Always leave Taycan plugged in to 120V charger regardless of SOC?

[Gino]

I was wondering if there is any data to suggest it’s a bad idea to leave my Taycan plugged in to my 120V Porsche charger whenever it is in my garage? I haven’t it set to stop charging at 85% and usually don’t plug it back in until SOC goes below 40% but my wife hates waiting until below 40% and prefers to plug it back in as soon as she gets home. Will the battery suffer in the long term if I let her do this or is there data to suggest this behavior to always top off the battery is of no concern?

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[satchurator]

This will not harm your car, but it's still not advisable unless you are super confident that your 120V wiring and NEMA 15-5 outlet are tip-top quality, able to bear continuous amperage draw and have no other competing loads on the same circuit. Since most US homes wiring do not rise to this level of robustness, I believe that this is the reason that Porsche discourage L1 charging except in emergencies.

 

[satchurator]

Regarding repeatedly charging to the hilt at 100%, this perennial question often reignites a tiresome debate that is fueled by the flat-earther fraternity owner subset who cling to a desire to always charge to the max, contrary to the advice in the manual.

It's straightforward to set the general profile charging limit to 85% and then schedule charging to 100% ahead of a longer trip (however if you are dependent on L1 charging you are at a big disadvantage there). The definitive guidance is in the manual - daily charge limit to 85%. Note that some owners for certain model years have recently received guidance to limit to 80% while Porsche work through a battery recall.

 

[bn8959]

I think you’ll find there will be little issue. I now set my limit to 75% and tend to keep it in the 50 to 75 range (although I believe batteries are least stressed if they remain within the 40-60 range). You’ll probably find benefit in periodic deeper cycles though, particularly if you can do a rebalancing cycle occasionally, so keep it healthy and maintain highest level of total capacity.

 

[Gino]

This will not harm your car, but it's still not advisable unless you are super confident that your 120V wiring and NEMA 15-5 outlet are tip-top quality, able to bear continuous amperage draw and have no other competing loads on the same circuit. Since most US homes wiring do not rise to this level of robustness, I believe that this is the reason that Porsche discourage L1 charging except in emergencies.

I’m not worried about my wiring or the plugs since I only use the highest rated NEMA 5-20P outlets in my garage, the wiring is 12/2 solid copper & I only use screw terminals rather than quick connect plugs which are usually the source for overheated plugs which eventually melt with long sustained current draw.
My charging cable or the plug never even gets more than warm to the touch after charging for as long as 19 hours but typically no more than 11 hours from 9pm to 8am.
I also put a temperature thermocouple in the outlet to see what the max temp it reaches and it never exceeds 96 degrees in the winter months & 100 degrees in the hottest part of the summer. I’m going to double check again this summer when it hits 100 degrees outside to see what the receptacle gets to at 2pm after a long overnight plus all day charge to make sure the outlet stays well below spec.
Anything above 110 degrees is worrisome & the plug wiring connections should be checked and the actual load verified at the outlet. If other loads are on the same outlet the total load must be determined to stay at no more than 80% of total load.
To draw 10A on a 20A NEMA 5-20 receptacle indefinitely is no problem but if the total of additional loads on the same outlet gets above 6A then you can begin to see the surface temperature of the receptacle rising above 110 which won’t melt the receptacle which is rated up to 140 degrees but I try to avoid going above 110 degrees. When temperatures get to 140 degrees it’s usually a combination of using quick connections on the back of cheap receptacles, arcing at the blade contacts because they are loose or making poor contact or you’re running too much current by exceeding 80% of the max power rating of the receptacle.

 

[satchurator]

Sounds like your L1 setup is up to the job! It also sounds like your electrical-IQ/interest is quite high; why not opt for a 50A circuit and get the benefit of 9.6kW charging? That would avoid the multi-day charging experience of dropping to 40% and climbing to 100%.

In my case, I have a hardwired 80A EVSE, and keep my general charging profile at 65%. For local runs and commuting that limit is fine, and with 19.2kW charging, it's a relatively quick charge to zip up to 100% for a longer trip.

 

[Gino]

Sounds like your L1 setup is up to the job! It also sounds like your electrical-IQ/interest is quite high; why not opt for a 50A circuit and get the benefit of 9.6kW charging? That would avoid the multi-day charging experience of dropping to 40% and climbing to 100%.

In my case, I have a hardwired 80A EVSE, and keep my general charging profile at 65%. For local runs and commuting that limit is fine, and with 19.2kW charging, it's a relatively quick charge to zip up to 100% for a longer trip.

Unfortunately I live in a townhouse community where the garages are across the main driveway through the community. There is no 220 circuit going from my home to the garage and there is only 1/2 metal emt going 80 feet between the garage & the townhome.
No electrician will touch it without being held harmless if they break the buried 12/2 & 14/2 romex wires in the conduit to meet code. If one of the wires breaks underground and the driveway must be dug up to replace potentially corroded EMT then I’m on the hook for this expense which is estimated at $30K to $40K.
It’s not worth taking the chance. We have 3 other ice vehicles and only drive the Taycan locally since it has 35% of the range of my ICE vehicles which I use for long trips.
In the meantime I’m planning to buy a second home close to the beach where I’ll be able to park/charge the Taycan at 220V and buy an ICE 911 or Boxster to go in my existing garage and just forget about charging at 220…
Plus my association will not approve installing a 220v circuit in my garage since they don’t want to suffer the consequences if the driveway has to be dug up even if it’s at my expense.
I’m looking forward to buying an ICE or hybrid Porsche and a home for my Taycan…

 

[Avantgarde]

I believe the main reason Porsche advised against using the L1 charger on a regular basis was not because of overheating concerns but because it was causing issues with the low voltage battery. Speculation was low speed L1 charging was keeping the car awake for extended periods which was depleting the LVB and for whatever reason Taycan’s original software setup did not allow the LVB to be charged by HVB unless the car is driven, similar to an ICE vehicle. This reasoning was never officially confirmed by Porsche but the advice came right around failed LVB pandemic. Porsche did software recall to solve the LVB problems and some speculated fix simply enabled HVB charging LVB when the car is not driven. If this is true, regular L1 charging should no longer be a problem. I predominantly used L1 charging for the first 1.5 years of my Taycan ownership and did not have a problem. If i was in your situation i would still use it, feeling better given the software fix I mentioned above.

 

[whitex]

Hookup 240V to your car. You can even repurpose a 120V 20A circuit and install a 240V 20A using the same wiring if you have a circuit you can dedicate to car charging (get an electrician unless you know what you're doing). That will give you 3.8kW charging which should satisfy your needs well. Go up from there at will (I have 19.2kW, 240V/80A, but it's overkill even for me).

As for keeping it plugged in, I would recommend it. Recent study showed that batteries with the kind of chemistry Taycan uses tend to last longer with shallow charging cycles (often, short charging, vs. less often but long cycles) - something about some crystal molecules in the battery growing with more energy and shrinking as battery depletes, so the higher the SoC range, the higher the mechanical stress due to the battery expanding and shrinking more, than if you just charged more often less.

I've been driving EV's for 12 years now, including Taycan for over 2 years now, always kept them plugged in whenever the car is in the garage - so lots of shallow charging cycles. My batteries have held up really well (the longest owned EV was 8 years with one of my Model S, minimal battery degradation by the time I sold it). My Taycan is set to charge to 85% whenever in the garage, 100% before longer trips, car is always plugged in while in the garage, battery seems happy with that.

 

[Gino]

I believe the main reason Porsche advised against using the L1 charger on a regular basis was not because of overheating concerns but because it was causing issues with the low voltage battery. Speculation was low speed L1 charging was keeping the car awake for extended periods which was depleting the LVB and for whatever reason Taycan’s original software setup did not allow the LVB to be charged by HVB unless the car is driven, similar to an ICE vehicle. This reasoning was never officially confirmed by Porsche but the advice came right around failed LVB pandemic. Porsche did software recall to solve the LVB problems and some speculated fix simply enabled HVB charging LVB when the car is not driven. If this is true, regular L1 charging should no longer be a problem. I predominantly used L1 charging for the first 1.5 years of my Taycan ownership and did not have a problem. If i was in your situation i would still use it, feeling better given the software fix I mentioned above.

I think you’re right. The 12V battery would not be maintained by the main battery unless the SOC is at >50%.
I could see how it could be a problem for the 12v battery if the SOC is below 50%.
I will ask my dealer about this.
If the 12V battery is not getting charged by the 120V charger and the 12V battery relies on the main battery when at >50% SOC or while the car is being driven.
If this is the case then I’m better off keeping it plugged in even when I’m at 40% because it will take at least 8 hours to charge it back to 50% when the 12V battery will start charging again. That is if I find out the 12V battery is getting charged as well as the main battery when plugged into the 120V charger.
When I asked my dealer about putting a trickle charger on the 12V battery he told me it would be unnecessary if I have the vehicle plugged into the 120V or 220V Porsche charger.

 

[Gino]

Hookup 240V to your car. You can even repurpose a 120V 20A circuit and install a 240V 20A using the same wiring if you have a circuit you can dedicate to car charging (get an electrician unless you know what you're doing). That will give you 3.8kW charging which should satisfy your needs well. Go up from there at will (I have 19.2kW, 240V/80A, but it's overkill even for me).

As for keeping it plugged in, I would recommend it. Recent study showed that batteries with the kind of chemistry Taycan uses tend to last longer with shallow charging cycles (often, short charging, vs. less often but long cycles) - something about some crystal molecules in the battery growing with more energy and shrinking as battery depletes, so the higher the SoC range, the higher the mechanical stress due to the battery expanding and shrinking more, than if you just charged more often less.

I've been driving EV's for 12 years now, including Taycan for over 2 years now, always kept them plugged in whenever the car is in the garage - so lots of shallow charging cycles. My batteries have held up really well (the longest owned EV was 8 years with one of my Model S, minimal battery degradation by the time I sold it). My Taycan is set to charge to 85% whenever in the garage, 100% before longer trips, car is always plugged in while in the garage, battery seems happy with that.

Unfortunately California electrical code for garages requires a 12/2 & 14/2 120V lines. The 12/2 120V is for the garage door opener & outlets & the 14/2 is for lighting. I am not allowed to turn the 12/2 into a 220V line. I have to pull at least a new 12/3 romex along with the 14/2 romex and my association will not approve any removal or replacement of the existing Romex from the townhome to the garage.
Charging at 120V at 10A has been working quite well for the last 6 months with no issues and Porsche said I can charge as long as I want all the way to 100% SOC but did caution me to not charge to 100% and leave it that way for days. They told me only to charge above 85% before going on longer trips where you need the most range.
We don’t use it for long trips since we have 3 other vehicles with 400-500 miles range which we prefer to use instead.
Our Taycan has found its comfort zone around town and never more than a 160 mile round trip in Southern California so our 225 mile top range suits us fine.
I’ll buy another home close to the beach and use the current place as an office and for family/friends visiting from out of town.

 

[whitex]

Unfortunately California electrical code for garages requires a 12/2 & 14/2 120V lines. The 12/2 120V is for the garage door opener & outlets & the 14/2 is for lighting. I am not allowed to turn the 12/2 into a 220V line. I have to pull at least a new 12/3 romex along with the 14/2 romex and my association will not approve any removal or replacement of the existing Romex from the townhome to the garage.
Charging at 120V at 10A has been working quite well for the last 6 months with no issues and Porsche said I can charge as long as I want all the way to 100% SOC but did caution me to not charge to 100% and leave it that way for days. They told me only to charge above 85% before going on longer trips where you need the most range.
We don’t use it for long trips since we have 3 other vehicles with 400-500 miles range which we prefer to use instead.
Our Taycan has found its comfort zone around town and never more than a 160 mile round trip in Southern California so our 225 mile top range suits us fine.
I’ll buy another home close to the beach and use the current place as an office and for family/friends visiting from out of town.

Sad that they will not let you convert to 240V (you could get 240V LED lights no problem, and use the 14/2 for 240V charging - AWG14 allows 15A, so you can charge at 12A, at 240V that would be 2.88KW). However, if 120V has been working for you, just keep the car plugged in whenever you're in the garage. While charging, the car should be replenishing the 12V (except perhaps some 2020 Taycans from what I heard). If higher rate charging ends up being needed, you could pickup a 20KWh+ battery bank (sold for campers) which will charge at 120V whatever current, but give you a 240V output (typically used for RV's). If you leave it charged in the garage, you will always have 10KWh or 20KWh+ ready to be transferred to your car at ~6-9KW, after than L1 speeds I presume (never used one of those battery banks beyond 0% SoC).

 

[satchurator]

I believe the main reason Porsche advised against using the L1 charger on a regular basis was not because of overheating concerns but because it was causing issues with the low voltage battery. Speculation was low speed L1 charging was keeping the car awake for extended periods which was depleting the LVB and for whatever reason Taycan’s original software setup did not allow the LVB to be charged by HVB unless the car is driven, similar to an ICE vehicle. This reasoning was never officially confirmed by Porsche but the advice came right around failed LVB pandemic. Porsche did software recall to solve the LVB problems and some speculated fix simply enabled HVB charging LVB when the car is not driven. If this is true, regular L1 charging should no longer be a problem. I predominantly used L1 charging for the first 1.5 years of my Taycan ownership and did not have a problem. If i was in your situation i would still use it, feeling better given the software fix I mentioned above.

Interesting theory @Avantgarde. I recall that the avoiding L1 charging guidance happened also around the time when Porsche was rolling out their second attempt at a recall on the PMC+/PMCC. My perception at the time was that they had evaluated the legal and safety risks of these dodgy overheating chargers and this came up as an adjacent risk. IIRC it was in the same body of comms around the EVSEs. Whereas the LVB issue had already been tackled in updates 1+ year prior.

 

[Gino]

Sad that they will not let you convert to 240V (you could get 240V LED lights no problem, and use the 14/2 for 240V charging - AWG14 allows 15A, so you can charge at 12A, at 240V that would be 2.88KW). However, if 120V has been working for you, just keep the car plugged in whenever you're in the garage. While charging, the car should be replenishing the 12V (except perhaps some 2020 Taycans from what I heard). If higher rate charging ends up being needed, you could pickup a 20KWh+ battery bank (sold for campers) which will charge at 120V whatever current, but give you a 240V output (typically used for RV's). If you leave it charged in the garage, you will always have 10KWh or 20KWh+ ready to be transferred to your car at ~6-9KW, after than L1 speeds I presume (never used one of those battery banks beyond 0% SoC).

I’ve been thinking about getting a battery backup but realized in an emergency the last thing I want to do is drive my EV anywhere. In California where I live an emergency is likely an earthquake/fire, a Tsunami ir an attack by China which would devastate infrastructure. The last place you want to be is away from home. I’m better off just storing fuel for my ICE vehicles and keeping a few 5-10 gallon containers for water. At that point I couldn’t care less if my 12V battery dies…
I work with the DOD on National Security preparedness & technologies so unfortunately when I start thinking emergencies I go a lot further than power outages and weather emergencies that are only temporary and easy to ride out.
I hope we never experience anything worse…
I guess for now charging at 120V with my setup & use case works well for me and appears it won’t degrade my battery in doing so. I at least still have until 2030 to find out if my battery has degraded due to slow 120V charging…

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