Charging with a generator

Charging with a generator

Has anyone ever charged your vehicle with a portable generator? I purchased an adaptor cable to connect my charger cable to my generator that has a 30 amp twist output.

At first it appeared as it would work since i got a flashing green but then it failed. I was expecting the generator to sence the load and accelerate but it never happened.

It would great to be able to do this with a power outage.

mathwhiz | 27 February 2017

kmanauto has done a bunch of videos on the subject:

mdd | 27 February 2017

To each his own, but...

It seems to me that charging your electric car with a gas generator is missing the point.

dortor | 27 February 2017

It's not missing the point as an emergency backup.

mdd | 27 February 2017

So, you're going to buy an electric vehicle and always carry a gas engine as backup -- and gas? Why not just buy a PHEV instead?

eric.zucker | 27 February 2017

It's heresy, for sure.

Most small generators up to 5kW produce very poor quality current, unless they use inverter technology.
They're OK for power tools, incandescent or halogen lights, electric heaters but not for electronics, TVs, computers, etc.

To have a reasonable charge time on a Tesla you want a powerful set (at least 10-15 kW), it's not something you want to be carrying around.

mdd | 27 February 2017

Why not just put in a V8, with a 12-volt lead acid battery to run the electrics. Genius.

RIchgpilot | 28 February 2017

Mdd, this is an academic question as an emergency back up. Take a chill pill. If you have nothing consrtuctive to offer get lost

RIchgpilot | 28 February 2017

Mdd, this is an academic question as an emergency back up. Take a chill pill. If you have nothing consrtuctive to offer get lost. Down in florida we have piwer failures after hurricanes.

RIchgpilot | 28 February 2017

Mdd, this is an academic question as an emergency back up. Take a chill pill. If you have nothing consrtuctive to offer get lost. Down in florida we have power failures after hurricanes.

jaysonmobile | 28 February 2017

When I get our MX I'll be borrowing my dad's Honda 20i generator for a test.

Heard of the "Nullabor"? It's just nor devoid of trees but of charging opportunities too.

Hint: Australia, driving west to east and back. Check out the map

inconel | 28 February 2017

Is it possible to use the powerwall as backup charger for a Tesla car?

dortor | 28 February 2017

Have you priced 85 kWh of powerwall?

Model_D | 28 February 2017

If I was using a generator to charge an X:
Set the charging amps to the lowest you can on the X
Slowly increase it to about 50% of the generator's rating
If you need a faster charge, avoid going above about 80% of the max continuous rating of the generator

RIchgpilot | 28 February 2017

Thanks Dwepilot. Ill try again

dortor | 28 February 2017

6x14 kWh (84 kwh) of Powerwalls is estimated cost of $33,000 according to the Tesla website…

Leli001 | 28 February 2017

Why would you recharge the entire car battery in an emergency? Even generators are usually sized to only provide power for essentials, such as: frig, boiler, pumps, and a few lights; during an emergency, not the entire house.

Rocky_H | 28 February 2017

Rather than a new thread, you will find a lot more information from the previous threads where this has been discussed. The two main problems are:
(1) Most generators don’t have a real ground, and the Tesla charging system will sense this and won’t run.
(2) Most generators don’t generate a clean AC sine wave output, and the Tesla charging system doesn’t like that either. Some good generators do have this, though.

RIchgpilot | 28 February 2017

Thanks Rocky, got it

inconel | 28 February 2017

@Leli001 yes exactly no need to charge fully at once. And with solar panels it can become a much more reliable backup system. With traditional generators we are still dependent on uninterrupted supply of gasoline or gas.

Rocky_H | 28 February 2017

@RIchgpilot, Regarding problem (1) of the missing ground problem, in some of those threads, I think people have found ways in some generators to hack in a real ground to solve that issue.

RIchgpilot | 28 February 2017

So now I just need determine if my block is due to grounding, sine wave or slower amp up. Thanks

eric.zucker | 1 March 2017

Grounding is easy. Drive a sturdy 3 ft metal rod into the soil outside (not a flowerpot), wet the soil around it, and connect it to the generator. Generators normally have a bolt on the frame to attach a ground line.

I confirm the 80% derating rule. A 20 kVA genset provides 16kW of usable power. Mind also if it's peak load, or constant load rating. Different manufacturers use different standards.

For backup power I have a 2 kW inverter with 300Ah of 12V batteries as primary, short-term, clean, quiet backup power. Then I can fire up the generator if the outage lasts more than a couple hours. This will save the contents of our fridge and freezer, and power the essential stuff.

RIchgpilot | 1 March 2017

Thanks Eric. I see the grounding issue is solvable

keiki | 2 March 2017

Lost power for over a week during last hurricane in NY. Even gas stations ran out of fuel. My wife was in hospital and an electric vehicle with a back up generator for charging would have been a real lifesaver.

eric.zucker | 4 March 2017

@keiki: what does your backup generator run on? No matter how large your tank, you'll run it dry sooner or later.
A generator needs regular maintenance or it won't start when you need it.

If you really want backup power, get solar, wind, or micro-hydro which do not require any fuel, along with battery storage such as Powewall to have power at night.

Model_D | 4 March 2017

Eric. You are comparing spending $900 to at least $9,000 and 1 square meter to at least 10 square meters. Two of the three ideas need equal or more maintenance that a backup generator. Some people just want some cheap, small peace of mind.

eric.zucker | 4 March 2017

@Dwepilot : I disagree. A generator is useless if you can't get gas, likely situation in an emergency.

OTOH solar will bring you clean power year round without noise or smell, actually more than amortizing its cost over its lifetime.

What good are the square meters on your roof otherwise? If your roof is unproductive, might as well put it to good use.

$15k buys me 40 square meters, producing 7000 kWh per year. Where I live I get $5k state subsidy, so net $10k out of pocket. 7000 kWh is about $1600 savings on my utility bill per year.

Model_D | 4 March 2017

I have solar. When there is a power failure my system simply shades the roof. It would not charge my X. If I had an inverter with the simple emergency backup, it would charge at 3 mph for 4-6 hours a day on full sun days only. If I spent another $5,000 to $10,000 I could install a battery backup system which automatically separates my house from the grid and could charge my X about 5-20 kWh per day.
A $600 generator could charge my X at 4.8 kW until it runs out of gas. Then I could get more gas.
People are free to get whatever they want but should be aware of what is really required and how much they need to spend.

RIchgpilot | 4 March 2017

Feel free to thread drift this all you want but this started out as a simple generator/charging tech question. The value of a solar system belongs somewhere else.

MyXinTx | 4 March 2017

I can report that my home back-up generator (Honeywell) running on Natural Gas does charge my Tesla along with my house, although not very portable.

eric.zucker | 5 March 2017

@dwepilot: you are right, today, grid-tied systems won't work if there is an outage.
This is an aberration - if you have local generation, you should be able to use your own power independently from the grid. Such systems are still complex and expensive.
I see this as an opportunity...

mdd | 5 March 2017

Nope. Still makes no sense.

keiki | 5 March 2017

Sorry I did not clarify. Was referring to a whole house backup generator powered by a natural gas line for a power outage as I mentioned with the Hurricane we experienced in NY a while ago.
From reading so of the replies, I should check with professionals for correct information.

MyXinTx | 5 March 2017

@keiki - Like I mentioned, when I tested my backup 200 amp panel off grid and on my natural gas home generator, my HPWC charging at 60amps acted as though is was on the grid...with just a few LEDs and fluorescent overheads on.

I did not test with any high-amperage draws like HVAC.

torself | 6 March 2017

Have anyone seen this ? Might be a good solution if you can afford it:

Pink Floyd Roadie | 18 March 2017

I wonder if my hamster can generate enough power to charge my X from its spinning cage? ;-)

dortor | 18 March 2017

That's how PG&E does it between 11 pm and 7 am for the off peak $0.12 kWh.

eric.zucker | 19 March 2017

@pink Floyd roadie: Pedaling on an indoor bike, I would generate about 250W during half an hour. That's 125Wh, or .125 kWh. I'd have to do this during 360 hours non stop to fill a half full 90D battery.

A hamster weighs 100 to 200 times less than I do, assuming it's power output is in proportion, we need 36000 to 72000 hours of running to produce the same energy.

A hamster's life span is about three years, you wouldn't want to ruin its youth, say two years of adulthood. Get him running 8 hours a day, 5 days a week, two weeks vacation (minimum social benefits, or else the hamster running unions be be flogging you publicly with cooked broccoli), you're getting about 2000 hours of productive running from each.

In short, to charge your half full 90D or P90D Tesla overnight you need 4500 to 9000 hamsters running for you. That's for weekdays only, as weekend work needs to be compensated with extra time off.

To err on the safe side, accounting for maternity leaves, etc, I'd figure a workforce of about 20,000 to 30,000 hamsters should be a minimum.

If you don't drive too much that is.

The main issue is that hamsters produce CO2 and other global warming gases, so better keep your power plant hush-hush or the environmentalists, WWF, and other animal welfare guys will be after you.


Pink Floyd Roadie | 19 March 2017

Eric....ha, that's great analysis. Must be a scientist ! :-)
I'm off to the pet store ;-)

Pink Floyd Roadie | 19 March 2017

dortor, oh but wait. I lived in the bay area for several years. While that 12 cents might be the rate at night, I (and my neighbors) NEVER paid that low rate. That is probably the Tier 1 rate and PG&E has 5 tiers. Even with solar PV on the house we were always paying almost 30 cents per KW in the night TOU rate because of the tiers.

JPPTM | 19 March 2017

Pink--you must be on an odd plan. The EV-A rate (for electric cars) has NO tiers, but 4 time slots, cheapest overnight, most expensive at peak afternoon time. This plan really only works if you have solar to offset the egregious $0.40/kW peak day rate. If no solar, then you might be better on an 'old fashioned' plan with tiers.

dortor | 19 March 2017

What JPPTM said - EV-A has no tiers jus different rates at different times of day.

Pink Floyd Roadie | 20 March 2017

JPP, good info. I chose an E6 plan in order to maximize the income from the solar PV during peak hours. And at that time, a year ago, PGE would set up new customers on an E1 plan unless the customer specifically asks for the plan you refer. Interestingly I ran into a lot of neighbors whom has no idea there were different plans and were paying high tier rates unnecessarily. :-) I think you helped clear up some info for other people.

dortor | 20 March 2017

the following links discuss the California PG&E rate plans

the actual rate schedule is here:

kWh are prices as follows - no tiers

Summer - Peak: 0.44738, Part-Peak: 0.2466, Off-Peak: 0.12179
Winter - Peak: 0.31325, Part-Peak: 0.19447, Off-Peak: 0.12453

I was moved from a NEM E-7 plan which was fairly cheap to EV-A - which has worked out to be "not so bad" but I've had better. EV-A is the cheapest plan for me with Solar and my EV charging.

sholtz77 | 3 August 2018

@mpwitte Let's do it....shoot me an email sholtz77

bonhari03 | 3 August 2018

I get it. The Zombie Apocalypse! We have to be ready! I will be following this thread closely!

jjgunn | 6 August 2018

Slightly off-topic but we need more people to use Superchargers between 11PM - 7 AM in California. Help Tesla save money.

Energy team at the Tesla store told me...."90% of their customers charge at the worst time."

FYI.... I'm in the 10%..... are you?

vvvasilev | 31 October 2018

Guys, what about computer UPS? I have two spare ones of 5 KW each. Can I carry them in the trunk as a backup if I can't find a free charging slot?

hpjtv | 1 November 2018

@vvvasilev and how much range will you be losing as opposed to gaining with that extra weight?

Mcole94 | 3 January 2019

If you’re racing on a drag strip, it could be used to top off during the down time.