Is slow charging with 110 v outlet bad for your battery?

[Wildbill]

I picked up my white AWD, 19" wheel Model 3 about 2 weeks ago. Coming from a 2001 Mercedes (that's right, my last car was from 17 years ago), I feel like I am driving a spaceship everyday. It has exceeded all my expectations and imaginations.

But I still have not installed my NEMA 14-50 outlet yet. One electrician told me that my circuit breaker cannot support it. Another told me that I may be able to get away with a NEMA 14-30 outlet.

So, I have been charging with my regular household 110v outlet in the garage, getting 4 miles per hour. This is OK for now, since my daily commute is 40 miles total round trip, and I can charge 10 hours on weekdays and longer on weekends.

But I noticed that when I charge to 80% of capacity I am getting only 245 miles today, but I vague remember I was getting 247 miles last week. (Theoretically, I should have 248 miles since 80% of 310 miles=248 miles)

Is the slow charging with 110v outlet degrading the battery? Should I install the NEMA 14-30 as soon as possible?

 

[dhrivnak]

No unless you have temperature extremes as battery heating an cooling are restricted with 110v. But lower than 100 and above 25 should be fine.

 

[Eno Deb]

No, it is not harmful. And your battery isn't degrading, it's just that the range displayed on the screen is not an exact number but an estimate that can vary by a few percent.

 

[brockm]

It’s not bad for the battery. But you’ll actually end up using a lot more electricity to charge. Lower voltage charging has much lower efficiency, due to the need to step up the voltage in the charger.

If your electricity is cheaper at night, but the charging speed forces to do daytime trickle charging, that wasted electricity will add up to much higher power bills. So eventually the cost of not paying the electrician adds up quite a bit.

 

[Akikiki]

Wildbill, both answers above are accurate. One rule of thumb to remember - that Tesla has told us - A happy Tesla is a Tesla plugged in.

And yes, if you can't install the 14-50, (that's 40 amps of charge) then the 14-30 (that's 24 amps of charge) is better than the 110 (which is probably a 15 amp circuit - so its 12 amps of charge). As you can see the 24 amps is twice as fast or half as long to charge as the 12 amp 110 your car will pull.

Sounds to be that you would find this helpful. Charging Your Tesla (S/X/3) | TeslaTap

 

[Kirby64]

It’s not bad for the battery. But you’ll actually end up using a lot more electricity to charge. Lower voltage charging has much lower efficiency, due to the need to step up the voltage in the charger.

If your electricity is cheaper at night, but the charging speed forces to do daytime trickle charging, that wasted electricity will add up to much higher power bills. So eventually the cost of not paying the electrician adds up quite a bit.

Unless the difference between trickle charging ('prime time') pricing and off-cycle pricing is pretty substanial, it's actually unlikely you'll pay for the installation of a 14-50 or what-not. Cheapest you're looking at is probably, what, $750 for an electrician? (That's a good price for an install). I've seen prices on here SIGNIFICANTLY higher. Just in parts it's usually around $300.

Assuming all equal on pricing, people have noted the difference in efficiency between 120V and 240V is roughly 85% vs. 70%. Let's use those numbers. I think I'm being pessimistic on 120V and optimistic on 240V... but anyways.

Assuming you drive around usual driver per year (12,000 mi a year), and assuming you get average efficiency (240Wh/mi), then you'll spend roughly the following per year on electricity:
2880 kWh of electricity from the car
Assuming 85% efficiency gives you:
3388 kWh at the meter.
Assuming 70% efficiency gives you:
4114 kWh at the meter.

Delta:
726 kWh.

Let's assume you pay $0.20c/kWh (most people outside of Cali pay less...):
That's $145/yr in extra cost. Payback time on a $750 install is 5.1 years. Unless you can snag an electrician for cheaper, or your off-peak vs. daytime charging rates are substantially different, you're never going to make it back in power charges.

Reasons you'd want to go 240V have to be:

• More range added in shorter time (even 120V 20A only adds ~80mi overnight)
• Commutes that mean the charge added by 120V isn't sufficient (or, weekend traffic that means it isn't sufficient)

Personally I use 120V 20A as my main charging and I don't have any troubles. My round trip commute is only 40mi a day though.

 

[MorrisonHiker]

Wildbill, both answers above are accurate. One rule of thumb to remember - that Tesla has told us - A happy Tesla is a Tesla plugged in.

And yes, if you can't install the 14-50, (that's 40 amps of charge) then the 14-30 (that's 24 amps of charge) is better than the 110 (which is probably a 15 amp circuit - so its 12 amps of charge). As you can see the 24 amps is twice as fast or half as long to charge as the 12 amp 110 your car will pull.

Sounds to be that you would find this helpful. Charging Your Tesla (S/X/3) | TeslaTap

Just a reminder: the Gen 2 MC will only give 32 amps on a 14-50 outlet. The original Gen 1 MC would provide 40 amps on a 14-50 outlet.

 

[Wildbill]

Thank you everyone for your reply.

I am glad to know that I am not harming the battery.

It is also interesting to know that others are using the 120v outlet to charge.

 

[ebmcs03]

I use the 110v a lot. I’ve had EV since 2014 and never installed a L2 Charger LoL.

It’s mainly because the Fiat 500e was a lease and I only had 10,000 miles a year to use so I had more electricity than miles to use.

But at $750 up front cost that’s a lot of electricity if I can get by with 110. So I have not convinced myself to fork out the L2 installation.

 

[rainforest]

It’s not bad for the battery. But you’ll actually end up using a lot more electricity to charge. Lower voltage charging has much lower efficiency, due to the need to step up the voltage in the charger.

If your electricity is cheaper at night, but the charging speed forces to do daytime trickle charging, that wasted electricity will add up to much higher power bills. So eventually the cost of not paying the electrician adds up quite a bit.

Can others confirm whether it’s true that I will be using much more electricity?

 

[ebmcs03]

Can others confirm whether it’s true that I will be using much more electricity?

Yes. You will. But not “much” more. There’s overhead that is used to convert the AC power to DC. The longer that inverter needs to run the more electricity is wasted to convert that power.

I thought i read it was around 300W an hour for over head to run that AC converter and cooling system etc.

 

[stonelance]

If you look at the charging rate table with the various charging plugs, 240v adds almost 4 times as much range per hour at 20 amps as the 120v (15mph vs 4mph). That seems to indicate it is almost twice as efficient?

 

[Nilnoc]

It is also interesting to know that others are using the 120v outlet to charge

I have charged my Model X on 120 volts for the past 7 months. I don't have a daily commute, more like a daily shop. Nevertheless, we go a visiting out of state a lot. 'Ava' has 10.4K miles under her belt. At least half is long distance miles. And there have been 47 supercharges.

My Tesla charges at 2.9 mph, or 1 percent per hour. I've managed fine and avoided a bill of well over $1000 to get a 240v line buried on it's 150 ft trip from house to detached garage. The trick is to always be charging in the garage.

 

[Jedi2155]

120v uses "much" more electricity than 240v charging. In regards to battery health, its probably better for it though lol.

 

[corduroy]

When I first got my Model 3 (sooner than expected) I was frantically getting quotes to install a 14-50. But after a while I realized, the 120v in my garage was working out just fine. My commute is 30 miles round trip and I always make up that charge at night. Now, I'm in no hurry to spend a chunk of change on an electrician.

I don't think it is bad for the battery at all. My only thought was, I wonder if it is more wear and tear on the charger inside the car to be running almost all of the time when my car is parked at home.

 

[Kirby64]

If you look at the charging rate table with the various charging plugs, 240v adds almost 4 times as much range per hour at 20 amps as the 120v (15mph vs 4mph). That seems to indicate it is almost twice as efficient?

Charging table is inaccurate for the 120V Model 3 options listed. Actual results for 120V 20A are ~6-7mph. Still an efficiency gap, but significantly less.

 

[Kirby64]

120v uses "much" more electricity than 240v charging. In regards to battery health, its probably better for it though lol.

Very unlikely. Most Li-Ion chemistries allow at least 1C charging without significant degradation (i.e., a 2Ah battery should be able to charge at 2A fine and not suffer much degradation).

0.5C or 0.1C charges would be considered pretty conservative.

Pack voltage fully charged of the Model 3 is ~420V or so. Assuming 75kWh battery, that gives us a ~178Ah pack.
Keep in mind the AC power has to be converted to DC to charge the battery, so losses are incurred.

Even assuming a fully efficient charge circuitry, you're looking at a max of 240V*48A = ~27A at 420V. That's a ~0.15C charge rate.

By comparison, superchargers at 115kW charge at well OVER 1C, so you can see why Tesla warns they may cause battery degradation over time.

 

[Akikiki]

When I first got my Model 3 (sooner than expected) I was frantically getting quotes to install a 14-50. But after a while I realized, the 120v in my garage was working out just fine. My commute is 30 miles round trip and I always make up that charge at night. Now, I'm in no hurry to spend a chunk of change on an electrician.

I don't think it is bad for the battery at all. My only thought was, I wonder if it is more wear and tear on the charger inside the car to be running almost all of the time when my car is parked at home.

I am not trying to sell you something. But you took delivery in warm weather in Minnesota!! You've not experienced a winter with your Tesla yet. Please start looking here and on TM (particularly under Model S and X) for range loss in cold weather. I have nothing to gain in my prediction, but I suspect that your 120v charging is not going to keep up with battery charging and you will likely see no gain after charging for hours. You need your battery warm/hot when you leave in the a.m. This cost your range to warm the battery and the cabin. You want the charge to finish just about the time you are ready to unplug and leave. Well finishing and unplugging at the same time should not be a problem for you, I am betting (I am concerned for you) that you will still need charging and have not topped off. Even if you are charging in a garage. I hope your garage is heated.

I've had my S's now for almost 6 years. And in a warm climate. Although, I've not personally experienced this issue, I have read many threads and posts about it. I recommend you get some quotes and see if you can at least install or re-route/share your 14-30 dryer circuit with your car. Even if you think you don't need more charging capability, at least be ready to add.

 

[Brenzo]

Also, don't be afraid to go with the 14-30, or even a 6-20 or 6-15 if it helps keep the install costs down by allowing electrician to simply add an additional wire or two through existing conduit to your outlet box. You'll still see a significant improvement in charge speed, even if you won't lose a ton of range in mild Bay Area winters. For your daily use, the 14-50 is likely overkill.

 

[Jedi2155]

Very unlikely. Most Li-Ion chemistries allow at least 1C charging without significant degradation (i.e., a 2Ah battery should be able to charge at 2A fine and not suffer much degradation).

0.5C or 0.1C charges would be considered pretty conservative.

Pack voltage fully charged of the Model 3 is ~420V or so. Assuming 75kWh battery, that gives us a ~178Ah pack.
Keep in mind the AC power has to be converted to DC to charge the battery, so losses are incurred.

Even assuming a fully efficient charge circuitry, you're looking at a max of 240V*48A = ~27A at 420V. That's a ~0.15C charge rate.

By comparison, superchargers at 115kW charge at well OVER 1C, so you can see why Tesla warns they may cause battery degradation over time.

Focusing only on the charge rate in relation to cell impact, missing the picture in regards to BMS balancing performance. A lower charge rate would allow BMS balancing time to adjust to differences in module pack differences at finer level. Exactly what the limits of the BMS balancing circuit is, I'm not sure, but generally with the lower the charge rate, the easier it is for a pack to be balanced.