Nissan LEAF DC/DC Converter Decoded – Video

DEC 17 2014 BY MARK KANE 13

Nissan LEAF

Nissan LEAF

Jim, an EV enthusiast from Washington state, recently worked with the Nissan LEAF DC/DC converter used for charging the 12 V AUX battery from the high voltage battery.

By presenting and describing such materials, another door opens for all of those who would like use OEM stuff in their own projects. We already know that LEAF batteries are used in many projects.

Another chapter for Jim will be the LEAF’s on-board charger.

“I was able to get the 2011-2012 Nissan Leaf DC/DC converter running on the test bench. This unit takes the 280-400VDC HV battery pack input and converts it to 13-15VDC for the 12V AUX battery charging. It is very stable at 74 Amps 13.6V output. Easily adjustable voltage output with a simple 10V PWM signal running at about 9 HZ on pin 1 and pin 3 goes to +12V to enable.

Please use at your own risk! 360VDC HV battery is very dangerous and can be lethal if handled improperly.”

Categories: Nissan, Videos


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13 Comments on "Nissan LEAF DC/DC Converter Decoded – Video"

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Very interesting… Finally someone who knows what he is talking about……

I’m curious as to the ’12 volt loads’ in the Leaf.

Has any Leaf owner added up all the possible loads on this system? Brian tells me a cooling charger pump is line voltage driven, so I would assume it doesn’t any 12 Volt loading.

Curious as to the 12 Volt loads? Clearly you realize that most of the electronics in the car (lights, radio, car window motors, fans, pumps, dashboard, etc.) all run on 12VDC so they can use standard auto parts from other vehicles. Are you just trying to learn how much the car uses?

Yeah, although the 12 volt system in general is the “Latest New fangled Thing”, only being around in passenger cars since around 1954, I try to stay informed about the latest technology.

Speaking of which, most 1954’s had 25 or 30 amp supplies, which increased to 35 to 40 when air conditioning came out to take care of the larger evaporator fan and compressor clutch.
They then went to around 55 amps when rear window heaters became mandatory.

The leaf here is 75-100 and Clarkson Cote tells me the Volt is 130-150.

Just curious as to the overkill. Incidentally, the Voltage on the volt is horrible with the converter off. My 120 volt inverter keeps crapping out if it has to run on the 12 volt battery alone, and the lights get really dim right away. And that’s with a perfect battery.

Hi Bill! Hope you’ve been doing well.

The Volt’s DC-DC actually maxes out around 180A (175? 185? I don’t recall now) but when I use it for something else like a 1500W inverter, I tend to leave some headroom for the vehicle’s own devices that are using the 12V power rail.

You as well, and Merry Christmas. I couldn’t remember the exact figure that you told me but 180 amps is even more surprising, especially when you consider how lousy the voltage is by the dashboard when it is off. Any speculation as to why they put such a large thing in there? I know if the car is in mtc mode, the 12 volt battery will go dead in 2 1/2 hours just listening to the radio. I thought only people who had cars pre-1957 had that problem (when radios had tubes, and besides the heaters, also had to run the 250 volt supplies and the ‘continuous draw’ class A audio amplifier). Hybrid radios (1958-1962) solved that problem by cutting current consumption by a factor of 4. The tube plate voltage was 13.6, and the 2 transistor audio amplifier only drew around an amp, even if ‘class a’. The radio’s had the unique sound of a THUMP at turn on, then music 8 seconds later. Delco transistorized radios (1963-), cut consumption down to around 1 amp total, so you could listen roughly 40 hours before the battery would go dead.. Other makes at the time, and of course, more modern… Read more »

So the extra draw would be coming from the car in “aux” mode?

I was hoping for a Mehdi Sadaghdar style video with sparks and shocking.

Interesting that the DC/DC converter requires external regulation (the frequency input). Means one can’t use it on its own.

The factory EV components are highly integrated and interlocked compared to stand-alone conversion components. Not so convenient for hobbyists!

I would gather this is just a Rube Goldburg way of providing ‘Remote Voltage Sensing’. The ‘external voltage regulator’ would just have to change the pulse width to regulate the voltage, instead of providing the simpler ‘DC’ sense. Cars are always like this: They don’t put standard v-belts on cars most times, rather they use a microgroove vbelt. Which is fine except when you’re trying to hook an alternator as a ‘poor man’s’ 14 volt supply (or use the 3 phase ac output for speciallized uses – (They make reat Ham Radio Power supplies since its easy to smooth the ripple), and you either have to find your own micro grove pulley or find some way to change the one existing on the alternator to a standard ‘B section’ pulley) But generators and old alternators always had to be used with external regulators and its similar here… You also have to find a water source if youre doing something at all continuous. I wonder where he came up with the Schematic?? Nissan must be more detailed than Tesla, the most I’ve seen the service techs get is a block diagram.

Nice shirt in any means.
Kickinggass one car at a time.
Nice lab and wish my wife was as kind!

I am very interest in playing by getting a salvage Leaf (note I am a EE). Any suggestions on where to look for salvage Leaf’s near Oakland, CA? Where did you get the Schematic? And thanks for showing it in the video!!! Please do that in all your videos!

Note, my wife said: “Don’t you ruin our holidays by removing our tree for batteries!” 🙂 Jim

A working LEAF has a DISPLAY screen that shows the Cliamte Contol 0.6 power use and other systems 0.2 by the kW. It can be used to try and find the load on the 12 V system.

Hey everyone,I got a2011/2012 Leaf with the same DC/DC box. After my Leaf didn`t start in the morning the car got towed to a Nissan dealer.They told me the change the Junction Box(DC/DC converter) plus the PTC heat. That stuff is very expensive. Has anybody a wireing of the box or a repair station?
I would be very helpful,thanks in advance