12-volt batteries will be in cars until...........

[HerrStig]

Originally Posted By: supton
Originally Posted By: morris
what happens when a fireman cuts the frame open to get a person out, and hits 48 or 58 or 300 volt cable?


At 48 or 50V, I'm guessing nothing. Most firefighters are wearing gloves while doing anything, right? Takes almost nothing to insulate from 50V. 100V even. The tools they use also have rubber grips etc.

Given how it's likely they will cut through wire and steel car bits at the same time I'd think it'd just pop the fuse in the fuse block at the same time. Also, if the vehicle is unkeyed, most circuits go dead anyhow.

Now, if they were distributing 300V, that can be different. Don't forget, you have to have a full circuit for current to flow. Just cutting one wire won't zap you, unless if you cut that wire and complete the circuit by grabbing the bare ends. Since they are not apt to do that... Hybrids are getting pretty prevalent now, so we should ask a firefighter just what they've been trained to do while cutting open a hybrid.
I love all the "how safe it is "AS LONG AS" stuff. IF they wear gloves, IF the JOL doesn't touch ground and a hot lead at the same time......IF....

 

[carwreck]

42-volt system was used on GM Sierra/Silverado hybrid stop/start system, but still used 12 volt batteries.
It has 3 AGM batteries in series only for the starter/generator, 120-volt A/C invertor, and power steering. The rest of the truck uses a regular 12-volt system.

GM 2004 Siverado EMT training

http://www.motortrend.com/roadtests/trucks/163_0409_2004_truck_comparisons/viewall.html

 

[supton]

Originally Posted By: HerrStig
I love all the "how safe it is "AS LONG AS" stuff. IF they wear gloves, IF the JOL doesn't touch ground and a hot lead at the same time......IF....


12V will kill you too. Just takes a lot of work. It can certainly hurt you--a number of people have shorted out a 12V battery and gotten burns, either from a battery explosion or from a hot wire. I've read of someone shorting out terminals with a wedding band.

Don't forget, some electricians work on circuits live (depending upon what the work is). Most overhead line work is done hot also. Risk can be mitigated by training. And accidents can still happen.

Also--you can grab a 300V wire in a hybrid, and be standing on earth ground. And be fine. Just don't touch the car!

 

[volk06]

Volts won't will you, just give you a buzz. Amps on the other hand are a different story.

 

[friendly_jacek]

Originally Posted By: morris
what happens when a fireman cuts the frame open to get a person out, and hits 48 or 58 or 300 volt cable?


Even 12V will spark and can start fire if one does know what is doing.

The 48-58V could be life threatening only if one applied it to wet or open skin. 300V would be dangerous, but cars with such high traction voltage have HV cables hidden and protected under the chassis.

Besides, the emergency responders should be trained how to disconnect HV in hybrid/electric cars.

 

[morris]

ill take a guess that the higher volts WILL cause trouble some time. is there any good tests showing different?

 

[Garak]

I'll have to do some checking in my back issues of automotive magazines. I do recall an article somewhere discussing the various setbacks the manufacturers had when trying to actually implement the higher voltage systems. It apparently wasn't as seamless as they thought it might be, and more than likely, there were added costs they didn't want to incur.

I do recall GM wanting to implement the combined flywheel/starter/alternator arrangement and couple that with higher voltages, but for some reason, it did not pan out.

 

[Duffman77]

The logistics of the switch are huge, everything electrical on the car less the wiring needs to be redone. Since the OEMs have switched to a supplier based manufacturing model the OEMs have to get their suppliers to make the switch, they may be locked into supply contracts that may not facilitate an easy change. Stuff like the radios, batteries and lightbulbs may not be readilly available in the new voltage. As far as I know the electronics all operate on 5V but new regulators must be engineered into the system.

I think switching to 24V would be a lot easier as some HD equipment and trucks already run the system so their are suppliers out there making components. I just think that the OEMs think that if they are going to do a switch they are going to go to more than 24V.

 

[jagger]

Actually I read an article about this in a tech magazine, and it's mainly for reliability. Electric components are simply more reliable than hydraulics. So if you switch to a higher voltage, you can have electric power steering, brakes, air conditioning, etc. Plus there maybe additional benefits, such as weight reduction and reduced maintenance.

There are some challenges to switching over, hence it hasn't happened yet. Some manufacturers have found ways to tweak 12v systems, electric power steering is already doable on 12v.

 

[morris]

" more reliable than hydraulics". chrysler built race cars using a auto trans useing hydraulics, the go 8.xx seconds. where is your electric car going 8.xx seconds. i have a dodge with electronics, IT STINKS!!! it shifts when i dont want it to. and wont shift when i want it to. in the good old days my 1965 300L shifted great, with hydrauics. I DONT NEED ELECTRICS, IN A CAR. KEEP YOUR ELECTRICS!!!!!

 

[GMBoy]

Higher voltage will be in our near future not for all the luxury equipment but rather for things like electronic power steering (which we have today), electric HVAC and the like to help with better MPG's.

 

[friendly_jacek]

Originally Posted By: GMBoy
Higher voltage will be in our near future not for all the luxury equipment but rather for things like electronic power steering (which we have today), electric HVAC and the like to help with better MPG's.


Yap, Prius runs electric A/C compressor from high voltage bus, over 200V. All the water pumps are also electric, but at 12V.

 

[jagger]

Electric is just easy to maintain, if the motor dies, simply replace it. No need to deal with hydraulic hoses, leaks, master cylinders, pumps, etc.

I'm not sure if the switch to higher voltage is feasible, as doing anything outside the norm is very challenging for Detroit.

 

[GearheadTool]

Originally Posted By: volk06
Volts won't will you, just give you a buzz. Amps on the other hand are a different story.


What is that, like the "put the 9V battery on your tongue" type deal? I thought I was going to maybe die when I first did that. Then it felt cool

Then I realized it was stupid.

Not sure who thought of that idea, to do that?

 

[Duffman77]

Originally Posted By: GearheadTool
Originally Posted By: volk06
Volts won't will you, just give you a buzz. Amps on the other hand are a different story.


What is that, like the "put the 9V battery on your tongue" type deal? I thought I was going to maybe die when I first did that. Then it felt cool

Then I realized it was stupid.

Not sure who thought of that idea, to do that?

It means that if you are in an insulated boom truck like the utility workers use you can touch a 100,000V bare wire with your bare hand and nothing happens. Take away the insulation so that the current flows and poof you will turn into a pile of charred ruins. Don't try this at home kids.

 

[tonycarguy]

Originally Posted By: supton
Originally Posted By: morris
what happens when a fireman cuts the frame open to get a person out, and hits 48 or 58 or 300 volt cable?


At 48 or 50V, I'm guessing nothing. Most firefighters are wearing gloves while doing anything, right? Takes almost nothing to insulate from 50V. 100V even. The tools they use also have rubber grips etc.


First, if the firefighter is not touching the frame of the car, then he's not completing the circuit so it's harmless to cut into the cable. Secondly, batteries are DC not AC. AC is more dangerous than DC. Shorting a DC circuit will cause burns. AC stops your heart. They are different.

Btw, static electricity is thousands of volts -- but how many people have been killed by walking on carpet with socks while wearing a wool sweater?

 

[TFB1]

Originally Posted By: tonycarguy
Originally Posted By: supton
Originally Posted By: morris
what happens when a fireman cuts the frame open to get a person out, and hits 48 or 58 or 300 volt cable?


At 48 or 50V, I'm guessing nothing. Most firefighters are wearing gloves while doing anything, right? Takes almost nothing to insulate from 50V. 100V even. The tools they use also have rubber grips etc.


First, if the firefighter is not touching the frame of the car, then he's not completing the circuit so it's harmless to cut into the cable. Secondly, batteries are DC not AC. AC is more dangerous than DC. Shorting a DC circuit will cause burns. AC stops your heart. They are different.

Btw, static electricity is thousands of volts -- but how many people have been killed by walking on carpet with socks while wearing a wool sweater?



But the current is in micro amps, try that 10Kv or so with a amp or two behind it, we'll be reading your obituary... And with enough voltage DC will kill you just as quick as AC, at 48v or so neither is going to give more than a little tingle and conditions must be right for that...

 

[ffhdriver]

Originally Posted By: supton
I do believe all the hybrids still have a 12V "traction" battery. If nothing else to just start the engine. One major issue that has to be dealt with is powering all the sensors and electronics in the vehicle. The drive to make smarter sensors and lower power means the IC's themselves do not run on voltages above 30-ish volts. Adding buck convertors in various places will add cost, and parts, and as we know, adding parts can mean reduced reliability. Most sensors, and certainly all the computer bits, will still be running well below 12V. The 42V is only for heavy loads, like electric motors or heaters, or powering the 15kW stereo amplifier (or whatever it is they now put in).

I think 12V will be around for a long time to come. The altenator itself might go to 42V, and a buck convertor might be used from that to charge the battery; but I think the 12V battery will be around for a while to come.

Just my SWAG.
Traction batteries on hybrids are not 12 volts. They're HV batteries 200v+. Hybrids don't use the 12v battery to start the ICE, an electric motor does that. This is true on Ford and Toyota hybrids I'm familiar with.