Alternative energy: Can flashlight batteries run a PC?

greenspun.com : LUSENET : TimeBomb 2000 (Y2000) : One Thread

A generator is out of my budget.

My plans call for moving to a non-electric lifestyle when the power goes out.

I'm planning on buying a solar panel which will recharge nicad flashlight batteries. I'll use the batteries for occasional radio, cassette and compact disk playing.

I learned this week of the Ten-Tec company, which for $300. sells a shortwave radio add-on for your computer. See

Could flashlight batteries provide enough power to operate a small desktop computer like mine?

If so, is there a battery-powered gizmo to plug the computer into?

-- GA Russell (garussell@russellga.com), May 11, 1999

Answers

See http://www.tentec.com

-- GA Russell (garussell@russellga.com), May 11, 1999.

GA;

Might need a few to many flashlight batties for an acceptable system.

you might check out a site like http://alt-energy.com/catalog/sunpwr.html

or many of the other solar sytems sellers out there.

PS. You will probably need 200-300 watts for a typical desktop system with a regular monitor (Not Gas, LED, or Laptop type display systems.)

Good luck

-- helium (heliumavid@yahoo.com), May 11, 1999.


GA,

If you'll shop around, you should be able to find a shortwave radio for less than $300 that'll make those guy's PC card look like a crystal set, and if you look hard enough, that SW radio will run off of flashlight batteries all by itself.

If you need to run your PC for other reasons, a 300 watt inverter (with the financial mess in Asia, they're cheaper than ever--under $100) and as many trolling motor batteries as you can stand will run your computer.

I have done this using an inverter as described (300 watt) and a bank of 10, 12 volt, lead-acid batteries of the type used for deer feeders, home alarm systems, etc. The system consisted only of the PC and a VGA monitor, but it worked quite well. Using trolling motor batteries (about $70 at Sam's), you can extend the "run time" of the system as far as you care to, and you might be able to use your solar panel to recharge with (it will depend on what voltage your solar panel puts out. If it's more than 12 volts, you can make it work.).

Keep in mind however, that Nature never gives you something for nothing. You'll have to trade time for charging capacity because the trolling motor batteries will store a heck of a lot more energy than even a lot of flashlight batteries. You'll almost certainly need a much larger solar panel setup to charge the bigger batteries (unless you're willing to wait for several weeks for the smaller panel to do the job).

Technically, the answer to your question (can I run my PC off of flashlight batteries?) is yes, but you'd need so many of them and connecting them together in the right way would be a real pain and you'd STILL need the inverter. You're better off by far to just get a 12 volt deep-cycle battery. Trolling motor batteries are hybrids (a compromise between the type of battery needed to start an engine, like in your car, and the type of battery used to propel a golf cart) but OK for this.

-- Hardliner (searcher@internet.com), May 11, 1999.


Check into 6 volt deep cycle batteries. I'm going with 4 6 volt, 370 amp hr batteries, converting to a 12 volt system. Batteries run me about $100 each. You need storage. Solar is not good for too many hours in the winter, and on cloudy days, well . . you'll we whistling dixie before listening to the radio. You could probably get by with a pair of 6 volt batteries. Make sure they are deep cycle. Golf cart batteries or equivilent are OK. Then you will be able to run your computer and connect to an internet that will probably be dowwwwwnnnnn. Good luck.

-- Daryl (rushmore@dailypost.com), May 11, 1999.

Hardliner wrote:

>If you'll shop around, you should be able to find a shortwave radio >for less than $300 that'll make those guy's PC card look like a >crystal set, and if you look hard enough, that SW radio will run off >of flashlight batteries all by itself.

Akshully, the Ten-Tec receiver is probably better than most any separate receiver you can buy for $300. You do need a good outside antenna, though, so you won't pick up too many of the PC's radiations.

>If you need to run your PC for other reasons, a 300 watt inverter >(with the financial mess in Asia, they're cheaper >than ever--under $100) and as many trolling motor batteries as you can stand will run your computer.

Yup. 300 W inverters are available for about $65 around here (at an auto parts supply store).

>I have done this using an inverter as described (300 watt) and a bank >of 10, 12 volt, lead-acid batteries of the type used for deer >feeders, home alarm systems, etc.

Much better are 2 golf cart batteries (they're 6 volts each, so you need pairs of them for 12 volts). Sam's has them for about $45 each, and they're designed for up to 50% discharge, unlike auto batteries.

With the battery-inverter setup, you should also get a small "intelligent" battery charger for the times when there is AC power. In addition to that, a smallish solar panel or wind generator (with charge controller) would complete the setup.

-- Dean -- from (almost) Duh Moines (dtmiller@nevia.net), May 11, 1999.



Dean,

Well, I've managed to prove to myself yet again that making assumptions makes other things as well. I hadn't bothered to go to the website GA provided and check out the Ten-Tec receiver before I composed my post to GA. I simply assumed that it was another add-in card for a PC and assumed a lot of fancy graphics would be used to justify the price.

After reading your post, I DID visit the site and found out the FACTS. As I recall, you're a radio amateur and almost certainly have a better handle on what is available than I do, so I'm inclined to agree with your quality comparison. The "specs" for the RX-320 are pretty impressive. Sensitivity, selectivity, TRIPLE conversion--all well into the excellent range. Also, the RX-320 is NOT a PC card. It is a standalone receiver, minus some control and audio circuitry which is provided by the PC over connecting cables. That explains how they can make a BETTER box than a discrete receiver for the money.

In fairness to myself however, the "crystal set" comment was a smart aleck aside (those are always the ones that get you!) while my main point was that a standalone SW receiver could easily be had that would run off of flashlight batteries.

The reason that I described the battery bank that I had used was simply because it was what I had (I have a source for FREE batteries of this type in nearly unlimited quantities so I use them for lots of things) and to demonstrate the viability of the inverter/storage battery setup for powering the PC.

You're right about golf-cart batteries being better (I indicated that trolling motor batteries were a compromise), but the first thing GA said was that he was on a budget. Trolling motor batteries are "good enough" for this application (nothing's going to draw much current here--at least not compared to the final of a ham transmitter!). More to the point, they're cheaper to get a workable rig out of, and they're already 12 volt so there's no need to connect multiple batteries together. If I were building a UPS for my computer systems (and I didn't have all these free batteries) I'd certainly use true deep cycle batteries (like golf cart batteries). If I were building a rig for occasional or emergency use on a budget, I'd go with trolling motor batteries and use the cash savings for other needs. I would NOT use automobile batteries unless I had no other choice.

And finally, let's keep in mind that if we're talking about running a radio off of emergency power because the mains' power is down, we're not likely to be looking to pull a weak, distant station out of a chaotic mix of radio transmissions and electronic noise from all the electrical paraphenalia of our technology crazed society. The more power that is "up" around the world, the more noise and vice versa. The receiver only needs to be good enough for expected conditions.

-- Hardliner (searcher@internet.com), May 12, 1999.


Thanks for your many suggestions!

I'll study what all of you have said before making a final decision.

Truth be told, I may decide that use of the computer isn't worth the expense we are looking at (in a post-electric society). On the other hand, perhaps the ability to live a lifestyle similar to what we now take for granted will be the distinction between rich and poor in the future.

By the way, in regard to radio reception, I recommend that everyone pick up a crystal radio set for $15 or so. Even in a worst case scenario, it couldn't be the biggest prep mistake you make.

Isn't it great to have these discussions on this forum?

While the contributors to this thread may disagree among themselves, we atleast have an intelligent discussion which provides the basis for further consideration in private.

I think it's important to remind ourselves that all of you have contributed something of benefit to me and to the rest of the forum's participants.

Those whom we call pollys do not merely disagree with us about the likelihood of a problem post-January 1. They disrupt our conversations while offering *nothing*. Not one polly has contributed a morsel of benefit to anyone even once.

Best wishes to all who have indeed contributed.

-- GA Russell (garussell@russellga.com), May 12, 1999.


Mr. Russel,

If you want to go the battery/inverter route, and you are determined to use your computer with the setup (you said "small," but didn't say if it needs to plug into the wall, or if it is a laptop type, with its own batteries), then get an inverter with a pure or nearly pure sine wave output. The cheaper inverters only offer a square wave output, which the common PC cannot handle. You might want to consider line conditioners anyway, just in case.

A power company employee recommended both sinewave-output inverter and line conditioners when he was asked how to minimize harmonics in a generator/inverter output that would have supply power for a PC.

Sorry for delay with this offering. I have to work my web time into a very variable schedule.

-- LP (soldog@hotmail.com), May 12, 1999.


Moderation questions? read the FAQ