daveo4EV
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- David
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Team,
sometime's it's interesting to inspect the objects we use everyday but never really look at - this posting has been well received else where and shed's "high level" light on how this whole L1/L2 AC EVSE charging works in North America - nothing to see here if you don't care - but for the curious - this is a quick primer on the internal's of the J-1772 connector - it's limitations and design…it's simple really - not much to see here…
read on - enjoy and comment as you see fit…
Any electrician worth their salt can swap between a plugbased EVSE and hardwired EVSE setup in less than an hour once you have circuit/box with the power source/supply sorted to the "box" location…less than $30 worth of Home Depot parts can convert any hardwired connect to a plug (50 amps or less) - and you can always remove the plug and just hardwire any electrical device directly to the wires that were used for the plug (15 amps or more)…if you're 50 amps or smaller swapping between plugs and hardwiring is trivial…easy and honestly can be done in less than 30 min and some wire nuts…safely and to building code.
most EVSE's only use 3 wires - 2 hots + ground - the 4th neutral wire is _UNUSED_ - except in juice box - which uses the neutral and one of the hots for a 120V feed to run the onboard Juice box computer, but the actually charging of any L2 North American EV is purely a 3 wire affair - two hots + ground.
in fact one can PROVE that the Neutral is unused in L2/AC/240V charging because the J-1772 connector lacks a connector/pin for an electrical neutral - there would have to be "6" connectors inside the J-1772 plugs design and there are only "5" electical connections - see photo below…
* - for L1 charging - it's still a 3 wire affair - but it's 1-hot, 1 neutral, 1 ground (like all 120 V circuits in North America) - but in the case of L1 vs. L2 - the same connector/pin is either Neutral/Hot in the J-1772 connector - so it's alway 3 wires _ONLY_ - either two hots + ground - or 1 hot + neutral + ground - there is never a J-1772 EV charging session with a 2 hots + neutral + ground…
https://en.wikipedia.org/wiki/SAE_J1772
the vehicle communicates with the EVSE via the blue connectors/pins - this is how the vehicle starts/stops the flow of power from the two "red pins/connectors" and also "learns" how many amps the EVSE can provide - the blue pins also serve the role of active communication "circuit" and unless they are actually communicating with a vehicle the EVSE's main job #1 is to never ever under any circumstance allow the two "red" pins to have any power flowing for safety - this is why an EVSE is _NOT_ a extension cord - power is never flowing if it's not plugged into a vehicle - making the J-1772 plug inert and safe in the rain/sleet/snow - you can drop it a puddle and it won't matter because the blue-pins won't see a "car" talking and therefore the EVSE "relay" is "open" with. no power on the high-voltage "red" pins…
as you can see from this picture there is _NO_ electrical Neutral in L2 charging - so the neutral blade/pin in the NEMA 14-50/14-30 supply cable is inert and unused - it serves no role in the charging of the vehicle - there is no PIN/connectors in the J-1772 plug for a 240V + neutral connector.
this is why Porsche can sell a NEMA 6-50 & 6-30 supply cable for the PMCC/PMC+ - the PMCC/PMC+ don't require/use the neutral connector - on the 14-50/14-30 supply cables there is the 4th blade for neutral, but it's a dummy blade and isn't wired up - it's provide for compabiltity with the NEMA 14-xx plug type - but isn't even used - if you look inside the PMCC/PMC+ end of the supply cable there is no wire/connector for Neurtal - only the two "hots" and the ground…
EVSE's are really very very simple 240V devices - and if you manage to get them two 120V feeds and a ground - you're done…the plug shape/type/size is really just un-necessary complexity.
sometime's it's interesting to inspect the objects we use everyday but never really look at - this posting has been well received else where and shed's "high level" light on how this whole L1/L2 AC EVSE charging works in North America - nothing to see here if you don't care - but for the curious - this is a quick primer on the internal's of the J-1772 connector - it's limitations and design…it's simple really - not much to see here…
read on - enjoy and comment as you see fit…
Any electrician worth their salt can swap between a plugbased EVSE and hardwired EVSE setup in less than an hour once you have circuit/box with the power source/supply sorted to the "box" location…less than $30 worth of Home Depot parts can convert any hardwired connect to a plug (50 amps or less) - and you can always remove the plug and just hardwire any electrical device directly to the wires that were used for the plug (15 amps or more)…if you're 50 amps or smaller swapping between plugs and hardwiring is trivial…easy and honestly can be done in less than 30 min and some wire nuts…safely and to building code.
most EVSE's only use 3 wires - 2 hots + ground - the 4th neutral wire is _UNUSED_ - except in juice box - which uses the neutral and one of the hots for a 120V feed to run the onboard Juice box computer, but the actually charging of any L2 North American EV is purely a 3 wire affair - two hots + ground.
in fact one can PROVE that the Neutral is unused in L2/AC/240V charging because the J-1772 connector lacks a connector/pin for an electrical neutral - there would have to be "6" connectors inside the J-1772 plugs design and there are only "5" electical connections - see photo below…
* - for L1 charging - it's still a 3 wire affair - but it's 1-hot, 1 neutral, 1 ground (like all 120 V circuits in North America) - but in the case of L1 vs. L2 - the same connector/pin is either Neutral/Hot in the J-1772 connector - so it's alway 3 wires _ONLY_ - either two hots + ground - or 1 hot + neutral + ground - there is never a J-1772 EV charging session with a 2 hots + neutral + ground…
https://en.wikipedia.org/wiki/SAE_J1772
the vehicle communicates with the EVSE via the blue connectors/pins - this is how the vehicle starts/stops the flow of power from the two "red pins/connectors" and also "learns" how many amps the EVSE can provide - the blue pins also serve the role of active communication "circuit" and unless they are actually communicating with a vehicle the EVSE's main job #1 is to never ever under any circumstance allow the two "red" pins to have any power flowing for safety - this is why an EVSE is _NOT_ a extension cord - power is never flowing if it's not plugged into a vehicle - making the J-1772 plug inert and safe in the rain/sleet/snow - you can drop it a puddle and it won't matter because the blue-pins won't see a "car" talking and therefore the EVSE "relay" is "open" with. no power on the high-voltage "red" pins…
as you can see from this picture there is _NO_ electrical Neutral in L2 charging - so the neutral blade/pin in the NEMA 14-50/14-30 supply cable is inert and unused - it serves no role in the charging of the vehicle - there is no PIN/connectors in the J-1772 plug for a 240V + neutral connector.
this is why Porsche can sell a NEMA 6-50 & 6-30 supply cable for the PMCC/PMC+ - the PMCC/PMC+ don't require/use the neutral connector - on the 14-50/14-30 supply cables there is the 4th blade for neutral, but it's a dummy blade and isn't wired up - it's provide for compabiltity with the NEMA 14-xx plug type - but isn't even used - if you look inside the PMCC/PMC+ end of the supply cable there is no wire/connector for Neurtal - only the two "hots" and the ground…
EVSE's are really very very simple 240V devices - and if you manage to get them two 120V feeds and a ground - you're done…the plug shape/type/size is really just un-necessary complexity.
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