Batboard

My wife just bought a new Mercedes. It has a 24 volt sytem!

I did some research on this, and it turns out that all of the major auto manufacturers plan to convert to 24 Volts in the NEAR future! This will allow for higher electrical wattages in a smaller package, all other things being equal. New vehicles have increasing electrical demands, as much of the auxiliary systems (e.g., A/C, power steering, camshafts being replaced with electric valve controllers, etc.) are changing from being mechanically driven to DC powered.

We had just bought a W7 dash mount ASTRO Spectra radio for her car (for our copter business), so I guess we will have to shop around for a voltage converter! (She loves her brand new Merc!)

I'm going to make some calls to The Big M on Monday to see what their plans are.

Larry

Check with your aircraft radio shop. A lot of Cessna highwings (182s, etc) are now 24v. They should be able to direct you to a 24/12v converter that will handle your needs.

The ones we use only put out about 15 amps, though, as we are limited to 10w out on VHF in aircraft. You will need more for your Astro mobile.


Jack

something you may want to check - The car may have a converter already installed onboard since there are going to be some accessories which are 12v - cigarette lighter jack - bulbs.......

ASTROMODAT wrote:My wife just bought a new Mercedes. It has a 24 volt sytem!

Do they TRY to make things as complex as possible? Sheesh. Lighter plug? Nah, they proably made that 24 volt and try to sell you a $300.00 adaptor to step it down to 12 so you can plug your cell phone in.

Actually, most aren't changing to 24v. They are going to 36V (42V operating). This is already decided upon by many manufacturers and it's already into play with the SAE, whom is currently writing up the new guidelines and requirements for OEM manufacturers around the world. There will still be a 12V tap available on the batteries (or converter, as per SAE).

There are several big reasons for this change.
1. cut current requirements by a third.
2. lighter weight (less wire gauge required)
3. electric assis power steering
4. fully electric HVAC systems as trunk-mounted modules.
5. electric light-off catalytic converters to reduce cold start emissions
6. electric/hydraulic or pneumatic valve actuation systems will become a closer reality giving us more power with a smaller engine and yet have better economy.

Finally- we will be able to feel a shock from an automotive system!

This brings up the question: what's going to happen when "installers" that are totally in the dark connect a $4600.00 digital mobile radio to the 24/36V system? It will be like the old Lucas electrical systems. You see....SMOKE is actually what makes an electrical device operate. The wires carry smoke to the device.
This is why it's always a good idea to use a good quality adhesive style shrink tube on all connections. With a good seal, smoke stays in the wire.
A lamp uses a little smoke, hence the small wire. A starter motor uses tons of smoke, so you need the large diameter cable fo this application. If an electrical device fails, it will leak smoke as you all know. Pinch a wire. What happens? You will release smoke since the pressure builds up in the wire! A 36V system will produce three times as much smoke as a 12V system. If you connect a 12V radio to a 36V system, this means that you will release appoximately 200% more smoke than what the average modern Motorola radio normally produces after immediately being placed in service.
If you keep the smoke contained within the entire electrical system with no leaks, you did a good job.

(ok....maybe I DO smoke crack)

$4,600 radio? You must be referring to the old analog Spectra. A new ASTRO Spectra (fully optioned) lists north of $5,300.

Larry

$5,300 for a two-way radio is still like smoking crack...

...Like smoking crack, I'll gamble with an eBay $1000 Astro Spectra

Please don't shoot the messenger. I was just pointing out the LIST price for these radios. As a business, I can't go to Ebay and buy a few dozen radios, nor can a PD, etc.

Larry

Ouch! And Westmoreland County, PA is going to that format on their new 800 system that's gonna save the world.
I still can't figure out how a small FD surviving on fish frys can muster enough money to switch to this system.

24, 36, 72, 1025..I don't mind what voltage they're going to be running in the new vehicles...just so long as they STAY AWAY from going back to positive ground systems!!!!! (remembers an old MACK install & shudders.......)...Z

Two things. The smoke goes up with the SQUARE of the increase in voltage, the resistance being the same. Nine times as much smoke on 36 volt - oh happy day. The other - six volt postitive ground was a pain, but the early Motrac was plug configureable to do 6/12 +/-.

I like positive ground systems. I get to charge about $4600.00 to change them over to negative ground!

Try an outfit called Newmar for a converter. They are not cheap, but are very well built and stand up to harsh enviroments. We use them in locomotives to convert 72V to 12V for the newer radios. The input and output are isolated, which is good for some applications.

I have the opposite problem in one of my vehicles. It is a 6 volt system (actually I run 8 volts, much better cranking). I solved this problem with a gell-cell battery that I charge up weekly.

Josh