charging from alternator effects on fuel milage

[SternWake]

True, my alternaotr forced to seek 14.7v with a depleted battery would require more work from the engine than if it were only allowed to sek 13.6.

BUt 'quite a bit more" in terms of fuel used, well Heck,
I don't care. I'm driving anyway, I want maximum alternator contribution, rather than maximum MPG.

Since you cannot control the voltage your alternator is allowed to seek, and you don;t mind running your generator when driving, by al lmeans use the honda to power the adjustable voltage meanwell or powermax as 14.8v always wins over 13.7 when the batteries are depleted and time to rechrge is limited.

I'd save the option of charging house bank from the alternator though for If/ when your driving pattern changes.

Sell the surepower 1314 voltage sensing solenoid, and put this in its place:

https://www.amazon.com/dp/B011EYWMDS?psc=1

 

[jonsun]

I highly doubt a honda generator needs replaced in 6-7, mobilesport. they are built to last.

I have a POS champion 4kw running 200-400hrs a year for 9 years and it's going just fine.

 

[Spaceman Spiff]

How much does alternator charging effect fuel milage?

Sternwake wrote
"MS Since you generator recharge I guess you are curious as to whether you are better off running the generator powering meanwell/powermax rather than employing the alternator."

Exactly  ,  I've been running  some numbers and I came up with  this.

My Honda genset uses approximately .33 cents per hour in fuel to charge  the batteries 

I believe a traditional alternator would cost ballpark . 60 cents a hour to charge batteries while driving and
a setup like your 14.8volts adjustable regulator would cost quite a bit more in fuel then a traditional  alternator. 

The Honda would need replaced every (estimate) 6-7 years @ $1050 but i believe the fuel savings
would pay for it.

Make sure you are comparing apples to apples.

A Honda EU200i produces 1596 Watts (13.3 amps @ 120V and uses 1/4 gallon of gas per hour to do it (Honda specs.).  Now add in the inefficiency of your battery charger.  If you are using the 12V plug you are only getting a maximum of 8A.

For a 100 amp alternator to produce the same 1596 Watts will require ~10.2 horsepower (assuming 55% efficient alternator, 21% system efficiency).
http://www.delcoremy.com/documents/high-efficiency-white-paper.aspx

From here it gets complicated.  If you are running a 100 HP vehicle at close to maximum output, adding 10.2 HP will noticeably effect gas consumption.  If you are running a 400 HP engine at 1/4 output you will hardly notice it.

Using your numbers (33¢/hour), the Honda is barely outputting any current (@$2.2/gallon, that calculates to 7 hours RT per 1.1 gallon tank as compared to 8.1 hrs at idle with no output).  Using 60¢/hr for engine alternator and way more assumptions than I am comfortable with, I come up with between 350W and 560W; 25% to 40% of a 100 amp alternator (57% of the more typical 70 amp alternator).  So I don't think your comparison is valid.

Note that 21% efficiency is an average for vehicles requiring a 100 amp alternator to run things.  Actual efficiencies vary from >70% to ~3%.

 -- Spiff

 

[Mobilesport]

.need to edit. ......

 

[Mobilesport]

The Honda 2000i will run at least 9 hours on a full tank.
A full tank holds 1.1 gallons
1.1 gallons of gas cost $2.97
$2.97÷9=.33 cents per hour

IF I go by your lower gas price of $2.20 then it even cheaper.

 

[John61CT]

I can't see those tiny quiet gennies running thousands of hours between rebuilds.

And for regular charging use you'd definitely want a quality high-amp charger/power supply, ideally manually adjustable, NOT running off the tiny built-in DC output.

But really for me the ideal would be a small quiet motor driving a high-output alternator, say 120-140A continuous, never mind the complexity and inefficiency of outputting 110AC then converting back to 14V DC.

Pretty sure 5-7 HP would be enough, whole charger could be <80 lbs. IMO too bad these aren't commonly available.

 

[jonsun]

Make sure you are comparing apples to apples.

A Honda EU200i produces 1596 Watts (13.3 amps @ 120V and uses 1/4 gallon of gas per hour to do it (Honda specs.).  Now add in the inefficiency of your battery charger.  If you are using the 12V plug you are only getting a maximum of 8A.

For a 100 amp alternator to produce the same 1596 Watts will require ~10.2 horsepower (assuming 55% efficient alternator, 21% system efficiency).
http://www.delcoremy.com/documents/high-efficiency-white-paper.aspx

From here it gets complicated.  If you are running a 100 HP vehicle at close to maximum output, adding 10.2 HP will noticeably effect gas consumption.  If you are running a 400 HP engine at 1/4 output you will hardly notice it.

Using your numbers (33¢/hour), the Honda is barely outputting any current (@$2.2/gallon, that calculates to 7 hours RT per 1.1 gallon tank as compared to 8.1 hrs at idle with no output).  Using 60¢/hr for engine alternator and way more assumptions than I am comfortable with, I come up with between 350W and 560W; 25% to 40% of a 100 amp alternator (57% of the more typical 70 amp alternator).  So I don't think your comparison is valid.

Note that 21% efficiency is an average for vehicles requiring a 100 amp alternator to run things.  Actual efficiencies vary from >70% to ~3%.

 -- Spiff

you're not running 1500w charging batteries. look at the 50% load. it's more like an 1/8th of a gallon. No matter how you want to look at it, it makes zero sense to run off an alternator if you have a generator.

as for longevity 
http://forums.outdoorsdirectory.com/showthread.php/97738-How-many-hours-on-your-EU2000

the lifan, champion, ryobi's @ 50% the price do a very good job too. maintain them and you're good for thousands of hours. not to mention much easier to change than an alternator.

 

[Spaceman Spiff]

The Honda 2000i will run at least 9 hours on a full tank.
A full tank holds 1.1 gallons
1.1 gallons of gas cost $2.97
$2.97÷9=.33 cents per hour

IF I go by your lower gas price of $2.20 then it even cheaper.

I'm not arguing your 33¢/hr number, I am saying at that rate the Honda is close to idle, generating little current.  Add a load, fuel consumption goes up; at 1600 watts it cost $2.97÷3.4 hours = 87¢/hour.  And you aren't factoring in the losses in the charger.

My contention is that your 60¢/hour number for your vehicle alternator seems to represent the alternator delivering significant amps to the house battery; which is not a fair comparison to an idling generator.

I started out trying to answer your initial question "[font=Verdana, Arial, sans-serif]How much does alternator charging effect fuel milage?".  I got sidetracked when I could not reconcile your cost of alternator charging with the output of the Honda (sorry).[/font]

[font=Verdana, Arial, sans-serif]Back to your original question: I cannot begin to tell you what it costs to charge your batteries with your vehicles alternator because I do not have enough information and the cost would vary widely depending on that information.  Answers to these questions are easier to measure than calculate; just make sure you are measuring the same thing.[/font]

[font=Verdana, Arial, sans-serif] -- Spiff[/font]

 

[jonsun]

the honda is not at idle at 8.1hrs per .96 gallon tank. it's at 1/4 load or 400w. charger inefficiencies are about 95% so you're looking at roughly 7.5hrs run time on a gallon of gas with an output a bit over 25amps @ 14.8v or again about 1/8th of a gallon per hour WITH A CHARGING LOAD.

 

[highdesertranger]

400 watts is not going to run a very big charger. highdesertranger

 

[Mobilesport]

Space man Spiff wrote
"My contention is that your 60¢/hour number for your vehicle alternator seems to represent the alternator delivering significant amps to the house battery; which is not a fair comparison to an idling generator."


Correct , my .60 cent number did refer to a alternator delivering big amps.
My generator is'nt idling though, it runs in eco mode powering a 40 amp charger w/ 14.8 volt output.
I've ran the generator many times powering a 4 amp 5000btu ac in ecomode and the
full 1.1 gallon fuel tank lasted at least 9 hours if not 11 , when not in ecomode only 6 hours maybe  7

 

[Spaceman Spiff]

I am going to bow out of this conversation.  It is obvious to me that we are not communicating and it is distracting from an interesting question.  Thank you for giving me an interesting problem to work on for a couple of days; I did learn some new things about alternator charging.

 -- Spiff

 

[jonsun]

400 watts is not going to run a very big charger.  highdesertranger

The meanwell 35a is 600w. 400/14.8 - 5% = ~25a

Perfect for a single 100-120ah battery, maybe a little too much

 

[John61CT]

Depends on chemistry, 25% of the AH rating (.25C) is fine for most lead, it's OK to charge AGMs at .5C, although getting up that high may not be worth the actual time saved since it only applies to the early bulk phase.

Except maybe burning fuel only for charging, saving engine runtime.

LiFePO4 and Firefly Oasis will accept higher than 1C, in that latter scenario would be great, get the bank up to 100% in under an hour.

Not to mention there's no need to even get the bank full, as regular lead and AGM require for longevity.

In a context of fossil-fuel as the only charging source, the higher up-front investment in these chemistries + high-amp charging would definitely be much cheaper in the long run. Except long-haul trucking and motor yachts where the engine's running all day every day anyway.

 

[SternWake]

 it's OK to charge AGMs at .5C, 

Not All AGMS.  Most of the cheaper ones say to limit it ot 0.3C.

I think theses 'budget' AGM's can be pushed harder, but not every recharge from a well depleted state.  The cheaper AGMS do not have the lower resistance of Northstar, Odyssey and Lifeline, and likely heat up when charging to a more significant degree, and are more likely to go into thermal runaway, or simply open the vents and offgass, and dry out faster.

Monitor battery temperature if one can and does exceed 30% charge rate on a lower $$ AGM.  The commonly touted 'AGMS can accept higher charge currents and thus recharge faster' is not always true.

And the speed increase mostly applies to bulk, not absorption, when it is applicable, and it is likely only applicable when the battery is young and healthy.

And Fireflys are not exempt from the 3.5 to 4 hours from 80% to 100%  when depleted to below 70% rule of all other lead acid batteries, and there is not enough reports of their performance in actual use to see if they live upto their claims.  I hope they do, but  I recommend saving the praise or recommendations for them until they do.  When AGMS first came out they made many of the same performance and antisulfation claims, and reality proved otherwise.  The heaviest promoters of the Firefly, are friends with the holder of the patent.

As far as additional load of a depleted battery and a voltage regulator asking for and maintaining a high voltage, well, Do hyper miler eco modders advocate never driving at night so that their alternator does not have to make the ~15 extra amps required to run the headamps and running lights?

One might be able to estimate fuel usage required for a generator powering a charger to take a battery from 50% to 80%, but unless one has a fuel flow meter, and performs actual tests where the other variables are controlled, it is a complete and utter guess devoid of reality as to how much more fuel a heavily loaded alternator will require of an engine, compared to an alternator not having to charge a depleted house bank.

Total guess unless one has this or a similar tool:

http://www.defender.com/product3.jsp?path=-1|311|2349076|2349081&id=2502045

It would be an interestng experiment to perform, If I were being paid to perform it.

If it all comes down to daving money, then adequate solar would reduce load on alternator and engine and generator, and extend battery life, but there appears to be a solar hole in the upper midwest.

 

[John61CT]

Not All AGMS.  Most of the cheaper ones say to limit it ot 0.3C.

Note with a single 100A batt, that's still 30A, and most people have or will need more than that, a charger investment to me should include some room for growth, and/or the ability to minimize fossil fuel runtime when dedicated to charging.

But yes, as with other categories, I tend to ignore the cheapest side of AGM; I doubt it would last longer than top-notch FLA. I suppose, if my only mount spot required a sideways mount AND I wasn't willing to cut my food and discretionary budget for a few months to be able to afford to invest in the good stuff. . .

My ex is visiting, took the kids out for dinner, nothing fancy, the Uber + total single meal cost her more than the difference between a POS garage charger and a nice Sterling unit at 40A.

Fireflys are not exempt from the 3.5 to 4 hours from 80% to 100%  when depleted to below 70% rule of all other lead acid batteries, and there is not enough reports of their performance in actual use to see if they live upto their claims.  I hope they do, but  I recommend saving the praise or recommendations for them until they do.  When AGMS first came out they made many of the same performance and antisulfation claims, and reality proved otherwise.  The heaviest promoters of the Firefly, are friends with the holder of the patent.

Point of Firefly is there's no need to charge that top 10-20% until it's cheap and convenient to do so. Sure you may double the lifecycles getting it to true 100% say every other time, but doing that once a week or even once a month, you'll still get triple or 5x maybe 10x any other lead bank under that sort of PSOC abuse.

If you can get to 100% all the time, then FF is less likely to be worth the investment, but if you're stuck in a PSOC context, and will be able to live within their spec'd recommendations, I'd bet real money on solid payback over the years.

Yes I know the Maine sailing mafia are friends with Kurt Kelley since he moved there. Nigel Calder and Maine Sail at least reported going to lunch with him, and likely got a free bank for writing up their detailed reports based on hands-on experience.

And Ocean Planet Bruce signed on as NA distributor.

None of that causes me to distrust anything these guys have to say on that or any other DC energy subject without hard evidence to the contrary.

Especially since that PSOC tolerance can't be found anywhere else in the lead-based world, and I haven't found a way to go LFP yet without spending over five times the price per 100AH.

 

[mariasman]

How much does alternator charging effect fuel milage?

It depends. However, there are a few guidelines that can help answer the question. The relevant factors include the efficiency of the alternator and the efficiency of the engine.

A typical vehicle alternator is on the order of 50% efficient in converting mechanical energy into electrical energy. The efficiency of the engine during highway driving is on the order of 20%. So, the system is converting roughly 10% of the gasoline energy into electricity under these conditions. Yeah, it's a rough estimate, but not far off.

So, once one knows the charging rate, then figuring gasoline consumption is a matter of multiplying the additional electrical energy delivered by alternator by a factor of 10 to estimate the quantity of fuel consumed. Useful conversion factors here include: one KWh is about 3412 BTU, gasoline has roughly 115,000 BTU per gallon. So, for example, assume the charging rate were 40 amps on average at 13 volts for one hour. This equates to 520 watts for one hour, or 0.52 KWh, which equates to about (0.52)(3413) = 1774 BTU of electricity. Multiply by 10 to yield about 17740 BTU of gasoline, or roughly (17740/115,000)=0.15 gallon gasoline consumed for charging.