Technology

We have a granny charger that came with one of our EVs that we use as a backup and with our caravan to charge on sites that allow it. As I am UK it tops out at 2.4kw (10A @ 240v) and its annoyingly slow even charging for more than 12 hours at a time.

Our main home charger is 7kw, and as we get cheap electric every night for 7p a KwH for 5 hours, we can charge about 40kwh in that time period. Means even our largest battery is fully charged in two nights from completely empty. If we tried that with the granny charger it would cost significantly more, as it would be up to 40p a KwH outside of the main hours and take 40 hours to charge the same amount.

Now if you doing only a few miles a day, less than 40 miles (4 miles per KwH, charge for the 5 cheap hours using the cars charging timer, charge 10 KwH), it might work out ok for you, but then charging every day cannot be good for the battery? I know it would get annoying quite quickly. It would also get pretty painful if you have more than one EV, we have three between us and the kids, so its not remotely practical.

I watched the video and it seems to make good points, but no matter how many times I see something related to US power circuits it just feels so ... antique? I have 3x25A fuses on the house and several 3x16A outlets around so getting 11kW out is just a matter of plugging in a socket.

Obviously it would be a good thing to have controls so that water heater, floor heating or sauna stove aren't all on together but I think I've replaced a single 25A fuse over 10 years we've lived on this house and I'm pretty sure that was caused by a small(ish) surge on the grid and not our load.

In recent test of a German auto club they found out that it‘s cheaper/ more effective to charger faster. You loose a lot of energy if you load slow over hours.

This energy is taken by the electricity of the car. So, while charging the car is on and takes some Watts. There are just a few brands that have decoupled the charger circuit from the overall electric circuit of the car.

Can’t find the article now, but I think charging a PHEV through a standard power plug had about 20% energy lost. It was clearly visible that a charger is a good choice.

Edit: link https://www-adac-de.translate.goog/rund-ums-fahrzeug/elektromobilitaet/laden/ladeverluste-elektroauto-studie/?_x_tr_sl=de&_x_tr_tl=en&_x_tr_hl=de&_x_tr_pto=wapp

You‘ll loose

• ~10-30% AC 2.3kw Standard Power Plug
• ~ 5-10% DC 11kw Wallbox
• Internal car electronics are crucial: Is the loading circuit de-coupled or the entire car On?
• Temperature or pre-heating the battery before loading reduces losses at DC charging

You might not need 50 amps now. But that line is a 1 time cost and maybe you'll want to weld one day.

I agree with this youtube comment:

As an electrician (in Australia), I agree with your basic premise. However, if you are asking me to install an EV charger, unless you tell me “I want it to charge slowly with a limited current capacity”, I am going to assume it is to charge an EV under ALL situations - fast to slow, for whoever may drive one today or in the future, even with a potential new homeowner. We generally do our work with the priority order (1) safety - nobody gets an electric shock and nothing catches fire; (2) avoidance of nuisance i.e. the thing you just installed doesn’t work and keeps tripping the breaker 😑 (3) avoiding needing replacement electrical work for at least 25 - 50 years

Also I live in a townhouse with no garage. Our charger is between the neighborhood sidewalk and our parking spaces, so I'd prefer keeping it plugged in as little as possible to minimize any issues with foot traffic (neighbors, delivery people, garbage pickup, etc). I've seen other townhouse EV owners literally run an extension cable over the sidewalk to do an L1 charge for their EV and that's just asking for trouble.

I think “might be overkill” would be a better title and position than “usually overkill.”

There is absolutely a subset of EV drivers that could get by with a level 1 charger (ignoring time of day rates), but most people would fall behind anytime they drive further than the average number of miles. Sure, taking 10 hours to recharge your Chevy Bolt overnight when you’ve driven 40 miles is doable; 64 hours when you’ve returned home from a longer trip isn’t.

I own a PHEV, and installing a level 2 charge has been one of the best quality of life and financial changes.

Good video. Accurate information.

Two notes:

1. For North American homes: I agree with the overlooked value of a downrated circuit for EV charging, but I don't think he talked about a possibly better option for downrating: Using an existing 120v circuit (at whatever current rating) already wired in the garage . Remove the outlet, install EVSE (charger), and swap the breaker for a 240v one (at a current rating matching the original. So if you have a 120v 15A circuit (white romex) you can use the exact same wire for a 240v at 15A. If you have a 20A (yellow romex) you would end up with a 240v 20A. You get more than double the speed of charging with zero new wires added, only changing the breaker and removing the old outlets. Note: If you have multiple outlets in your garage all fed from this same circuit, this would mean all of your outlets in the garage are now 240v and not usable for regular 120v items.

2. He didn't like Smart chargers. Thats a valid opinion, but smart chargers can do some nice things that I like. Some will also talk to each other if you have two chargers, such as if you have two EVs. They can be configured to share the same wire to the breaker box, so you can plug both cars in at night, one car will charge, then when that is complete, the other will charge automatically without having to unplug one car and then plug in the other. It will charge the least charged car first ensuring the best balance of charge to both cars assuming both cars can't be charged to full in one night. If you have solar panels, some smart chargers can talk to the solar system and be instructed to only charge when there is excess power that would otherwise go to waste. It can do this automatically so if clouds go overhead and not enough juice is available from the sun, the charging stops. As soon as the clouds clear and there is an excess again, charging resumes automatically. For outdoor charging, you can also configure most Smart chargers to only charge you authorized cars. So you don't need to worry about someone rolling into your driveway when you're not home (or a bad neighbor) and running up your electricity bill.

could this be an article instead of a video? I'm not spending 32 minutes watching this, tbh

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