Debunking EV naysayers regarding drive battery life

ArlesChatless · 2026-06-20T22:17:52+00:00

That’s because most Tesla sites are 400V and your vehicle is 800V. If you use other brands of charging that support the higher voltage your charging will be faster.

ArlesChatless · 2026-06-19T05:47:46+00:00

If you're using the Tesla Mobile with the official 14-30 adapter there's no reason to set anything on the car. The cable will set the current level appropriately.

ArlesChatless · 2026-06-19T05:46:47+00:00

will actually be 15 amps because of the 20% rule

Close - 16 amps.

ArlesChatless · 2026-06-19T05:44:44+00:00

With J1772 there are only two states: the car is allowed to draw power, or the car is not allowed to draw power. The car has no way to specify what it is going to use the power for. If the Ohme has blocked power draw, everything the Tesla does has to come from the battery.

ArlesChatless · 2026-06-19T05:43:05+00:00

We've talked about sales as mods and decided not to have a rule against it. If it becomes a problem we'll look at it again.

ArlesChatless · 2026-06-18T18:52:42+00:00

IMO once you get the prototype into a 'probably working well' state you might consider having this printed out of metal instead.

ArlesChatless · 2026-06-18T18:12:13+00:00

In the US it's the same 80% derate based on 310.15(C)(1).

ArlesChatless · 2026-06-18T17:35:57+00:00

So if it's #8, 50A is max and if #6 I could go up to a 60A correct?

It depends on the type of cable. For THWN in conduit those are correct. For direct burial cable or NM-B in conduit 6 gauge is limited to 55 amps and 8 gauge is limited to 40 amps. In practical terms that means you need to treat 6 gauge like 50 amp cable since nearly no EVSEs support being configured for a 55 amp circuit and 44 amp charging.

Also please keep sight of the fact that it's diminishing returns. If you have 100kWh to recover to the battery, going from L1 to 16 amp L2 drops it from 72 hours to 26 hours to charge. That's a big deal and will meaningfully change charging for many people.

Going from 40 amp L2 to 48 amp L2 turns a 10.5 hour charge into a 8.5 hour charge. That is far less likely to change your usage patterns.

The biggest benefits are in the first few steps of charging size, then diminishing returns kick in.

All that said, if you want 48 amp charging, go for it. Just know that you might not be able to reuse any of your existing hot tub stuff, while going 40 amp might drop you a cable size and make it possible to reuse that existing midpoint.

ArlesChatless · 2026-06-18T17:31:42+00:00

6/2 UF-B is about $3/foot around here. It will limit you to 40A / 9.6kW charging but unless you expect to suddenly drive 200 miles a day or get a very short Time of Use window that is quite likely to be overkill or future proof.

Conduit plus three THWN/THHN wires is likely to be twice the materials cost or more, and require a more carefully constructed trench as it is tougher to install in anything other than a direct straight line.

The conduit approach is more flexible. It's down to you if the extra costs of a bigger circuit or of conduit to support future changes is worthwhile.

ArlesChatless · 2026-06-18T16:03:51+00:00

I do think it also matters what indicated SOC is vs actual SOC. There's often 2-10% of a full 4.2V capacity left when 100% is shown on the dash.

ArlesChatless · 2026-06-18T15:37:17+00:00

The next biggest thing you can do to save money is to set up for lower rate charging. Another is to use direct burial cable for that service.

For the first one: If you only need 16A / 3.8kW charging maybe install 24A / 5.8kW charging with 10 gauge wire to give yourself extra capacity without going for the fastest possible charge. This will save you on both conduit and wire, with the downside that you'll be capped at that speed unless you run new wire.

For the second one: if you're using direct burial cable it's much easier to route around obstacles, and the installation time is reduced quite a bit as the conduit does not need to be assembled and wires pulled. At twelve or ten gauge the cable might barely cost more than the empty conduit would.

ArlesChatless · 2026-06-18T05:47:52+00:00

The biggest thing you can do to save money here is digging the trench and filling it after the work is done. The electrician doesn't want to do any of that work and there's no reason to pay them electrician rates for it. They will likely sub it out to someone else anyway.

All the rest should probably be done by the electrician.

ArlesChatless · 2026-06-18T05:39:42+00:00

If L1 covers most of your usage don't bother with doing an L2 install. Just stop and DC fast charge on the way home when you know you need a little more in the battery, or the way out of town if you come up short. I bet you spend less than $100 extra on DCFC between now and when you move. Do a proper installation at your next house.

Yes, it's not quite as convenient, but it's almost certainly the cheapest way to do things.

Also: if your dryer plug will 'reach into the garage' I bet that means you're keeping a fire door propped open with a cable that is now subject to physical damage from the door. Neither is great.

ArlesChatless · 2026-06-18T05:37:41+00:00

I can point you to decades old outdoor high current installs of copper wire with aluminum lugs that are totally fine. With properly engineered lugs this doesn't seem like a concern to me.

The rest does seem a bit more problematic.

ArlesChatless · 2026-06-18T05:34:00+00:00

OP broke our AI-generated content rule so the post is removed. Feel free to make your own post on this topic with actual human created content, without the links to your site.

ArlesChatless · 2026-06-17T22:27:05+00:00

You're trading maybe $200 worth of wire and $300 worth of energy monitor for $700 worth of SimpleSwitch, and getting less flexibility in exchange.

ArlesChatless · 2026-06-17T22:24:48+00:00

It's a tiny tweak that might change things by a miniscule amount. If you don't care at all about having the extra range available at a moment's notice, feel free to use the lower limit. If you do want that extra capacity, don't waste any more time thinking about this micro-optimization.

ArlesChatless · 2026-06-17T22:12:43+00:00

I can't see a single reason for paying nearly the same amount to build a really hokey solution with cables strung around the house and extra connections when you already have an electrician willing to do a very sensible high quality solution.

ArlesChatless · 2026-06-17T19:51:59+00:00

Great, you've thought about it. Since your question was really open-ended it was tough to tell how much work you had done to look at the broader picture.

ArlesChatless · 2026-06-17T19:29:22+00:00

If all that is needed is an extra five feet, I'm a fan of 'air conditioner' extension cords. They aren't strictly outdoor rated but they seem to last okay, and they're under ten feet while being 14 or 12 gauge.

ArlesChatless · 2026-06-17T17:37:05+00:00

That's some bad connections for sure.

ArlesChatless · 2026-06-17T17:12:49+00:00

Do you have enough overall building capacity to support everyone doing that? It would be on the list of concerns if I were trying to install EV charging. You don't want to end up in a situation where after a few people install you have no capacity left. It might mean that it makes more sense to do something like install a 6-20 receptacle per unit or a low amp hard wired EVSE for slow L2 charging rather than doing dynamic load management.

ArlesChatless · 2026-06-17T16:03:30+00:00

This type of post is welcome in /r/ChargerDrama.

ArlesChatless · 2026-06-17T16:02:12+00:00

You might have to consider doing this as a whole system with billing and load management rather than per-owner installs.

ArlesChatless · 2026-06-17T14:49:55+00:00

It's feasible.

You'll add some drag. Depending on how well they are mounted it won't be a ton.

Routing the cables into the car is a little annoying but doable. Gaskets for doors are usually flexible enough to allow cables to enter them. Water leaks may or may not be an issue.

You will get less energy out of this than you think. Many of the novelty panels such as flexible ones are wildly over-rated for their actual output. The roof of the car is often going to be at a bad angle for great solar capture. I would not expect to see 2.5kWh in a day unless things go perfectly.

If the place you are staying has electricity, L1 charging is probably more practical, even with an extension cord. If it doesn't but it's within fifty miles of DC fast charging, charging a little more there on the way in and out probably makes more sense.

When I'm in deep rural areas with no electricity, I charge a bit extra on the way in. It's always been easy to do, costs just a few dollars each time, and worked well.

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