Using 120v to 240v transformer and two generators?

[Ultimate Walrus]

Hi!

I’m curious if anyone has used a 120v to 240v transformer to get the Lightning to charge faster, especially at campgrounds where 30a RV outlets are available, or even to get more juice from a 120v generator.

I want to get a Lightning, but currently tow a travel trailer with a Tacoma. We frequently do long off-grid stretches without hookups. I realize that isn’t ideal for a Lightning given the lagging infrastructure, but I’m trying to puzzle out ways to make it work.

I could get a giant 260lb generator, but I think it’d be a lot more practical to have two smaller generators that sync together, like the 2000w hondas, or the Yamaha EF2000is that I already have. This could deliver up to 3000W of power, but I wouldn’t be able to actually use it, because the amount of power EVSEs will accept from 120v is limited. I need 240v.

I’ve seen other threads where people were puzzling out how to get more juice from 120v. It did seem like in this thread the user @V8Nissan was successful in using a 120v to 240v transformer, but they still only drew 8a/240v/1920w. I’m hoping that with a transformer like this, it’s possible get 15a/240v/3600w from the 30a 120v RV outlets, or at least around 12.5a/240v/3000w from the two generators I could run in parallel. Though I assume a bit of energy is lost in the conversion.

The other thing I thought of with the generators is that, if plugging them together with the twin cable syncs their phases, and their regular outlets still work, it could be more efficient to use a simple combiner cable and forego the transformer altogether, at least for the generator solution. But that solution seems a little sketchy unless I can use a multimeter or something to verify the output before plugging in the vehicle.

Does anyone with electrical knowledge have thoughts on that, or have you tried anything like I described? Thanks!

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[Maquis]

Once you get 240V, the charge rate will get determined by the EVSE.
You need to:

1. Determine the charge rate you want to achieve.
2. Select an EVSE that’s capable is that rate and is able to be set to the desired rate.
3. Come up with a way to derive 240V capable of the desired charge rate.

About 2.8 KW is the most you’re going to get from a TT30 and transformer. Probably less with transformer losses. You could do that with the Ford Mobile Charger using the 120V dongle on 240V.

Keep in mind that if you use a generator, pictures of your setup will go viral in the anti-EV circles.

 

[rraustad]

The 120 to 240 transformer won't help because 30 A at 120 VAC on the transformer input will give you 15 A at 240 VAC at the transformer output. So same power.
The parallel generators would work if they synchronized their output. I would check the manufacturer's website to see if this is possible. For 120 VAC generators I am not sure how that would be possible. Syncing 2 generators to match the waveform and work in parallel (same voltage with twice the current) would seem easier than syncing 2 to get 240 from 120.

 

[Pioneer74]

If you're going to carry a generator and gas to charge your truck, why not just buy a Powerboost? If you order a truck right now, Ford is discounting the Powerboost to equal the cost of just having the 3.5 Ecoboost.

 

[wighty]

The 120 to 240 transformer won't help because 30 A at 120 VAC on the transformer input will give you 15 A at 240 VAC at the transformer output. So same power.

The truck has a limit of 12 amps on 120v (this is regardless of the EVSE supplying 24amps off a TT-30 or whatever 120v connection)... so the whole point of the 240v conversion is to allow the truck to charge faster than ~1.1k-1.2kw. 240v and 12a would give you somewhere around 2.2-2.4kw (estimating conversion losses) which is a big increase overall.

 

[Heliian]

I wouldn't bother with trying to reliably get 240v power from 120v random sources or running multiple generators. It's added weight to carry too.

At 120vac, you'll get about 1% per hour charge for an ER.

Ideally for the lightning, you would go to campsites that already have 240v and bring an evse that has adjustable current and a bag full of adapters.

 

[hturnerfamily]

I've successfully used my good 'ol 'Dual 30amp to 50amp' "Y" electrical adapter at a campground that offered TWO 30amp 120v outlets at each site(crazy, I know, but apparently this 'highest state park campground in Georgia's 'upgrade' to their campground several years ago netted only adding another 30amp outlet at the pedestal, instead of the 240v 50amp you might expect).

But, regardless, the TWO 30amp outlets DID work, and DID provide FULL power for my EVSE, although, to be safe and not to trip the two rather 'weak' breakers, I dialed my adjustable EVSE down to 24amps... worked fine all night. I plugged my camper into the 20amp outlet.

For those willing to contemplate 'other' options, you may have to go outside the bounds of 'normal' camping, and see if you can access two 30amp outlets from two neighboring sites - with a 30amp RV extension cord, if it will reach.

 

[Ultimate Walrus]

Once you get 240V, the charge rate will get determined by the EVSE.
You need to:

1. Determine the charge rate you want to achieve.
2. Select an EVSE that’s capable is that rate and is able to be set to the desired rate.
3. Come up with a way to derive 240V capable of the desired charge rate.

About 2.8 KW is the most you’re going to get from a TT30 and transformer. Probably less with transformer losses. You could do that with the Ford Mobile Charger using the 120V dongle on 240V.

Keep in mind that if you use a generator, pictures of your setup will go viral in the anti-EV circles.

Thank you for the helpful answer! I’m not too concerned about maximizing the 30a outlet as we spend most of our time off-grid, but I do want to make sure those generators work well. You’re probably right that the 3000w from the generators will be lowered in the conversion. That’s why I’m curious if Yamaha twin tech can handle a 240w combiner cable plugged into the 120v outlets. I will have to dig into how the tech works. If they are actually two separate circuits just synchronized, maybe it would work. If the circuits become actually joined somehow, maybe it wouldn’t. This page implies a multimeter could tell me if it’d work (need to be careful and follow the advice of not holding probes in either hand).

Thanks also for the heads-up about the anti-EV circles. Running a generator is pretty normal when you have a travel trailer so I’m not too concerned. We do appreciate our privacy though. The infrastructure is passable enough at this point that I hope we’d be using it rarely for range extension.

An added bonus of this setup would be that we can use the Lightning to power our travel trailer when we’re living off-grid. If we run out of solar power at night (usually happens when we both work all day on our computers while powering the starlink), we could switch to the Lightning, and recharge it later with a trivial amount of generator time… and it’s a chore we could put off for days if we wanted. I honestly hate running generators at campgrounds if I can help it, so being able to partly live off the Lightning’s 131kwh battery bank instead of fully off our dinky 2.4kwh trailer bank would be a game changer.

 

[Ultimate Walrus]

I've successfully used my good 'ol 'Dual 30amp to 50amp' "Y" electrical adapter at a campground that offered TWO 30amp 120v outlets at each site(crazy, I know, but apparently this 'highest state park campground in Georgia's 'upgrade' to their campground several years ago netted only adding another 30amp outlet at the pedestal, instead of the 240v 50amp you might expect).

But, regardless, the TWO 30amp outlets DID work, and DID provide FULL power for my EVSE, although, to be safe and not to trip the two rather 'weak' breakers, I dialed my adjustable EVSE down to 24amps... worked fine all night. I plugged my camper into the 20amp outlet.

For those willing to contemplate 'other' options, you may have to go outside the bounds of 'normal' camping, and see if you can access two 30amp outlets from two neighboring sites - with a 30amp RV extension cord, if it will reach.

This is cool! I saw your other thread where you mentioned that. Though it’s not guaranteed that it would work even with an outlet from a neighboring site, right? If they’re on the same circuit, my understanding is that it wouldn’t work.

 

[Maquis]

This is cool! I saw your other thread where you mentioned that. Though it’s not guaranteed that it would work even with an outlet from a neighboring site, right? If they’re on the same circuit, my understanding is that it wouldn’t work.

The two circuits must be on opposite legs of the service to get 240V, not just a separate circuit.

 

[Ultimate Walrus]

I found another page that would imply getting 240w out of two 2000w generators isn’t possible, or if it is you’d have to resort to some hacky wiring that I wouldn’t dare to try. I think that, after I get the Lightning, I’ll just get a 120v/240v transformer and do what I can to measure its efficiency before I pull the trigger on another generator. Looking at the size/weight of all the 240v generators that would be quiet enough to run in a campground, it’s a little ridiculous (it’d stick up out of the truck bed). I just need something for emergencies and to give me a few extra miles for destinations like Moab.

 

[Maquis]

I found another page that would imply getting 240w out of two 2000w generators isn’t possible, or if it is you’d have to resort to some hacky wiring that I wouldn’t dare to try. I think that, after I get the Lightning, I’ll just get a 120v/240v transformer and do what I can to measure its efficiency before I pull the trigger on another generator. Looking at the size/weight of all the 240v generators that would be quiet enough to run in a campground, it’s a little ridiculous (it’d stick up out of the truck bed). I just need something for emergencies and to give me a few extra miles for destinations like Moab.

Honda inverter generators produce 240V and can be parallelled. I don’t own one, but I’ve seen it discussed on other sites. But you cannot connect 2 120V gennys in series to get 240.

 

[Adventureboy]

Hi!

I’m curious if anyone has used a 120v to 240v transformer to get the Lightning to charge faster, especially at campgrounds where 30a RV outlets are available, or even to get more juice from a 120v generator.

I want to get a Lightning, but currently tow a travel trailer with a Tacoma. We frequently do long off-grid stretches without hookups. I realize that isn’t ideal for a Lightning given the lagging infrastructure, but I’m trying to puzzle out ways to make it work.

I could get a giant 260lb generator, but I think it’d be a lot more practical to have two smaller generators that sync together, like the 2000w hondas, or the Yamaha EF2000is that I already have. This could deliver up to 3000W of power, but I wouldn’t be able to actually use it, because the amount of power EVSEs will accept from 120v is limited. I need 240v.

I’ve seen other threads where people were puzzling out how to get more juice from 120v. It did seem like in this thread the user @V8Nissan was successful in using a 120v to 240v transformer, but they still only drew 8a/240v/1920w. I’m hoping that with a transformer like this, it’s possible get 15a/240v/3600w from the 30a 120v RV outlets, or at least around 12.5a/240v/3000w from the two generators I could run in parallel. Though I assume a bit of energy is lost in the conversion.

The other thing I thought of with the generators is that, if plugging them together with the twin cable syncs their phases, and their regular outlets still work, it could be more efficient to use a simple combiner cable and forego the transformer altogether, at least for the generator solution. But that solution seems a little sketchy unless I can use a multimeter or something to verify the output before plugging in the vehicle.

Does anyone with electrical knowledge have thoughts on that, or have you tried anything like I described? Thanks!

I have been successful in pulling two 120v 30A feeds to provide 240v 30A to my EVSE set to 24A. This works at my marina and will work the same in an RV park provided you find oppositely phased circuits. I built an adapter to bring two 120v 30A RV plugs to one 14/50R and installed connection lights in the box to confirm the opposite phase on the converter box before plugging in the EVSE. EVSE must be adjustable so that can be set safely below the 30A mark (like 24A). This gives me a 5Kw charging rate. You need to know what you are doing for this to work and not blow the breakers (or worse) and leave the campers in the dark. I use this setup every weekend.

This guy did a similar thing with a premade RV adapter: https://www.f150lightningforum.com/...outlets-for-240v-power-at-a-campground.11973/. This didn't work for me since I needed the L5-30P marine plugs but electrically it is the same.


The generator thing kind of defeats the purpose. It will be loud in a quiet RV park at night (even with the 2 Hondas or Yamahas) and slow since they will only be able to charge at say 16A at best.

 

[chl]

Hi!

I’m curious if anyone has used a 120v to 240v transformer to get the Lightning to charge faster, especially at campgrounds where 30a RV outlets are available, or even to get more juice from a 120v generator.

I want to get a Lightning, but currently tow a travel trailer with a Tacoma. We frequently do long off-grid stretches without hookups. I realize that isn’t ideal for a Lightning given the lagging infrastructure, but I’m trying to puzzle out ways to make it work.

I could get a giant 260lb generator, but I think it’d be a lot more practical to have two smaller generators that sync together, like the 2000w hondas, or the Yamaha EF2000is that I already have. This could deliver up to 3000W of power, but I wouldn’t be able to actually use it, because the amount of power EVSEs will accept from 120v is limited. I need 240v.

I’ve seen other threads where people were puzzling out how to get more juice from 120v. It did seem like in this thread the user @V8Nissan was successful in using a 120v to 240v transformer, but they still only drew 8a/240v/1920w. I’m hoping that with a transformer like this, it’s possible get 15a/240v/3600w from the 30a 120v RV outlets, or at least around 12.5a/240v/3000w from the two generators I could run in parallel. Though I assume a bit of energy is lost in the conversion.

The other thing I thought of with the generators is that, if plugging them together with the twin cable syncs their phases, and their regular outlets still work, it could be more efficient to use a simple combiner cable and forego the transformer altogether, at least for the generator solution. But that solution seems a little sketchy unless I can use a multimeter or something to verify the output before plugging in the vehicle.

Does anyone with electrical knowledge have thoughts on that, or have you tried anything like I described? Thanks!

You might look at this system: https://quick220.com/pages/electric-vehicle-charging

For my 2012 Nissan Leaf, I bought a GE Watt Station and had it wired with a 240v plug and outlet in my garage so it would be portable. If you did that with your Ford charger, you could unplug it and take it with you to a camp ground/RV site, eh?

As and aside, soon after the Nissan Leaf came out, an engineer developed and began selling a modification to the 120v portable EVSE that came with the Leaf so it could plug into a 240v outlet and provide a bit faster charging. The name of the company was "EVSE Upgrade."

If I recall correctly, the 120v portable EVSE that came with the Leaf would draw 12A when plugged into a 120v outlet. However, all the components were over-engineered so they could handle more current, up to a maximum of 20A.

The EVSE Upgrade modification allowed the portable Leaf unit to plug into a 240v outlet (you could specify which plug configuration you needed) and would draw 16A - besides the Leaf, would work with any J1772 compliant EV.

 

[hturnerfamily]

and, an interesting note along with the 'modified' 240v power for the LEAF - the CHEVY BOLTS my sons just acquired the last 6 months, both came with the typical '120v emergency EVSE', but, and thanks to GM/Chevy for providing this, these EVSEs will ALSO work off of 240v power supply, meaning that the Hot and Neutral for 120v become Hot and HOT for the 240v service, and charge the car twice a 'fast', although neighther are 'fast', of course - it's just another 'option' if you have an existing 20amp 240v outlet, or a NEMA 14-50, etc.

also, since the BOLT is capable of either 8amp or 12amp charging(you can do this on the main screen), the 240v option not only doubles the 8amp option, but also the 12amp option, providing THREE times the speed versus the typical 8amp 120v plug-in option.

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