Questions about charging

Discussion in 'General' started by Stephen Cerruti, Oct 22, 2020.

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  1. Stephen Cerruti

    Stephen Cerruti New Member

    I have a little knowledge, that makes me dangerous.

    I understand that it is better over the long term to charge your battery more slowly.
    I understand that it is better to keep your battery between some set points (maybe 30%-80%, depends on vehicle.)
    My TOU plans give me a 6 hour window for charging (midnight to 6AM.)
    The vehicle will drive 90 to 100 miles per day.
    The vehicle has a range of 208 miles.

    This implies charging every day at a rate of at least 90 / 6 = 15 miles per hour but to be safe 120 / 6 = 20 miles per hour.

    Looking at the ChargePoint Flex table leads me to a 30 to 40 amp circuit (probably 40.)

    Based on the information in the installation guide the charger can be configured to charge at a slower rate than the provided circuit.

    1) Please correct my initial assumptions.

    2) Is there a benefit to future proof the installation to provide a bigger circuit and throttle it down for normal use or is this just a waste of money? (for my fellow agile geeks YAGNI)

    3) Is there a way, with the ChargePoint Flex (or other charger) to choose a higher rate for a specific charge and leave your scheduled charges at the lower rate? (Maybe you should just visit a public charging station?)

    4) Specifically for the ChargePoint Flex, is it worthwhile (in your opinion) to set up WiFi in the garage just for the charger? Can you just use the car's hotspot and what are the downsides of that i.e. do I care about the charger when the car is not in the garage?
     
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  3. bwilson4web

    bwilson4web Well-Known Member

    1) Please correct my initial assumptions.

    If you live in a temperate climate, you'll need extra power to handle AC and heating. I'd recommend a 50A, 240VAC (North America) circuit.

    2) Is there a benefit to future proof the installation to provide a bigger circuit and throttle it down for normal use or is this just a waste of money? (for my fellow agile geeks YAGNI)

    The car will set the charging rate and the one you have today should not limit your future choices.

    3) Is there a way, with the ChargePoint Flex (or other charger) to choose a higher rate for a specific charge and leave your scheduled charges at the lower rate? (Maybe you should just visit a public charging station?)

    I don't know the ChargePoint Flex but my two can limit the current and schedule time to charge. Just remember the car sets the maximum limit.

    4) Specifically for the ChargePoint Flex, is it worthwhile (in your opinion) to set up WiFi in the garage just for the charger? Can you just use the car's hotspot and what are the downsides of that i.e. do I care about the charger when the car is not in the garage?

    I did for my two JuiceBox 40 Pro chargers using T-Mobil, mobile hotspots. They cost $10/month each but it means I get the data as well as the ability to configure them remotely.

    Bob Wilson
     
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  4. TTXGPFAN

    TTXGPFAN New Member

    Well, this thread died months ago, but after owning my Bolt for 6 months and using (and eventually creating an adapter for) my stock EVSE I have been thinking about similar things. A lot. I'll add this in case it might help someone.

    At 100 miles if I play it down the middle and assume you are getting 3 miles per kWhr. That means not factoring in heating and cooling, you'll need to replenish 33.3 kWhrs in that 6-hour window. That works out to a 5.5ish kW charge rate needed. Assume a long distance from the panel and 220V. That means you'll need at least 25.25A. So a supply of 32A from the EVSE would seem to do the trick. But US regulations only allow you to pull 80% of the amps the circuit is made for. So that is a 40A circuit. Now, you only want to do this once. So if you want it as future-proofed as possible, you don't want to pay for wiring to be run twice. Pay up for the 50A circuit for a 40 charger, or 60A for a 48A charger, 70A to cover up to 56A.

    But if you want to make sure you are being frugal, think about the most range you feel you will need to replace. I made an adapter so I have the EVSE that came with my Bolt running on 240V and giving me almost 3kW. That has proven to be more than enough really for my 52-mile commute and coming home from a 200-mile road trip with less than 15% of my 66kWhr pack. I also average about 3.55 miles per kWhr between cold and warm weather. YMMV.
     
  5. Paul K

    Paul K Active Member

    You can also run into trouble if your supply panel relative to potential load is not up to snuff. I live in a semi-detached with all electric heat serviced by a 125amp panel. The electrician informed me that I would have to either upgrade to a 200amp panel or reduce the potential load. I had the baseboard heaters taken out as I only use the basement for a workshop and storage. This allowed a 30amp dock to be installed with a 40amp circuit and it's more than enough for my needs.

    I use the charging timer in the Leaf to select an interval to bring it up to around 80% finishing up at 7am when higher rates kick in. BTW before this I usually managed with just the 110v outlet plugging in as soon as I got home. For busier days I might stop at an public L2 charger and go for a walk or jog while it topped up.
     

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