning.

 

[Pricedm]

Hello, I am new to the EV world and have a Tesla home charger that charges my 2022 Tesla model S at 48 amps. My question is; should I really charge my model S every night, even if I only drive 5-10 miles a day or sometimes none at all. Is it better to charge my car every night or will my battery health be the same if, say, I charge my battery three times a week and on the weekend?

@AI Chappelle welcome to the EV club. Lots of threads and ideas on best practices for charging here on TMC.

My experience after 3+ years, which includes info from Tesla and useful posts here: 1. plug in when at home. This allows car to pull 1 - 2v from the grid, instead of car battery, for basic activities. 2. Use the battery range 10/20% to 80/90% on a regular basis for non-road trips. So no, don't keep charging in the same range over and over. Example: charge to 80%. Once charged, set charge to minimum amount. This will prevent charging until you use stored energy--but, car will be able to draw 1-2v when plugged in at home.

 

[iamnid]

This is not accurate. Plugging in every day does not negatively affect range or displayed range. Your displayed range did not change because you plugged in too often…

There is no reason to avoid charging every day. Plugging in more often does not mean more degradation. Each time you plug in does not count as a charge cycle. The wider swing in the state of charge is worse than charging every day. It’s better to go 80-50 twice rather than 80-20 once.

The charging cycles absolutely affect the range displayed. I agree it doesn't affect actual range. Unless you discharge regularly, the BMS seems to lose track of your true capacity. I haven't seen it in my Model Y but our Model 3 SR+ will drop to 185 miles (or thereabouts) after a few weeks of only driving a few miles a day and charging up to 90% daily. After a day or two of discharging it down to 20% or so and back up to 90% the stated range at 90% will go up to 200 or so.

I just use percentage on my Model Y so whether this is happening or not to my Model Y, I don't know. But it's like clockwork on our Model 3 - daily charging with only small discharges in between makes the stated range drop quite a bit. I know it's not actually affecting the range of the battery, I get that, but it's disconcerting to see if you're new to Teslas like I assumed OP was due to the nature of the question.

I agree with your advice though, there's no reason not to just charge every day.

 

[jcanoe]

This allows car to pull 1 - 2v from the grid, instead of car battery, for basic activities.

I think you mean amps, not volts. I don't see the green light on my EVSE except when the Tesla Model Y is powered on or charging. When the Tesla Model Y is parked, in sleep mode, there is no green light on my EVSE, i.e. the charging cable is not energized and no current is flowing.

Perhaps you leave Sentry mode and/or Summon mode on at your home location. In this case the Tesla Model Y would remain awake, consume 230W for the computers, cameras etc. If you are set up for charging using Level 1 (120V) then that would be approximately 2 amps at 120V; if you are setup for charging using Level 2 (240) then this would be approximately 1 amp at 240V.

 

[Pricedm]

Volts....the car is plugged in not for charging, but for the ability to use the grid, instead of battery, for any needs.

Yes, charging every day does no harm. But it can lead to the BMS not really "knowing" battery bounds/capacity. I use to keep my car in the 190 - 250 range. After a few months of this, it thought 100% was 280 miles. After I drove to <10% displayed range and recharged, display showed full around 310 miles. Refer to MASTER THREAD: Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health

 

[jcanoe]

1 Volt X 0 amps = 0 Watts power being added. The photo demonstrates that when charging has been completed the Tesla Model Y is not using any grid power. Yet the Tesla Model Y is clearly powered on, the screen is active. The power used, assuming no HVAC, would be ~230W. If the Model Y was using grid power the voltage would nominally be 120V or 240V, the amperage would be greater than or equal to 1 amp.

 

[cgell]

1 Volt X 0 amps = 0 Watts power being added. The photo demonstrates that when charging has been completed the Tesla Model Y is not using any grid power. Yet the Tesla Model Y is clearly powered on, the screen is active. The power used, assuming no HVAC, would be ~230W. If the Model Y was using grid power the voltage would nominally be 120V or 240V, the amperage would be greater than or equal to 1 amp.

Is it possible that it’s just showing that no power is being used for charging the HV battery? Do those numbers definitely show all power input?

 

[jcanoe]

Is it possible that it’s just showing that no power is being used for charging the HV battery? Or do those numbers definitely show all power input?

I have my Model Y set to display % state of charge (SOC) not miles. The charging status will show % SOC, kWh added, current/max amperage and voltage. The kWh rounds to the nearest whole value.

As far as I am aware if the value for current amps is greater than 0 then the Tesla Model Y is actively charging unless you have scheduled departure set. If Scheduled Departure is set then you may see just a few amps being used while the Tesla Model Y is waiting to begin charging. This may indicate that the on-board charger is energized, ready to charge at a later time. The voltage displayed is always the nominal voltage (either 120V or 240V) until actively charging, then the voltage may vary slightly from the reference value.

Other indicators to check:

The light on the charge port is green while actively charging; blue when charging has been completed.

In the the Tesla app the charging cord connected to the Tesla vehicle graphic displayed on the main app screen intermittently glows green while actively charging.

 

[SkagitDoug]

Sorry, I didn’t intend “do what you’re comfortable with” to be dismissive but rather to go by your own experience.

Then you also read Tesla recommends deep discharge once in a while to get more accurate BMS measurements. Supercharging is convenient but also not great for the battery either. What seems worse, frequent Supercharging or charging at home every other day as needed? Is daily charging still best if I only use 10% that day?

Boy, was I ever run through the ringer about a year ago when I mentioned Tesla's recommendation to "deep-cycle" the battery to improve BMS accuracy. More than one person commented that "...everyone knew that isn't true," or words to that effect.

 

[DanDi58]

I echo @jcanoe 's comment about leaving the SOC set to percent. A lot less to worry about that way, since it will always show the current charge of the battery correctly. I don't really care what the car says about miles, since I know it's based on the EPA rating not my driving style or conditions. So, I use % and bring up the energy graph if I want a more detailed view of what my wh/mi are. And then I stop when the car says to stop.