Leaf or Bolt charging ~ current limiting

3 replies [Last post]
Joined: 07/15/2009
Points: 490

I put a J-1772 on my VX-1 and just got an adapter to put on Zero now. I guess it is like charging a Leaf or a Bolt. I just swipe my card and charge at U-Mass Lowell or the free one in Maynard. I don't understand the limitations of the charger though. I don't mind 12 amperes ~ 1440 Watts but does it still will do 12 amps, or does it do more like 16 Amperes if you use 240 volt NEMA 6-20? There are so many on Amazon and eBay. I was told it can be plugged into 240 volt with an adapter to change 120 pin out to 6-20 type. Rather then risk burning out a small charging cord, I found a BSA Electronics Duosida Level 2 car charger charges your car 3x faster than level 1, with a NEMA 6-20 all ready installed. So the charger is still in any car but the J-1772 just gets it to the actual vehicle. It must somehow determine how much current to draw? My scooter the VX-1 does 10 amp on pack and 12 amp or so from wall and if I use 6-20 outlet it only will draw 7 amperes. The more voltage I give it the less current it will draw. So I figure a BOLT will do about the same scenario? Half the current.?
I didn't know that charging device can be programmed as Brad says he uses "Open Source software". I will get his charger or charger cord vs Nissan or GM 's Voltec charger cord.
Why use an adapter when one can get a nice designed unit with proper plug and still be able to charge directly or use a dryer plug ~ 10-30 to 6-20 if you have one. It will draw what it needs and not the full 30 amps of dryer? I guess also if it is 240 volt with that type of plug is is like "backwards compatible" to 120 volts? Like a computer brick on a laptop, 100-250 volt input. Does any one use the Chevrolet Volt, 120 volt trunk charging device on 240 volts with an adapter cord? Or does it blow up? It is a $400.0 replacement cost.
Some of the part numbers are 23487635, 24277224, & 24276685. No matter where I charge my motorcycles I always read 10 amps on Vectrix speedometer and wonder how the car chargers work with J-1772 cords or charging devices.



Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.
Joined: 07/09/2011
Points: 851
Re: Leaf or Bolt charging ~ current limiting

Think of it as like plugging a cell phone charging adapter into a 120 volt, 20 amp circuit. Does the circuit try to cram 20 amps into the little phone charging brick? No, the device draws what's needed and no more. EVs are the same way, albeit a little more sophisticated. The onboard charger draws its rated current if that much is available, and whatever is available below that if less.

Joined: 03/26/2012
Points: 229
Re: Leaf or Bolt charging ~ current limiting

Going on from what LeftieBiker accurately and succinctly said, most modern EVs (the LEAF included) have circuitry in them that requires they be connected to the mains via an 'electric vehicle service equipment' or EVSE. Note that this is *not* a 'charger' - that is in the EV. It is simply a glorified switch whose principle function is to provide as safe a charge as possible.

One of the main functions (if not *the* main function) of the EVSE is to establish a simple form of analogue electronic communication with the EV and it does this using a device called an 'electronic protocol controller' or EPC. This why you can't simply connect L & N to the EV charging socket and expect it to charge. The EV won't start a charge without the correct comms.

In the US I gather most of your low power (Level 2, Mode 3) public EVSEs have tethered J1772 plugs. You must all be a lot more trusting than we are here in Europe as all our public EVSEs are 'free cable' types where the EV driver has to supply the connecting cable, all of which have a Type 2 male plug on the EVSE end and then either a Type 2 or Type 1 (J1772) plug on the car end - appropriate to your EV. The principle advantage of this arrangement is that one basic (and relatively cheap) EVSE can service all types of car, not just those fitted with a Type 1 charging socket.

In a free cable EVSE the main function of the EPC is to ensure safe charging by limiting the rate of charge (ie amps) according to the amp-carrying capacity ('ampacity') of the connecting cable. It does this by measuring the value of a resistor fitted between the PE and PP pins on the EVSE end of the cable which is coded according to the ampacity of the cable.

A tethered EVSE does not need to do this because the tethered cable is specified according to the maximum output of the EVSE at manufacture.

Thus, the EPC 'advertises' the maximum current available to the EV upon first connecting and the EV chooses accordingly and off it goes.


Regards, Martin Winlow
Herts UK

Joined: 11/22/2006
Points: 1383
Re: Leaf or Bolt charging ~ current limiting

Note that a level 2 EVSE typically limits the charging rate not based on the gauge of the charging cable but on the circuit the EVSE is connected to. My kit-built EVSE at home is connected to a 30 amp 240 volt clothes dryer circuit, so I set it at 25 amps. My Smart ED only draws 15 amps and the TC charger in my CuMoCo scooter only draws 5 amps (or 10 amps at 120 volts - it stays at 1200 watts either way).

Regarding the EV owner having to bring their own cable in Europe due to cable theft, I guess the reason we don't have to in the US (in spite of a higher crime rate) is simply becasue in the US, EV's and EVSE's are still quite rare and the stolen EV plugs and cable have no market except for the copper, and new laws require scrap dealers to get ID information of every seller.

Do the European thieves steal the cable for sale and use in another EV, or just for the copper?

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

Who's new

  • AllThingsElectric
  • albertom
  • Bohdan
  • Username
  • Dean b
Customize This