Laptop Charge While Camping; Long Term (Newbie Question)

Re: Laptop Charge While Camping; Long Term (Newbie Question)

Other than trying to do this with a 80 watt+ solar panel, possibly a storage battery, and inverter/converter for you laptop... You are correct that you are not going to find much out there that will reliably and cheaply power any electronic equipment that consumes more than a little bit of power.

Even running an inverter off of your car battery, you will only be able to run the laptop for a couple of hours before the car battery starts draining below 80% capacity (probably around 200 Watt*Hours)--which will damage the battery over long term use.

You could get a storage battery that you can drain to 50% capacity, and charge it when driving the car--but a "car sized" storage battery is only going to give you 500 Watt*Hours of energy before you should recharge it. May be 10 hours of use.

For reliable, and fairly cost effective power, a small generator is still probably going to be your best bet. Honda makes a range of small and very quiet generators (1kW, 2kW, 3kW) that should run you around $700 USD for the 1kW and ~$900 USD for the 2kW version (in the US, I purchased my 2kW unit from www.mayberrys.com).

http://www.hondapowerequipment.com/gensup.asp

Fuel wise, according to Honda's numbers, the eu2000i uses, at low power, about the same amount of fuel per kW generated as the smaller eu1000i (but generates much more electricity for the same fuel usage). Depending on your needs, you can probably run the laptop for an hour or two on batteries and on the generator for a couple of hours and charge at the same time. In theory, 1 gallon of gasoline should give you about 2.8 to 5.8 kWhrs of electricity--the equivalent to 5-10 car sized storage batteries. In either generator, if it is just your laptop plugged in, they will run for around 15-16 hours per gallon of fuel.

Hmmm... Lets try another tact (running a generator several hours per day may not be what want). Looking at the IBM web site, the new versions of the Think pad should last around 8-10 hours per battery charge using the extra capacity battery option...

http://www.pc.ibm.com/us/accessories/battery/alldaycomputing.html
http://www-131.ibm.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=-840&langId=-1&partNumber=92P1119&storeId=10000001

The larger batteries recharge in 4.3 to 12 hours (laptop off vs on?). The battery (above link) is rated at 4.5 amp*hours at 14.4 volts = 65 watt*hours. If your laptop will run for 8 hours on a charge, then the average consumption is around 8 watts.

At 8 watts, that is quite a small load, and a storage battery, car battery or even buying a couple extra batteries to recharge on the way to town and back may be a good deal. I would feel pretty safe charging two of these batteries without starting the car ((good for 16+ hours of run time). A Honda 1000 watt generator would be way overkill if you did not need the electricity for anything else.

Unless you have found a 12 VDC to Laptop adapter, you would probably be better off getting a small 200 watt inverter that can connect to the car/battery and just charge the laptop directly. To see what your "real" power usage would be in this case, I would suggest you get a hold of a power meter, like the Kill-A-Watt (~$34 USD) and measure your true power consumption. It appears your supply is sized to run both the laptop and charge the battery at the same time (rated for a worst case use--makes sense).

http://www.amazon.com/gp/product/B00009MDBU (Kill-A-Watt meter at Amazon)

If you were going to be in the bush, away from gas/electricity for a long time, it might be worth trying to figure out if you could run the laptop directly off of a Solar PV panel--but you would probably need to contact IBM (or an electrical engineer) to see if the laptop's input would be compatable with the solar panel's output (wide voltage range and less than full current output). You could also look for a 12 VDC charger for the batteries themselves.

And, running for a few days on the Kill-A-Watt meter will help you see how much power is affected by your use (bright screen in day, lots of power, typing at night with screen backlight set low, much less power, etc.). You might be OK just running off a trolling motor battery that you charge once a week.

Your thoughts on how you would like to proceed from here?
-Bill

Re: Laptop Charge While Camping; Long Term (Newbie Question)

Hi Niel,

I did not think I was in disagreement with you Niel... I suggested the inverter/converter assuming that both would be similar solutions. The "car converter" has, of course, some sort of buck/boost/inverter type circuit. And wether or not it would be more energy efficient to go 12 vdc to 110 vac to 16 vdc or just 12 vdc to 16 vdc via a car/laptop converter depends on the individual designs -- but it would probably be better to obtain the 12 vdc converter. And it would be best to measure using a volt/amp meter.

The "hours on end..." of use would apply to operating the laptop itself (4-6 hours per day of the user) and, if the internal batteries are used, IBM (see battery link) says that it takes 4.3 to 12 hours to charge the internal laptop battery. Either use would require many hours of some sort of power. Charging the car battery (assuming a 20% capacity, 200 watt*hour discharge) would probably take an hour (+/-) of idling or driving to fully charge back to full capacity.

And, in any case, we where writting our posts at the same time and I did not see your's (or address any of its points) until after I posted mine (got the new post warning)... I was just using both user information (72 watts 4-6 hours per day 450 watt*hours) and IBM's information (8 watts * 6 hours = 50 watt*hours or almost 1/10 the amount of power originally assumed) to form a couple of options (generator if 72+ watt load, batteries/solar if 8 watt load) and leave it to Bonny to tells us how she (?) wishes to proceed from here.

The current crop of laptops from IBM use only and average of 8 watts (if the battery link is correct--did not find the R40 information but am assuming it is still close), and if I was on a trip where solar was much preferred over generators and/or storage batteries, it is very possible that connecting a (as an example) twenty watt 12 volt (actually ~17 volt) solar panel directly on the 16 vdc laptop input (with an 18 volt zener diode clamp and a Schottty blocking diode to protect the laptop) may actually be enough to charge/support the battery/cpu during the day and use the laptop in the evening. Using the laptop in the evening/night is also energy efficient because of the lower use of backlight.

Of course, not having the laptop (perferably a cheap EBay purchase to test on), solar panel, and bench top lab supply in front of me--it would not be possible for me to guarantee that any non-standard DC input configuration for the laptop is safe and reliable. Failing that, then going back to an AC or DC power input brick with a hybrid solution of solar/generator and/or battery is the only off-the-shelf solution I can think of.

-Bill