Running your computer on 12volts

[charles_reed]

Sorry, should have added this in my post: Some Dell laptops have an unusual pin and I don't think any of the ones supplied with the standard 12v plugin things will work. Thus you either need Dell's own 12v charger or equivalent or an inverter. If, like me, you already have a 12v adapter for other items but it doesn't fit your laptop then an inverter is not a bad choice. If 80%-90% efficient then it is no great shakes and it means you now have a future proof way of charging phones, etc.

As an aside the mobile and laptop manufacturers were supposed to be standardising chargers which would be a great help. However, they don't seem to be making great progress...

Yes, Dell laptops have a "funny" power input plug.

It is, however, incorrect to assume that none of the convertors will fit - I found the 150watt Maplin one does have an adaptor that fits, but won't recharge batteries in my Dell 8600, but will run the computer.

It will supply up to 25 volts in 1 volt increments from 14.

There has been a definite increase in input voltages, with an inverse move in CPU volts over the last 2 years.

The CULV MSI mini-laptop I bought this year needs 21 volts, but has a motherboard voltage of 1.8. If it had a similar-size battery to a netbook it would give a similar 8-12 hour endurance - however, in packing laptop performance into a netbook size the battery has ended up as a minute afterthought only giving 8 hours under light load and 4.5 when it's working hard

 

[Sakura]

The recipe for the "funny" plug is: Cut the wire 3inches from the plug and solder on-wire socket, and the plug on the other side (adapter side). This way it keeps your laptop safe, from accidental wire pull (ripping the DC socket out) and allows you to use any additional power source with standard plugs.
Tested on my toughbook - thumbs up

 

[Cari bean Pie rat.]

12v

On the same subject, has anyone found a way of charging a computer staright from 12v without stepping up through 240v and back down via trasnformer and charger? What are the issues and what kit do you need?

A computer power supply contains only a 12 v dc and 5 v dc to my knowledge and I think it would be easy to do.
You would just need a 12 v dc and 5 v dc regulated supply which are both available in switch mode form.
The 12 v dc is the problem you would have to have a well charged 12 v battery to do this whereas a 5 v regulator would run happily for a while on even a low charged 12 v battery.

 

[Grehan]

As a matter of interest, what is the % waste or degree of inefficiency comparing stepping up to 240v and then plugging (say) A 19v transformer to feed the machine, with stepping 12v to 19v . . . ?
Forgive a naive follow-up, which is, "does the machine get as much power resource (sorry, the best term I can manage) from the 12v>19v as compared with the 12v>240v>19v . . ?

 

[BrianH]

As a matter of interest, what is the % waste or degree of inefficiency comparing stepping up to 240v and then plugging (say) A 19v transformer to feed the machine, with stepping 12v to 19v . . . ?
Forgive a naive follow-up, which is, "does the machine get as much power resource (sorry, the best term I can manage) from the 12v>19v as compared with the 12v>240v>19v . . ?

Most units I see advertised quote "up to" 90% efficiency - here is a typical example.

I favour this route to run my computer on board despite the 10-20% efficiency loss because the power brick is an efficient filter. Some computers can be highly vulnerable to voltage spikes and I don't want to turn off the computer every time I start the engine.

 

[noelex]

Most units I see advertised quote "up to" 90% efficiency - .

In practice the inverters do not achieve this level of efficiency, at least with the small load of a laptop. Using a 12v dc converter will save about 20 to 30% in power consumption.

 

[OldBawley]

Question to Sakura,

Please explaine in detail the funny plug system. Me not understand.

 

[Pete7]

As a matter of interest, what is the % waste or degree of inefficiency comparing stepping up to 240v and then plugging (say) A 19v transformer to feed the machine, with stepping 12v to 19v . . . ?
Forgive a naive follow-up, which is, "does the machine get as much power resource (sorry, the best term I can manage) from the 12v>19v as compared with the 12v>240v>19v . . ?

Grehan, on board last week I tried the two options with our basic Dell Vosto laptop and nearly full laptop battery.

Firstly, coke can 100w 12v > 240v and then the normal mains dell charger. Saw an increase of 4ah draw on the Sterling gauge when the laptop was switched on.

Secondly (following day) Dell 12v > 19v charger running off the house bank at 12.8v, saw an increase of 2.2ah on the Sterling gauge when the laptop was switched on.

Both times were for an hour of net surfing so the ah draw could settle down and the laptop battery be fully charged.

So for the odd hour it doesn't make much difference, but an evening spent surfing the net would start to mount up especially if SWMBO is using her laptop too.

Pete