Diesel Place banner

1 - 20 of 32 Posts

·
Registered
Joined
·
825 Posts
Discussion Starter #1
I need some advice. Since I have two 12V batteries in parallel putting out 12 volts, why can't I take a wire from the positive post of the first battery to the positive post of the second battery in series giving me 24 volts, and run that wire and only that wire to a 24 volt heater? Seems to me if I keep them separated from the rest of the vehicle electrical systems, I should be able to run both 12 and 24 volt accessories! Anybody see the shorts in my thinking??

Whoops, I see the short in my thinking, and it won't work. I withdraw my post.
 

·
Registered
Joined
·
8,655 Posts
you would need to run the truck neg to one battery, the truck pos to the second battery, then run the left over neg and pos to each other to run in series

no you cannot have both 24v and 12v from the same batteries...either one or the other.
 

·
Registered
Joined
·
4,722 Posts
Wouldn't more than 18 volts do a number on the 12V components in the truck...Like the computer?
 

·
Registered
Joined
·
8,655 Posts
yeah, running 24 v in the truck would kill it


on another note, I was talking to a guy at a bar claiming to be an electrical engineer that works with moho's (motorhomes) and he said that with all the electrical stuff nowadays in a car, they will be switching to 48 volts!!!
 

·
Registered
Joined
·
2,473 Posts
I call BS theres no reason for it. Look at the tractor trailers they are still 12 volts and look at all the electrical stuff they have. And most only have a 160amp alternator. And one of em
 

·
Registered
Joined
·
16,610 Posts
In a few years you are gong to see all automotive go to 42 volt systems. No Bs here, wait and see ;)
 

·
Registered
Joined
·
8,655 Posts
In a few years you are gong to see all automotive go to 42 volt systems. No Bs here, wait and see ;)
yeah, that is what the guy said, it wasnt 48. he said he was going to invent a device that allows the 42 v cars to be compatible w/ 12v trailers
 

·
Registered
Joined
·
2,473 Posts
But then why havent the big rigs done it if it is such a great thing. Im not saying it wont happen im just saying if it is the way of the future why hasnt it been done on the real power drwers??
 

·
Registered
Joined
·
8,655 Posts
But then why havent the big rigs done it if it is such a great thing. Im not saying it wont happen im just saying if it is the way of the future why hasnt it been done on the real power drwers??
that is a very good question
 

·
Registered
Joined
·
68 Posts
They've been working on standards for 42v automotive systems for a few years now. They hit a bit of a snag though. When you run 42v through a standard switch it arcs and ruins the contacts. This info is 3 or 4 years old.

Google SAE 42v
 

·
Registered
Joined
·
817 Posts
Gee. I better go home and replace all my 120V switches in the house.
 

·
Registered
Joined
·
266 Posts
In a few years you are gong to see all automotive go to 42 volt systems. No Bs here, wait and see ;)
Max Power,
I am interested to hear why 42VDC is the wave of the future? Is this for hybrid or electrically powered drivetrains?
D.
 

·
Registered
Joined
·
16,610 Posts
Higher voltages are more efficient. Today's cars are electronic systems on wheels. It's getting to the point where 12v systems are just barely getting by and the increase to 42v will solve a lot of problems as we continue to add more electrical and electronics to vehicles. It's essentially the same thing as when we went from 6v to 12v. It's coming!
 

·
Registered
Joined
·
68 Posts
Gee. I better go home and replace all my 120V switches in the house.
To be more specific...42vDC arcs the contacts. I believe AC circuits are less prone to arcing. I'm not an electrical engineer...but I pretend sometimes :D .
 

·
Registered
Joined
·
370 Posts
They've been working on standards for 42v automotive systems for a few years now. They hit a bit of a snag though. When you run 42v through a standard switch it arcs and ruins the contacts. This info is 3 or 4 years old.
Exactly. There is a safety reason why they are thinking about 42V vs 48V. It has something to do with a UL standard (which has nothing to do with automotive) or the physics of electricity. I think 46V is the magic number to stay below...

...The main driving force for the 42V is to run a giant starter and a small electric motor that will drive your accessory belt. At a stoplight, your engine will stop with the motor driving your belt, keeping your accessories running. When you hit the gas, a 42 V starter will spin your engine to 1500rpm within 1/2second (much like a golf cart). This was a big emissions campaign a few years ago. I was invited to the "42V Working Group-Arcing Sub Group" consisting of a large room with engineers from ford GM and DC. Everybody had the same arcing problem and nobody wanted to talk about what they were doing to fix it. They were all scared of "helping the other guy out" and eventually being beaten to market by their competitor. We went to one meeting and called it a waste of time (WOT;) ). This was back in 2001 and they were shooting for an '05 release. I have not heard much talk of this internally anymore, it seems to be shelved until they can figure out the switch arcing deal.

42V would also help with lowering the current draw, however I was told by Delphi that this alone would not force them to change to 42V, it would have to involve the Big Starter to see a cost benefit.

Not quite a :rant: , but almost ):h
 

·
Registered
Joined
·
693 Posts
42V was supposed to bring Higher mileage, greater conveineance(sp) and 1000 watt class D amps built into radios. It still could but my thought is someone is going to loose alot of money if it does, thats why it will be awhile
 

·
Registered
Joined
·
5,255 Posts
Watts is watts though, and that is what is being drawn from the engine.
With higher voltages, smaller conductors can be used, and LED lighting becomes far more efficient, but the hard truth is that P=I*E
Watts = Current * Voltage.

If "x" amount of work is needed to be done (watts), then an increase in voltage will reduce the amperage, but the amount of power drawn from the engine is still the same.

Again, the advantages of higher voltage are smaller conductors and fuses, but the disadvantages are the safety of the tech (above 40 volts it is VERY easy to kill yourself, even 24 can be touchy if you are sweaty), and higher voltages will carry longer and more intense arcs, even at a lower power load.

I was working overhead on a signal under the power lines coming from Hoover Dam heading into Victorville... about 500kv I was about 60 feet below the lines. The street light fixture I was next to has burn marks on top of it.
I was getting a "buzz" when I touched the grounded pole (body picking up voltage from the free air like an antenna, very common)... I isolated myself except for my fingertip and carefully drew my finger back. I was able to maintain a hair-fine arc about an inch long.... looked cool.
 

·
Registered
Joined
·
118 Posts
doable...

A little off the current topic,but the original poster wanted to know if he could have 24-volts of 12...yes,you can. you can go backwards too and get 12 off 24.
The real trouble comes with trying to keep the series bank properly charged.
www.vanner.com has an explanation and the equipment to make it all work.
Back on topic...high voltage systems already run in trucks right now...The unit injectors in ford powerstrokes already use something like 120 or 160-volts to operate
 

·
Registered
Joined
·
167 Posts
24 from 2x12 Kludgey, but it would work.

For the purpose of running a heater, what the o/p asked about.
You COULD separate one of your batteries and float it on top of your vehicle's 12 volt positive, i.e. connect it's negative to your vehicle's 12 volt positive, but make DURNED SURE that the resulting 24 volts (above your vehicle's ground) ONLY EVER gets to the 24 volt heater. I suggest using the battery that is "optional" on the gas version of your truck, probably the one farthest from the starter. Of course you wouldn't be able to charge that battery from the vehicle's 12 volt system until you put it back in PARALLEL with the regular battery. A double pole, double throw switch with center off would do it, wire the two batteries to it for series, parallel and off.

I'm assuming that the heater in question is for short term use, i.e. until the truck warms up.
 
1 - 20 of 32 Posts
Top