Converting to dual alternators

[DUG]

Why such resistance to opening your mind and thinking about problems and instead burying your heads in the sand?

My head isn't buried in the sand. I did it the way I did because that's the way I wanted it. There are many options for getting 12 and 24 volts on my deuce and I decided this was the best way for me.

It's pretty cheap, compared to some other options. It also gives me some protection against draining a battery I need to get home.

You asked the question, I answered. No need to bum out my bitchen kewl thread.

 

[tm america]

jasonS with what you are proposing you wouldn't gain anything by doing so..even if it did work...the idea of adding a separate 12 volt system is to be able to run 12 acc. without worrying about possible damage to the 24 volt system...now if you try drawing off the first battey and charging it with a separate 12 volt alt....?here is the problem i see the chance of both batteries being equally discharged and charges by two separate alts is slim to none...first off the alts would have to able keep the batteries at exactly the same volts or it will fofce the 24 volt alt to over charge or under charge the second battery..for instance if the 12 volt alt charged the first battery faster than the 24 volt alt charged the pair the first battery would have more volts than the second possible fooling the 24 volt alt into thinking they are charged.this could cause the second battery to be charged at a lesser rate than the first battery and in time make the second battery fail.
Also doing this doesn't give you the ability to run a dual purpose battery on the 12 volt side for camping and still be able to start the truck at the end of the weekend and charge both systems...So even if it could be done it would give little benifits with more risks than it is worth...but i say give it a try let us know how it works out ..keep us posted how it works out after six months, a year and so on it would be interested to see what happens

 

[DUG]

Sorry for the hijack, I'm done.

Please fix the spelling error in your previous post. I like my threads neat and tidy.

 

[tm america]

dug after looking at the pics i can see i'm gonna have to offer a dessert tan option.I like the primary filter set up is that one of westfolks set ups or something you came up with?

 

[rat4spd]

Why such resistance to opening your mind and thinking about problems and instead burying your heads in the sand?

No sand around here, only cold azz snow. I prefer to keep my head out of it.

I'm not saying what you propose won't function. I question why bother and why no one else does it. I generate electricity for a living, and one thing common to most parallel generating sources is that there is typically only one thing controlling the show, ie one voltage regulator, one master, ect...

So instead of consuming time worrying about what regulator is charging what battery and the voltage spread between cells, in the end, this thread is not about that. Dug did what he did for a reason, theoretical assumptions aside, what he did works perfect.

 

[DUG]

dug after looking at the pics i can see i'm gonna have to offer a dessert tan option.I like the primary filter set up is that one of westfolks set ups or something you came up with?

It's Westfolks, but there are several threads on doing it yourself.

And they will be tan pretty soon.

 

[JasonS]

here is the problem i see the chance of both batteries being equally discharged and charges by two separate alts is slim to none...first off the alts would have to able keep the batteries at exactly the same volts or it will fofce the 24 volt alt to over charge or under charge the second battery..for instance if the 12 volt alt charged the first battery faster than the 24 volt alt charged the pair the first battery would have more volts than the second possible fooling the 24 volt alt into thinking they are charged.this could cause the second battery to be charged at a lesser rate than the first battery and in time make the second battery fail.

Unless you have REALLY discharged your batteries, the alternator will be at full voltage almost immediately. If you regularly deep discharge your batteries, you run the risk of damaging your alternator and thermal runaway of the batteries, and GUARANTEE short battery life. Even designed-for-deep discharge batteries have their lives cut short with deep discharge.

The extent of your "charging" system is to apply a constant voltage. It doesn't observe the voltage/ current and change it's operation. It JUST works to maintain a constant voltage. If one alternator is malfuctioning, things will go awry; though this possibility exists with any system.

You are correct. If the "12V" alternator is at 16V and the "28V" alternator is at 26V, the upper battery will not be fully charged. If the "12V" alternator is low and 12V accessories are used, you may run the lower battery low and damage it. None of this invalidates the concept, though.

Also doing this doesn't give you the ability to run a dual purpose battery on the 12 volt side for camping and still be able to start the truck at the end of the weekend and charge both systems...

I was not disputing the value of this type of setup. That's really not the crux of the argument. However, don't think that your SLI batteries will last very long with this type of use.

I am a relative newby in the realm of lead acid batteries but the aformentioned arguments are first year engineering basics. Newby is probably a relative term. I have 10.5k lbs of lead acid batteries in my laboratory. If I didn't have a project deadline looming in Feb, I'd tackle this immediately just to prove a point. However, we should be able to argue the technical merits of ideas.

 

[JasonS]

No sand around here, only cold azz snow. I prefer to keep my head out of it.

I generate electricity for a living,

My line of work, too. But, I bet we are coming from different directions.

Why did I post the question of the need of a third battery? Because it is often state that it is a REQUIREMENT and I don't believe that this is true. I was trying to bring something more to the table than just a "it won't work."


Dug did what he did for a reason, theoretical assumptions aside, what he did works perfect

I have never disputed this.

 

[DUG]

I'll be running a cheap harbor freight winch 3-4 times per year to load ATVs, I'm installing a back up camera, maybe some lights and the biggest inverter I can buy for under 200 bucks to run whatever a person can run off of such an inverter. I will probably run a wire so the 12 volt alt can keep the battery in the M105 camper topped off on the way to DIRTBAG.

The 12 volt side won't be overloaded. Truthfully I didn't really need such a setup, i just kinda wanted it.

I also plan on ordering a spare 24 volt alternator since it's cheap enough.

 

[rat4spd]

My line of work, too. But, I bet we are coming from different directions.

That's probably a good bet. DC is harder to wrap around when dealing with AC all the time.

 

[JasonS]

Be careful with low cost inverters. Their output is not galvanically isolated from the battery. If your third battery is grounded to the chasis and you connect the neutral to the chassis you'll let the magic smoke out.

 

[tm america]

i'm not saying your way wouldn't work ..just that the draw backs are with little gain .. there are several ways to get 12 volts for accesories,voltage reducers,battery equalizers,separate systems..dual voltage alts each has it's good and bads and are designed for different draws...my set up allows you to customize your 24 volt and 12 volt system to your indvidual needs and do so at a reasonable price...the stock alt is a 60 amp..my kit gives you the abilty to run 40,60,or 100 amp alts in either location for little or no difference in price ..And offers the option to run different amp alts for 12 and 24 volts with the added safety of knowing if one fails the other will still be working ..i'm not sure if you could do that with two alts charging two batteries?i am by no means a electrical engineer..i have worked in the automotive industry for almost 20 yrs and go off of real world experience..i know first hand what one says can't be done gets done everyday and works....
so to some up what i'm saying..i'm not saying your way won't work..i'm saying it gives little gain and no redundency to the system as a whole..i would also like to see your results..but i think buying the extra 75 dollar battery would be well worth it since that is the only difference from the three and two battery set up..one allows you to run your 12 volt system down and still start the truck .The other doesn't.

 

[steelandcanvas]

Just some history on this, someone else last year mentioned this could be done. (Two alternators, in a series 24V system) He went down in flames. I'm not taking sides, just informing.

 

[JasonS]

Look at Figure 1 in the following link. Same concept as what I have suggested exept they have replaced the 12V alternator with a 12V DC-DC converter power supply.

http://www.allbatterysalesandservice.com/graphics/52109-52204-52206-52208-52210.pdf

Note especially:

5. Connect the 12V and 24V loads directly
to the batteries, NOT the Equalizer
terminals. If this is not done, the loads
may reduce the ability of the equalizer to​

balance the battery charges.

This validates that controlling the mid battery voltage equalizes battery charge.

 

[JasonS]

how an equalizer works vs how two alts work can be very different as the equalizer has the abilty to monitior both batteries and send power where it is needed at the same rate

You keep assuming that the charging system has intelligence when it does not. If they have the save voltage, the effect is the same.

...if you are using two alts you most likely have two different charging rates..

Not unless you are in a current limiting situation and I have NEVER seen that in a vehicle.

Charging rates are set by the battery condition and the charging voltage (and to a lesser extent, the impedance under very high current but that is only if you are current limiting). You will almost never be current limiting so that leaves the voltage and battery. Different alternators (25A, 100A, etc) will charge at the same rate if they are putting out the same voltage.

My point is that you CAN connect a 12V alternator to the midpoint of the batterys and it WILL work. I don't care about any other ancillary points.

 

[tm america]

i decided to delete some of my posts to this thread as it seems it has become a debate of some type...i'm not in that kind of mood it's the holiday season.thanks for posting on your install dug..if anyone has any questions about the kits i sell pm me and i will do all i can to help you out and answer your questions...Guys christmas is just one week away don't forget to put something under the tree for yourself?

 

[LowTech]

Right now JasonS has 666 posts . . . wonder if that means anything

 

[DUG]

Right now JasonS has 666 posts . . . wonder if that means anything

Where's the pics of your set up? Any word on those wheels?

 

[LowTech]

I'm not going to hijack this thread w/ wheel talk, I'll post that on my other thread.

I'm back in the desert and have found the photos that I mentioned earlier.
I'll post a write-up here

Have heard that we could have a prob w/ the fact that both the 12V & the 24V systems have a common ground. Any thoughts on that from anyone?

 

[DUG]

Have heard that we could have a prob w/ the fact that both the 12V & the 24V systems have a common ground. Any thoughts on that from anyone?

I've never heard that and lots of people are doing it. Have you had any problems yet? So far I'm only running a voltmeter on the 12 volt side but I have a winch ready to add on.

Besides, if it wouldn't work Rat4Spd - who used to make electricity on a nuke underwater and now does it as a civie, would have told me it wouldn't work.