Level 1 charging sufficient for low daily miles?

[MHS_MY]

So let me preface that I'm a newbie to the MY and EV driving in general so appreciate some patience here...

My daily driving is pretty limited and typically averages ~30 miles since I work remotely (even before COVID). So far, I can charge at Level 1 and easily get 60-80 miles during the time between school drop off/pick up, short errands, and overnight. For longer range/rapid charging, supercharger stations are easily accessible.

My house is older and the garage has a basement, crawlspace, slab, and plaster walls between it and the breaker so installing level 2 charging will be challenging and expensive I'm sure. I wanted to give some time with the level 1 charging before upgrading but so far it's been just fine.

Q: Is there any impact to the battery long term charging at Level 1? What is the optimal range to charge to for low daily mileage (I'm currently set to 80%)?

 

[silverstoned83]

There is no impact to battery longevity when charging with 110v. The main downside, besides the slow charge rate, would be the efficiency loss of converting 110v AC to DC for the battery pack. This would mean that every charge is costing slightly more than it would with 240v due to the conversion from 240v AC to DC being more energy efficient.

I would set the charge limit to 60% at the highest if you’re only driving 30 miles a day. You want to cycle the battery as close to 50% as possible in order to preserve the batteries health over the long term. I would only charge to 80% if I was planning on traveling 150 miles. Any further than that, I would then charge to 100%.

 

[jcanoe]

For 30 miles per day driving charging using a 120V/15 amp outlet should be ok as long as you plug in for at least 10 to 12 hour every day. I would stick with 80% charging limit. That way if you need to take a longer drive your vehicle is already charged to 80%. It would take many hours, too many hours, to charge from 60% to 80% so you could take a longer trip. At 120V and 8 amps you would at most gain ~3 miles per hour of charge. If you can charge at the higher 12 amp rate, something that you can only safely do if there are no other appliances running on the same circuit, then you be able to gain ~4 miles per hour. In cold weather charging will be slower because the vehicle will periodically warm the battery pack, robbing power that would otherwise be available for charging.

I would suggest that you replace the NEMA 5-15 or 5-20 receptacle you plan to use if it is older than 5 years. Receptacles that are old do not provide a tight connection for the plug, can overheat. Spend a bit more and to replace the existing outlet with a contractor grade or hospital grade receptacle of the same type as the existing receptacle. Never use the push in terminals to connect the wires; always use the screw down terminals.

 

[Rockster]

You're fine. No need to go to the expense and trouble of 240v charging if you don't need it. I echo the advice to just keep it charged to 80%. That way you're covered if the need for an unexpectedly longer trip crops up and keeping it at 80% all the time is perfectly fine.

 

[herg]

In cold weather charging will be slower because the vehicle will periodically warm the battery pack, robbing power that would otherwise be available for charging.

I had read the same, but this video shows otherwise.

 

[jcanoe]

I had read the same, but this video shows otherwise.

Two points:

The battery pack represents a large thermal mass. To cold soak the battery pack the vehicle would have to left unplugged in very cold weather for more than 12 hours. If the Tesla vehicle is not plugged in I do not believe that the battery temperature management system will draw power from the battery to automatically warm the battery pack. In warm weather, as long as there was at least some minimal battery state of charge (I'm thinking 20% SOC), the TMS would cool the battery pack using a combination of the fan and the AC. If the battery pack is colder than 32F the TMS will initiate warming the battery before any charging can happen. Outdoors in very cold weather the battery pack may have to be warmed every few hours for perhaps 10 or 15 minutes. At least in a Model 3, during these battery warming events some power is drawn from the battery so the electric motors can be operated in such a way as to produce heat instead of propulsion. These battery warming events will lengthen the time needed to complete charging of the battery.

You should never do what the owner of the Model 3 does in the video when he plugs in the Tesla charging plug connector to the vehicle before plugging in the mobile connector. It is even more important to always unplug the Tesla charging plug from the vehicle before unplugging the mobile connector from the electrical outlet to avoid electrical arcing at the receptacle.

 

[MHS_MY]

Thanks all, very helpful information! It is a newer outlet in the garage so the plug seats well.

The charging rate is usually 5 miles/hour but sometimes drops to 4, occasionally 3.

I'll stick with this for now and see if my driving habits change to warrant a level 2.

 

[Spacep0d]

So let me preface that I'm a newbie to the MY and EV driving in general so appreciate some patience here...

My daily driving is pretty limited and typically averages ~30 miles since I work remotely (even before COVID). So far, I can charge at Level 1 and easily get 60-80 miles during the time between school drop off/pick up, short errands, and overnight. For longer range/rapid charging, supercharger stations are easily accessible.

My house is older and the garage has a basement, crawlspace, slab, and plaster walls between it and the breaker so installing level 2 charging will be challenging and expensive I'm sure. I wanted to give some time with the level 1 charging before upgrading but so far it's been just fine.

Q: Is there any impact to the battery long term charging at Level 1? What is the optimal range to charge to for low daily mileage (I'm currently set to 80%)?

We're in the same boat. For some complicated reasons, I cannot yet install any kind of L2 charger or a Tesla Wall Connector (whish is sitting right here in my office). May have to sell it here, but that's another story.

At this point we're a two-Tesla household and both my girlfriend and I only trickle charge. 5mph charging isn't so bad overnight, and is pretty decent over a few nights as we mostly work from home. Neither of us has a commute and my girlfriend doesn't need to work for a while (which is in part why she has a Tesla).

In any case, Trickle or L1 charging has been more than fine. If I need to quickly top off for a trip I can use my Supercharging miles, and I still have 900+ free Supercharging miles so that helps.

In theory, I REALLY want to install my Tesla Wall Connector, but the reality is that I think trickle charging might be just fine for us, for now. I'm still trying to get this thing installed but it's not going to be easy, I can't get an electrician to commit to doing the job, and it will be hella expensive.

So for now, trickle charging is it, and it's not so bad. Helps to have a garage so we can charge (ideally off-peak) when we want.

 

[Oldmanelectron]

Remember the old saying, if there is nothing wrong with it don't fix it. Each person's needs are different. If you are doing fine with a level one charge, why spend the money for a higher charge rate? However, having a contingency plan incase your needs might change is a good idea. Replacing your old 120 vac outlet with an industrial grade 120 vac outlet may be a prudent move. Charging does cause heat and heat will cause your outlet to deteriorate faster. Also a higher grade 120 vac outlet may help increase your charge rate.

 

[Gizmotoy]

I charged my Model S on 120V/15A for years. Last year, knowing I already had full 20A wiring, I upgraded my 15A GFCI outlet to a 20A. It was convenient and worked for my needs. Just do what works.

 

[Koolio46]

I charged my Model S on 120V/15A for years. Last year, knowing I already had full 20A wiring, I upgraded my 15A GFCI outlet to a 20A. It was convenient and worked for my needs. Just do what works.

Similar...I don’t need more than 20amps (would be nice just in case but not doable due to cost and location of where my breaker panel is).

I had an electrician convert my existing 20 amp / 120v circuit to a 6-20 (240v) and that gives me 14 miles per hour. Perfect for my needs and a lot cheaper.

 

[qdeathstar]

i am currently level one charging only and driving about 15 miles a day and it seems to be working out just fine, even with the sentry mode. basically you gains 30 miles a night.

 

[Pilot1226]

You should be fine at 5-15. If you need slightly more in rare occasions, consult an electrician to see if a 5-20 makes sense.

Otherwise 240V is more efficient and will be better over time for cost savings. If you have time of use metering from your utility company it is more advantageous to get all your energy during off peak periods.

meaning if you pay 8 cents per kWh from 12A-5A, you want to get all your energy during that time. 120 will take longer.

 

[powaking]

Will work fine but is certainly the least efficient way to charge. Over time and in the long run it might cost more than if you were to bump it up to 220v. Even if its just a 6-15 that would be better than a standard outlet.

 

[Barrygold]

There is no impact to battery longevity when charging with 110v. The main downside, besides the slow charge rate, would be the efficiency loss of converting 110v AC to DC for the battery pack. This would mean that every charge is costing slightly more than it would with 240v due to the conversion from 240v AC to DC being more energy efficient.

I would set the charge limit to 60% at the highest if you’re only driving 30 miles a day. You want to cycle the battery as close to 50% as possible in order to preserve the batteries health over the long term. I would only charge to 80% if I was planning on traveling 150 miles. Any further than that, I would then charge to 100%.

exactly this. Per teslafi 120v charging in my experience is only 82% efficient. Its usually 98%-100% efficient charging on 240v

my last 120v charging session drew 9.7kWh and only put in 7.9kWh into my battery.

 

[jcanoe]

exactly this. Per teslafi 120v charging in my experience is only 82% efficient. Its usually 98%-100% efficient charging on 240v

my last 120v charging session drew 9.7kWh and only put in 7.9kWh into my battery.
View attachment 596340

I question the claimed efficiency of 98% to 100% for 240V; nothing is 100% efficient. A better estimate for Level 2 charging efficiency is 90%.

 

[Pilot1226]

Well, if you take the roughly 300 Watts overhead away from 11,520 (240V@48A), that would be 11,220 Watts or 97.3%.

But that also assumes the full hour was needed to charge.

 

[Barrygold]

I question the claimed efficiency of 98% to 100% for 240V; nothing is 100% efficient. A better estimate for Level 2 charging efficiency is 90%.

I get a lot 97% to 100% reports. I understand nothing is 100% efficient. Just relaying the info from TeslaFi that is based off of actual data and not my estimate.

 

[jcanoe]

There are many parts of the charging process where losses will occur including:

warming of the wiring while charging,

warming of the battery pack while charging,

AC to DC conversion losses while charging

active cooling of the on-board charger while charging

in warm weather active cooling of the battery pack while charging, after charging has been completed,

active heating of the battery pack in cold weather prior to charging, while charging in cold temperatures.

If you plug in and start charging as soon as you arrive at your destination or arrive back home the battery pack will most likely be closer to the optimal temperature for charging, i.e. 120F, than if you have set up delayed charging. Charging later that evening, when the battery pack is cooler, may not trigger warming the battery pack unless your navigation destination is a SC.

One of the reasons why Level 1 charging is less efficient than Level 2 charging, i.e. ~80% versus ~90% efficient, is the amount of time spent charging. Charging at Level 2 can be 2x to 10x faster than charging at Level 1. For every hour that the vehicle is charging there is some level heat loss through the wiring and the charging circuitry.

 

[frankvb]

One of the reasons why Level 1 charging is less efficient than Level 2 charging, i.e. ~80% versus ~90% efficient, is the amount of time spent charging. Charging at Level 2 can be 2x to 10x faster than charging at Level 1. For every hour that the vehicle is charging there is some level heat loss through the wiring and the charging circuitry.

And the other reason is that the car will never go to sleep during charging. That in itself is in the order of 200-300W.

The slower you charge, the larger that is as a percentage of the charging power.