Tech question, dual alternators

Captain Goddammit · Post by **Captain Goddammit** » Mon Jul 21, 2008 8:29 pm

I want more electricity on my mutant vehicle with less generator use. This year, I mounted a second alternator where the A/C compressor used to be. Since the internal regulators respond to battery voltage via the field wire, it seems the second alternator's output would tell the first one not to charge, and vice versa.
I'm thinking each alternator needs to be a separate system with it's own battery. Anyone know something about this?

Also: I have a battery isolator on the original alternator, separating the starting battery and the "house" battery. Since the alternator's field wire is connected to the starting battery, which is under very little load most of the time, it occurred to me that a large load on the house battery doesn't trigger the alternator to increase it's output. If I wire it to trigger on the house battery, it won't do anything for the starting battery during the day when I'm not running all the lights etc. and have no load on the house battery.
Am I gonna have to wire the field to a switch and manually select "day" or "night" mode?

ygmir · Post by **ygmir** » Mon Jul 21, 2008 9:10 pm

IIRC;
the RV type battery isolators let charge go one way, but, not drain..so, if you put two batteries in and put most of your load on the extra battery, it'd leave the starter/vehicle one alone and run/charge the accessory one. So, with an alternator to each, the output would rise as voltage dropped, kicking in the main/vehicle alternator if the accessory one can't keep up.......
How big are the alternators you have?
They sense when to charge by voltage, and, if one is working to hard on the accessory, and, can't keep up, the voltage will drop on the main and tell the other to charge.......

That's how I see it, anyway........

Make sure nothing is wired in series, or, you'll get 24V........

Or,
you could run your accessories from one battery/alternator, and, just have a heavy solenoid switch between them, and, monitor the voltage with a gauge.......and, if the one is getting overloaded, hook em together with the switch.......

I'm sure someone here knows more than I but, that' my thinking.....

good luck
Ygmir

Captain Goddammit · Post by **Captain Goddammit** » Mon Jul 21, 2008 9:58 pm

To clarify: I'm going to add more batteries, not just use the second alternator to charge the existing second battery. I have enough electric draw that this system will only slow the rate the batteries drain. I have an onboard Honda generator for when I need it but I like just running off the boat motor.
I believe these alternators are 65 amp, but the boat is idling most of the time so I'm probably not getting more than 10 or 15. What I really need to do is make an idler shaft driven by a small pulley, with a large pulley that drives the alternators to gear them to spin at least twice the RPM. This vehicle never sees road use. It's a tall order because it's a transverse engine/transaxle with extremely limited space for such a thing... but then, making a boat drive on land was a tall order too.

ygmir · Post by **ygmir** » Mon Jul 21, 2008 10:06 pm

you might want to check on the speed needed for your alternators. I'm pretty sure the work well at low speeds, maybe not idle, but, not to far above......

65 amp alternators are pretty big.......780 watts each......

Grainger will probably have the pulleys you need in stock, just give them measurements of what you have, and, how much faster you want them to go, and, they'll figure the size for you and ship it, and, reasonable priced.
I did this with a compressor I built.
their tech folks were great, asked a few rpm, etc questions and then came back with what diameter pulley I needed and sent it.......
so, maybe you could just change the alt. pulleys and not mess with the engine side.

Just a thought

Smudge · Post by **Smudge** » Mon Jul 21, 2008 11:41 pm

alternators only make their rated amperage at high rpm, at lower rpm they definitely put out less amps. 65 amps isn't a huge alternator.
aess.com is an alternator site that I got a catalogue in the mail for.
I saw lots of listings for 90 amp alternators.
If you want 130 amps from one alternator, you can buy one, but #1 it's going to cost you like $500.00 and #2 it'll only put out that sort of power at high rpm. Double rpm could work for you, but you'd better not run the engine at high rpm. To me, it sounds like the dual alternator thing would be a real winner but the question still is how well they'll run together in parallel. Call your alternator shop and ask them about the wiring.

I built a hydrogen gas generator from a book I bought at eagle-research.com and in that book were a number of alternate wirings for alternators that are likely unimportant to your application, but the thing I did was as follows.
I opened the alternator case, soldered 3 leads directly to the power output of the stator BEFORE the stock bridge rectifier, ran those through drilled hole to a $5 bridge that ran directly to my HHO generator. This can be risky if your electrical application is capable of drawing near to or over the rated amperage of the alternator. Does this help you? Possibly not at all, but it got me to go to my local alternator shop and share stories.

He'd built a custom rig for a guy who was involved in illegal CB radio competition for who could make the highest wattage spike signal.
It was built in the back of a van, because of course you'd want such a device mobile for when every sensor owned by the fcc triangulated on your ass in a second. They didn't talk, just mic down and have people verify signal strength and that was the whole competition.
Ok in the back of this van was a spare chevy 350 solely dedicated to running electricity to the CB. It had a steel arc mounted on the flywheel end of things and on it was mounted like ten or sixteen alternators, all of which had been tweaked to run 16 volts. Additionally, the button on the microphone was also connecte4d to a nitrous oxide squirter so that the v8 wouldn't bog down and stall when he miced up the radio.
So yes. Hit the alternator shop and they can likely help you figure this project out.

Yes, you can run multiple alternators and it's a lot cheaper than a 'high amp' alternator or a 100 amp alternator from a tractor trailer.
Those things, or marine spec alternators are built to put out max rated power continually. Having an alternator blow out when you're out to sea could mean your life. Trouble is they don't fit on your ac bracket.

With adding batteries, make sure all of the batteries are new.
Solar/wind folk have to replace all of their batteries in a bank at the same time. If they don't, basicly it just loads the new one until it's as burnt as the older ones leaving you with an old set of batteries.
I'm wondering what on earth you are using that much power on?
I'd reccomend getting some mil spec or gold plated battery connectors and fatty wires, but maybe you've got that part figurd out.

Captain Goddammit · Post by **Captain Goddammit** » Tue Jul 22, 2008 12:25 am

You can also get 120 amp alternators for $10 from a Cadillac at the wrecking yard. For a mutant vehicle that only sees a week of use at BM, that's the source for almost every component.
Since this boat never sees road use, doubling the alternator belt speed is feasible. Physically doing it in the space I have is a challenge, though.
I have a lathe and I might make some really small pulleys for the alternators; that'd by far be the easiest solution, but experimentation will tell us how small they can be and still get a bite on the belt.
I don't mind running each alternator completely separately, with it's own battery, because I have two inverters and can just plug half of my stuff into each one.
What is the power for? Mostly lights. Lots of lights.

The issue that is making my brain hurt most is that of managing the charge rate of a starting battery and a house battery from one of the alternators.
Maybe the crude, simple and cheap solution is to trigger the field from the house battery, and just keep a big light on during the day so the alternator senses a load and turns on enough to keep the starting battery topped off... but then it'll overcharge it cuz it won't shut down... brain hurts...

gyre · Post by **gyre** » Tue Jul 22, 2008 7:49 pm

You're making my head hurt.
If the house battery is charged up, why do you want more charging?

It is important to have identical batteries from the same lot when possible.
Can you just run both batteries on one circuit at the same time?
Nothing wrong with having switching possible too.
Optimas can be used as starting batteries even in the deep cycle version, unlike some.

I see no problem with running discrete power systems.

I would think the best approach is one big alternator.
I have been quoted $350 on a rebuilt heavy duty one.
Cheaper if you bring one in.
More efficient design, lots of diodes, heat sinking.

All alternators are rated on a curve.
Every rating is based on an rpm, some cars list two or three.
200 amps at idle is possible.
My local shop used to rewind standard ones to up power.
That is an alternative, though not as good.
Be sure to not stress the bearings.

I have posted power curves before but I can't locate them just now.
Typical rpm ratings are idle, fast idle, 3000 rpm (most common, I think) and 4500 rpm.

Can you use more efficient lighting?
What the hell are you powering?

Anyone ever use low pressure sodium?
Pure amber, make a nice bounced light under a vehicle.
55 watts + ballast is 10,000 lumens. Available in 12 volts.
HID special colored metal halide bulbs would work.
Green and blue are really effective.
That's what lights vegas.

http://www.ceniehoff.com/
http://www.electricmotorsvc.com/NewAlternators.html

http://www.elreg.com/product/15.aspx
http://www.elreg.com/product/9.aspx
http://www.elreg.com/category/8.aspx
http://www.elreg.com/category/11.aspx

130 A at idle
http://www.americanpowerinc.com/

http://www.prestolite.com/pgs_products/alt_search.php

Captain Goddammit · Post by **Captain Goddammit** » Tue Jul 22, 2008 11:01 pm

Keeping the house batteries charged while under load is the problem. Most of my constant power draw is lighting, I have incandescent "rope lights", fluorescent lights, and sometimes a halogen or two going. I need about 8 or 9 hundred watts.
I also need to use junkyard parts and not buy $300 alternators for a one-week-a-year mutant vehicle who's electrical parts are going to get murdered by corrosive alkaline dust.

But yeah, I think I'll just eliminate the isolator, it makes managing the charge rate of two different battery/loads impossible. I officially quit worrying about that problem!

The biggest challenge I'm working on is making a bigger crank pulley to speed the alternators up, so I get a LOT more output from what I already have.

ygmir · Post by **ygmir** » Tue Jul 22, 2008 11:14 pm

for the bigger crank pulley, you might try a parts house or junkyard with an intelligent person there. They can cross reference stuff and probably find the bolt pattern, and belt width along with diameter you need on another vehicle.....
Or.....if your fan pulley is larger.........double it and use it for a drive,
Or.......if you can find a pulley with the correct belt fit and diameter, you can re-drill the mounting holes.
Since your engine is mostly idling, perfect balance may not be as critical.....
If some one you know can weld and has a lathe, they could weld a larger pulley on your crank pulley, centered, and, drive your alt off that........

sorry,
Just a few thoughts........

I've gotten 100 amp, 24V military alternators cheaply, say, under 50 bucks.......

a lot of the larger amp alternators are actually 120V and they change it to 12V for the car..........

yikes,
someone stop me, I do so love to make things "non standard"......

Ygmir

Captain Goddammit · Post by **Captain Goddammit** » Tue Jul 22, 2008 11:27 pm

I have a welder and a lathe... unfortunately the diameter drive pulley I need (10" is max that will fit without major surgery) is too big for my lathe.
There isn't going to be a stock balancer/drive pulley the diameter I need so I'll have to make something that bolts to the existing balancer, using the three tapped bolt holes used for pulling the balancer.
No fan pulley, electric fans on this mutant. The serpentine belt runs only the alternators. Space is VERY tight, it's a transverse engine/transaxle setup, so this is all more of a bitch than it ought to be. Goddammit. I just have to figure out a slick way to make this part. There WILL be more lights on the Land Yacht!

gyre · Post by **gyre** » Wed Jul 23, 2008 1:01 am

I do not think you should get rid of the isolator.

There is a company that makes custom pulley sets for fords etc.

I think a better alternator might save money.
Brushless may be less trouble too.
What about rewinding what you have?

I think you should get rid of any incandescent you can.

I can help you max out effic.
All fluor and hid are not equal.

Post by **mdmf007** » Wed Jul 23, 2008 4:08 am

You said yuou onlyneed 8-900 watts. Thats not a serious draw.

Look at emergency equipment. throw the switch on a siren, lightbar on the roof, and a dozen more strobes throughout and then you can get 4-5 thousand watts of draw.

we have one 200 amp alternator and it is more than enough. theres also two batteries on an A or B bus or AB combined battery isolator switch. You don need to make this more complicated than it is. Custom pulley sets are going to kill you if your trying to do it on the cheap end..

good luck - have fun with the wiring, and make your connections right, dont simply twist them together or use wire nuts, or cheap conectors. 90 percent of your electrical troubles on a custom job can be traced back to shitty connections.

DONT USE ON AUTOS

EVEN MORE EVIL ON AN AUTO

Take 5 minutes on a splice, and do it right - youll never dick with it again.
Cut corners, and youll just be fixing it again, or burning out wiring.

later

Captain Goddammit · Post by **Captain Goddammit** » Wed Jul 23, 2008 6:47 am

Oh hell no! There's not a single twist or squeeze-tap on the whole boat!
Yeah, the draw isn't that huge and the alts I have will take care of it but they need a little more RPM.
I'd love a bigger alternator, but an expensive high-output alternator that is going to eat playa dust and corrode and die on a one-week-use vehicle that gets fresh electric parts every time it gets used isn't cost-effective when all I need is a little more RPM on these stock junkyard $10 units that I can carry spares for and throw away when they die of playa-poisoning.

I am gonna go with the battery switch plan, I like that. The isolators have voltage drop, and only allow the alternator to sense one battery, whichever the field is wired to, so the other battery either overcharges or undercharges. If you wire the field to both it gets "fooled" into not charging much at all.

If I could even get a decent pic of the tight space it has to happen in I'd post it, that's really the only thing making this tough.
I need to make a drive pulley just under 10" diameter that will fit around the stock balancer. And my lathe only handles 7".

I'd love more efficient lighting, but that's also not cost-effective when you need hundreds of feet of it and fuel to haul the goddamm thing to the playa is gonna be $1500 this year, seriously fucking up the mutant-vehicle improvement budget!

EspressoDude · Post by **EspressoDude** » Wed Jul 23, 2008 7:15 am

What you want is a used Delco-Remy from a big caddy or buick. Buy a spare at the wrecking yard. Maybe put new brushes in.

1974 p/n 1117144 or 1117145 or equal.

The test specs are 110 amps / 14.0 volts at 2000 rpm (alternator on test bench)....150 amps at 5000 rpm.

Use starter sized cable from the alternator terminal for minimal voltage drop.

Use marine or race car battery switches

I have one of these alternators in my blowboat with 3 grp 27 deep cycle batts and it will stall a cold 13 hp yanmar diesel.

Captain Goddammit · Post by **Captain Goddammit** » Wed Jul 23, 2008 7:23 am

Is that 110 amps/14 volts at 2000 RPM alternator speed, or engine crankshaft speed?

gyre · Post by **gyre** » Wed Jul 23, 2008 9:52 am

I called the local shop and they can raise the amperage 20 to 30% but they also say your issue may be the kick in speed on the regulator.
They need specifics on what you have.

They think you need the bigger alternator built to run at idle.
It would help if you can tell them exact rpm you are running when you are driving.
Pulley sizes too.
Custom pulleys aren't as bad as they used to be thanks to cadcam.
Really common thing now.

If you give me exact details, I can ask what they recommend.
They make fast idlers for vehicles, if you need that.
I imagine you are past idle when driving, but let me know.

Do you think you could do a 2 stage pulley system to up the speed?
That would leave your crank pulley stock.

EspressoDude · Post by **EspressoDude** » Wed Jul 23, 2008 1:07 pm

The rating is bench tested alternator/generator, not engine rpm

Here is a link to current production Delco alternators and output data, along with wiring for parallel alternators

http://www.delcoremy.com/LiteratureDown ... cGuide.pdf

Zulegoona · Post by **Zulegoona** » Wed Jul 23, 2008 7:01 pm

So whatâ€™s the plan for working the Honda into the system if you still need to?

we got to keep those blenders grinding that ice

Captain Goddammit · Post by **Captain Goddammit** » Wed Jul 23, 2008 8:36 pm

OK I went and took some pictures.
This is looking up from below:

This is looking down from above:

Space is tight, there's little room for a step-up idler, and no room to stack pulleys on top of the existing stuff.
I could make the drive pulley/harmonic balancer bigger though. The balancer needs to still be there, but I could do something to increase it's diameter from 6 1/2" to a max of 10" before it interferes with several things.

The alternator pulleys are already as small as practical.

An off-the-shelf pulley isn't likely to exist that will do what I want to do.

Increasing engine idle isn't an option unless the DMV doesn't mind that I make a bigger wake. The boat idles in first at about proper playa speed already.

Maybe I just forget it, run it as-is, happy enough that I have over twice the amps I had last year. (Last year the house battery didn't get charged properly because it was hooked through an isolator, and the alternator was only reading the charge level of the starting battery. And I do have two alts now.)

When it isn't enough, I just plug into the generator instead of the inverters.

The blender WILL be running even if I have to hook up the alternator to an exercise bike!

gyre · Post by **gyre** » Wed Jul 23, 2008 10:16 pm

Let me know if you want to look into stepping up your existing alternators.
They tell me your problem may be related to the sensitivity of the regulators, those all being very different.

Email me info or I can put you in touch with the shop here if you want advice.
I don't think the isolator should be the cause of any problem, though if you have to wire only one battery to the alternator I could see that being an issue.
I don't really understand that part.
All I think they do is prevent one battery from discharging into the other, which is useful.
You can switch batteries in and out and still have diodes in place if the wiring allows it.

If you are using quartz floods and any other high draw incandescents, that would be the first place to upgrade.
Did you know you can stretch elwire unsupported 60 feet?

Let me know if I can help point you to any more efficient lighting.
The colored HID I mentioned uses standard housings and ballasts.
It does not require special theatrical housings.
Blue or green would look good under a boat.
If you have an inverter that will drive them, it can be done fairly cheaply.
You probably need 175 watts to justify it.
400 watts are the best deal.
Remote ballasting can be done too.

gyre · Post by **gyre** » Wed Jul 23, 2008 10:19 pm

Can you mount smaller drive wheels easily and gear up the engine rpm that way?
Just a thought.

Captain Goddammit · Post by **Captain Goddammit** » Wed Jul 23, 2008 10:44 pm

Can't go any smaller on drive wheels, they're already only 14s with 185 tires, barely enough for the 5000 pound cruiser plus another 2000 pounds of passengers, and ground clearance is about 2 inches.

As handy as it is, the isolator has to go; the alternator can only charge at a single level at any one time. If I wire the "field" trigger wire to the starting battery, it won't step up the alternator output to keep up with a big house battery load. If I wire it to the house battery, it'll step up to that load and overcharge and boil the starting battery.

These alternators are going to die quickly from all the playa dust they are going to ingest under my boat. That rules out any expensive high-output units. I run junkyard units, and bring spares, because they need to be disposable. Just look at the photos of the balancer/crank pulley! I have to replace much of the boat's electrical stuff every time it goes to BM.

gyre · Post by **gyre** » Wed Jul 23, 2008 10:58 pm

I may regret driving out there.

Some of the big alternators are sealed and still run cooler.
Some are brushless.
Harsh conditions are what they are made for.

Have you tried diesel fuel as a protectant?
Works really good for something you can wash off.

Boeshield is good too and Kano Labs has great stuff.
Haven't tried them on the playa yet.

EspressoDude · Post by **EspressoDude** » Thu Jul 24, 2008 6:31 am

I would recommend using battery disconnect switches, and feed both alternators to the non battery(load side) of the switches. Connect a battery to each switch (battery side). That way both batteries receive equal charge level when running the engine. When not running disconnect one or both batteries.

or use a (1) (both) (2) marine switch with alternator disconnect like those by Blue Sea or Guest Marine

Captain Goddammit · Post by **Captain Goddammit** » Thu Jul 24, 2008 7:08 am

Yeah, that's how I have my real, floating-in-the-water boat set up.
The problem is that I could kill my Land Yacht batteries while the engine was running... not just when "at anchor". The load exceeded the available charge. But overall it looks like I'll have to connect everything and keep aware of start battery voltage while running everything, and put the heavier loads on the second alternator/battery bank I just added.
And use the generator when I need to.
But dammit, if I could just spin those alternators faster...

MozyBonz · Post by **MozyBonz** » Thu Jul 24, 2008 8:33 am

You didnâ€™t look at the link I put on the contraption thread did you?

Diamond Precision ProductsÂ® wrote: Custom
We match your specific requirements and design specifications (up to 24inches) with the expertise of our Certified Product Consultants and the experience of our manufacturing engineers. This collaboration insures that only precise, efficient, and cost-effective products are produced.

http://www.diamondprecision.com/ps.htm

Captain Goddammit · Post by **Captain Goddammit** » Thu Jul 24, 2008 5:22 pm

That's the one, but it's also the engine's harmonic balancer. I need to keep that but I want to increase the diameter of the outer pulley to about 10". Even my Peterbilt's Caterpillar uses one about the same diameter as this one, about 6 1/2". That Cat has a huge alternator that shows a 50 amp charge rate at idle... but it's $$.
I did look at the link but nothing they sell is remotely like what I want, so it'd be a custom made item. Too Expensive to have done commercially.
I'm considering getting a few extra balancers from the local pull-a-part yard and separating the outer grooved pulleys from the balancers (they're pressed together with a rubber strip between).
Then, cut them somewhere and heat them with a torch and unbend them slightly, increasing their radius, until I can trim two of them down to fit together and weld as one larger pulley.
Then sort out how to attach it and make some electricity!
Or just forget the whole thing and use what wattage I can get from the two alternators at the speed they already turn.

Whatever the solution is, it has to be pretty cheap. Custom or super-high output alternators, commercially custom-made pulleys, low-power LED or EL wire lighting etc. are all terrific but not practical for this getting-old mutant vehicle that could become scrap at any time.

gyre · Post by **gyre** » Fri Jul 25, 2008 1:00 am

These guys have a 2 inch pulley if that helps.
They should be able to tell you if larger stock main pulleys are out there.
They do make a supercharger pulley.
http://www.marchperf.com/index.html

Post by **mdmf007** » Sat Jul 26, 2008 6:24 pm

Changing pulleys isnt hard to do - Sometimes its finding a belt that your tensioner can still tension is aproblem though. Alot of times it is too short, or just a hair too long to fit right in.

Just another thought to consider.

Captain Goddammit · Post by **Captain Goddammit** » Sat Jul 26, 2008 6:26 pm

Yeah, I'm already running a custom-fit belt after replacing the A/C compressor with an alternator.

I have a bitchin' solution in the works! Let there be lights! And blenders!