Charging Question

[silverstoned83]

I realize we are in the Model Y forum; the following is from The Tesla Model S Owner's Manual, page 177.

Tesla strongly recommends leaving Model S plugged in when not in use. This maximizes the lifetime of the Battery Your Model S Battery is one of the most sophisticated battery systems in the world. The most important way to preserve the Battery is to LEAVE YOUR MODEL S PLUGGED IN when you’re not using it. This is particularly important if you are not planning to drive your Model S for several weeks. When plugged in, Model S wakes up when needed to automatically maintain a charge level that maximizes the lifetime of the Battery. This also protects the 12-volt battery. There is no advantage to waiting until the Battery’s level is low before charging. In fact, the Battery performs best when charged regularly.

https://www.tesla.com/sites/default/files/model_s_owners_manual_north_america_en_us.pdf

While I think there is some important notes to take from this recommendation, it also doesn’t surprise me that Tesla doesn’t go into more detail since they need to minimize room for interpretation, even if there are many reasons/situations when this does not need to be adhered to.

Maintaining the 12v battery, especially in cold weather, is a good reason worth noting. Another would be when in hot weather..by plugging it in, the battery management system will then allow cooling of the battery to preserve the health since they don’t like being too warm.

 

[Srad600Volt]

I realize we are in the Model Y forum; the following is from The Tesla Model S Owner's Manual, page 177.

Tesla strongly recommends leaving Model S plugged in when not in use. This maximizes the lifetime of the Battery Your Model S Battery is one of the most sophisticated battery systems in the world. The most important way to preserve the Battery is to LEAVE YOUR MODEL S PLUGGED IN when you’re not using it. This is particularly important if you are not planning to drive your Model S for several weeks. When plugged in, Model S wakes up when needed to automatically maintain a charge level that maximizes the lifetime of the Battery. This also protects the 12-volt battery. There is no advantage to waiting until the Battery’s level is low before charging. In fact, the Battery performs best when charged regularly.

https://www.tesla.com/sites/default/files/model_s_owners_manual_north_america_en_us.pdf

Gotcha, your statement makes sense in that context, thanks. I find it interesting that these statements were excluded from the MY manual (or at least I have been unable to find something like this). I wonder if it was intentionally omitted and if so, why? I really won't pretend to be an expert on these things, but this particular item is pretty vague in the MY manual.

 

[amnesty_that]

Gotcha, your statement makes sense in that context, thanks. I find it interesting that these statements were excluded from the MY manual (or at least I have been unable to find something like this). I wonder if it was intentionally omitted and if so, why? I really won't pretend to be an expert on these things, but this particular item is pretty vague in the MY manual.

It’s in the Model Y manual as well page 153

 

[Srad600Volt]

It’s in the Model Y manual as well page 153

Ah ha, I was looking in the wrong section (under "charging"), but it's listed under the "battery information" section. Thanks. Looks like it was not omitted after all. Seems like an odd thing to do though, but I have to assume the manufacturer knows best (I guess).

 

[frankvb]

Tesla can state whatever they want, but they can't change the laws of physics... As posted by a few people earlier, Lithium Ion batteries are happiest when charge level is kept close to 50%. Now in reality things are fine if kept in between 20 and 80% most of the time. There is no inherent advantage in plugging it in every day.

 

[jcanoe]

While I think there is some important notes to take from this recommendation, it also doesn’t surprise me that Tesla doesn’t go into more detail since they need to minimize room for interpretation, even if there are many reasons/situations when this does not need to be adhered to.

Maintaining the 12v battery, especially in cold weather, is a good reason worth noting. Another would be when in hot weather..by plugging it in, the battery management system will then allow cooling of the battery to preserve the health since they don’t like being too warm.

My understanding is that Tesla vehicles will monitor the state of the vehicle's 12V battery and periodically charge the 12V using power from the lithium ion battery pack regardless of whether the vehicle is plugged in. This involves the DC-to-DC inverter and draws some power from the battery pack to charge the 12V battery. Over many days this would deplete the charge of the battery pack if the vehicle has not been plugged in.

As long as there is sufficient charge in the battery pack the Tesla vehicle will automatically maintain the temperature of the battery pack to keep the pack from becoming too warm. This would include automatically circulating coolant through the battery and radiator, turning on the radiator fan and running the AC compressor as needed to keep the battery from becoming too warm. Cabin overheat protection, when enabled, will turn on the AC when the cabin temperature reaches 105F to cool down the passenger cabin. Cabin overheat protection is only active for 12 hours after the vehicle is parked, unless you remotely power on the vehicle to reset the 12 hr timer. If the state of charge of the battery pack is less than 20% then I don't believe it is possible to precondition the cabin; this probably also disables cabin overheat protection.

Keeping the vehicle plugged in during cold weather, when temperatures drop below 32F is probably a good idea; the vehicle's battery temperature management system can then maintain the temperature of the battery pack in an acceptable range. When the battery pack is allowed to cool below 32F then charging is not possible and regenerative braking is not available until the battery has warmed. There is no risk to discharging the battery pack, i.e. running the HVAC and other accessories to preheat the car or to drive the car when the pack is cold. The pack would be damaged if it was allowed to charge when too cold.