How much gas does your genny use? And a charging question

[Naio]

After generous advice and hand-holding from folks here, I experimented with running my van engine to charge house batteries when dry camping, as I do not yet have a genny or solar. I used an MSW inverter and a 30 amp 'smart' charger. Now I have results to post and subsequent questions.

I did this for a total of 7 days at two campgrounds. At the first cg, I felt bad because my van engine was louder than the neighboring gennys. At the second cg, I did not, because some gennys were louder than my van, so I felt I was fitting in with social norms :).

It's hard to estimate, but it seemed to take about 1/2 gallon per hour, idling the van. Seems like a lot of wasted energy. How much does a small generator use? OTOH, the van gets nice and warm for sleeping at night!

Charging this way took a LOT longer than plugging in to 120v. I don't have an ampmeter yet, but it took around 3x as long. Same charger. Is there anything I can do to speed things up? My alternator is 105v, so I don't think that is the problem.

[pnichols]

Thanks for the link on Ford special application packages. I had searched for this in the past and not found the information so nicely laid as it is in that link.

I'd think that the ultimate Class C Ford chassis would be to start with an E450 Type III with a limited slip differential, but probably no RV manufacturer would build a Class C on one.

[Gdetrailer]

pnichols wrote:

Gdetrailer wrote:
You have a built in "regulator" (older alternators used a separate regulator which was often mounted near the battery), many newer alternators also communicate with the vehicles BCM (Body Control Module) and the BCM will control the alternator rotor current and has charging curves that it will follow.

Thanks for your long explanation on how altenators work. I already was aware of most of what you said as I used to be an EE before retirement.

However I'm not sure that I laid out any "misinformation" in my long post explaining what happens in my case - including what is implied and stated in Ford's published performance specifications for their V10 engine 130 amp alternator. Our motorhome came with twin coach batteries and I doubt that Winnebago would expect them to burnout/destroy/blow fuse links/whatever on the chassis alternator system under any conditions that these batteries might be in - including them being completely flat. Our Ford motorhome has a computer controlled 5-speed (6 speeds internally) TorqShift transmission, so most likely the altenator also has what you call a BCM to go along with the other computers on board. It's indeed keeping the alternator from over-heating under heavy current loads - probably as you say via control of rotor current - hence protecting it during recharge of low RV batteries ... as I would expect to be happening. By the way, our motorhome's engine has a huge radiator fan that of course does two things - it sucks air through the radiator to cool it and pushes air back onto the alternator to cool it. Just as a side point, our motorhome can continue to travel with a blown alternator .... just run the built-in generator when going down the road and tape the boost control "ON" so that the generator is supplying all engine current by means of the coach and starting battery being all connected together in direct parallel ... as Winnebago designed it.

Regarding flat vehicle batteries - I have throughout my life had some "flat" vehicle starting batteries and after jump starting the engine - let the engine idle for hours to bring the flat battery back up. This is even including 1950/1960's era engines with their vintage generators and alternators in cold Michigan winters. I'm of the opinion that modern alternators are capable of more than we think.

The marine community expects a lot out of their boat engine alternators all the time and I don't think that all of their marine engine alternators are necessarily the special marine versions with sophisticated battery charging circuits built in.

I doubt that ambulance packages include better technology alternators .... just maybe a bigger one, or maybe two instead of one, of the same type that came stock on my E450 chassis.

You incorrect.

Ambulance prep has CONSIDERABLY higher amperage alternators over the standard non prep package..

2014 Ford AMBULANCE PREP PACKAGE

Per, link above for F350/450/550..

Ambulance (47A/47L) and Fire/Rescue (47J)
Prep Packages
47A
47L
47J
Dual heavy duty alternators, 157-amp plus 200-amp (67A)


In other words, 357 AMPS worth of alternators!

F350 vans get a 225 Amp alternator which is MORE than a non prep package will get.

Additionally the package INCLUDES.. EPA Special Emergency Vehicle Emissions which IS DESIGNED for long extended idling.

Along with Elevated Idle Control (SEIC) has been integrated into the control module
and is standard.

Depending on vehicle the package often includes dual batteries..

Basically in a nut shell, Emergency vehicles are typically bought with the Ambulance/Emergency Prep Package.. Fire companies typically do not buy a vehicle directly off the dealer lot.. They can't if they want to be able to get warranty work done. Using a non ambulance prep vehicle for ambulance or emergency use WILL VOID the warranty.

By the way, using the vehicles alternator for a "one off" recharge of a dead battery isn't going to kill the alternator..

However REPEATED CONTINUAL usage in that mode WILL SEVERELY SHORTEN THE LIFE OF THE ALTERNATOR.. Along with many other components under your hood..

I have rebuilt a few alternators over the years, mostly due to extreme high mileage usage so I am familiar with what can go wrong with them.. One of the more interesting failures was one that started to charge at a lower current than it should..

When I opened it up, I found three of the six diodes had broken solder joints.. The high mileage with normal under the hood heat from heavy hauling had created enough expansion and contraction of the diode leads that it broke the solder joints. Resoldered the diodes and put back together and it charged like it was new again..

The point is, extended idling creates a lot of underhood heat, the engine compartment really relies on the vehicle MOVING for the MAJORITY of the time the engine is running. The radiator fan is designed to ASSIST during low speed, stop and go traffic and heavy long hill pulling. At idle that fan is LOAFING.. Just because it is spinning doesn't mean it will keep the under hood temps in check under extended idling.

HEAT is your enemy, it will destroy electronics very quickly..

You are more than welcome to do what you want to do..

[Almot]

Naio wrote:
Wow, lots of good (and contradictory) information, on this page and the previous.

People here can be rather technical. This why I find this section of forum useful. Read the last post by Landyacht, it's easy to see why some posts contradict each other - too many variables.

Naio wrote:

As for my electricity use: I don't heat food, make coffee, run a furnace or fridge, etc., on batteries. I use tent camping equipment for lights, food, etc.

Sounds like prime candidate for solar.

Without a furnace your daily draw should be 25-40 AH a day. This includes DC circuit of propane fridge and occasional laptop charging.
250W solar will harvest that much in AZ in December on a clear day. On a dark winter day it will harvest 10-20 AH a day, depending on how dark.

At 40 AH daily draw, with 2*100AH battery, you can store enough energy to last 3-4 dark days with partial solar charging and without running your engine, so the battery will be down to 50% on day 4. Or - unlimited stay with running your engine on those dark days for 20-30 minutes, and no engine running on clear days. Don't know if in places like QZ there can be 4 dark days in row, in Baja this doesn't happen.

2*100 AH battery can be either 2*6V flooded GC mounted outside, or 2*100 AH AGM mounted inside.

[John___Angela]

NinerBikes wrote:

John & Angela wrote:

NinerBikes wrote:
Strange that my 2013 Touareg TDI diesel with a 3.0 liter motor and one battery has an alternator rated for 220 amps, maximum.

Those touaregs are amazing. A fellow hooked onto a 3800 pound trailer for a test pull yesterday, set the cruise at 90 KMH and went up what was probably a 6 grade hill and it just ignored the hill. Something like 400 pounds torque and 340 HP. Heck of a machine. Hitch weight was around 400, hardly dropped. Didn't even need an equalizer hitch.

406 ft lbs, 240 HP, and only 5000 lbs of SUV that's AWD, all the time. My TT, dry weighs about the same, but I go easy on my motor and slow down going up hills, usually 40 to 45 MPH. It will go faster, but I don't like working the little motor that hard, I'd like 300,000 miles out of the drive train if I treat her right. Tongue weight and payload weights on the vehicle are what to watch out for.

It's a light diesel motor, so I treat it and run it accordingly, don't abuse it, and don't burn enough fuel to get the tranny and engine working too hard or too hot. I limit fuel consumption rate in the instant mpg reading in the dash to a max of 4.5 to 5 gallons of fuel burned an hour, when going up hill. If I am showing 10 MPG instant mpg, I'm keeping it at 45 mph or less for speed, if the grade is that steep. If it drops off to 8 mpg, 35 MPH up hill is all I do. Making heat and not being able to get rid of it is the enemy of these VW products. Again, they are light diesel motors. Only a fool uses cruise control on a vehicle like this going up hills and grades. Poor practice when trailering, operator needs to be more proactive and less lazy.

Porsche with it's Cayenne, and VW with the Touareg split the development costs in designing this SUV platform that is shared between the two brands. It was built originally for Europeans to tow their Caravans (TT in North American speak) to the Alps to go summer camping. Americans now are coming around to using them here for the same purpose. I believe in 2014, ALL Touaregs came with a 7700# rated hitch and tow package, in the USA. It was no longer an option.

Thanks for the correction on the HP. Still very impressive. I think he was just testing how it felt as I don't think he actually tows with the cruise on. He was using it as a reference from an earlier trailer.

On a much smaller scale we use our little diesel smart car to tow our 500 poundish tent trailer and Kayak to local lakes. Around 50 HP and 96 pounds torque but of course much lighter too. I put it in 5th for hills to keep it in the torque band but it never struggles with that light of a load. ALways sounds happy though. When not towing we pretty much get the rated economy of 3.30 L/100 km; 71.3 US mpg although that drops off when running at 110 (70 mph) on highways, interstates etc. Way fun though. Go figure, In europe the gas smart car have higher tow rating than the diesels, having said that it is a bigger motor and different transmission for the gasser.

[NinerBikes]

John & Angela wrote:

NinerBikes wrote:
Strange that my 2013 Touareg TDI diesel with a 3.0 liter motor and one battery has an alternator rated for 220 amps, maximum.

Those touaregs are amazing. A fellow hooked onto a 3800 pound trailer for a test pull yesterday, set the cruise at 90 KMH and went up what was probably a 6 grade hill and it just ignored the hill. Something like 400 pounds torque and 340 HP. Heck of a machine. Hitch weight was around 400, hardly dropped. Didn't even need an equalizer hitch.

406 ft lbs, 240 HP, and only 5000 lbs of SUV that's AWD, all the time. My TT, dry weighs about the same, but I go easy on my motor and slow down going up hills, usually 40 to 45 MPH. It will go faster, but I don't like working the little motor that hard, I'd like 300,000 miles out of the drive train if I treat her right. Tongue weight and payload weights on the vehicle are what to watch out for.

It's a light diesel motor, so I treat it and run it accordingly, don't abuse it, and don't burn enough fuel to get the tranny and engine working too hard or too hot. I limit fuel consumption rate in the instant mpg reading in the dash to a max of 4.5 to 5 gallons of fuel burned an hour, when going up hill. If I am showing 10 MPG instant mpg, I'm keeping it at 45 mph or less for speed, if the grade is that steep. If it drops off to 8 mpg, 35 MPH up hill is all I do. Making heat and not being able to get rid of it is the enemy of these VW products. Again, they are light diesel motors. Only a fool uses cruise control on a vehicle like this going up hills and grades. Poor practice when trailering, operator needs to be more proactive and less lazy.

Porsche with it's Cayenne, and VW with the Touareg split the development costs in designing this SUV platform that is shared between the two brands. It was built originally for Europeans to tow their Caravans (TT in North American speak) to the Alps to go summer camping. Americans now are coming around to using them here for the same purpose. I believe in 2014, ALL Touaregs came with a 7700# rated hitch and tow package, in the USA. It was no longer an option.

[John___Angela]

NinerBikes wrote:
Strange that my 2013 Touareg TDI diesel with a 3.0 liter motor and one battery has an alternator rated for 220 amps, maximum.

Those touaregs are amazing. A fellow hooked onto a 3800 pound trailer for a test pull yesterday, set the cruise at 90 KMH and went up what was probably a 6 grade hill and it just ignored the hill. Something like 400 pounds torque and 340 HP. Heck of a machine. Hitch weight was around 400, hardly dropped. Didn't even need an equalizer hitch.

[NinerBikes]

Strange that my 2013 Touareg TDI diesel with a 3.0 liter motor and one battery has an alternator rated for 220 amps, maximum.

[Naio]

Wow, lots of good (and contradictory) information, on this page and the previous.

As for my electricity use: I don't heat food, make coffee, run a furnace or fridge, etc., on batteries. I use tent camping equipment for lights, food, etc.

[pnichols]

Gdetrailer wrote:
You have a built in "regulator" (older alternators used a separate regulator which was often mounted near the battery), many newer alternators also communicate with the vehicles BCM (Body Control Module) and the BCM will control the alternator rotor current and has charging curves that it will follow.

Thanks for your long explanation on how altenators work. I already was aware of most of what you said as I used to be an EE before retirement.

However I'm not sure that I laid out any "misinformation" in my long post explaining what happens in my case - including what is implied and stated in Ford's published performance specifications for their V10 engine 130 amp alternator. Our motorhome came with twin coach batteries and I doubt that Winnebago would expect them to burnout/destroy/blow fuse links/whatever on the chassis alternator system under any conditions that these batteries might be in - including them being completely flat. Our Ford motorhome has a computer controlled 5-speed (6 speeds internally) TorqShift transmission, so most likely the altenator also has what you call a BCM to go along with the other computers on board. It's indeed keeping the alternator from over-heating under heavy current loads - probably as you say via control of rotor current - hence protecting it during recharge of low RV batteries ... as I would expect to be happening. By the way, our motorhome's engine has a huge radiator fan that of course does two things - it sucks air through the radiator to cool it and pushes air back onto the alternator to cool it. Just as a side point, our motorhome can continue to travel with a blown alternator .... just run the built-in generator when going down the road and tape the boost control "ON" so that the generator is supplying all engine current by means of the coach and starting battery being all connected together in direct parallel ... as Winnebago designed it.

Regarding flat vehicle batteries - I have throughout my life had some "flat" vehicle starting batteries and after jump starting the engine - let the engine idle for hours to bring the flat battery back up. This is even including 1950/1960's era engines with their vintage generators and alternators in cold Michigan winters. I'm of the opinion that modern alternators are capable of more than we think.

The marine community expects a lot out of their boat engine alternators all the time and I don't think that all of their marine engine alternators are necessarily the special marine versions with sophisticated battery charging circuits built in.

I doubt that ambulance packages include better technology alternators .... just maybe a bigger one, or maybe two instead of one, of the same type that came stock on my E450 chassis.

[John___Angela]

All good info. Before we did our cable upgrade we did some checking with a couple mechanics as well as posted on a couple of forums to see how a 130 amp alternator (what we have in our E350 based motorhome according to the specs and my mechanic) would hold up to a 40 to 50 amp load current for an hour or two. General consensus from those who had experience with large competition type sound systems, large external light units (4 X 4's etc) and others with everything from trailers full of freezers to pump setups. etc. Anyway, the one caution was to be sure to monitor the current for excessive loads, eg, starting out with dead batteries either on the additional apparatus or the truck/van battery. However, if the van battery was already charged, none had any problem with the 130 amp alternator supporting 40 to 50 amp extended loads. We generally see mid to high 30's at idle, more when the toaster or microwave is on. In my case it is never more than an hour as the two group 31 AGM's take a charge easy and once it starts to drop off below 15 or 20 amps I shut it down. Our primary (off grid) charge source is the 320 watt(ish) solar array. However sometimes the weather doesn't cooperate and its nice to have a back up. In our case a generator is out of the question. We have been doing this for 7 or 8 years but not a lot. A bad year might be 20 hours, not so much most years. Depends. We are already over 180K on the odometer and all is well. If I blow up the alternator someday I'll probably put a 160 amp in there. Have to watch the batteries acceptance though. When the dometic fridge dies a residential or 12 volt compressor type will go in and we will put in a couple more AGM's. Meanwhile, if anyone wants to cite a success story of using the alternator as a good backup high current charge source, we are it.

On edit, keep in mind that during the charging of the coach AGM's there are no lights, fans, heaters etc on. Really most of the current heads for the AGM's.

[Almot]

NinerBikes wrote:
...change out all your light bulbs to lcd lights, to use less battery and conserve more amps, daily.

Yes. LED lights is a must in energy conservation - especially for snowbirds. It's dark at 6pm in winter, and then either mosquitoes become active at sunset or it gets cold shortly after (or both). So you have to stay inside and burn lights for 3-4 hours until you go to bed.

You will still hear sometimes comments against LED - not because of radio noise caused by certain types of LED lights, but because of "unnatural" color. Pay attention to color temperature. If you want the same yellow-ish light as those old 18W bulbs, get LED with 2700-3000K color temperature. The higher the number, the "whiter" or "bluer" it becomes. In the kitchen I prefer more whiter color of 3000-3500K.

[Gdetrailer]

pnichols wrote:
I don't understand all this talk about being hard on vehicle alternators. Aren't they protected from burn-out regardless of how they're used?

It sure seems to me that's the way that they coulda/shoulda been designed in the first place. I assume that my RV's Ford 130 amp alternator can supply - if I spin it at high enough engine RPM - somehwere around 130 amps as long as I want it to, or until it's temperature protection and/or amperage protection kicks in .... whichever comes first. What am I missing here? :h

Per my Ford alternator's RPM versus amperage output curve, it can deliver around 60-70 amps at true engine idle. I assume it can do this forever, as the footnotes at the bottom of the curve say nothing about "intermittent use only".

Maybe alternators in the good old days could be burnt out - but modern ones have adequate protection? I can't anyway anyhow wrap my brain around being able to out smart the built in over-temperatue and/or over-current protection electronics in modern vehicle alternators.

Regarding long term idling of late model V8 and V10 engines .... I believe that Ford based (and probably Chevy based) ambulances and other emergency vehicles sit idling for hours at incident sites. And also, how about police cruisers .... they sit idling for hours along roads even in extreme heat with their air conditioners running, don't they?

A lot of mis-information in the above quote..

There IS NO "burn out protection" built into the alternators.

You DO have FUSEABLE "LINKS" involved with the stock vehicle wiring, but they are there to protect the wiring in case of a wiring short..

Inside a alternator you have one set of brushes with one "commutator" that the brushes ride on.. The brushes supply power to the rotor and that power magnetizes the rotor..

You have a built in "regulator" (older alternators used a separate regulator which was often mounted near the battery), many newer alternators also communicate with the vehicles BCM (Body Control Module) and the BCM will control the alternator rotor current and has charging curves that it will follow.

The rotor when powered and turning is energizing the stationary coils called a stator.

The stator output is three phase AC which can't be used with a battery..

So the output of the stator is connected to a full wave diode (AKA "rectifier") which converters the three phase AC into an unregulated/unfiltered choppy DC voltage.

You also have a pair of bearings rotating also..

You have ALL of the above mentioned items crammed into a space of a 50 pack spindle of CD or DVD blanks.

Here is a real nice cutaway drawing of an alternator from the website link below..



You will notice that the regulator, brushes and the diodes are located IN THE BACK of the alternator.. Newer alternators have a fan on the back of the stator to help cool those items.. older alternators do not..

Then add in that pretty much ALL vehicle manufacturers place the alternator ON TOP of the engine and if not on top on the side of the engine but basically in about THE HOTTEST PLACE YOU CAN FIND ON A ENGINE.. Not to mention the alternator ENDURES ALL the HOT AIR being pulled through the engine radiator/A/C condenser/transmission cooler and if equipped the power steering cooler..

So what can go wrong?

The alternator will easily get heat soaked just sitting still, then add in a very long term heavy load and you can easily over heat the regulator and or the diodes.. Not to mention the wear on the brushes and bearings..

Years ago I had someone pull off in my yard when the bearings in their alternator locked up and took out the serpentine belt.. They lost battery charging, power steering, engine cooling (no water pump turning)A/C and anything else driven by that belt.. Was a fairly new truck..

Should be pretty easy to see as to why it isn't a good idea..

GOOD DESCRIPTION OF AN ALTERNATOR

Per the website above.. (please pay attention the bolded section)

So what is the purpose of the alternator ?

An alternator is designed to maintain the state of charge of a cars battery while the car is being driven by providing the energy required to power the cars electrical system.

What are limitations of the alternator ?

ALTERNATORS ARE NOT DESIGNED TO RECHARGE A LOW OR DEAD BATTERY !
Charging a dead or low battery is the job of plug in battery charger only!
As stated above an alternator is designed to maintain the state of charge of a battery. Due to the huge power requirements of the normal operation of a cars electrical system today the alternator usually runs at or near its maximum output the entire time the car is driven. A dead or low battery adds to the work the alternator is required to do. There simply is no way for the alternator to recharge a low or dead battery and power the electrical system at the same time.

Low or dead battery would happen to describe a RV battery which has been heavily discharged..


as for ambulance or emergency type vehicles that USE IS addressed by the vehicle manufacturer in a "ambulance/emergency use" option package and certifications.. Does not apply to non ambulance prepped vehicles..

Do what you want, it is your vehicle..

[pianotuna]

Hi Land,

Another competent installer is http://www.starlightsolar.com/Home.html in Yuma.

They are doing LI batteries, too.

[NinerBikes]

Almot wrote:

landyacht318 wrote:

... she won't be installing solar on her roof by herself. The labor to do this job, and how most paid installers do halfass jobs using halfassed wiring, is not a desirable route, though Solar itself is great at silently getting 80% batteries up and near to 100%, a job the alternator is Not good at, and neither is a grid powered charger hooked to a generator or a MSW inverter.

Installers are getting better, there is more of them to choose from. Even with the most stupid and lazy laborer there is an option to make them do it YOUR way, and this is what I would do if I were the OP. Do you research, ask, order most crucial parts and specify how it needs to be done - what panels, controller, panel mounts, wire gauge. Then just be there. Not much different from dealing with contractors in Mexico - you have to be there or they won't work or won't do it right (I would say, in Mexico almost never they would do it “right” because have no right tools or knowledge how to use it). Usually solar installers won't argue and will do what you tell them to.

So far I've heard of only one source for quality solar installers - www.amsolar.com. Some of their contractors are mobile, traveling all over. I don't endorse this company and didn’t buy any parts from them. Shop around for parts.

For DIY ideas, you can browse The list of completed projects
The very first link on the List is by Sleepy - on a small motorhome. Old post, panels are cheaper now and people install more and larger panels. As I see, the only time she needed help was to lift panels on the roof.

Yes, solar will often charge to 80% and near 100%.

Yes, solar does does a better yet job of charging “from” 80% to 100%, because these last 20% are slow, no matter what charging source, and it’s better to let solar do this after initial boost by generator or engine in the morning than running a generator for another 3-4 hours.

Yes, solar can charge from 50% to 100% as well. Energy conservation is the key, especially with a small solar. If you can make your coffee on propane, and reheat leftovers also on propane, a 200-300W solar in the South in winter will charge to 100% most of the time.

One other power hog is a furnace. Some people chose to replace it with Olympian catalytic heater from Amazon - those are non-vented, but apparently it works. I'm trying to get a vented cat heater for over 6 months now, from the only company that makes it, and am losing my patience already. But, with plenty of sun and nights above freezing, a furnace could still fit in the solar "energy budget".

Yes, bigger battery bank is important for off-grid, especially while on solar. Because you need to be able to ride through bad weather days. There aren't too many bad days in snowbirds destinations, but you still need to store at least 1.5 days supply. Which means - you need to do you "energy audit" - determine know how much you typically draw. Many people don't know. And - whether you can minimize this draw - a lot of people can't or don't want to.

If increased battery bank requires AGM due to space considerations - then get AGM, why not? They don't release fumes and can be mounted inside. Only Lifeline brand of AGM has very high charging rate, all other brands typically state that you should not exceed 0.3C charging rate, and this is about the same rate as with flooded. I recall reading 0.2-0.3C "recommended" rate in the manual of popular Troyan flooded batteries.

/\ He pretty much covered all the bases when it comes to electrical energy, except one.... change out all your light bulbs to lcd lights, to use less battery and conserve more amps, daily.