BrockWI
Well-known member
AHhhhhh I get it now, so that is really a separate sensor line, not the power or ground lines.
BrockWI said:AHhhhhh I get it now, so that is really a separate sensor line, not the power or ground lines.
If you don't go anywhere after getting home from work and haven't exhausted your traction battery yet because you also get to charge at work then sure, you wouldn't need the high power EVSE. But for folks who don't get to charge at work and come home with an exhausted battery but need to run errands here and there in the evening very soon after they get home, then a high power EVSE would come in handy to replenish the battery more quickly so they can go about running their errands sooner rather than later.maini said:I just realized that now I actually do not need to buy, make or do an EVSEupgrade to a L2 charger
I have been using this for a few days now and I would say with a daily round trip of 35 miles and sometimes getting a charge in the office I need to charge only sometimes at home and only kind of a top off from 60% and the charger I have made can do the job in about 3-4 hours.
So even if I spent around $300 to convert my EVSE to EVSE upgrade or spend another $350 to make my own Open EVSE I might be able to charge the car at say 20 Amps about an 1 hour faster in my use. Even from a 20% level I think I may gain only about 2-3 hours of faster charging over my EVSE which is charging at 12AMPS. I usually plug it in the nights so I do have from 11PM to 7AM about 8 hours to get a charge. So I guess I saved about $300 already. So far I am still not seeing a need for a L2 charger greater than 12AMPS. Any thoughts.. How is your high power EVSE being used?? Do you always charge at 20+ amps?? What rate do you charge at??
maini said:Moderator please make sticky. Many people are asking for the link to this.
QueenBee said:maini said:Moderator please make sticky. Many people are asking for the link to this.
Definitely don't want to encourage people to do this...
The Neutral (White) wire in the original 120V configuration is actually not a "neutral" but an identified conductor as it carries the same current as the "Live Black" wire. When connected to a single phase balanced 240V circuit (or 3 phase) it now becomes a true neutral as it now carries only any unbalanced current. Correct terminologies aside, I don"t think I would be prepared to modify the only available 120V back up on board charging system supplied with the car. Nor would I modify any part of the charging system.maini said:BrockWI said:So where exactly did you put the resistor, between which lines? (hot & neutral?). Is it inside the stock evse case or in the plug end, not that it should matter, just where it fits best.maini said:DO THIS AT YOUR OWN RISK!! In order to fool the EVSE that it still has the FDCD I soldered a 33K Ohm resistor between the two terminals. Rest of the instructions are exactly the same. I used a 12AWG 4 core wire with a L14-30 plug. Wired as below
OK.. just to clarify the 33KOhm resistor is NOT between Live and Neutral. PLEASE DO NOT DO THAT.
Just to be clear in the original cord you will find Live(Black), Neutral(White), Ground(Green) wires.
Just need the right tools:feathersjr said:The chaps at Nissan decided to put Tamper Proof screws underneath the plastic tabs, kind of a Torque head with a pin in the middle. Had to drill them out, just a PIA.
feathersjr said:I just bought a 2015 Leaf, and decided to do this mod on my trickle charger. I intend to use it as a 240V charger only, since I picked up an extra 12 Amp 120V charger from a Fiat owner.
The chaps at Nissan decided to put Tamper Proof screws underneath the plastic tabs, kind of a Torque head with a pin in the middle. Had to drill them out, just a PIA. I measured the resistance of the Thermister (the 2 yellow wires) and a room temperature it was about 17.1 K Ohms. No where near the 33 K Ohms that I've seen posted. I placed the plug in the sun and watched the resistance start to drop down which is what a termistor will do. So I am puzzled about the value of the resistance I am reading. Perhaps the latest EVSE has been modified somewhat? I will continue and find a resistor from a box of stuff I have laying around and see if it works out OK.
Be kind, this is my first post
turbo2ltr said:Just because it works, doesn't mean it's right. Not saying it's wrong, but engineering isn't about "if it works", it's about "is it designed properly". Unless you have done a complete analysis of the circuit and it's components, you can't be sure you aren't pushing a part past it's limit and won't start a fire sometime down the road.
If the two yellow wires go to a thermister in the OEM plug (I have no idea if they do, I have no experience with it and just going by what the previous poster said), then it's there to monitor temperature of the plug. I would assume that if the temperature got too high (too low of a resistance) then the EVSE will stop charging. It's a safety feature that has been bypassed with the addition of a 33k ohm resistor that tricks the EVSE into thinking the plug is very cold. Obviously there is some code in the EVSE that checks to make sure the thermistor is within a certain range. Taking it away would put the resistance outside of the acceptable range and throw a fault.
I am curious though where the term "Frequency Dependent Charging Device"/FDCD came from and why, if there is a thermister connected to the two yellow wires, are they labeled so. Searching google, it seems to be a term that was made up by whoever did the instructable and perpetuated by the OP.
nedfunnell said:I am also an engineer, so I feel qualified to add my voice to the technical discussion.
A few things to point out:
[*]This modification, if performed as specified, does not apply 240v power to any component not rated for it.
[*]The extra 120v is flowing through a separate, fully insulated conductor.
[*]The loss of the FDCD/thermistor is real, but the risk can be fully mitigated by the use of properly rated connectors. More on this below.
[*]No additional current is flowing than in the original design- 12 amps both ways. Therefore, no more heat can be produced.
[*]This modification is intended to be carried out by technically savvy persons, able to assess the inherent risk of doing so.
On the FDCD/thermistor: I believe this is indeed a thermistor. Measuring the heat of the connector is a bright idea on EVSEs which operate at(not beyond) the limit of the design and code. Especially true with flaky, old, or corroded outlets out there. I've warmed up some connectors pretty hot myself. However, please consider this- this modification replaces the original connector, rated for 15A, with a new one rated for 30A. This instantly mitigates any risk of operating without temperature feedback, because the connector is no longer being operated anywhere near its limit- half, in fact. Furthermore, many other EVSE designers saw fit to leave a temperature measurement device out entirely, even with a plug being used at its limit. Based on these facts, I see no risk at all in bypassing the FDCD/thermistor when a higher-capacity connector is used. Notably, if you were going to use a 15A connector, you'd just going to be leaving the original, FDCD/thermistor-equipped one on there- so it's a wash anyway. Even if operated with a 15A connector without a temperature measurement device, the risk is no more than Fiat owners take every day with their non-protected EVSE plugs.
On the heat question: This modification works because of two equations: P=V*I, or power is voltage multiplied by current. The EVSE tells the car to draw the same current before and after the mod. So previously, 120v*12A=1440W of charging power available. After the modification, it becomes 240*12A=2880W, so double. The power flowing through the wire is double, but the power dissipated as heat in the wire does not double. Why? That is the second equation for finding power: P=I^2*R, or power is resistance times current squared. Voltage isn't in that equation at all- I could run 12A through a wire a 12V, 120V, or 1200v and the wire would heat up the same amount. The resistance of the wire remains constant unless it is damaged in some way.
Regarding "pushing" outlets near their max power- a standard NEMA 5-15 outlet is rated for 15A. EVSEs draw only 12A because the National Electric Code states that plugs, connectors, and receptacles should be used at their maximum power only intermittently, not constantly. When in constant use, the maximum allowed is 80% of the nominal maximum, or 12A in the case of a 15A outlet. 12A is already a reduced rate for safety, and if the connector is in serviceable condition it will do fine with a 12A constant load. If it is faulty, there is a real risk, but that goes for any piece of equipment. Don't plug your EV into suspect outlets.
Bottom line: I believe that this modification is safe when carried out by qualified persons. You know who you are. If in doubt, spend the dough on EVSEupgrade.
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