Discussion of combining 24 and 12 volt systems

[FireFighterHill]

So as not to futher hijack http://www.steelsoldiers.com/deuce-modification-hot-rodding/61104-converting-dual-alternators.html

I propose we talk about the different ways to integrate a 24 and 12 volt system into MV's and the pros and cons of different set ups.

 

[FireFighterHill]

On of my ideas for a 24/12 system would be to have a 3 battery system where as 2 batteries are used for 24v and the 3rd which sits behind a isolator is used for 12v application. My question is what would happen when you use a 24 volt alt to charge a single 12v battery? How would the Alternator or generator react to that 3rd battery?

 

[FireFighterHill]

I believe something like this might work instead of a equalizer 24V with Auxillary Start Sure Power Battery Separator

 

[Recovry4x4]

My path to simplicity is to use a 24 to 12 inverter. They can be had in a variety of amp ratings and provide 12V for most needs. My needs are very basic. Run a 120 /400W inverter off of a 12V recepticle. I have 24V powertools so no need to charge cordless tools. The 120 inverter runs my laptop, charges my phone and such. Guess I could even run my old fashioned Q-Beam off it. Not running any booming sound systems or need high amperage for trailer brake systems. Everything on the trucks is 24V so no issues there either.

 

[tennmogger]

On of my ideas for a 24/12 system would be to have a 3 battery system where as 2 batteries are used for 24v and the 3rd which sits behind a isolator is used for 12v application. My question is what would happen when you use a 24 volt alt to charge a single 12v battery? How would the Alternator or generator react to that 3rd battery?

The 24 v alternator and regulator would react poorly to the connection of a 12 v battery, even through an isolator. Shortly thereafter the battery would complain too.

One way to do what you want is to keep the 24 v system just as is but add the 12 v battery as you said. Then use a 24v to 12v converter (one of our members sells them) to keep the 12 v battery charged.

I use that system on a 24v vehicle. The separate deep-discharge 12 v battery is maintained by a Wilmore 24-12 converter any time the vehicle is running. It's fairly straight forward to use relays to turn on the converter when the truck is running, key on, but off when key is off. (Don't want to leave the converter charging the 12 v system if the truck is off because the 24 v battery will be discharged.

This system has been trouble free for me in a couple of vehicles (24 v Unimogs) for many years.

Bob

 

[tm america]

There is one problem with using a 24 volt to 12 converter to maintain the 12 volt battery voltage...First off a converter puts out 12 volts..It takes 14.6 to or at least 13.2 to actually charge a 12 volt battery.what you would end up with if you di it that way is the 12 volt battery would stay around 10 volts under light use heavy use it could drop to the point where the converter couldnt keep up..if a alt put out 12 volts it would be bad and discharge the battery.You could use a battery equalizer as they split the voltage from the alt to the different batteries as needed.or you could use a 12 volt alt to charge the 12 volt battery

 

[vinnies10]

I just bought a an converter from 24 to 12 it puts out 13.8 volts at 36 amps. im waiting for a warmer day to put it in and it was like $180. It's an industrial power series 40

 

[tm america]

You could have got my 12 volt alt kit with a 100 amp alt for 175 or you could have got my kit with a 60 amp alt for 150?.And it doesnt run down the 24 volt system ..so the truck always starts even if you run the 12 volt side completely dead/

 

[Blood_of_Tyrants]

As tm america says, you need more than 12 vdc to operate 12 v equipment and keep the battery charged, you will need about 14 vdc. Some converters are adjustable so you can bump it up a bit.

 

[tm america]

the main differences in the different ways to do this are ...amps,redundecy of having different sysytems .cost..if you are only looking to install a radio . a converter might be a great choice for you .. if you want to add trailer breaks ,radio and some lights a converter or battery equalizer might work good for you ..adding things that have a larger draw like winches and hydrualic pumps a separate 12 volt system with an another alt is probably the best way to go ...if you are building a camper and want to be able to run off the 12 batteries when not running the separate system with a 12 volt alt is the only way to go...some can do some things the separate system can do everything the other set ups do and more.....then the question is price?you could add my kit for 75 plus the cost of an alt,belt and battery...if you want to go cheap hit the junk yard 10 bucks for an alt .belt is about 5 bucks battery depends on what kind you go with ..junk yard has them for 10-20 bucks...so if you go with junk yard stuff this is how it goes..brackets 75,alt 10-20 battery 10 -20...total less than 125...If you go new,,brackets 75 alt 70, battery around 75..belt 5 ..total 225...that is for a 60 amp setup add about 30 bucks for 100 amp...so around 250 for a 100 amp stand alone system...converters are..150-300 depending on the amp rating..not sure on the price of equalizers but last time i checked they were more than converters..So look at what you need it to do?What you want to spend ?
oh did i mention you could run the various welder - high amp alt setups with my brackets

 

[FireFighterHill]

I think the ultimate set up would be to have a Dual battery 12v set up opposite the 24v system and completely separate. That way if you somehow managed to kill your 24 batts or 24 alt/gen you would have 2 extra batteries you could swap in there place and make it home.

 

[tm america]

I think the ultimate set up would be to have a Dual battery 12v set up opposite the 24v system and completely separate. That way if you somehow managed to kill your 24 batts or 24 alt/gen you would have 2 extra batteries you could swap in there place and make it home.

i couldnt agree more..that would be the altimate set up..

 

[FireFighterHill]

I mainly wanted to discuss different combination's and ways to get a 24/12 system. I also wanted this thread to be someplace we could explain why or why not a system works the way it does and clear up misconceptions.

 

[FireFighterHill]

So to start out lets look at probably the easiest setup that is drawing 12v from a single battery of the two batteries that make up the 24v system.

Pros: No additional batteries or alt/ gen needed.
Cheap all you gotta do is run wire from 12v item to the battery
Good Idea if all you ever want to run is a cig lighter for your GPS or Cell phone charger.

Cons: Creates a battery imbalance if great enough the alt/gen will over charge the other battery and under charge the battery being used for 12v.
May leave you stranded if the batteries drop below enough voltage to spin the engine.
Decreases battery and alt/gen life.

 

[FireFighterHill]

The next cheapest least labor intensive solution would be a 24 to 12 volt converter.

Pros: Easy to install. Provides steady 12v supply with less worry of damaging batteries or charging system, give you full capacity of the batteries.

Cons: if you drain the batteries to far you can damage the batteries and charging system and possible leave yourself stranded.

 

[tm america]

as far as different ways to get 12-24 volt systems ..there a couple ways that have come up ...one that has been the main discussion is running two alts to two batteries in series....i think it could work under certain conditions but i have yet to see it done ...if it worked as some say i think there would be systems like that in place out there ..Does anyone know of any vehicles or equiptment that uses this system?I would love to see someone try this setup in different conditions..Such as running a winch or radio..Would it have large amounts of rf interference?Would the batteries change evenly ?Would the alts be overloaded?What would the long term durability be?So many questions..I would love to hear from someone that has actually done this ...Not just people that are guessing at what would happen because of a therory..WHO has ran this type of set up what were your experiences?

 

[FireFighterHill]

If anything I say is in correct I welcome being corrected and educated.

 

[tennmogger]

Dual alternators sound like an awful lot of work! Isn't that a typical CUCV setup (that's always broken )

As many pointed out, most converters put out higher than 12v. "12v", and "24v" are just nominal voltages and never meant to be exact. My converters are adjusted to 13.8 v, a good long term float voltage for many types of batteries, including gell cell and lead acid.

the main differences in the different ways to do this are ...amps,redundecy of having different sysytems .cost..if you are only looking to install a radio . a converter might be a great choice for you .. if you want to add trailer breaks ,radio and some lights a converter or battery equalizer might work good for you ..adding things that have a larger draw like winches and hydrualic pumps a separate 12 volt system with an another alt is probably the best way to go ...if you are building a camper and want to be able to run off the 12 batteries when not running the separate system with a 12 volt alt is the only way to go...some can do some things the separate system can do everything the other set ups do and more.....then the question is price?you could add my kit for 75 plus the cost of an alt,belt and battery...if you want to go cheap hit the junk yard 10 bucks for an alt .belt is about 5 bucks battery depends on what kind you go with ..junk yard has them for 10-20 bucks...so if you go with junk yard stuff this is how it goes..brackets 75,alt 10-20 battery 10 -20...total less than 125...If you go new,,brackets 75 alt 70, battery around 75..belt 5 ..total 225...that is for a 60 amp setup add about 30 bucks for 100 amp...so around 250 for a 100 amp stand alone system...converters are..150-300 depending on the amp rating..not sure on the price of equalizers but last time i checked they were more than converters..So look at what you need it to do?What you want to spend ?
oh did i mention you could run the various welder - high amp alt setups with my brackets

 

[3dAngus]

I got whipped on this site talking about chargers for 12-24 volt battery systems so I will avoid.
One good thing that came out of it though was there was a fella making some special brackets here where you guys could put up 12 volt alternators. Best idea yet. I would think almost any alternator would do, as long as it fit, but of course, that is assuming you use the 12vdc side for low current applications, meaning less than ten amps or so for lights, computers, special applications, but definitely NOT hooked up to your starter. Ha!

You can probably find him through the search engine using the right keywords.

 

[tm america]

Dual alternators sound like an awful lot of work! Isn't that a typical CUCV setup (that's always broken )
i make the brackets to add the 12 volt alt install time is about ten minutes ...the dual alt setup i sell is not like the cucv.. it it a stock 24 volt system ...and a saparate 12 volt system like would be used on a 1979 chevy truck.It is super reliable and well proven... the 24 volt stock electrical system is unchanged with my setup unless you want to upgrade to a modern higher amp 24 volt alt.the alt i use for the 12 volt system is the same one used one chevy cars and trucks from the 1950s - the 1990s..The cucv uses two alts to get 24 volts totally different than what my system is..My brackets cost 75 and use an alt that most guys have laying around their garage already...i dont think you can beat the price and ease of install..i ship my brackets preassembled with all the bolts needed