Not exactly building a car, but thoughts?

[coogle]

Hey all,

I am a full time RVer with a motorcoach and I tow a 2018 Nissan Leaf behind us as we travel. I have a crazy idea of being able to use the power in the car for the RV as extra juice when parked somewhere without access to the grid. The RV largely runs on 12V and I currently have two 400aH batteries and a 3000W inverter for some outlets.

Has anyone attempted something like this before or have any advice? Asking around a bit it seems that when on the Leaf provides ~135A to it's 12V circuits so it seems like I could basically jumper the two vehicles together conceptually. Interested if anyone else has any experience or thoughts.

 

[amberwolf]

I don't recall the specifics, but I think if your car supports V2H it can feed traction battery voltage out the charge port under specific circumstances (may require a command, or a mode set), which you can then use to power an inverter (AC output) or DC-DC capable of that voltage, whatever it is your car charges at.

If your car supports V2L it already has an inverter in it, so can provide AC power to run things (like wall-ac-powered devices) that are less than however much power that inverter can supply.

If you want to run off the 12v supply in the car, then as long as the car isn't using it you could run whatever up to that supply's limit, minus whatever safety factor you might want to implement. But..how many Ah or Wh is that 12v supply? If it's a separate battery from the main traction battery, it'll probably be fairly small.


So...how much extra current do you need, at what voltage, for your RV's devices?

Or are you just looking for extra Wh? If just this, you don't need a lot of current, you just use a DC-DC capable of current limiting and converting the 12v (or main battery voltage) to a voltage just high enough to be the same as charger voltage for your 12v RV system.

I'd recommend that if the car itself doesn't have one in place already that you add a protection so that when the car voltage drops to some safe, still usable as a car, limit, the converter / inverter shuts down and alerts you. That way, you don't end up with a car you can't drive somewhere in the event the RV cannot be driven from that spot for any reason and no charging is available.

 

[Papa]

Do you have solar on the coach? If not, I would encourage the installation of maybe a kW or two, instead of tapping the Leaf. I have a small 1.3kW off-grid array and easily cook (via induction) or run my 450W AC essentially free most of the daylight hrs. Or... use the solar for charging the Leaf.

 

[coogle]

I don't recall the specifics, but I think if your car supports V2H it can feed traction battery voltage out the charge port under specific circumstances (may require a command, or a mode set), which you can then use to power an inverter (AC output) or DC-DC capable of that voltage, whatever it is your car charges at.

Interesting. I don't know a lot about EV systems specifically so I'll have to research what V2H even is!

If your car supports V2L it already has an inverter in it, so can provide AC power to run things (like wall-ac-powered devices) that are less than however much power that inverter can supply.

That's def. not my intent, my rig already has an inverter on board so in this case I'd want to feed the DC system and let my inverter do it's job.

If you want to run off the 12v supply in the car, then as long as the car isn't using it you could run whatever up to that supply's limit, minus whatever safety factor you might want to implement. But..how many Ah or Wh is that 12v supply? If it's a separate battery from the main traction battery, it'll probably be fairly small.

This is where I'm trying to get some clarity. I do know there is a separate 12V battery that's tasked with, for example, flipping the relay in the traction battery when the ignition is activated. Asking around a bit someone seemed to indicate to me that my traction battery is putting out something like 360V, which is then converted into 12V/~135A for the 12V systems once the car is on. I'm not sure what is powered by the 12V system -- is it the motors (that feels wrong), or is that 135A things like the A/C and Heater, lights, etc?

Either way, could I technically just jumper my 12V battery in the EV to the 12V house wiring and take advantage of that 135A? Obviously as you mentioned a DC-DC is needed but conceptually that seems like a reasonable approach?

Or are you just looking for extra Wh? If just this, you don't need a lot of current, you just use a DC-DC capable of current limiting and converting the 12v (or main battery voltage) to a voltage just high enough to be the same as charger voltage for your 12v RV system.

I'm just looking for more Wh -- I have 2x 200Ah LiFePO4s in parallel right now and the idea would be I could plug the car into the rig and extend that. The master fuse off the RV batteries is 100A.

I'd recommend that if the car itself doesn't have one in place already that you add a protection so that when the car voltage drops to some safe, still usable as a car, limit, the converter / inverter shuts down and alerts you. That way, you don't end up with a car you can't drive somewhere in the event the RV cannot be driven from that spot for any reason and no charging is available.

That would be ideal - I'm not sure how this would work here though because the voltage I want to measure is the 360V coming out of the primary battery, not the voltage coming out of the 12V system / secondary battery. My general thinking right now (which is what I'm trying to validate) would be basically wiring a plug straight off the 12V battery terminals that I could plug in a cable to connect to the RV. Then, on the RV side I'd install a fuse for some reasonable amount of current (I haven't figured out how much current is "reasonable" yet) on the RV side followed by a DC-DC to feed 14.6V into the RV systems. Getting a DC-DC that has built in current limiting is a good call too.

 

[coogle]

Do you have solar on the coach? If not, I would encourage the installation of maybe a kW or two, instead of tapping the Leaf. I have a small 1.3kW off-grid array and easily cook (via induction) or run my 450W AC essentially free most of the daylight hrs. Or... use the solar for charging the Leaf.

I don't at the moment -- it's pricy, but certainly it's on the plan. This is sort of a secondary project and exploration of if I needed to do it can I/how could I, and for how much sort of thing that would give me some flexibility in a pinch.

 

[PaPaSteve]

There are a few Leaf sites and /or E-car experts that may be better suited to answer your question.

My Nissan Leaf Forum

The forum for all aspects of the Nissan Leaf

mynissanleaf.com

Dala's EV Repair

Dala's EV Repair. 1,825 likes · 3 talking about this. Located in Vaasa, Dala's EV Repair aims to be the first in Finland to offer cheap battery repairs and replacements for electric vehicles,...

www.facebook.com

EV Rides – EV Battery Experts

Our Team

Meet our exceptional team of experts who are passionate about converting vehicles to electric and delivering top-notch results. Our team comprises two seasoned electrical engineers with extensive experience in designing electric vehicles for both motorsports and road use. Supporting them are two...

ev-works.com

 

[coogle]

Just FYI I found this article, which was particularly helpful for this answer:

CHAdeMO V2H - Home Power Backup - 300MPG.org

Ever since modern, commercially produced electric cars starting coming out in 2011, there has been talk of using them as power backups. There have been a hand-full of products out there, but with limited availability, prototype only, or non-U.S. power specs. So, I thought I’d try my own.On my...

300mpg.org

 

[ZeroEm]

Just FYI I found this article, which was particularly helpful for this answer:

CHAdeMO V2H - Home Power Backup - 300MPG.org

Ever since modern, commercially produced electric cars starting coming out in 2011, there has been talk of using them as power backups. There have been a hand-full of products out there, but with limited availability, prototype only, or non-U.S. power specs. So, I thought I’d try my own.On my...

300mpg.org

My take is the Leaf battery is close to 390V, would not mess with that. I have a 2013 Leaf still. Have not used it as a backup, thought about it. Have charged my phone during a black out. I was thinking about jumper wires so the leaf would charge your batteries but would not pull more amps than the car's inverter can supply. They are working to make EV plug in to the house grid so power can go back and forth. Have not kept up with that.