generator vs. van alternator charging

[akrvbob]

Working the alternator that hard will greatly decrease it's life, and the engine isn't going to be happy either. I wouldn't be surprised if in the long run you ended up paying more in repairs than you would have for a generator.

There is an old saying that says use the right tool for the job, and you are using the wrong tool for the wrong job. Doing it every so often is no big deal, doing it constantly for a summer is a very big deal.
Bob

 

[steveh2112]

is there really any downside to running the van on high idle for a couple of hours? i guess the engine might get a bit hotter than while driving since it isn't moving, but since all newer vehicles have an electric fan and i expect are built to handle crawling along in traffic on hot summer days, i doubt its a serious problem. here in Thailand i see people leaving the engine running for hours while waiting for a ferry boat, or Bangkok traffic, or something, just so they can run the aircon.

how long would it take to charge a group 29 marine battery from say 50% to 90% charge at whatever the alternator could put out, say 55A or so?

i'm thinking my load requirements are tiny, just a low power laptop and maybe a 12V LED tv to watch a bit of TV in the evening, and some LED lights. no fridge, hopefully no fan. i'm thinking 50-100AHrs/day at 12V. so depending on efficiency that might be 2-5hrs i guess which is a while i suppose. maybe i need to forget the LED tv and just live with the laptop screen. living in a van is all about compromises i suppose.

also, i can always start up the van any time the battery level gets low or i need to charge the laptop battery, it not like solar where i have to wait for the sun.

 

[mariasman]

Just food for thought. The thermal efficiency of a large internal combustion such as a truck or van engine when running at a fast idle and used to drive a relatively low power load such as an alternator is quite low - literally on the order of 5%. Now, consider the efficiency of a typical automotive alternator - about 50-60%. Overall efficiency in converting the energy in gasoline fuel to DC electricity for end use would be on the order of 3% (and this is generous). What this means is that you would be consuming roughly one gallon of gasoline fuel (about 115,000 btu) - and likely more - to generate one KWh of electricity (3412 btu - or roughly 83 amp hours at a nominal 12 volts). Since you estimated your daily loads at 50-100 AHrs/day at 12V, then you're proposing to consume on the order of one gallon of gasoline fuel each day to charge a battery. That equates to nearly $1000 each year in additional fuel costs assuming daily use. Also consider the additional costs entailed in added engine/alternator wear, or the costs that will be seen in frequent battery replacement.

It makes more sense to save the money required to purchase a 400 watt solar system with MPPT, then find a reasonably sunny spot to set up a remote array. Alternatively, it makes more sense to save the money required to build a battery charging system using a good small engine and alternator as this will generate the same electricity with roughly 1/3 the fuel consumption and without putting stress on the vehicle engine system - and it can get a better charge on the battery allowing it to last longer. As a side benefit, the heat from the small engine might be put to use in water heating if desired.

 

[ttpadilla]

Mechanical efficiency issues aside, I'm more concerned about the pollution that would be pumped into the areas you'll be visiting, as your vehicle runs on high idle for hours a day. Have you considered the environmental impact of your plan? I know I cringe when I have to start this motor home up to drive it, and that's one of the reasons I'm trying to trade it in for something smaller. Depending on how dense the surrounding trees and bushes, you might be a little uncomfortable surrounded by the exhaust of your own engine.

 

[SternWake]

A group 29 battery depleted to 50%, when placed on a 55 amp charging source whose absorption voltage is 14.8v will get to ~75% in about 50 minutes, ~80% in 1 hr 15 minutes, 85% in 1 hr 40 minutes and 90% in about 2 and 10 minutes hours.


If your vehicles voltage regulator only allows 14.2, then add 35% to those times

The alternator might get so hot that the voltage regulator drops to 13.7 maximum to protect it.

5 days of 13.7 might not fully charge a battery.

So you can beat up your engine and your battery just by cycling it from 50% to 80%, but you should strive for a full charge weekly if you want this battery to last more than a few months.

I would only idle my engine, or high idle it in an emergency.

My 13.3 inch LED TC draws about 1 amp.  My laptop ( with fully charged laptop battery,streaming a video draws close to 3 amps and watching a DVD is 3.5 amps.  Add another 3amps if laptop battery is drained.

The LED lighting is fairly insignificant as far a a load goes and some LEDs are much more efficient than others.

http://www.amazon.com/Philips-12964...4-3490464?ie=UTF8&refRID=0EWM9BGH436CKFCNPQVY

The above link is a warm white T10 wedge base bulb I have that gives at least 50% more light than cheaper LEDs for even slightly less amp consumption.

I don't see you requiring more than 15 amp hours a night which will give you a couple days before falling below that 50% level.  Still not great for the battery, but it will work.

Some engines are prone to carbon build up on intake valves and combustion chambers when idled for excessive times which make it run poorer and less efficient.  Driving it like you stole it can give it the 'italian tune up' and blow out some carbon.

Your listed electric loads are quite light, except if you are to watch the Laptop playing a DVD each and every night.  I was up in the Sierras last October and there were a one or 2 TV stations up altitude, in some locations.  In others i could not even get a single AM radio station.  And those were deep in the valleys. 

I Also think there will be likely be some locations where a portable 100 watt solar panel can be of use to you.  YOu could even just hook it directly tho the battery for the brief times, and for longer times just make sure the battery does not get above 15.3 for too long.

When your battery is all punch drunk from doing 50 to 80% for two weeks, then a sunny location for a day and the panel re aimed at the sun 3 times should be able to get the battery upto that very desirable 100% charged area.  Just use 10 gauge wire for upto a 25 foot one way length.

IF you find the panel directly on the battery, gets the battery to and above 15.3 regularly, then you need a controller in that usage.

 

[steveh2112]

thanks again. i keep flip flopping on this

i guess if i get one of these http://www.renogy-store.com/100-watt-solar-panel-kit-p/kit-starter100p.htm that's only $179 which isn't a really big deal and 1 panel should be easy enough to set up.

i've seen a few camps which have clear view of the sky, my first stop will be Lumsden Bridge Campground off 120 between Groveland and Yosemite 37°50'54.17"N 120° 1'48.08"W

that one look ok for solar and a few others i found so.

 

[Bela's Mom]

Steve, the one you linked to is out of stock.  May I suggest that you go through Amazon and get the one without the roof brackets (if you are not going to install on the roof that is).  It is less expensive and you could use the extra money to purchase 30 or 40 feet of cable so that you can set your panel in the sun and park in the shade. You buy one cable and cut it in half. The cut ends go into your charge controller and the MC4 connectors connect to your panel. You can then put the panel 15-20 feet from your vehicle.

 

[Canine]

I will admit that I don't know a lot other than what I've read n this great forum however the Yamaha or Honda 1000 is so quiet and fuel efficient that I'd really question running my van for hours at high idle. Even f I could find a 200 plus amp alternator to replace the stock 120-130 with, there's a lot of cost to making that switch and you have no ac power for anything else, while the generator can power tools and the like.
Of course running a solar panel makes a lot of economic sense being that the sun s "free" yet you have to be sized correctly, aimed at the sun correctly, and spend a fair amount for mppt controller, proper cables, inverter, etc... Then there's the cloudy days issue...

I'd probably favor the genny if you are out in the boonies. Plus, you can use it for emergency charging your own starting battery if need arises...

Decisions. For me it's an easy choice, my high top van has no flat surface to mount 2 panels. So no solar. I've seen guys who pull a 4x6 trailer that's all set up for solar but I can't do that in town. Life is complicated.

 

[SternWake]

You don't need a flat surface to mount a framed panel, or even a bendable one. I have both on my raised fiberglass roof. 198 lovely freedom loving fridge and laptop powering watts.

 

[Theadyn]

Same hi top no flat surface van here. I've been reading this and trying to absorb. My question is, if you were going to be driving most days anyways, like what is in my plans, wouldn't connecting to your alternator work fairly simple and efficient enough? My needs are small, 12v fan and ever so often a small dvd player. My other stuff will be charged up while driving. Right now my van will be used for roadtripping, not full time living where parked a lot. Thanks for any input.

 

[highdesertranger]

from what you just described theadyn that would work fine. it's also cheap and easy. highdesertranger

 

[MK7]

Or you can upgrade your van's alternator with an aftermarket, hi-amp one. This is what people with huge stereo systems do. The stock alternator is around 60 amps. You can get 200a alternators for like $110 for most vans. You'd have to upgrade to thicker wires though, or you may risk the stock wires catching on fire.

At idle, a 200a alt should be putting out more juice than the stock 60a. Then you can wire in a 2nd battery if there's space under the hood or use a battery relocation kit for like $50-75.

A quick search, I find this kid's 200a alt is recharging his dead battery at 15.8v and at idle (Honda Civic):

 

[Canine]

Theadyn, if you are constantly on the road then maybe just don't bother with anything other than a small inverter, perhaps between 400-700.  You don't need a generator or solar install IMHO.  Now as soon as you stop for 2-3 days without driving, you start the process of your (likely) 100 amp hour marine battery discharging down to that dreaded 50% level where it needs to be brought back up again.  That's the rub, just how will you do it.  You've already gotten tons of input on these threads about generator vs solar vs alternator, so you have to look at your budget, your future anticipated usage of a van, and make your decision.  Here's my 4 ideas, for what it's worth:

1) If you can afford to spend the $400-$700 (materials only) for a simpler 100W solar (I'd upgrade to an MPPT controller and the Renogy flexible panel though) and battery setup (FLA battery is a lot cheaper than AGM but you already know the trade offs, right?) then do that. On the cheap end with the PWN controller, regular glass panel and FLA marine Walmart battery it's about $3-400, the better controller, AGM battery and flexible (4 pound) panel is about double...

2) Or you could purchase a new Honda or Yamaha 1000 (Amazon $1,085 vs about $792 for the Yamaha 1000, don't know why the difference) plus the hassle of carrying gas (can't carry inside very easily, fumes and spills, and it is hard to safely and securely mount a can outside...) and then you should buy a (bicycle type) cable lock (Amazon, various brands and lengths up to 6', costs vary from $12-30).  Plus some National Forests won't let you run a gennie just anywhere during fire bans...  see below for a recent example:

"The Groom Creek Fire District’s fire restrictions mirror those of the Prescott National Forest.
PRESCOTT, AZ (May 24, 2014) – Due to increasing fire danger the Groom Creek Fire District and Prescott National Forest will implement Stage II fire restrictions. These additional fire restrictions will remain in effect until District officials determine that conditions have changed sufficiently to reduce the risk of human-caused wildfire.

Stage II fire restrictions prohibit the following:
Building, maintaining, attending or using a fire, campfire, charcoal, coal, or stove fire, including fires on private property, developed campgrounds and improved sites.
Smoking, except within an enclosed vehicle or building.
Discharging a firearm, air rifle, or gas gun, except while engaged in a lawful hunt pursuant to state, federal, or tribal laws and regulations.

Operating any internal combustion engine from 9 a.m. to 8 p.m.

Welding or operating acetylene or other torch with an open flame.

Exemptions to the restrictions include the following:

Using a device fueled solely by liquid petroleum or LPG fuels that can be turned on and off. Such devices can only be used in an area that is barren or cleared of all overhead and surrounding flammable materials within three feet of the device.

Operating generators with an approved spark arresting device within an enclosed vehicle or building or in an area that is barren or cleared of all overhead and surrounding flammable materials within three feet of the generator.

Operating motorized vehicles in compliance with forest Travel Management regulations."

***********************
Anyway, solar is a bit cheaper and usually every two days you can get something., on the flip side, this month of May in Denver and in Oklahoma City (where I have family) they have not had more than about an hour of sun a day all May, they tell me.  So solar during this bad weather spell wouldn't have worked...  There's always a possible "fly in the ointment".

3)  The cost of that 200 amp alternator (Amazon $138 plus $18 shipping):

Product Description.  NEW 200 AMP HIGH OUT ALTERNATOR TO REPLACE 95 AMP UNIT ON THESE APPLICATIONS:

FORD E-SERIES VANS 04-97 4.6L(281) V8 Std, 95 Amp
FORD E-SERIES VANS 04-97 5.4L(330) V8 Std, 95 Amp
FORD E-SERIES VANS 04-97 6.8L(415) V10 Std, 95 Amp
FORD F-SERIES PICKUPS 02-97 4.6L(281) V8 Std, 95 Amp
FORD F-SERIES PICKUPS 01-99 5.4L(330) V8 Std, 3G Alt, Exc Lightning
FORD F-SERIES PICKUPS 98-97 5.4L(330) V8 Std, 95 Amp
FORD F-SERIES PICKUPS 01-99 6.8L(415) V10 F-250 thru F-550, Std, 95 Amp
FORD HD TRUCK F450 Super-Duty 02-99 Ford 6.8L(415) V10 Gas Ford System (Std. 95A)
FORD HD TRUCK F550 Super-Duty 02-99 Ford 6.8L(415) V10 Gas Ford System (Std. 95A)

REPLACES PART NUMBERS:

AC DELCO 334-2273

FORD F65U-10300-EA, F6PZ-10346-RA, F7UU-10300-AB

MOTORCRAFT GL-372, GL-497.

VISTEON KJ

This is brand new alternator and requires no core. This High Output Alternator is what you need for high amp stereo systems or for extra reserve when you need it. If you have any questions please feel free to call our Tech Department at 1-866-695-0363.
***************
and then there is the cost of rewiring the heavier duty alternator as SternWake spoke of, it won't be as much as the solar setup and you will always have it with you...  Then there's the trade off of extra wear on your engine and the gas costs and carbon footprint... (Turn in your Earth First card if you do that).  

4) Buy a jump start self contained battery system (like this) as an extra portable source: (this is by far the cheapest way to get extra power for the short term but you have to plug it into a/c power to recharge it...)

"Stanley J5C09 1000 Peak Amp Jump Starter with Built in Compressor
by Stanley
882 customer reviews | 203 answered questions
List Price: $99.99
Price: $79.00 & FREE Shipping. Details
You Save: $20.99 (21%)
In stock but may require an extra 1-2 days to process.
Ships from and sold by Amazon.com.

1000 Peak Battery Amps / 500 Amp Instant Starting Power
Includes a 120 PSI air compressor, DC & USB charging plugs and a high powered LED light that rotates 270 degrees

Consists of reverse polarity alarm for safety along with a top-mounted rubber molded handle for easy grip
Heavy duty metal clamps and Number 6 AWG cables
Contains power/charge indicator and audible & visual reverse polarity alarm
Item is Hazmat and non-returnable
› See more product details"
*******************************

I hope this helps you or any other readers. By researching, I am not doing your work as much as educating myself and offering what I have found for others to read. I get no income (wish I did) from any purchases anyone makes of these products, blah, blah,blah...

 

[SternWake]

There is no guarantee an alternator with a high amp rating is going to output more juice at idle speeds than a lower rated alternator.  I cannot find the exact page now, but Balmar, a respected name in marine alternators has some charts showing their lower amp alternator outperformed one of their higher rated alternators upto a certain rpm.

Alternators are rated at their maximum output, and this is achieved when they are cold, spun very fast, with a huge load placed on the electrical system and cabling capable of passing that much current



Also, a 200 amp alternator is no guarantee that it can recharge a battery faster than a 100 amp alternator.

The battery itself decides how much amperage it is going to accept at the voltage that the voltage regulator allows.

A group31 lifeline AGM battery depleted to 50%, requires 92 amps for 14.4 volts to be achieved instantaneously at the battery terminals.

My Northstar group 27 is higher, about 105 amps for 14.7v to be reached instantaneously.

Any high amperage would force the voltage higher.  So in the case of the lifeline, a 200 amp alternator could not recharge the battery any faster than a 100 amp alternator as the battery cannot accept any higher amperage anyway.

It could if there were a hundred amp load on the vehicles electrical system.

In general alternators with higher ratings will be more able to handle the incredibly high heat that an alternator can produce when maxed out.

The ability of an alternator to produce at idle speed varies widely among different platforms.

And no mattery how powerful the alternator is, a battery requires time to get from 80% to 100% charged, and in this range a 300 amp alternator is not going to recharge the battery any faster than a 35 amp alternator.

The voltage regulator  in a vehicle is basically like the solar controller, but it is programmed timidly, as it assumes that the engine starting battery is 95% or higher and all it is doing is replacing a very small amount of depletion while also running all the vehicular electrics.  It is safer to undercharge a battery so most vehicles voltage regulators only allow voltages in the mid 14's for a brief period before lowering the maximum voltage to the mid to high 13's.

Voltage is electrical pressure, so with less pressure there is less flow.  Less amperage flow.  Slower battery recharging.  So that 350 amp alternator only allowed to make enough juice to hold the system at 13.7v is recharging the battery quite slowly.

So a vehicle with an Auxiliary battery well wired to the alternator can in theory recharge a depleted battery back upto 80% state of charge quickly, this is also dependent on the vehicles voltage regulator allowing the mid 14's to be the desired voltage for the duration.  many vehicles stubbornly revert to 13.8, and charging slows way down.

In some Vehicles the voltage regulator is in the engine computer.  Some others it is internal to the alternator, and some others have externally mounted regulators.

Those with the externally mounted regulators are the lucky ones as they can get an adjustable voltage regulator and force higher voltages for longer.

manipulating the voltage regulators in the other 2 systems is much more complex and the engine computer might make it impossible or put the computer at risk of damage.

How exactly vehicular voltage regulators decide how long to hold 14.x volts before dropping to 13.6-8 is something I have not yet figured out.

What i do know is on my Dodge, fatter cabling between alternator and depleted battery allows the ECM's vr to hold high 14's for longer, compared to when I open the extra parallel alternator circuit.  But still sometimes it decides 13.7v is plenty when i know the battery is still under 80%.

Where the battery might accept 35 amps at 14.7v, it will only accept about 7 to 8 amps at 13.7 volts.

The guy in the honda holding his battery at 15.8v, is severely overcharging a 12v battery.  Only time a flooded battery should be taken that high is during an Equalization charge, and these are only attempted after a regular 'full' recharge and no more than 5% of the rated capacity can be applied to get the battery upto 16 volts.  So no more than 5 amps for a 100 AH battery.  And the charging must be termnated when temperatures appraoch 120F or when specifc gravity stops rising.

If a depleted battery is hit with a charging source which allows 15.8v to be achieved, then this amount of pressure into a depleted battery will seriously shorten the life of the battery if not kill it outright.  While 92 amps takes a lifeline agm at 50% to 14.4 instantly, if one wanted to achieve 15.8 instantly it would likely take 200 amps or more, and this might turn the battery into an IED.

So the alternator Can be a very capable bulk charging source, upto 80% state of charge, but only if the voltage regulator allows voltages to be held in the mid 14's for the duration of the bulk charge.

I would not recommend upgrading a functioning alternator with a higher rated alternator just in the hope of faster battery recharging.  If replacing a failed alternator, then you can upgrade.  Vehicles with voltage regulators internal to the engine computers, like Dodges from '88 and newer, are limited in their options.  Too big an alternator can fry the engine computer.

Some newer vehicles also have battery temperature sensors and alternator temp sensors and will adjust voltage accordingly, but NONE of them are optimized for recharging a depleted deep cycle battery tacked onto the circuit. 

 

[Optimistic Paranoid]

2) Or you could purchase a new Honda or Yamaha 1000 (Amazon $1,085 vs about $792 for the Yamaha 1000, don't know why the difference) plus the hassle of carrying gas (can't carry inside very easily, fumes and spills, and it is hard to safely and securely mount a can outside...) and then you should buy a (bicycle type) cable lock (Amazon, various brands and lengths up to 6', costs vary from $12-30).  Plus some National Forests won't let you run a gennie just anywhere during fire bans... 

I hope this helps you or any other readers.  By researching, I am not doing your work as much as educating myself and offering what I have found for others to read.

Dusty,

While both Honda and Yamaha generators have what they optimistically call a "12 volt DC charging port", in fact they are all unregulated and limited to a maximum power output of 8 amps.

If you are going to depend on the generator, you really need to also buy a good, modern, ac battery charger, say a 20 amp or more, with Bulk, Absorption, and Float modes and ideally an equalization mode if you are running an FLA battery.  These are not cheap, but without one you will be running the genny a lot longer and probably not charging the battery completely.

Regards
John

PS:  If you really want to charge via the alternator, you should do what the boaters do - a second, separate alternator, with it's own voltage regulator hooked up directly to the house battery, and no connection at all between the house and the engine electrical systems.

 

[LeeRevell]

Good list on Ford HO alternators for Gen Four. I need to see if an equivalent is available for Gen Three.

 

[Canine]

Well, I'm about od'd on charging issues... Too many possibilities. Lucky for me I am a real minimalist as far as power goes, and right now get by with nothing but the starter battery yet I will plan on a very basic single Walmart marine and either the alternator or a small folding dash solar, knowing it won't produce much more than a trickle.

While I'd like to have a Renogy flexible 100A panel on the roof, all the associated "must haves" or "want to have" parts drives the price from $300-400 to double that. It's like buying a van. "Gee, if I could just get this and that and the other, then it would be really neat". Yeah, and double or triple the price too. So for now, I'll wait until I have either a flat top van to mount a real solar setup on, or some other neat solution falls from the sky. If I could just find someone's ac wall outlet on a 2x a week basis, I'd be set...

How you guys with super stealth minivan's, cv's or passenger vans with no solar mounted use a lot of power without driving 30-40 highway miles a day I don't know. However, thanks to Optimistic Paranoid, SternWake, LeeR, HighDesertRanger and others, I have more descisions and options than fat boy here has fingers and toes!

That's ok, something to do on these now empty of work due to layoff days sitting (now) at McDonalds while people eye my table and wonder how many cups of free refill coffee I am going to drink... (While the laptop and iPad recharge).

Have a wonderful holiday weekend out there, don't drink and drive and stay safe!
(I thought about starting a thread entitled "A funny thing happened while I was at Twin Peaks in Waco drinking coffee last week" but thought the better of it...)

 

[MK7]

Sternwake, that's some good info again and thanks. What you said about the kid in the video charging his battery at such a high voltage does make sense.... that he can fry his car's computers and/or blow up his battery. As I recall, he went with a 200amp alternator. Not sure if he was revving the motor to get such voltage or was it just at idle. So maybe going from a stock 65a alternator to a 200a one is way too much but just a 120a or so, alternator upgrade could be ok.

If at idle, this Honda kid is getting such high voltage to recharge his battery, then going with a bigger alternator, but not as big as this kid's 200a one, should work well as now, the Vandweller is getting much more charging power just at idle as compared to the stock 65a alternator. Just one big thing is to upgrade the stock wires that connects to the alternator with much thicker ones, as I know people with Mustangs have set their car on fire by not doing so.

Also, how do people with LowRiders that have $10,000 crazy stereo systems and hydraulics to make their car stand almost straight up on 2 tires with 10-15 12v car batteries in the trunk get away with such 200a or bigger alternators.....and it's more like, a must have, for such applications? Do they have a bunch of other stuff to protect their computers? Or maybe their cars are pre-computer era, classic cars?

 

[Optimistic Paranoid]

The audio people are into a whole different world.

[video=youtube]

 

[SternWake]

Dangnabit I just lost another post.


Bringing a fully charged battery to 15.8v is nothing impressive.  If it is an AGM battery is is quite foolish.

I just bumped my fully charged AGM to 16v for a few seconds and it only took 3 amps and the amps were tapering rapidly before I lowered it back to a sane 13.6v float.

A van dweller needing to recharge their depleted house battery when driving from A to B is a lot different than the whole insane stereo crowd who are mainly looking to mitigate the huge loads their insane stereos can draw.

A van dweller should just increase the amount of copper between alternator and battery to give the stock alternator the best chance of recharging the battery back upto and perhaps past the 80% charged mark.

A higher rated alternator requires fatter copper, and in the case of most Van dwellers the stock alternator can make all the battery can accept, the weak link is the length and diameter of the original copper between the two.

And Always keep in mind, recharging from 80% to 100%  takes TIME.  Hours.  NO matter what charging source is employed.

Just because a 200 amp alternator is employed, does not mean it will actually ever output 200 amps when underhood.  The battery, the rpm, the temperature, the circuit resistance , and the pressure regulator, are all factors which affect battery recharging via alternator.

There is no just throwing a single bigger number at a battery.  Several bigger numbers, yes. and when the battery gets to the  80% charged range it fights them.