Talk:42-volt electrical system

This article has not yet been rated on Wikipedia's content assessment scale.
It is of interest to the following WikiProjects:

Please add the quality rating to the {{WikiProject banner shell}} template instead of this project banner. See WP:PIQA for details.

Automobiles Low‑importance

	Cars portal This article is within the scope of WikiProject Automobiles, a collaborative effort to improve the coverage of automobiles on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.AutomobilesWikipedia:WikiProject AutomobilesTemplate:WikiProject AutomobilesAutomobile
Low	This article has been rated as Low-importance on the project's importance scale.

Trucks

	This article is within the scope of WikiProject Trucks, a collaborative effort to improve the coverage of trucks on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.TrucksWikipedia:WikiProject TrucksTemplate:WikiProject TrucksTrucks
???	This article has not yet received a rating on the importance scale.

Technology

This article is within the scope of WikiProject Technology, a collaborative effort to improve the coverage of technology on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.TechnologyWikipedia:WikiProject TechnologyTemplate:WikiProject TechnologyTechnology

Please add the quality rating to the {{WikiProject banner shell}} template instead of this project banner. See WP:PIQA for details.

Energy Low‑importance

	Energy portal This article is within the scope of WikiProject Energy, a collaborative effort to improve the coverage of Energy on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.EnergyWikipedia:WikiProject EnergyTemplate:WikiProject Energyenergy
Low	This article has been rated as Low-importance on the project's importance scale.
	This article has been marked as needing an infobox.
	This page has been marked as needing an image.

Please add the quality rating to the {{WikiProject banner shell}} template instead of this project banner. See WP:PIQA for details.

Electronics Low‑importance

	Electronics portal This article is part of WikiProject Electronics, an attempt to provide a standard approach to writing articles about electronics on Wikipedia. If you would like to participate, you can choose to edit the article attached to this page, or visit the project page, where you can join the project and see a list of open tasks. Leave messages at the project talk pageElectronicsWikipedia:WikiProject ElectronicsTemplate:WikiProject Electronicselectronic
Low	This article has been rated as Low-importance on the project's importance scale.

Notes

All this stuff needs specific references and I'm wary of quoting too many Web pages.

Advantages of a higher voltage

Motivation for increased voltage - higher demand by accessories such as air conditioning, power steering, adaptive suspension, electronically-controlled valves. Could need several kw electric power on a vehicle, compared to about 1 kW in a passenger car today. More power needs more current at 12 v, larger and heavier wires. A higher voltage would be useful.

All-electric drives would allow unused loads to be switched off, reducing parasitic drag on the engine. Applications in both mass-market cars and for military vehicles which could use electrically powered systems for weapons and sensors.

The reason to go to 42 V is that this is about the highest voltage that can be used without running into safety codes on insulation and contact - many codes only regulate equipment for voltages 50 v and higher. Using 42 volts allows the same wires to carry 3 x the power as a 12 volt system.

With a lead-acid battery system, 6 cells for a nominal 12-volt system needs almost 14 volts for charging the battery. Using 3 times as many cells gives 36 volt "nominal" but a 42-volt charging system. The convention seems to be use the charging voltage - a lead-acid "12 volt" battery with 12 volts on its terminals is essentially a dead battery, when charged it will show 13.6 v or more.

Discuss why not just go to 24 v (28 V charging)- which is well established in heavy trucks. maybe an sAE reference describes this?

Just a comment, "about 1 kW in a passenger car today". That is huge amount of power, I know this is just a talk page but cars with 42A electrics? Surely this is an exceptionally large power drain. Headlights take about 100W and that is a major drain on many (IMHO most) car electrical systems. Mtpaley (talk) 22:43, 16 April 2010 (UTC)[reply]

Well, let's see. A kilowatt at 12 V would be closer to 83 A. An ignition system takes substantial power (10 A, perhaps?). Low beam is 2 x 55 watts, high beam is 2 x 65 watts on some cars anyway. My car has various motor operated gizmos like a sun roof and power seats, and electric seat heaters. There's more than just headlamps - marker lights, turn signals, daytime running lights, brake lights, dashboard lights. The stereo takes a couple of amps. There's a powerful blower for the heating and air conditioning. Many cars have electric radiator fans which are pretty big loads (20 or 30 A?). And that's not counting things like electric power steering, adaptive suspensions, electric power brakes, and many other toys and gadgets that the Car of the Future will have. I think it's a reasonable statement, but my best reference is packed away at the moment. --Wtshymanski (talk) 14:38, 17 April 2010 (UTC)[reply]

System components

42-volt system would need a new alternator and battery. Could use a combined starter motor and alternator, controlled by power electronics - combined with a 42 V battery bank this is used to create "mild hybrids" which use an electrical assist to add several hp for acceleration and to idle-stop engines instead of idling at standstill. To power 12-volt accessories would use either a solid-state converter or a second 12 volt battery recharged from the 42 volt system. Separating the engine cranking battery from the ignition and accessory battery would solve one big problem with automotive electrical systems.

Limitations and obstacles

It's hard to break direct current at voltages higher than 12 V because there's no natural current reversals as found in AC circuits. The same switch that is rated to interrupt 15 Amperes at 120 v AC might only be rated 1 Ampere at 120 v DC. 12-volt switches haven't needed design features to limit arcing such as spring-loaded fast break contacts, or arc containment and dispersal features as found in higher-voltage dc switching devices.

Not all the wires get smaller - very fine wire breaks easily, so devices that only draw an ampere or so at 12 V will not get smaller wires. Maybe 1/3 of the wires in a car get smaller at 42 volts.

Corrosion is a problem according to [1]

Incandescent bulbs of the sizes used in cars work quite well at 12 v and are cheap and simple. 42 V gives no advantage for LED lamps, but might be useful for hid headlamps which have relatively high power.

A great deal of auto electronics works well at 12 v and developing semiconductors to switch and tolerate a 42 v environment is a challenging field of development. Low-power electronics doesn't benefit from 42 v (computers, navigation systems), 42 V might help high-power sound systems. Chief advantage is for electronics controlling mechanical systems such as engine valves and suspension. If 42 V devices all switched electronically, avoids the problems with snap switches.

Slow introduction

Toyota produced a low volume luxury Toyota Crown with 42 V electrical system, sold only in Japan. General Motors is incorporating 42-volt elements in vehicles like the 2005 Silverado hybrid truck.

Merge from 42V?

I have a slight preference to merge material from 42V to this article, on the grounds that "42-volt electrical system" is more descriptive than the curt "42V". I am biassed, of course - [2]. --Wtshymanski (talk) 14:10, 25 November 2011 (UTC)[reply]

I agree with you on the direction of the merge. However, noone seems to have started a section on a Talk page that actually contains the merge proposal, with the rationale from the nominator. Someone may feel free to invite me back if that ever happens. Cheers. N2e (talk) 15:33, 25 November 2011 (UTC)[reply]

Why, this is that talk page discussion. The rationale is pretty obvious - same topic, two articles, should be one article. --Wtshymanski (talk) 17:50, 25 November 2011 (UTC)[reply]

Merge makes sense; using this name for the merged page makes sense.--NapoliRoma (talk) 00:52, 26 November 2011 (UTC)[reply]

SUPPORT the merge, per rationale that the two articles cover essentially the same material. Should be merged. Which seems to be the consensus of the commenters to date. N2e (talk) 00:18, 9 September 2012 (UTC)[reply]

Looks like the merge was done on 2011-12-01. --Kvng (talk) 13:59, 10 September 2012 (UTC)[reply]

Done Cool. That was not clear in the discussion previously, but with your note, and this one, it now is. Merge has been completed. Thanks. N2e (talk) 17:15, 10 September 2012 (UTC)[reply]