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.

 

[Logic11]

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...

'activating the regen braking when I brake the RV'
is what I thought I'd see!

Just an idea that may be worth looking into as it's a direct drive induction motor. (No drag while coasting)
If the 2 12V systems are connected while towing your RV's alternator should be able to stay off most of the time, saving fuel.
Should give you free power when parked/camping
Should be safer with the extra braking and save a LOT on RV brake pads and disks.

There seems to be a lot of modding and info going on so figuring something out shouldn't be too difficult.


As far as connecting the 2 12V battery systems go:
(from an electrical guy who normally electrifies diamond and gold etc processing plants)

I NB that the std 12V Leaf battery is a 48ah unit that can handle 125a on its own (plus the 135a (1850 watts) from the big pack = 260a total)
That 12V battery is there to handle load spikes above the 135a available from the 300 volt pack and does so without blowing anything on the HV side.
ie: No 'HV side may blow up?' worries. The electronics are designed for it.

That gives you a total of 848ah from the combined 12V systems.
ie: For RV load spikes you'd get an extra 260a X 13.7v = 3560 watts from the Leaf.

As long as your average amp load while living in the RV is below 135A (1850 watts); it will charge all the batteries when it is lower and you should be good for days on end.
I'd add a 260a fuse or breaker in the the line/s joining the 2 lead acid battery systems.


Running household loads:
From: Factsheet: Nissan LEAF Vehicle-to-Home (V2H)

A Vehicle-to-Home (V2H) system enables customers to store home generated renewable​

energy in their LEAF battery, or fill their battery when energy tariffs are low or even free.​

Customers can then draw energy out to power their home when it is needed or tariffs are​

high.​

Using V2H, owners of Nissan LEAF can use their cars as a power source for the household to​

save money on electricity bills, or as backup power during blackouts or emergencies and​

support the adoption of renewable energy.​

V2H also allows the Nissan LEAF's battery to be used for electricity storage, providing​

backup for buildings and private homes in preparation for a power shortage and/or outage.​

​

V2H Mechanism​

• Electricity from Nissan EV’s high-capacity battery is used at home via a bi-directional​

charger.​

• Reduction of monthly electricity charges by utilizing electricity rate plans of electric​

power companies and household solar power generation.​

V2H Benefit​

• Nissan LEAF can generate electricity consumption of approximately 12 kWh/day.​

• The electricity stored in Nissan LEAF B4 can sustain a household approximately 3​

days, while LEAF e+ B6 can sustain approximately 4 days (when outside power is​

disrupted).​

• V2H can be used in Nissan ARIYA, which launched globally in July, 2020.​

• As part of Nissan Energy share, V2H is helping solve environmental, disaster​

prevention and reduction.​

• Thru V2H, Nissan LEAF is charged while electricity rate is low (during the nighttime).​

• Stored electricity in Nissan LEAF is supplied to home when electricity rated are high​

(during daytime while everyone in your home use electricity appliance). This allows​

the usage of renewable energy when electricity is cheaper​

This means the Leaf already has an inverter providing 110 or 220 V AC directly.
So taking 400V down to 12V DC, then back up to 110V AC just adds inefficiency.

Besides joining the 12V batteries I would quick connect this 110V AC system to the RV in an either or system:
ie: When the 110V from the leaf is plugged in the system auto cuts and switches off your current system and visa versa.
This will take an electrician that knows his stuff.

Or you could just add extra plugs on a separate circuit. (inconvenient and extra wiring, vs auto changeover)

This would allow you to charge all your batteries without having to worry about the 'Lower than 1350 watts on average or the batteries aren't charging' thing all the time.

PS:
The V2H thing looks to be more complicated than the above would have you believe.
Probably because most govts want to make it as difficult as they possibly can for anyone to access electricity from anywhere besides their lucrative power hustle.
I don't have time/inclination to go through all that. Those are 'your shoes!', but frock them!
('frock'!? That's NOT what I typed! I think everyone should be able to use the U when the word government is in the same sentence! )