minmum volts needed to power computer?

[power4u]

Hello,
The Laptop AC adapter I have outputs 19 volts. I am now looking for a solar power generator so I can run my computer on a camp site in the day time. Must the solar power generator have at least 19 volts? So for example, if the power supply only provided 12 volts, then I would have to find a computer that runs on a lower voltage?

In advance, thanks for your help with this

[hyperballad]

laptop min power reqs.

When asking that question.. I need to know if your 12volt power supply is DC.. (assuming its from a panel setup) that's Plenty of power... just get an Power Inverter..
changes DC to AC... and a 12v DC will run Multiple laptops.. no worries there.. If I'm not mistaken.. the ACv necessary to run a laptop is only 70-90 volts... But I'm new to the solar panel thing.. so don't take my answer as fried gold.. I just know comps ~:>)

[Mike90250]

If the input power jack on your computer needs 19V to run and charge the battery, that's what you have to supply to it.
to recharge a battery, you have to force a higher voltage into it, than it stores.

A regular "12V " solar panel actually produces about 17V, so you need to look for a panel with Pmax of about 19-20V. And because panels seldom produce their nameplate power, you would need about 150W panel to power a 80W laptop.

[power4u]

let's use my laptop ac adapter as an example.

The labeling shows the following:
INPUT:100-240 VOLTS; 1.6 AMPS 50-60 Hz
OUTPUT: 19 VOLTS; 3.42 AMPS

I used conversion formula to convert the VOLTS&AMPS to WATTS:
so in terms of WATTS:
INPUT:160-384 WATTS
OUTPUT: 64.6 WATTS

I found out that in USA the electric voltage for outlets is 110-120 volts (most countries are double). Most outlets run at 15 amps + 120 volts, so this is 1800 watts needed to have the strength of a common wall outlet in USA.

Correct me if I am wrong, but I think the AC Adapter is meant to lessen the charge from the outlet to only what is needed by the computer? I would guess that if, for example, the power source input produces 70 watts, the AC adapter would convert the power supply to 64.6 watts, and the remaining 5.4 watts would be wasted?

So, I think for this AC Adapter, I would need at least 64.6 watts produced by the solar panels to keep the computer battery fully charged at all times? Otherwise, if the power produced is less than this, I would have to occasionally shut off my computer to give the computer battery the time to refresh itself?

[Sunking]

let's use my laptop ac adapter as an example.

The labeling shows the following:
INPUT:100-240 VOLTS; 1.6 AMPS 50-60 Hz
OUTPUT: 19 VOLTS; 3.42 AMPS

I used conversion formula to convert the VOLTS&AMPS to WATTS:
so in terms of WATTS:
INPUT:160-384 WATTS
OUTPUT: 64.6 WATTS

I found out that in USA the electric voltage for outlets is 110-120 volts (most countries are double). Most outlets run at 15 amps + 120 volts, so this is 1800 watts needed to have the strength of a common wall outlet in USA.

Correct me if I am wrong, but I think the AC Adapter is meant to lessen the charge from the outlet to only what is needed by the computer? I would guess that if, for example, the power source input produces 70 watts, the AC adapter would convert the power supply to 64.6 watts, and the remaining 5.4 watts would be wasted?

So, I think for this AC Adapter, I would need at least 64.6 watts produced by the solar panels to keep the computer battery fully charged at all times? Otherwise, if the power produced is less than this, I would have to occasionally shut off my computer to give the computer battery the time to refresh itself?

Sorry but it does not work that way. Solar panels are current sources and lousy ones at that. In order for your laptop internal charger to work, it must have a rock solid voltage source with the specified rated current. Anything short of that and the internal charger will shut down.

You can use a solar panel to charge a laptop, but it is not as easy as hooking up a solar panel with a plug to fit your laptop unless the laptop was specifically designed for that, and they are not. You gotta to have stuff between the laptop and panels. Stuff like charge controllers and batteries to change the current source to a voltage source.

[power4u]

Sorry but it does not work that way. Solar panels are current sources and lousy ones at that. In order for your laptop internal charger to work, it must have a rock solid voltage source with the specified rated current. Anything short of that and the internal charger will shut down.

You can use a solar panel to charge a laptop, but it is not as easy as hooking up a solar panel with a plug to fit your laptop unless the laptop was specifically designed for that, and they are not. You gotta to have stuff between the laptop and panels. Stuff like charge controllers and batteries to change the current source to a voltage source.

thank you for explaining this!

[Sunking]

thank you for explaining this!

You are welcome. It can be done, you just need a magic black box. Easiest way is to just simply buid a 12 volt battery system with say a 60 watt panel, 5 amp charge controller, 40 to 60 AH 12 volt battery, and an inverter to plug you Laptop power brick into. Very inefficient but works, no to mention very expensive to generate less than a penny of electricity per day..

Otherwise unless there is a product out on the market I do not know of you are going to have to custom design a current/voltage regulator and oversize the panel considerable so it at least has say a 6 hour window during the day to actually work.

[john p]

Silly as Sunkings solution is its the only practical one. Any other method of trying to charge the computers batteries with solar is either too complicated or requires non standard componants.
I know I tried a few other ideas over the last few years myself.and none were simple to implement.

[Sunking]

Silly as Sunkings solution is its the only practical one. Any other method of trying to charge the computers batteries with solar is either too complicated or requires non standard componants.
I know I tried a few other ideas over the last few years myself.and none were simple to implement.

John I think, or I should say I know it can be done but i have never tried or needed to do so.. Basically use a 24 volt panel made for 24 volt battery systems of say 120 watts and a simple 3-pin voltage regulator. You would not even have to worry about current limit as the panel itself will take of that.

[john p]

Sunking as you know there is no std voltage regulator that is 19v but 18v could be used or an adjustable regulator. but most of then are rated at 3a same for TO3 fixed volt regulators, and realy need to be used with a bypass power transistor and as there will be considerable heat they need to be mounted on a well finned heatsink then that needs to be mounted in an enclosure.To do all this so there is no possibility of damage to the computer power supply is most likely beyond the person wanting help..
Thats why I agreed with you its better to use an off the shelf 12v panel, charge controiller small battery and small inverter,, BUT as you said its a lot of things to have to save a few pennies.(well really it saves nothing as there is no possibility of a pay back period)

[power4u]

maybe buy a laptop with multiple battery bays, and then just carry 4-5 batteries at a time?

[Sunking]

Sunking as you know there is no std voltage regulator that is 19v but 18v could be used or an adjustable regulator.

Yes i know, but you can use many of them and raise the reference voltage up, and yes there are many challenges that have to be worked around. For someone in the electronic field can work around the challenges, and any consumer electronic manufacture can make such a device if there was enough demand production runs.

Otherwise the easiest work around for DIY is just plain ole 12 volt battery and inverter, wasteful and expensive, but it works.

[john p]

Otherwise the easiest work around for DIY is just plain ole 12 volt battery and inverter, wasteful and expensive, but it worksThat is why I said silly as it is its really the only simple practical way for most users.There simply is not a lot of users that have enough knowledge to connect up a regulator a few resistors and another power transistor and then mount them on heatsink ETC ETC.

[adnama]

Similar situation need info for solar dummy

I purchased from "Harbor Freight" a Thunderbolt solar 5 watt solar power system. with the impression that this would charge a laptop. Specs in the manual (manual sucks!) Peak Output: 15.5 V/3.92W/0.25A. Panel Size: 12-1/2" L x8-1/2"W x 5/8: H Battery Box: 12 V/2.6 Ah capacity. Operation instructions: Use a voltage Regulator (not included) between solar panel and battery to prevent overcharging battery and damage. OK- question? What size voltage regulator or solar controller? brand or configuration will work with this? and any other items that they failed to tell me I may need? Or is this purchase not enough watt to charge the laptop battery?

Yes i know, but you can use many of them and raise the reference voltage up, and yes there are many challenges that have to be worked around. For someone in the electronic field can work around the challenges, and any consumer electronic manufacture can make such a device if there was enough demand production runs.

Otherwise the easiest work around for DIY is just plain ole 12 volt battery and inverter, wasteful and expensive, but it works.

[inetdog]

I purchased from "Harbor Freight" a Thunderbolt solar 5 watt solar power system. with the impression that this would charge a laptop. Specs in the manual (manual sucks!) Peak Output: 15.5 V/3.92W/0.25A. Panel Size: 12-1/2" L x8-1/2"W x 5/8: H Battery Box: 12 V/2.6 Ah capacity. Operation instructions: Use a voltage Regulator (not included) between solar panel and battery to prevent overcharging battery and damage. OK- question? What size voltage regulator or solar controller? brand or configuration will work with this? and any other items that they failed to tell me I may need? Or is this purchase not enough watt to charge the laptop battery?

1. A 5 watt system with listed peak output of 3.92 watts should give you some idea of what you are up against. Any charge controller system will add additional losses.
2. The built-in chargers in most if not all laptops test the power availability before even trying to charge, and they seem to want to see on the order of 50 watts before doing anything.
3. If you build an external charger circuit (a bad idea given smart battery management interfaces found in many laptop batteries), charging at ~3 watts will take more than a week to recharge a 50% discharged laptop battery.
4. If you use the panel with a battery that fits into the included battery box (12V, 2.6 AH) the panel could be an effective charger. But the amount of energy you could take from that battery each day would be very limited.