June 24 ‘2013
Foreword to the reader:
At this stage please consider this blog personal describing private work unrelated to Metric Mind Corporation main business. It describes one of my EV related projects – professional upgrade of charging system in my Nissan Leaf 2011 model with additional 10kW charger working as power booster. For impatient – jump to the bottom of the blog to view photos of the upgrade. All others – read on.
The technical work is pretty much completed. All the information presented here is released as open source project. I believe is the most beneficial way for technically inclined Leaf owners to carry out (and improve) such upgrade themselves. Others can hire local experts to perform the work as it requires some specialized equipment (such as a vehicle lift) and basic knowledge of electric circuits. Businesses are welcome to come up with completed kits for similar DIY or professional upgrades. If you decide to roll up your sleeves, and do something like this on your own, please check out my disclaimer.
Why did I do this and what’s the benefit of such upgrade? A few situations you’d be able to take advantage of this:
- You’re invited to a dinner to your friend’s house who don’t own an EV (so no EVSE at their home) but you just came back from work and running errands, so your leaf is near empty. Unless round trip is within remaining leaf’s range, you cannot take it there. With this upgrade you can.
- You’ve got invited to an interview or a meeting to a business across the town (say, 70 miles away) which will last for about 1 hour. You cannot take your Leaf there unless before or after the meeting you will find L2 public EVSE and waste at least another 2 hours to be able to get back or find a quick DC charging station.
- You went camping. Not that your Leaf is the best suitable vehicle type for this activity, but you have no option to take it if round trip distance is beyond its range,period. (Not to mention that if your Leaf is the only vehicle you have, you can’t make such trips unless you borrow/rent another vehicle). With described upgrade you can plug in at any RV park on your way and recharge while having a snack.
- You just came from work and your Leaf is almost empty. A friend invited you to come over to watch a football game which starts in about 1 hour. You cannot take Leaf there – it won’t make it on remaining charge. 1 hour is not enough to recharge it from your EVSE so you can make it back home. With this upgrade you can.
You get the point. I’m sure you have been in similar situations where you wish your Leaf would be able to charge in like 10-15 min just enough to make it wherever you’re going. Well, with this upgrade you can put in 3.7 miles worth of energy for every 5 minutes you charge – and that’s without any L2 home EVSE. With an EVSE it’s even faster – 4.4miles for every 5 min of charging (assuming 4miles/kWh energy consumption).
The possible scenarios are many, but ability to plug into anyone’s dryer socket and get charged up (aside getting it done 4 times faster than with stock portable EVSE) an not to worry about it was appealing enough for me. I’m well aware that in some more progressive cities public L2 charging
stations are all over the places where you usually hang out, but recharging there it’s far from being convenient and it’s not the point. The point is you have to go and charge/wait there instead of just going wherever you wanted to go. And, pray that by your arrival this public EVSE is not occupied by another EV owner…
So below is more technical description of what I did.
The Leaf’s stock Nichicon charger is rated at 3.3kW output power (3.6kW input power), so with 10kW upgrade total charging power will be 13.3kW. This allows charging Leaf’s 24kWh battery to 80% in less than 90 minutes if residential level II EVSE is used. In addition to this, the power can come from any regular household 240VAC outlet and the Leaf can charge without EVSE of any kind – all you need is stock Nissan trickle charge inline EVSE that comes with every Leaf (in this case internal charger is limited to 1.4kW so the total charging power is reduced to 11.4kW and charging time increases by 10 min and will be ~100 min to 80% SOC). This means freedom to charge fast anywhere – in a garage, in the work shop where that portable welder is usually plugged in, in any RV park, shore power dock for boats, any home 240VAC socket (dedicated or – electric dryer) – anywhere where you can find regular standard 240V 30A to 50A outlet.
The upgrade uses one, two or three OEM EV chargers made for the job and about the only ones you’d want to consider if you want the system to work as reliably as the rest of your Leaf – BRUSA NLG513-U1-01A-A01 (formerly known as NLG513-WA). These are water cooled units with output spec similar to that of stock charger, current and power adjustable on the fly by a simple potentiometer. Chargers were programmed to run in automatic mode and loaded with booster charging profile. They are mounted under the trunk floor so no extra trunk space, cabin space or under hood space is taken – all interior and exterior appears stock. Regardless of the upgrade option, total boost power can be adjusted from zero to maximum available by a knob under hood where a power meter along with boosters status indication is installed. You can monitor line voltage, monitor and adjust line current or line power to any desired value, and monitor total power factor. This ability comes handy if you can plug to shared circuit or the outlet limited to say 30A – in this case you just set line current to slightly under 30A to prevent circuit breaker from tripping and keep charging. The power and current displayed and adjusted as total for stock and booster combined.
The concept of the upgrade is simple and will be clear from this block diagram. The booster
consists of one, two or three BRUSA NLG513 chargers. The stock charger communicates with Leaf’s BMS and timers as before, and knows when to slow down or stop charging. All booster does is looks at AC current consumption by the master (stock Nichicon charger) – if master is running at full bore this enables boosters at full power as well. Master does not know (and does not need
to know) that additional current is being injected into the battery. The current measurement is done inside the battery pack and all the BMS sees is the rate of charge and controls master accordingly. When BMS determines that enough Ah was put back into the battery (which now happens quicker), it commands over CAN to master to slow down and eventually quit charging. The line current draw by master quickly decays and ceases. The added current sensor detects this condition and simply disables boosters as well. That’s it. No CAN communication or pilot controlling boosters is required – they basically monitor master’s current and double (or triple or quadruple it depending on how many booster units you install) – this is described well in the user’s manual for the NLG513 charger. Booster #1 is somewhat special – it’s digital outputs are used to indicate the progress of charging using three blue LEDs – very similar to the stock indication in Leaf. Other boosters, if present, can have the same charging profile, but their digital I/Os are unused.
The stock functionality of Nissan portable EVSE trickle charger (the “brick”) from any 120
VAC outlet is 100% retained and no interference of boosters occur. If 240VAC is not supplied, booster(s) remain off and not visible to the rest of the vehicle, so you can charge from any 120VAC outlet as before. Moreover, you can take advantage of boosters working off of 120VAC for about twice as fast charge as 12A portable EVSE allows. In this case each booster is limited to about 9A
total input current, or total of up to 27A in addition to stock EVSE. So you can plug the system into a 120VAC outlet and dial total line current to be just under 20A – 12A will be drawn by stock charger and additional 8A by booster. This will recharge 67% faster than just portable EVSE at 12A alone.
One may initially choose less expensive option with one booster and see if this satisfies quicker charging needs. Because cabling and mounting provision is made to use one, two or three boosters, adding more units later on is simple plug and play procedure that takes about 1 hour.
Also, boosters will charge and maintain along auxiliary 12V lead acid battery. There have been reports that if Leaf is left connected to an EVSE for extended period of time (weeks) to maintain traction battery, this keeps VCU, security, Carwings comm, timers, climate control and other subsystems on, drawing power from 12V battery which is not being recharged, thus runs dead. The suggested cure is not to leave Leaf connected to EVSE, but this will prevent traction battery from
being topped off and ready after that long vacation time, although self-discharge rate is quite low. With proposed booster upgrade this is no longer the issue since as long as boosters are powered, even if they don’t charge traction battery, they do charge auxiliary 12V battery so the car’s
subsystems can keep working if so desired. As each booster has isolated 12V output (actually 14.2V meant to maintain on-board auxiliary 12V lead acid battery) it is used for that purpose – whenever AC power to boosters is present, they will output at least 0.5A into the 12V battery even if main power is disabled. Because internal power supply is set up as current source, all outputs
can be paralleled and total current is automatically shared between all the boosters equally. With 3 booster units you will get >1.5A of charging current. Finally, BRUSA NLG513 chargers have analog voltage input allowing to set AC line input current (and so output power) from zero to maximum
with a single resistor. I installed potentiometer connected to analog inputs paralleled for all the boosters since they can share analog ground signal. This way I can dial any desired line AC current (0…16A per boost unit) simultaneously for all the boosters. This is relevant if the circuit breaker is
not rated for the maximum current all the boosters can consume, so you can dial the current about 20% less than this rating to prevent tripping. Monitoring is done by line current meter installed under hood next to the potentiometer knob. The pot can be replaced wit ha few fixed resistors and multiple switch to select predetermined line current from few common values, say 20A, 30A, 40A and 50A. Normally limiting power draw is done by CP (Control Pilot) signal from an EVSE, and it is trivial to make boosters to comply, but with just 240VAC outlet there is no CP source, so if you ever run into the 240VAC mains outlet which cannot handle 50A, adjustment can always be done manually. The power for boosters is fed using extra inlet with standard 250VAC 50A twist lock connector. Even though the additional inlet is not visible, I wish I could get away with feeding all the power needed though the existing J1772 connector. While the standard allows up to 70A AC current feed, it doesn’t mean actual hardware has to take advantage of full allowed capability – in fact the power contacts of Leaf’s J1772 inlet are designed to handle up to 30A continuous
current (up to 40A peak). It makes no sense to beef up the inlet contacts to allowed 80A if designers know the stock 3.6kW charger will only take 3600W / 240V = 15A (6.6kW – 27.5A).
So why didn’t I use second J1772 inlet, say, next to the stock one? Because three boosters will draw 48A from the mains and 30A rated contacts will overheat and fail in a hurry. Why then I did not split total 64A max current evenly between the two inlets? They each could handle 32A… Well, I could, but aside complications with routing, stock Nissan EVSE “Brick” would never provide me
with 16A 240VAC power, and I would have to have not one but two wall EVSEs to take advantage of such setup, which would defeat the purpose of freedom from any EVSEs. But the main obstacle is I would have to reprogram stock VCU to signal first EVSE that stock charger is now 32A capable (which it is not) and come up with my own pilot signal controller for the second EVSE. So comparing the choice between adding one 50A twist lock vs. adding one more J1772 inlet + two 32A capable EVSEs + pilot signal control circuitry makes it clear.
I wonder if most people just want faster charging but don’t mind to be tied to a home or public EVSE, or they rather want to be free from EVSEs of any sort. For the former, using existing J1772 inlet makes sense, but again, fast charging at 13.2kW (16.6kW with 2013 Leaf) is not guaranteed if an EVSE is not capable delivering that or stock inlet just can’t handle it – it may well get too hot and fail in a hurry. On the other hand, a 240VAC socket is usually capable of 50A (with 30A being minimum), and the solution described here does not require messing with CP signal modifications, so I went for it as a first step. Sure not everyone will want extra connectors on their Leafs no matter what the benefits. For the time being those will have to wait and be tied to their EVSEs and slow stock chargers. Also, realize, if you have 10kW booster, this doesn’t mean every EVSE out there will supply ~15kW (~3.6kW on AC side for stock and 11+kW for boosters) just because Leaf asks for it. The handshaking between EVSE and Leaf includes indication by EVSE how much current it can supply, so if it is less than what Leaf can absorb, the stock charger is throttled back to comply.
Common wall EVSEs are made to handle up to 32A mains current so that an EV can take full advantage of its stock charger (at least 6.6kW), but with 10kW upgrade this will no longer be the case – the more powerful charge you carry on-board – the less EVSE’s around will be capable of handling it. I’ve never seen an EVSE handling 48A mains. IN contrast, with 240VAC outlet there is no such limitation – if you have 50A breaker, you can get 50A charging current.
The 2013 model Leaf comes with 6.6kW charger that is moved upfront – this doubles charging power and halves the time required to achieve 80% of charge. 4 hours is pretty good, but still, with independent 10kW boosters you could have 16.6kW total charging power and recharge your leaf from empty to 80% in just 1 hour 12 min. But, again, this is not the only objective – the goal is to give you option not to use EVSE at all – freedom to go anywhere where public EVSE is not available.
The cooling lines will be extended toward the back of the vehicle where boosters are installed – much the same way as it is done for pre-2013 Leafs, possibly even re-using stock pre-2013 Leaf’s plumbing. I will have to look closer into 2013 model design when one will become available to me
If you choose to duplicate this upgrade, I would advise seeking professional installation
approach as the work requires to remove and re-install car’s battery for efficient and neat OEM-like cable routing – something simple (the battery is held in place by 12 bolts) but impractical without vehicle lift. With all the supplies available the work can be easily done in one day by one person. It is possible to route cables under body without detaching the battery, but keep in mind the conduits it will be exposed to the road and the outcome will be quite amateurish looking (and potentially unsafe if you manage to rub conduit against something on the road to the point that conductors get exposed or smashed together).
Most of the photos are self-explanatory, but I will expand description next to each photo as I go along. In this description I will use two NLG513 booster chargers available to me at the time the work is performed, but as mentioned, cables and connections are pre-made for 3 booster chargers, so I will install additional booster just for the completeness at my first good opportunity. For now two boosters and stock charger with portable EVSE that came with my Leaf work together just awesome. My usual routine is to charge from 30 miles to 80 miles range in 30 minutes which increases usability of my Leaf to the point that I may not need my second EV anymore.
So what’s next?
The feed back I’m hearing is that ability of recharging fast(er) is more important than that + independence from any EVSE, and use of additional non-1772 inlet is odd. Some people just want to plug in as usual and charge faster, that’s it. So my next upgrade may address these issues.
Pros (of using just J1772 inlet to feed all the power into Leaf instead of separate dedicated inlet):
- Your operation is identical to how you charge now – use the single inlet and J1772 compliant EVSE.
- No extra connectors in Leaf, the power
for boosters is supplied through the same power pins as for the stock charger
- You loose independence from an EVSE and cannot just charge at any location from a 240VAC outlet.
- You may not always take full advantage of
the booster’s power capability (esp. with 6.7kW and 10kW booster) because EVSE will actually dictate how much power it is capable of supplying and only that much is allowed to be drawn even though boosters themselves are capable of more. With 240VAC feed you always get full power output as long as circuit breakers can handle it (if not, you can manually dial in any desired current)
- Your auxiliary 12V battery will not get charged if the main battery is not being
charged (there is no power from EVSE at that time).
- You need to buy EVSE for home use -extra expense (compared to the independent 240VAC with own twist lock inlet solution)
- Likely more expensive upgrade as now the controller receiving info from EVSE about its current (power) capability and adjusting booster’s power not to exceed it will be required.
- chance that with 3 boosters contacts of your J1772 inlet port may get too hot and fail prematurely – this has to be investigated in more detail though. With two boosters there should not be any concern and with one booster it is not an issue at all since with one unit total charging power is6.6kW which is the same as for stock 2013 model with identical J1772 inlet.
Despite more apparent cons than pros, this variant is quite straight forward and might appeal to some Leaf owners more. It can be implemented without tapping into Leaf’s CAN bus and disrupting it’s stock operation. Another improvement I did not think about before but now is implemented is to unbolt stock ChaDeMo inlet and relocate it under the hood between radiator and inverter (see update July 29 below). The twist lock inlet goes in its place. This is kind of afterthought – the hole in the plastic bumper is already made and swing open license plate worked just fine, but both most often used plugs (in fact always used together) makes sense to locate next to each other side-by-side. In rare occasions when I’d still want to use quick DC charger, I’ll have to open the hood and plug ChaDeMo connector there, but I had to do this only once in 1.5 years of my Leaf ownership and even that was just for curiosity how this works rather than necessity. So for all practical purposes I’d say I never use QC inlet. So if I do need it, I can wait 5-10 min sitting in the car with open hood and it will get enough juice to always get me home. The info on this page is open source, I will add design details here as I get time to do it. Anyone is welcome to use
it, welcome to come up wit ha kit to sell to people, use information here as you see fit. Sorry, I cannot perform upgrade work for you – it’s too much effort for one person to organize.
Finally, please get used to proper units. Don’t display your ignorance claiming your Leaf stores 24 kWh worth of power in its battery or your car’s power consumption is 4 miles/kWh (or worse – 4 miles/kW), or Leaf has enough power in the battery to cover 100 miles – it sounds as silly as saying you stored 300hp in your gas tank, or your fuel economy is 4 miles/hp or 60hp gas engine is enough power to cover 400 miles. Power and energy are two related but very different physical
properties! If you care, see my rant about units usage here (ignore bottom portion of the page – the site appears in the identical style but actually belongs to my totally unrelated Audi conversion project).
One last remark – for obvious reasons all photos have embedded watermark – I tried to make it as non-intrusive as possible while still visible. Welcome to save and disseminate any material you find here with proper credits to this site and its author.
Enjoy the site and welcome to link it (or to it)! If you have questions or would like to suggest something or share notes, welcome to drop me a mail. Here it goes:
Trunk compartment (under trunk floor) – view from back – this is where booster chargers will be installed.
Trunk compartment view from front
Trunk cover off
Coolant hoses connection
Appearance of three NLG513 water cooled for 10kW booster option
Two NLG513 water cooled for just 6.7kW booster on rails initially will be installed and tested
Back side (Will be facing up)
Trial fit – temporary support
Trial fit – side view
Two units installed
Coolant hoses links
Side view – installed at the angle
Cooling loop re-routed through NLG513 chargers
Another view – cooling hoses
J1772 inlet removed
Stock wiring – resistor and diode buried here
Harness to be modified to install measurement circuit
Interlock loop of internal connector
Harness taken apart
New connections made. Note – splices are filled with water repelling compound
All crimp connections protected with anti-oxidizer (Noalox compound)
Harness modified – extra stub on top, otherwise – just like stock
J1772 inlet harness installed back. Orange stub – is what you see new
Inner connector from the harness toward the stock charger
Stock hardware – view from the front (rear seat removed). Charger on the left, ultracapacitor on the right
Charger harness detail
Battery power (Orange) and BMS (round black) connectors
Battery connector unplugged
Battery case connector
Battery cable harness is shielded
Preparing to splice wiring here
Modified copper clamps
Spliced high voltage wiring for NLG513 chargers feed
Stock harness restored
Underbody – there is really no good place to route power cables
The battery has to be removed and cables routed under floor together with stock harness
Vehicle is lowered so the battery lay on the battery support fixture
Twelve bolts around holding the battery removed. Vehicle lifted with battery remaining on the fixture
Overview of the battery on support stand
Battery – front view
Battery close up
Battery – rear view
Underbody cavity with stock harnesses and cooling pipes
Blue harness – new signal cable to the power meter and indication upfront
New harnesses and cables routed along the stock ones are not even visible
Close up detail – hanging black cable going toward trunk is AC power feed to the NLG513
Battery and signal connections – all identified and marked
AC current sensor PCB with split core CT clamped around charger AC feed wire
Another view of the sensor PCB
Checking and logging charging voltage on the battery terminals (cheap logging multimeter shows 1V lower readings than Agilent lab multimeter, but it’s just 0.25% discrepancy – pretty good for a Chinese tool…)
Precharging voltage ramp time measurement shows that no external precharging circuit will be necessary
Quick through-hole design (current sensor PCB shown on top, and panel meter display PCB on bottom)
Under hood view – right side is logical place for the panel meter (stock, before modifications)
This is good spot for the meter and indication/control
A cutout and mounting holes are made in the plastic cover
The panel meter installed (back view of the plastic cover)
Completed panel meter PCB with CT (current transformer) mounted in place
Close up – both stock and booster chargers AC inputs fed through the transformer – meter will measure total current/power
Plastic cover for the panel meter is printing on my 3D prototype printer
Completing printing process (it took about 45 minutes)
The part as comes out is good to use as is
Meter PCB covered with printed part (back side of Leaf’s plastic panel)
Plastic cover under hood re-installed. A knob below meter will adjust additional boost power from 0 to 100%
Testing with Nissan brick from 120 VAC source – line voltage reading
Testing with Nissan brick from 120 VAC source – line current reading (stock charger only)
Testing with Nissan brick from 120 VAC source – line power reading
Testing with Nissan brick from 120 VAC source – power factor reading
Location of the extra power inlet for twist lock 50A line power connector (this has been changed, see July 29 update below)
The power inlet will be installed here (this has been changed, so the hole turn out to be unnecessary. It is not visible under the license plate anyway)
Recessed inlet with flap cover – the license plate frame will be attached to this flap (this has been changed)
License plate attached to the flap cover – they will swing up open together on the flap’s hinge providing access to the inlet(this has been changed)
License plate final position – front view (the hinge right above the plate is not present in final installation
License plate final position – 45 degree view
License plate final position – side view
Junction box with breakout strips and cable glands prepared
Junction box – top view
Junction box installed
Chargers’ interface connectors crimp terminals and specialized AMP crimping tool
All three harnesses completed even though only two boosters are going to be installed for now
Power in, power out, panel meter indication, current sensor, chargers controls and serial interfaces – all fed through and prepared for wiring
Wiring – half way done. Crimping ring terminals
Wiring completed – it may visually look messy, but electrically it’s perfect. And that’s what really counts
Whole installation complete – view from the front. The spot for a third booster is empty for now
Same step – view from the rear
July 5 2013 update
50A 240VAC power plug and receptacle (this has been changed, see July 29 update below)
The plug is inserted and the license plate rests on it. Unless stock charger is running, only aux. lead acid 12V battery is being charged (this has been changed)
Another view of this connection(this has been changed)
Both connectors are plugged in – side view(this has been changed)
A 120VAC receptacle mounted inline about 1.5m away from the power plug and portable EVSE is plugged into it. Only yellow plug has to be powered from 240VAC to power everything (this has been changed)
Top view of all connections near Leaf (this has been changed)
All I need to carry with me for the universal connectivity anywhere is this cord (and optionally – adapters for different styles of 240VAC receptacles)
Preliminary full power test – line voltage as measured at the input socket
Total AC Amps consumed from the mains – this is true value and I can adjust booster’s portion of it with the knob shown on the left below the meter
Total power from the mains displayed*
Combined power factor of all the chargers is displayed
Auxiliary lead acid 12V battery is always being topped off while 240VAC is connected
Short video of the display in auto cycling mode and how the plugs are arranged
(82MB .mp4 file)
Experimental data plot obtained by data logging battery voltage with two boosters running (9.9kW total input power, 8.42kW total output power). The battery started charging nearly empty (6 miles remaining range was displayed on Leaf’s dash)
July 29 2013 update
The 240VAC 50A twist lock inlet took place of quick DC charge inlet, which in turn was relocated to under the hood. This proved to be so much more logical and convenient arrangement. This and other design details are below.
Schematic of new connections, current sensor circuit, etc. (.pdf file)
Layout of the current sensor PCB – I used through hole components and single sided PCB for simplicity (.pdf file)
CAD STEP file of the booster chargers brackets along with hole pattern template
Another view of the current sensor PCB with split core CT clamped around stock Nichicon charger’s AC input wire
The harness connecting data lines of the J1772 quick DC charger connector – unplugged before removal
Stock DC quick charging inlet and wire harness. Signal interface (black harness) is too short for the new inlet location
The signal interface is extended by 25cm. Now the inlet can be relocated. (Granted, this wiring will be inside corrugated loom again)
Twist lock inlet and adapter plate made from 10mm thick black nylon plastic. Its’ shaped after stock inlet flange
The twist lock connector is installed and AC power wires connected. Now it is going to take place of DC quick charge inlet.
Installed. Fits beautifully and looks great
The QC port is relocated right behind the hood latch. Its short power cables actually dictate exact position
Side view of the QC port installation. It’s held in place by two aluminum brackets. The coolant hose runs where it use to run
Now, this makes much more sense. Twist lock inlet receptacle is just as convenient to plug into as into the J1772 inlet
Close up view of both connectors. Looks great and works as a charm !
Aug 30 2013 update
This is final part of the project which is completed now. A third booster charger was installed for completeness and demonstration of usability. Total booster power is 10kW now; about 28 A of charging current supplied in addition to 9.5A provided by stock charger. If charging is done with stock Nissan EVSE “brick”, the total charging power is 11.2kW, (or 13.3kW with home EVSE) – twice as much as newer 2013 Nissan Leafs with 6.6kW stock charger offer. This means my 0…80% recharging time is down to 100 min (~ 87 min with EVSE) respectively. Another way to look at it is gaining over 1 mile of range for every 1 minute of charging at home without any EVSE’s. I’m impressed.
So final steps of the project depicted here:
Provision was made for installation of 3 units including coolant loop, power cabling and signal harnesses, so…
… installation was a snap. All it takes is placing new charger under the rack line up mounting holes and…
… securing it with four M6 bolts. Blue LockTite was used to prevent loosening bolts
Last step is to plug all cabling in place and fit cooling hoses onto charger’s inlet and outlet fittings
The job is completed. The only remaining step is to refill cooling system with fresh coolant. I didn’t want to re-use drained one
BRUSA NLG513 chargers are so flat (just 88mm) that should I needed, I could fit two layers of them
Side view of installed units. Eye candy…
Yet another view of complete installation before bottom cover will be put on
Close up view of charger control interface connections. Signal cabling is color coded for easier identification
Stock plastic cover is back on. As if nothing happened…
The test reveal that all 3 units run at full bore as expected. The output power of boosters can be adjusted if needed:
This video demonstrates that if the mains cannot handle 60A total current, you can adjust booster’s power down to zero leaving about 12A drawn by stock charger, as if booster is not there. (~20MB .mp4 file)
Earned bragging rights are now expressed in this bold message
* The power readout is accurate only for 240VAC feed. Because the meter has single voltage input to compute power, with dual voltage feed (120VAC to the stock charger and 240VAC to boosters) I had to switch it to 240 VAC only whenever this voltage is present. Since total power is computed by multiplying line amps by line voltage, the meter “ignores the fact that stock charger is getting only 120 VAC from the Nissan brick, so the portion of watts readout for the stock charger is twice as high – 2640W (240V * 11A) instead of 1320W (11A * 120VAC). So I have to mentally subtract 1.3kW from the total to get accurate watts figure. This would not be the case if stock charger is fed with 240VAC from home or public EVSE However, total drawn Amps readout is always accurate and this is what’s important to avoid circuit breakers tripping. This shortcoming can be fixed by using dual input voltage meter and processor to do math which might be on the improvements list. For now though, off-shelf panel meter works for me very well.
In August 2014 I had an opportunity to perform similar upgrade of a ‘2012 Leaf owner located in BC Canada. This time the main objective of the upgrade was a bit different – not as much charging anywhere without EVSEs, as to take advantage of dual L2 (32A) public
charging stations in the city where he can plug both handles of such station into his Leaf and charge twice as fast as a single EVSE with one plug
would allow. Both channels (EVSEs) combined would supply 64A total – exactly the current he can take full advantage of if he installs three BRUSA NLG513 booster chargers. On top of that, he wanted the ability to use twist lock to charge in garages, RV parks or any place where a
240VAC outlet (but no EVSE) is available. Of course, the Leaf should also work as stock with just one EVSE as well as with small 120 VAC brick EVSE that comes with every leaf. So the electrical schematic had to be refised on the spot, we came up with the solution and
accomplished the task successfully. His upgrade is now even more universal as mine as I cannot use dual charging
stations – I only have one stock J1772 inlet.
Below are few photos of this upgrade. Mostly it is no different than the work described above, so majority of photos
are depicting details of this specific upgrade.
What’s next? 25kW quick charge option on-board !
The built in 25kW quick charge option based on BRUSA NLG664 22kW charger paired with stock Nichicon 3.3kW one is in works. Complete bulk recharge (0-80% SOC) time of empty Leaf is ~45 minutes. Not quite as fast as 30 min using QC port, but I think extra 15 min waiting are worth not having to have a refrigerator size charger in your garage…
For now this option will be available to Leaf owners in Europe (or, rather, in any location with 50 Hz 3 phase mains)
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