# Solved: Power outage: running laptop from car



## BabbyBaboon (Sep 3, 2014)

Hi Guys! I am in South Africa and our power company is in danger of total collapse. Seriously. Do any of you know how one can run a laptop (Lenovo) from an automobile battery? Lenovo = 18v (I think) and cars run on 12v. Any ideas, please?


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## cwwozniak (Nov 29, 2005)

The quickest solution might be to purchase a power inverter that converts the 12VDC to an AC voltage that can operate the external power supply charger/charger that came with your laptop (230 VAC @ 50 HZ for South Africa, but the power supply may have a wider input range).

That setup might not be as energy efficient as some kind of direct DC-DC up converter that would go directly from an unregulated 12VDC automotive voltage to a regulated 18 VDC. I am not sure if such a device is commercially available.


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## cwwozniak (Nov 29, 2005)

I may have spoken too soon about the availability of a suitable DC-DC converter. I happened to receive an email from a US electronics seller that they had this unit on sale this week.

www.mcmelectronics.com/product/28-16910?scode=DD1535

The seller's product description does not make it clear, but the user manual shows that the power adapter works with both AC mains voltages and 12 Volt automotive batteries as well (via a cigarette lighter plug).

http://prudentway.com/admin/uploadfile/UserManual_ACDCAdapters120150HC.pdf

Not sure if it is available in your country.


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## valis (Sep 24, 2004)

one thing to remember is that whatever adaptor you get, it may not be providing the cleanest electricity to your rig. I've no clue how those things handle surges and whatnot, cwwozniak, any ideas?


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## Drabdr (Nov 26, 2007)

I'm just trying to get a picture of your setup. 

Are you wanting to charge your Lenovo laptop by plugging the laptop charger into a device that is plugged into the cigarette/ power adapter port on the vehicle while the vehicle is running? 

What is the input voltage rating on the laptop charger? 208Volts? 120VAC? or does it indicate a variable voltage?


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## DaveBurnett (Nov 11, 2002)

Surge from a battery?? Valis !
A laptop power adapter designed to run from a Cigarette lighter socket is perhaps the best, as Chuck says.

If you need mains voltage as well, look for an "inverter"


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## valis (Sep 24, 2004)

DaveBurnett said:


> Surge from a battery?? Valis !
> A laptop power adapter designed to run from a Cigarette lighter socket is perhaps the best, as Chuck says.
> 
> If you need mains voltage as well, look for an "inverter"


I'm guessing that doesn't happen? Never said electricity was my thing....


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## valis (Sep 24, 2004)

good readup on it.

https://raywoodcockslatest.wordpress.com/2012/12/30/car-battery-to-charge-a-laptop/


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## Drabdr (Nov 26, 2007)

valis said:


> *I'm guessing that doesn't happen?* Never said electricity was my thing....


Not totally out of the realm of possibilities, and always worthy of concern.

It really depends on the power source. If you're talking about a battery, yes the supply is fairly consistent (straight from the battery). However, adding the dimension of the automobile, now you have an alternator on there generating power. While your power generation should stay fairly consistent around 12VDC, it can vary around that.

However, if you're talking about a plant (I think some of those refineries around you have their control systems on DC voltage), being concerned about a surge and such is very relevant.


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## valis (Sep 24, 2004)

the alternator is what I am concerned about. I am pretty certain I've heard tales of popping electronics doing that....not 100%, but pretty sure.


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## cwwozniak (Nov 29, 2005)

An alternator can generate a nasty spike called load dump if the battery experiences a disconnection while the alternator is running.

http://www2.advantech.com.tw/eservi..._Challenges_Faced_by_Vehicle_Applications.pdf


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## BabbyBaboon (Sep 3, 2014)

Drabdr said:


> I'm just trying to get a picture of your setup.
> 
> Are you wanting to charge your Lenovo laptop by plugging the laptop charger into a device that is plugged into the cigarette/ power adapter port on the vehicle while the vehicle is running?
> 
> What is the input voltage rating on the laptop charger? 208Volts? 120VAC? or does it indicate a variable voltage?


Brad, your surmise is correct: charging from ciagrette lighter socket. The input specs for the Lenovo adapter are 100-240V @ 1.5 A, 50-60Hz.

From the discussion I glean the following:
1. The biggest potential problems are the running alternator and using vehicle equipment (e.g. wipers). Therefore connect only to the battery when the car is off. The cig lighter socket works only with engine running, therefore access constant live terminals.
2. Watch car battery power levels, do not connect laptop for long periods.
3. Optimise battery use of the laptop as per Lenovo Supprt suggestions: http://support.lenovo.com/en/documents/ht071804?tabName=Solutions
4. And of course, use a suitable converter/adapter.

This is INTERESTING. Thanks to all for the various references!


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## DaveBurnett (Nov 11, 2002)

Be aware that the open circuit voltage of a car battery is 13.2volts not 12. Each cell is 2.2volts.
Also that will rise to about 14.5 volts when the engine/alternator is running.


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## Drabdr (Nov 26, 2007)

DaveBurnett said:


> Be aware that the open circuit voltage of a car battery is 13.2volts not 12. Each cell is 2.2volts.
> Also that will rise to about 14.5 volts when the engine/alternator is running.


Good point, Dave. :up: One should always remember that voltage is nominal; it's never perfect.

Texas homes are 110VAC, nominal. However it varies from 105 to 115 VAC, from my experience.


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## Drabdr (Nov 26, 2007)

BabbyBaboon said:


> Brad, your surmise is correct: charging from ciagrette lighter socket. The input specs for the Lenovo adapter are 100-240V @ 1.5 A, 50-60Hz.
> 
> From the discussion I glean the following:
> 1. The biggest potential problems are the running alternator and using vehicle equipment (e.g. wipers). Therefore connect only to the battery when the car is off. The cig lighter socket works only with engine running, therefore access constant live terminals.
> ...


Pretty close. :up:

Personally (this is just me), if I were in your position, I would purchase a good inverter. These charge quicker, and will be more robust to any potential surge/spike you might see from your vehicle alternator system. Once a vehicle is running for a bit, the voltage should become fairly stable. Look for an inverter that is fused/ has an overload on it, and you should be fine. If you can't find one, the output adapter in your vehicle most probably is fused. So if you going to be driving a bit, charge your laptop then.

A bit off-topic now...

If your voltage supply on your home is that erratic, you need to consider other electrical devices you have in your home. Most things we purchase have some kind of electronics in them. Instead of investing something for your car, you may want to clean up the voltage in your home.


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## BabbyBaboon (Sep 3, 2014)

Good point, Brad (about surges etc at home). We get regular load shedding, and when the power comes back on, there could be a spike. Surge protection on ALL home equipment is essential. To date I have dodged that bullet. (I also have some solar solutions as back-ups). My biggest concern at present is the possibility of having no power to run the laptop for weeks on end in case of a total collapse and therefore being cut off from the world. Hence the car question.

I scouted around a bit and DC-DC converters are available in specialist shops in South Africa. I will also consider the inverter option. The manual for one converter confirmed the discussion: they warn you not to start the car while the laptop is connected (but dont give reasons). Thanks for the battery voltage advice, Dave.

To wind up - thanks to you all! i wish I could invite you all to a garage party! LOL


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## DaveBurnett (Nov 11, 2002)

Starting the car will cause a HUGE voltage drop momentarily and quite a drop while the starter motor is turning.


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## cwwozniak (Nov 29, 2005)

BabbyBaboon said:


> My biggest concern at present is the possibility of having no power to run the laptop for weeks on end in case of a total collapse and therefore being cut off from the world.


If there is an area wide total collapse of power for an extended period of time, you may still be cut off if your Internet Service Provider does not have backup power for every piece of hardware between your computer and the Internet.


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## BabbyBaboon (Sep 3, 2014)

Aaaah Chuck!! Now THERE is a problem . . . I know they run generators as back-ups, but that would last only as long as there is diesel. Maybe I must console myself with the thought that if the worst happens, it would at least be a good case-study for survivalists.


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## DaveBurnett (Nov 11, 2002)

And God help you if you live anywhere near "civilisation" !


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