By Mike Sokol
Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) noshockzone.org with the subject line – JAM.
NOTE from editor: Be sure to check out CarGenerator’s owner’s informative comments in response to readers’ numerous questions below.
Dear Readers,
Last month I wrote about an interesting non-generator technology for supplementing solar panels while boondocking. The biggest question most boondockers have about power is whether to take a generator or not. Sometimes this is an easy answer, since if you want to run an air conditioner or electric appliances such as an Instant Pot or convection microwave oven, then you’ve pretty much answered your initial question. Yes, any high-power appliances will require a dedicated generator (and hopefully a quiet inverter type) when you’re camping out in the great outdoors.
However, if you’re running a lot of your appliances from propane (water heater, cook stove, 3-way refrigerator, etc.) and don’t need air conditioning, then you’ve probably already figured out that you can get by with a reasonable amount of batteries and solar panels. If that’s the case then you don’t want to bother with a generator.
But what happens when the “sun don’t shine” for days on end and you’re watching your battery charge head towards empty (or 50% for conventional lead-acid technologies)? Do you really want to haul around a generator that you should start up every few months and run for an hour just to keep the fuel in good shape and the motor ready to start? I didn’t think so.
That’s why I was extremely interested in the CarGeneratorâ„¢ when I saw it at the Alumapalooza® Airstream Rally last year and asked the owner, Jonathan Schloo, to send me one for evaluation. Basically this is a 1,000-watt pure-sine inverter that’s been optimized and packaged to easily connect to your tow vehicle’s alternator via its battery terminals. It then outputs 1,000 watts of pure-sine AC at 120 volts that you can plug your RV shore power into.
So what can you do with 1,000 watts? Well, it turns out, quite a lot. The primary use for the CarGenerator is charging your RV’s house batteries with your existing converter/charger.
And the basic math goes like this. Watts is watts, no matter if it’s 12-volt DC power or 120-volt AC power. And since volts x amps = watts, if we raise the voltage a factor of 10x from 12 to 120 volts, then the amperage decreases by the same factor of 10. The CarGenerator with 1,000 watts of output makes around 8 amperes of 120-volt AC power by drawing around 80 amperes of 12-volt DC power from your car’s alternator at idle. That 8 amperes of 120-volt power goes into your RV’s shore power cord where your converter/charger converts it back to 12 volts (actually closer to 13.5 volts for charging), and can easily charge your batteries at 60 amps of 12-volt DC. That’s because 60 amps x 12 volts = 720 watts. So however fast your house batteries would charge on shore power (perhaps as much as 80 amperes), that’s exactly how fast you can charge them with a CarGenerator.
All this suggests you would only need to idle your tow vehicle engine an hour at a time every few days if the sun wasn’t shining to recharge your batteries or you had no solar panels but enough battery storage. And that would be enough watt-hours to allow you to power a 12-volt DC refrigerator (like the Vitrifrigo/Danfoss model I recently reviewed HERE) and a CPAP machine you need at night (no reviews yet), even if the sun wasn’t shining on your 200 to 600 watts of solar panels.
I promised you an update, and here it is. CarGenerator is now available with a TT-30 shore power outlet making it “RV Ready.” Now this TT-30 can’t supply 30 amperes of current from the CarGenerator since that would be 3,600 watts and the CarGenerator power output is only 1,000 watts, which works out to 8 amperes or so. But it makes a pure sine-wave 120-volt output at 60 Hz with less tan 3% THD (Total Harmonic Distortion), much like a Honda inverter generator. That means all of your RV’s electronics should be happy with it, and it won’t cause any overheating issues powering your RV’s converter/charger.
Also note that the TT-30 outlet is mounted “upside-down” on the side of the CarGenerator box with the ground pin at the bottom of the outlet instead of the top. That’s because it’s designed to drape the shore power cord over the top of the mounting strap for better strain-relief on your shore power cord – which is actually a pretty clever design.
Stay tuned for my RVelectricity newsletter next Sunday, May 31st, where I’m going to do a comparison of various generators for volume level under load at 23 feet, and including the CarGenerator being connected to my Nissan Frontier pickup truck. Getting interesting, isn’t it? For more information on the CarGenerator (in various wattage classes) please visit their website.
OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.
Let’s play safe out there….
Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
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Just watched his you tube videos where he demonstrates running your furnace, what he doesn’t tell you is he is running a gas furnace some where up north. What he doesn’t tell is this isn’t your typical furnace in the south that is total electric or a heat pump. So he is misleading people in that respect. He may have a good product but if he is going to sell nationwide he needs to get all his ducks in a row.
Thanks for the helpful advice, we will seek to clarify this is for a GAS furnace, not electric or heat pump. Unfortunately if you have an electric furnace or heat pump you have no choice , you need to have a big heavy noisy traditional gas generator to create the kw output required to drive this. In the context of this article and the main focus of RV use, the furnace use is really just a bonus anyways. thanks.
It’s an interesting attempt at a useful device, but I don’t really see the narrow usefulness band. It really is just a tiny PSW inverter in a plastic box, nothing more. So, operationally, a $100 item?? Put a cheap inverter in your trailer (even better weatherproofing, and more convenient!), and you’d have the same functionality.
1000W is pretty useless to me… not enough to run AC (25% enough w/o ++$300 softstart), and nothing else needs my generator. No, 2KW still isn’t enough. If you’re really only charging batteries, just connect your trailer and truck batteries with jumper cables and charge MUCH more efficiently than double-converting DC>AC>DC.
I have a 4KW inverter in my “setup” — for a time, I did mount it under the hood so it was always available with my truck for non-camping purposes. I have dual HD alternators that could carry that insane (350A) draw continuously. No, it didn’t get close to overheating because a truck big enough to carry that draw has lots of room under the hood for ventilation. Warm yes, but not that warm.
My bigger issue with that setup was that the engine compartment gets a more-than-desired amount of road dust, so I moved it back into my trailer bay and just use SERIOUS jumper cables when camping if I want the inverter to run from the truck. I really only bother doing truck-as-generator when generator nazis are around.
I haven’t done a fuel-efficiency comparison, but realistically, my inverter genny is almost certainly more fuel efficient than idling my truck — I might have to measure that just for curiosity now!
Also, my idling truck is louder than my inverter generator (really!), so it’s not a win for the generator nazi crowd either — which gives me perverse pleasure when they make me shutdown my quiet generator and start my truck… 😀
The usefulness and “why” of CarGenerator: to easily and safely make the power of your tow vehicle engine available for anyone camping, even in bad weather conditions. We have 1500/2000 watt models, but the 1000w model is mostly what our customers order, because it’s enough to modestly power the essentials of your RV like charging, lights, water pump, TV, laptops, etc. 1000w is low enough an amperage so that most tow vehicle alternators can keep up, plus 1000w is the upper threshold of what you can safely sustain through typical jumper cables. Higher than 100amps like our 1500/2000w models require installation of a dedicated high amp anderson style connector. So the important user friendly aspect here is that anyone can pull out their CarGenerator in less than a minute, and hook it up to their vehicle in any weather conditions, with no prior expertise, and create power for their RV trailer. It sounds like you are very comfortable working with high amperage automotive DC and installing cables and inverters in your truck, many people dont have this level of skill or comfort like you have. Double converting DC>AC>DC seems inefficient, however our inverter is 90% efficient with less than 3% THD very clean power, and its a big win in user comfort to simply plug in their standard 30 amp trailer power plug to power their RV the way the manufacturer designed it with no worries about matching battery chemistry, fusing, charge rates, etc. Were you able to run your 4kw inverter at a significant load sustained for a long period of time? Most inverters have an overtemp shutdown around 140F, and most engine compartments run closer to 200F range. Regarding fuel efficiency, the government website energy.gov lists fuel consumption at idle is .39 gal/hr, comparing with a Honda 3000w generator spec from their website is .47 gal/hr. You are SO right about if your idling truck is louder than your inverter generator, i’m pretty sure this product will not be a good fit in your case. On the other hand, people that have a quieter truck or tow vehicle this is significantly quieter. Mike will be doing a noise comparison article soon with a fully calibrated db meter, will be interesting to see what that shows also. Thanks again for your great comments and input, see you on the road.
In many states it is illegal to idle a vehicle for more than a few minutes. Let all of us consider our right to breath clean air.
First and most importantly, idling a modern fuel efficient vehicle with thousands of dollars of emissions management is far cleaner than running a portable gas generator with almost no emissions output management. In some cases this may not apply, say if comparing a massive diesel truck to a small generator. Second, many of the idling bylaws have clear exemptions they do not apply if you are using the vehicle to “operate auxiliary equipment”, which is where CarGenerator fits in. We have a standing offer for the first CarGenerator customer to get an idling ticket, we will at our option either pay it or defend it in court. With customers coast to coast for 4-5 years now, not one single CarGenerator customer has ever been ticketed and our offer still stands.
I don’t think an idling vehicle could/should sustain 80 amps. Modern diesels should avoid idling due to DPF loading. Also if the primary goal is to charge batteries, then the conversion to 120V adds an unnecessary ineffieciency.
CARGENERATOR: the industry rule of thumb is around half rated amp output at idle. So for example in this video below, a modest 2013 Dodge minivan with a typical 160 amp alternator, easily produces 70 amps as you can see in the video, to power the core items in the vehicle. While using CarGenerator your vehicle is stationary and therefore doesnt use lights, wipers, cabin fan etc so we instead simply pull that exact same power out and use it for powering our RV instead.
In the thousands of hours we run our vehicles, an extra 3-4 hours every few days while camping is not even a drop in the bucket and no harm to the engine. Please also see my more detailed response regarding diesel in comments below.
Our inverter is 90% efficient, so the tradeoff of simply attaching a CarGenerator and plugging in your trailer 30 amp standard shore power cord and not worrying about matching battery chemistries, charge rates, etc is worth it to our customers.
Here is the link showing a modest 2013 Dodge mini van easily powering 70 ampsDC for basic functions. With CarGenerator instead of using that power for lights, cabin heat, etc., we pull that power out and power up your RV instead safely and easily. https://youtu.be/CH2VNHf8IpY
Mike, Interesting concept. Following it carefully. In a future column,
would you consider one discussing updating house or storage battery packages to Lithium batteries?
The major hassle seems to be the very different charging requirements.
A primary interest of mine is emergency communications (ARES) and chasing hurricanes.
Need to power radios with maximum power out of 100 watts RF.
CarGenerator would work great for ARES, our output is pure sine wave with less than 3% THD so very clean. One of our most interesting customers Global Medic uses this in disaster situations to produce power for situational mapping using drones.
Check out this video: https://youtu.be/YMuDW2398b0
Mike, am I missing something here ? From what I can see it’s just a PSW Inverter. Is that it ?
Thanks.
Richard
The heart of CarGenerator is a pure sine wave inverter, but we’ve solved the impossible challenge: to keep the inverter DRY during any kind of bad weather when we usually need power most, and also keep it fully VENTILATED because inverters throw off a lot of heat. Then matched it with custom manufactured high heat proof booster cables that can take sustained engine heat, and much more. have a look at how we do it and how CarGenerator is more than just an inverter, here:
http://www.CarGenerator.com/technology
Everyone…. Since there were so many questions and comments about this CarGenerator article, I’ve asked Jonathan Schloo to respond to you here. Please play nice.
If you are just recharging the house batteries and don’t need 120 volt sine-wave output, then consider a dc to dc charger available in 20A, 40A (500 Watts) & 60A from Renogy starting at $130.
I have no interest in Renogy but just like their products.
CARGENERATOR: DC to DC chargers are useful, however they do require an install with appropriate heavy cables fuses, etc. The beauty and simplicity of CarGenerator is simply take it out of the box, and less than a minute to hookup to your tow vehicle and plug in your shore power cord, and voila you have power with no generator hassles. Plus CarGenerator serves double duty as a home backup generator to power your fridge, TV, gas furnace, and more.
Hi Mike
I’m a retired auto mechanic. Trying to pull 80 amps from a alternator on a car that’s just idling will very likely cause it to overheat and burn out. The reason being is it’s not turning fast enough for its internal fan to push through enough air to keep it cool. On a small car, the alternator might be rated at 100 amp output, but that’s only for a short amount of time like to cover a sudden demand for power windows, seats, etc.
CARGENERATOR: the industry rule of thumb is around half rated amp output at idle. So for example in this video below, a modest 2013 Dodge minivan with a typical 160 amp alternator, easily produces 70 amps as you can see in the video, to power the core items in the vehicle. While using CarGenerator your vehicle is stationary and therefore doesnt use lights, wipers, cabin fan etc so we instead simply pull that exact same power out and use it for powering our RV instead.
Here is the link showing a modest 2013 Dodge mini van easily powering 70 ampsDC for basic functions. With CarGenerator instead of using that power for lights, cabin heat, etc., we pull that power out and power up your RV instead safely and easily. https://youtu.be/CH2VNHf8IpY
First, let me say I think you have a great product.
The power a furnace requires varies widely depending on the type and size. A newer hot water circulating system will use a lot less than a forced hot air unit, 350 watts vs. 800+ watts.
Another thing I’d like to mention is its dangerous to create any sparks near a battery. May I suggest hooking up the negative cable second and to a clean spot on the engine, away from the battery.
I have used inverters connected to car alternators for many years (20). Long term, you can only expect 500W from an idling alternator. While HD alternators MAY put out more, it deserves real world investigation before you plunk down the big bucks here. Also, while the form factor (weatherproof, RV outlet, turn-key) is worthy of a retail price, pure sine wave converters can be obtained for $150.00 mail order. Anything over 500W continuous automotive system will have to come from the chassis battery for a very short while. I also use the “winch connectors” shown in the videos, but these are available every in 50-300A flavors. Nice package but I am afraid there is some disappointment out there without understanding “why?”. Sailors use special marine high output alternators on their auxiliary power plants at sea.
As Mike Sokol stated so well in his previous article, a typical modern inverter generator is simply: gas tank+motor+DC alternator+AC inverter. CarGenerator uses the gas tank+engine+alternator you already have. You are right you can connect an inverter to your vehicle and thats where we started also years ago with this product. However, usually you need power when its bad weather, and therefore we had to custom engineer a case that would both keep the inverter DRY and also highly ventilated because they create a lot of heat. You cannot mount the inverter in the engine compartment because its 190 degreesF or higher which will cook the inverter, and it cant live outside in the rain, and trying to hide it under a bucket or umbrella is risky at best. Our custom engineered case combined with custom high heat proof pure copper cables make it both easy and safe. You can expect more than 500w from an alternator because 500w / 13 volts = around 38 amps DC. Most tow vehicles would typically have 150-180 amp alternators our SUV has a 250amp alternator from the factory, so even half of that at idle can very easily provide power with no strain or hardship on the alternator. The golden rule of CarGenerator is to make sure the built in voltage display doesn’t go below 13.3 volts, this way you know you are never draining your battery, simply from your alternator. The “WHY” of CarGenerator is to make the power of an inverter available to anyone in any weather condition in less than a minute without any prior knowledge, easily and safely.
No mention of air conditioners, microwaves, etc. So I’m assuming CarGenerator won’t let you run your a/c. Is that right?
No, this version only supplies 1,000 watts.
Our larger units provide 1500 to 2000 watts, so those could potentially power an a/c depending on your specific model. Our 2000 watt model is only for use with vehicles equipped with dual alternators, so for example you can order a factory installed dual 220 amp alternator so this could easily power it. The intended use would be more for use at rest stops or having lunch or brief cool downs, Personally I wouldn’t run the vehicle all night just to keep things cool… and neither would I run a noisy generator. When its that hot, better to find a campground and plug in and enjoy the peace and quiet.
With today’s emission laden diesel engines, any and all idling is a no-no. There’s even a gauge showing your idling hours compared to driving hours. This idea, in my opinion, would not be something I would try.
There is lots of debate on both sides of idling. The fact is that millions of vehicles idle every day for long periods of time: taxis, delivery trucks, diesel city work vehicles and buses, police, and more. In the tens of thousands of hours our vehicle engine runs over its lifetime, an extra 4-5 hours every few days is not even a drop in the bucket. Here is an article published by Ford with an example of a contractor using their Powerstroke truck, driving 50 miles per day, and idling it for 6 (six!) hours, over 100 days and how the impact is simply to change the oil more frequently to factor for the extra engine run time not on the odometer. https://www.powerstrokediesel.com/docs/How_Idle_Time_Affects_Maint_Intervals.pdf
Interesting article, but it’s way old. They’re talking about the 6.0 which is two Powerstrokes ago. The 6.0 was plagued by all kinds of trouble, blowing head gaskets being a big one. Then the 6.4 came out, and it seemed to fare a bit better. But now, with the 6.7 being the current biggie (and there have been three versions of THIS one), the issue becomes one of the Regen system and the diesel particulate filter which, when it needs to be replaced, can be a spendy proposition. I belong to a couple of Powerstroke forums and when guys come on looking for advice on buying a used 6.7, almost everyone says to look at the idle hours on the dashboard and shy away from trucks with high idle time. I’m not sure what qualifies as “high idle time” though. The more idle time, the sooner the need to have the environmental gear replaced. The truck will literally go into “limp mode” if it gets too clogged up and a regen can’t be initiated.
Trucks used in police, fire and other city environments just have to ‘eat it’, and tax money will fix them when needed. I actually take MY 2016 6.7 to Ford for scheduled oil changes (gasp!) and other maintenance because changing stuff myself is just too much trouble. My shade tree mechanic days are long gone – [smile].
Thanks for your thoughtful reply. A very interesting point in the article is how exactly Ford defines “extended idling”:
* Over 10 minutes (not moving) per hour of normal driving
* Frequent low speed operation
* Sustained heavy traffic less than 25 mph
Gosh… if I think about how often the above items apply to many people, that sure is a lot of idling! All the people stuck in traffic jams, creeping along, etc.
There is another interesting product we’ve come across costs about $100 and plugs into your vehicle ODB port and adjusts to a high idle, that could also be an option to consider. https://www.waytekwire.com/item/85551/Inpower-DBT-LD-01-Light-Duty-Vehicle-Data-Bus/
Some diesel vehicles, like the Mercedes Sprinter should not idle for more then 15 minutes,
Or their smog system gets clogged up. They need to run hot to burn this stuff.
CARGENERATOR: Personally I own a 2014 diesel Mercedes GL350 with similar engine to the sprinter. I’ve idled it literally thousands of hours over years with no problems. There is lots of debate on both sides of idling. The fact is that millions of vehicles idle every day for long periods of time: taxis, delivery trucks, diesel city work vehicles and buses, police, and more. In the tens of thousands of hours our vehicle engine runs over its lifetime, an extra 4-5 hours every few days is not even a drop in the bucket. Here is an article published by Ford with an example of a contractor using their Powerstroke truck, driving 50 miles per day, and idling it for 6 (six!) hours, over 100 days and how the impact is simply to change the oil more frequently to factor for the extra engine run time not on the odometer. https://www.powerstrokediesel.com/docs/How_Idle_Time_
Wll the car alternator supply that level of power at idle?
Not likely
That’s something I’m going to test.
CARGENERATOR: Yes your alternator supplies plenty of power at idle, the rule of thumb conservatively is about half the rated alternator capacity at idle speed. Here is the link showing a modest 2013 Dodge mini van easily powering 70 ampsDC for basic functions. With CarGenerator instead of using that power for lights, cabin heat, etc we pull that power out and power up your RV instead safely and easily. https://youtu.be/CH2VNHf8IpY
If I am just charging my house battery with my car why not use a set of jumper cables from car to house battery?
It is possible but most house batteries, unless TPPL (thin plate, pure lead) suffer from low charge acceptance and IR (voltage) drop through the cable. So you end up with 13.5 – 14.0v minus .5 – 1.0v drop through the jumper cable resulting in 13.0 v at house batteries which will only charge a really depleted battery bank.
So how about a DC to DC battery charger? Surely that would be cheaoer and more efficient than converting DC to AC and back again.
you’re right a DC to DC battery charger is slightly more efficient, however CarGenerator conversion is 90% efficiency with less than 3% THD harmonic distortion so its very efficient, and very clean power. Plus a DC-DC battery charger requires an installation expense, heavy cables and fusing etc, whereas CarGenerator hooks up to your tow vehicle in less than a minute and you have power with no generator hassles and zero installation setup headaches, etc.
If your house battery is Lithium a car alternator can’t charge it fully.
yes in most cases you can do this, however matching battery chemistry, charge rates, etc can be worrisome for the average RV trailer owner. with CarGenerator simply hook it up, start your engine, and plug in your RV shore power cord just like in a campground and use the factory approved power converter charger to do the job right. CarGenerator is 90% efficiency so you are using your available power well this way.