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Forum: Using a Big Ol Battery

03 August 2006

Northstar – at 18:57

I am so sorry if this is a really dumb question but I just don’t know. And I’ve tried to read some of the alternate energy threads, I really have, but before too long my eyes glaze over and I eventually wake up with drool coming out the corner of my mouth. So, can any of you geniuses here tell me:

Can I somehow use a big ol battery like a car battery to recharge little ones, or to power a small device, or something like that? If so, how?

Eccles – at 19:19

Northstar -

I would prefer to do this in the Alternative power thread, but here is the short answer (can Eccles ever say anthing short-form?)

Yes, you can use a Big Ol’ Battery both to recharge smaller batteries or to power small devices.

A car battery is not your best choice as discharging it too heavily will damage it and it will no longer hold a charge.

You can run DC devices directly, or you can use AC devices by using a device called an inverter, which manufactures AC 120V from the 12V DC power of the battery.

Your problem is still where the power to refill the Big Ol’ Battery is going to come from.

So, a Big Ol’ Battery can help get you through a single night. To get any further, you should come on over to the alternative power thread where we can provide full support for you without tying up too many threads in the forum.

Melanie – at 19:23

I knew this was an Eccles question. Northstar, follow him over to that thread and learn more than you ever wanted to know.;-)

04 August 2006

pfwag – at 02:04

Buy a battery charger that plugs into the cigarette lighter of a car. It is being powered off the 12VDC “big battery.” That is more efficient than using an inverter to convert the 12VDC from the battery to 115VAC then operating an AC input battery charger off the AC. Some 12VDC input NiMh chargers come with an adaptor for using AC - it is nothing more than an AC to 12VDC power supply to act as a substitute for the 12VDC being provided by the cigarette lighter.

Eccles – at 06:24

Pfwag- That is only a partial solution. Where does his car get the fuel to keep charging the battery he is hooked to through the cigarette lighter for long-term operation?

Better he should come over to the Alternative Power thread and discuss the entire problem.

Hillbilly Bill – at 08:31

And while we are at it, the solar panels Eccles discusses in the Alternate Power thread would work well for someone that is looking to keep a laptop charged up and to also recharge some NiMh batteries. They are small, easy to move around, and would work well on a balcony or patio or even inside a sunny window.

What’s your plans to stay connected Melanie?

Northstar – at 08:48

Thanks Eccles, pfwag, Hillbilly Bill — I don’t know if I should be happy that the short answer is “yes” or depressed that I need to trudge over, head hanging, to those alternative energy threads and do my best at grasping the information therein.

I figured if TSHTF, I am just going to let go of most modern conveniences — refridgeration, computers, TV and so on. Ideally, though, I’d like to be come up with a small Rube Goldberg apparatus like: a small windmill or something to charge a big battery, to charge little batteries, to run a battery sewing machine. (If we are on a restricted diet, we’ll all lose weight and our clothes will need to be taken in or it will fall off, especially hubby’s. And the kids are growing and will need more clothes.)

This all springs from an article I read recently about how, in impoverished areas of Africa, people will carry around a car battery for days looking for a source of electricty to charge it. The answer was: providing low cost foot pumps to charge it with. (These are apparently available here for about $250.) It made me wonder: what are they running with the car batteries? And how?

Hillbilly Bill – at 09:16

Northstar – at 08:48

Honest, it’s not that complicated. Once you understand the definition of some of the terms used, the concepts will be clear.

For $250 you could have enough power to sew all you want and listen to the radio while you baste and hem. You won’t even be pumping anything with your foot. Step into Professor Eccles classroom, it did wonders for me.

pfwag – at 10:29

Eccles - I acknowledge your point but I was just answering the question. Most people are unaware that 12VDC input battery chargers for small cells even exist.

While there are other ways to keep a 12V battery charged, a full tank of gas in the car will provide enough energy to keep one or more batteries charged for a considerable length of time. (I haven’t done the math.)

If you even need to be charging a 12V battery by alternative methods that presuposses you have no electricity and haven’t had some for a good while. In that case, where are you going to be going in you car except to get the h*** out of Dodge? (And by then it is probably too late.) That leaves using the car as a battery charger.

IMNSHO, one of the biggest errors in the logic of most preppers is extending preps out too long as if things will remain fairly “normal” in a PBF scenario when society doesn’t have water, electricity or food for 1–3 months. WTSHTF the did-nots become have-nots, the GOVT can’t do much about it, all hell will break loose and the Govt will be able to do even less about that. Assuming ANY probability of that scenario playing out, it should have a profound impact on your preps making charging a 12V battery one of your smaller, but still significant for other reasons, problems.

Hillbilly Bill – at 10:36

pfwag – at 10:29

Your last paragraph makes a very valid point. I have tried to structure my preparations accordingly. If the water, power, gas, etc. are non-functioning for more than 3 months, I’m going to have lots more pressing problems than keeping my mayonaise cool.

Northstar – at 10:49

pfwag, I agree completely with what you’ve said. One of my problems with installing some kind of clever solar array or something is that it simply isn’t portable, not to mention, it would attract unwanted attention. I’m thinking that anything we could consider taking camping is probably best for us… for example, one use for small batteries addressing a large problem is communications. Walkie-talkies can keep our family in communication over short distances and are independent of any “service”. And I figured, as you did, that our cars wouldn’t be going anywhere if gas supplies were disrupted, leaving the batteries for small-power.

pfwag – at 10:58

HB - given the amount of food in the pipeline and the fact that PBF will sweep across the US in a matter of weeks, there will, in affect, be numerous New Orleans situations going on simultaneously that will far exceed the ability of Federal, State, and humanitarian agencies to cope. If power and water are out for more than a week over large areas simultaneously TSWHTF.

The best scenario we can hope for (besides BF never going person-person contagious, a miracle vaccine, or a miracle cure) is sporadic outages and shortages over the course of a year or so while PBF burns out. Being without double layer Charmin for a year is one thing. Being without food, water or electricity for more than a week is a whole new ballgame.

moeb – at 11:01

smiles… you really can’t count on the car to charge your battery. it’s simply not practical after what a week at best? besides if you did manage to keep gas in the vehicle it might be more important for some other cause. if you wish to go the route you say, perhaps a small generator would be useful for you. I don’t know, gas will eventually become scarce and thieves will be using ice picks on gas tanks to attain it. a solar panel is probably your best solution.

perhaps eccles would post the basic outlines of the $250 system BB speaks of and you can look it over here?

Hillbilly Bill – at 11:31

Northstar – at 10:49

A small solar panel(s) is/are portable and wouldn’t attract unnecessary attention.

MAV in Colorado – at 12:05

The system I put together IS very portable, the panels were offered in camoflage patterns. 125 watt, 116 ah =120lbs, installed in a wheeled toolbox.

http://tinyurl.com/j83p6

planning for the worst here

moeb – at 12:17

MAV that sure looks a lot like 18 volkswagon 3V solar panels linked together?

LEG – at 12:21

I;m not really thinking you got by with $250 on that setup…

MAV in Colorado – at 12:30

moeb, I don’t remember seeing a “per panel” wattage number. They are flexible, waterproof and per manufacurer, work if some cells take damage. I found them on a military communications page and worked backward to find them. Definetely not the cheapest watt/dollar, but I wanted durable, low profile and portable. Uni-solar and Global Solar apparently both have government military contracts for these. I went with the GS, slightly cheaper.

moeb – at 12:34

very interesting but I gather the solar wiz guys might recommend something else (looks over my shoulder) in fact I suppose I shouldn’t proceed. (does anyway) I find these solar panels on ebay for about ten bucks each. and while I link those I have together I don’t have 18.

my curiosity is that I like them and if they work for you then they might work for me :-) did you go with golf cart 6V batteries?

pfwag – at 12:39

moeb: thieves are using ice picks now to steal gas

Here is the deal on using a car battery:

While car batteries are actually rated for cranking and reserve power for automotive applications, a typical car battery can provide about 1200 watt hours of power. http://tinyurl.com/hxyte

If you aren’t planning on starting the car and/or don’t mind destroying the battery all that power is available. That means if you have a few 12VDC flourescent lights pulling a total of 120W they will operate for a little less than 10 hours (watts X hours). Battery capacity is usually rated at a 20 hour operating load. For loads that are larger the battery will provide less watt hours and vice versa for smaller loads.

However, the car battery needs enough energy to start the car. That means you can not discharge it more than about half way (less if it is really cold outside)if your battery is fairly new and if you want to be able to start the car. If the battery is old you can only go 1/4 - 1/3 down before the battery will no longer start the car. If you discharge the battery used to start your car too much and have no other means to recharge the battery you now will not be able to start the car. This is the biggest downside and risk from using this method. Also, it is worth mentioning that a lead acid battery’s capacity declines notably with temperature. This half the reason why it is harrder to start your car when it gets cold.

In any case, if you plan on using a car battery routinely for powering things outside the car, you need to know that car batteries are not designed for deep discharging which means you probably shouldn’t be discharging it more than 1/4 the way. Routinely deep discharging a car battery will reduce the amount of power it can provide every time you do it, greatly shortening the life (capacity) of the battery. This symptom will first manifest itself in the battery no longer being able to start the car (where a few hundred amps are required) when it used to even though the battery still has a lot of power to operate other 12VDC things.

This deteriorating situation can catch you unaware and you will then be in the situation of having a dead battery with no way to start the car. In this situation Murphy’s Law says that the only other car within a hundered miles will have the new style of battery with side terminals leaving you with nothing to hook your jumper cables to. I speak from personal experience - fortunately my cousin had a nifty little Honda generator, kind of like this http://tinyurl.com/3wqo3 that had a 12VDC output that plugged into the cigarette lighter.

Having learned that lesson the hard way in my youth, now when I go camping I use an old car battery for powering a few 12VDC flourescent lights for a few hours a night for a few days instead of the car’s battery. I bring the old battery back and recharge it leaving it sit until next time, where it is topped off the day before we go again. My current used battery is 3 years out of the car. When I replace my car battery it gets recyled to become the new camping battery. It did run out of power on a recent 6 day camping trip however. It is all a matter of watts being consumed versus remaining battery capacity.

To recharge the battery you have to put the watts removed back into the battery. An external lead acid battery charger or your car will do that. How fast that happens depends on the size of the charger, the size of your car’s alternator and other limiting factors. Keeping the conversation to using a car, if you assume your car is puting an average of 25A back into the battery that means it is putting about 300 watts into the battery. Thus it will take about 1 hour of running your car to replace about 1/4 of the power in a battery. A bit longer if you are booster charging the old battery. (CAUTION: there are right ways and wrong ways to do that.)

Naturally it is way more complicated than this but that is a good starting place. From actual experience it is about right.

The last remaining variable is how long will your car idle on a tank of gas? That mostly depends on the size of your engine. Also, be aware that some cars, especially older ones, won’t charge the battery anywhere near as fast when they are idling versus zipping down the freeway.

Of course, using a tank of gas to recharge a battery a number of times is a very poor use of energy. If you were planning on doing this more than about 8 time, given the price of gas you could buy a small generator (but not the Honda) for the price of the gas and do it much more efficiently. Or a small solar panel. However, even with the self imposed limitation of only taking the battery down half way, that is still 600Whr to be replaced. To replace that much power in a day with solar energy would require something on the range of a 75–100W solar panel which will be in the $300–400 range.

Finally, regardless of the source of recharging, unless you are using an old car battery that you just happen to have, buy a deep cycle battery for the application. A marine battery is a deep cycle battery. You’ll note that they cost about 50% more.

Here is a good link for more info on car batteries http://tinyurl.com/z5mvh

I trust this helps. All this and more will be in my comprehensive emergency/alternate energy report which I will do after I finish my comprehensive water report (currently 55 pages. Send me an e-mail if you want a copy pfwag@lycos.com of either. Free and I’m not selling anything.)

moeb – at 12:45

BRAVO! pfwag, nicely written

Hillbilly Bill – at 13:00

Concerning a system for under $250, this is what I was thinking.

Inverter

Solar Panel

As for the battery, you are on your own. I got a 115Ah deep-cycle marine battery at Wally World for under $70.

LEG – at 13:03

Thank you so very much pfwag for the clear comments ref using a car battery. Looking forward to your further thoughts in the alternate energy report.

pfwag – at 20:38

HB - the on-sale price is a very good $/W, especially for such a low wattage panel.

However, 15W isn’t able to do much more than to charge some smaller NiMh batteries or keep a bigger wattage charged to run maybe 2 DC input flourescent lights for an hour a day.

For anybody considering solar:

http://www.ecobusinesslinks.com/solar_panels.htm

http://www.beyondoilsolar.com/solarpanels.htm

And if the panels don’t have a 25 year warranty they are probably coming from China.

Also the FEDS, many states and many utility companies are currently offering credits & rebates on Solar Systems (and other energy saving things) but make sure you read all the fine print. There are some hoops to jump through. If you do you could get 50% (or more) of the system paid for. In Colorado, I believe it has to be a minimum of 1KW and grid connected.

HillBilly Bill – at 21:22

pfwag – at 20:38

I understand the limitations of the items I presented. I was following my comment that this would be workable for someone in an apartment who just wanted to charge up some batteries or a laptop.

05 August 2006

Eccles – at 01:57

pfwag- An excellent summary. There is one aditional warning to those who plan to use their car battery as a power source. The modern car contains numerous electronic devices and computers which remain up and running even when the vehicle is parked. These apply a constant small drain to the battery. Depending on the model, modern cars can drain the battery to the point where it will no longer start the vehicle in a few weeks or at most a couple of months.

To help insure this doesn’t happen, you should have a small solar charger that is designed to plug into the cigarette lighter to help recover the power lost by this constant discharge.

Even if you don’t plan to pull any power from your car, you will either need to plug it into a charger periodically dusing a SIP, or else discover some months later that you are stranded. Perhaps at a moment when you really need to move out NOW.

pfwag – at 03:04

Eccles - great point. I knew there was a reason to keep by 85 Camry around.

A lead acid battery has a fairly significant self discharge rate. Add the other you brought up it will go dead even faster.

Maybe the small panel HB brought up has a primary use after all.

The Captain – at 10:26

I have had great experience over the past 5 years or so with what is called a “solar trickle charger”. Do a Google search and you will find many starting at about $35. I have ATV’s, tractors, autos, etc that sit for extended periods of time and the batteries are always fully charged winter (down to 0 degrees) and summer. I leave them connected anytime they are idle and they have circuitry built-in so they don’t overcharge. It is great piece-of-mind to know your batteries are charged (as long as the batteries themselves are good). Happy motoring…

Eccles – at 10:40

The Captain- And, as it turns out, by keeping them fully charged in this manner, you actually extend the life of the battery by preventing an internal degradation process known as Sulfation.

Except for the initial cash outlay, I can’t thnk of any reason not to own/use such a charger.

Mari – at 10:53

I did a search on my state + solar + tax, and found out that as of last March my state DOES have a solar tax credit. Somehow I missed that important piece of news!

AVanartsat 11:02

Another tip given to me by an old auto mechanic is to make sure the top of your car battery is clean. It’s amazing how much current can “leak” from the positive electrode to the negative through the dirt that builds up on top of your car battery.

My mechanic friend suggested that every time you wash your car, make sure to clean the top of the battery also. Of course that doesn’t do much for those of us who never wash our cars. :)

pfwag – at 12:22

AVanarts - I’m with you. I have NEVER washed my 85 Camry but I do keep the battery clean and the oil changed. I also don’t lock the doors. If somebody wants to steal the barely working radio out of my unwashed car I’d rather they do it without breaking the window.

If you have top battery terminals, you also want to have those little red/green corrosion preventative discs around the terminals.

Mari - check with your utility company too. Some are providing rebates. And read all the fine print.

Mari – at 12:42

pfwag – at 12:22 - Yes, my utility company will rebate part of the electric bill under some circumstances.

pfwag – at 13:32

Mari - some utilities will pay you for putting power into the grid (reverse metering). Some also provide rebates for buying solar and energy saving products. In Colorado between the FED, State, and Excel they will cover about 1/2 the cost of a contractor installed solar electric system. I’m checking whether one could do all the work and save even more. However, I believe without grid connection some of the credits/rebates won’t apply. The Feds also are giving tax credits for other energy saving devices, including doors.

IDEALLY, as part of one’s emergency preparedness, one would engineer the smallest system that qualifies and install it yourself with the credits/rebates paying 75% of it. I still have to check my files and links, but in Coloraso I believe you have to have a minimum of 1KW and it must be grid connected.

08 October 2006

Closed - Bronco Bill – at 22:09

Closed to maintain Forum speed.

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