Thanks to all for excellent advice. My tractor batt. is dead, so I'll go charge it with car. One more question... I found 3 marine batteries but they're all dead. How long do I need to charge a marine battery with the car? About 15 minutes?
Will someone please ping the people who answered my invertor question? I would be forever grateful!!
Please send patches!!!
Pretty much depends on the battery capacity (amps x hours) and the alternator capacity (amps). A charged battery has a certain number of electrons it can deliver, and a charger will deliver a certain number of electrons per hour.
Edmunds says that the battery/alternator "ratio" in most cars is such that a half hour of DRIVING (faster engine speed results in more electrons per hour) will charge the car battery. GIven the same alternator, but a battery with twice the capacity, it'd take an hour - but you'd store up twice as many electrons.
If you're out of power long enough, you'll find out that a certrain amount of time in the recharger (hooked up to the car) will give a certain amount of appliance run time - regardless of the battery's capacity, assuming you don't charge the battery until it is "all the way full" of electrons.
An analogy might help too. Think of the battery as a bucket for holding electrons, and the alternator as a source (faucet) for filling the bucket. As long as you don't fill the bucket to the top, any bucket will hold the same amount of water for the faucet being on a certain amount of time. Likewise, any battery will hold a certain amount of "juice" if it is given a certain number of electrons, assuming it is't filled to overflowing.
"Amps" describes how fast the water flows into (and out of) the bucket. Amps times hours is the total amount of available water (electron) flow. And a useless electrical tidbit, 1 amp is 1 coulomb (6.25 * 1018) of electrons per second.
Nita- excuse my butting in, I'm an old mechanic, so I'll try to help... it may get technical, feel free to ask questions.
It will take longer than 15 minutes with a car's charging system- how long depends on how big the battery is, and how much current ( Amperes ) the charging system puts into it.
However, about 15 minutes at fast idle should tell you if the battery will take a charge, and give you some idea of whether to keep charging it or try the next one.
A battery is like a bucket of water- you can't take out more than you put in, and it takes some time to do that with a car.
If you have any choice in vehicles to use, pick the one with the heaviest-duty electrical system, like a truck. It will charge faster.
How old are those marine batteries? Three to five years is about the extent of any storage battery's life- they should have a date tag with dates punched. In any event, pick the newest one.
Check the electrolyte level-- there should be two rectangular blocks atop the battery ( if there aren't you have a "sealed" battery and can't check the levels in it )-- wipe around them with a cloth you don't mind losing ( acid will eat it ) and using a flat screwdriver, pry under the edges, working around the edge, until it comes off.
There will be holes about an inch in diameter- those are the cell tops where you check & top up electrolyte levels.
Remember, this stuff is sulphuric acid, so be careful-- if you get any on skin ( can't mistake it, it is oily and will start burning & itching ) rinse with water, a bad case, neutralize with baking soda ( Arm & Hammer, not Calumet ).
Using a flashlite ( no flames! hydrogen gas is present ) sight straight down-- you should see fluid. In fact there is a little split ring in the hole to indicate proper levels in each cell, and ideally, the fluid level will be up to it. If it is below that, or you see the plate tops ( grey metal lines ) you must add distilled water until the plate tops are covered and the split ring reached. One source of distilled water is the runoff from an air conditioner, but it may need to be passed thru a coffee filter to get junk out of it. In an emergency, you can use tap water, but it will eventually kill the battery. However, it is vital the plate tops be covered- if not done, the battery will not hold a charge, even if it normally can.
Optional- proceed with caution, this does not always work-- an old mechanic's trick to revive an old dead battery is to mix a few tablespoons of Epsom Salts with the distilled water, and top up all cells with that. Let it sit a while, and it may reduce sufation enough to revive the battery. If your batteries are over three years old, I would recommend tyring this first. If they are newer, just try topping up the cells with distilled water and a test charge.
To summarize:
Pick newest battery
Clean top, pry off cell covers, and cover the plate tops with distilled water or a mix of that & Epsom Salts
Charge for 15 minutes and try it. If it runs your gear a while, try charging longer. If not, repeat with next battery.
Best of luck- I wish I could be there, it's easy to do, but not easy to describe.
There is a way to blow the sulfate off the cells and make them work again but I'm not going to tell you how to do it. If not done right, the battery will explode. That's the last thing you need right now.
My opinion,
If your battery is that dead then you don't want to wait as long as it would take for car to charge it. And a dead marine batter would take a couple of hours to really charge. The best you do in a short time is to very partialy charge it.
Your best bet at this point is to park the car close to a door or window and hook the inverter right to the car battery in your car. You do not need to unhook it from the car. Then just run an AC extension cord from the inverter into the house and plug your computer into it. Just don't run the inverter for more than an hour or two at a time without running your car for a while or else your battery will go dead and you won't be able to start your car without getting jumped. But I am sure you could run your lap top for an hour or two on your car battery and still have your car start unless your car battery is almost junk. At this point it makes no sense to charge another battery from your car as that will just waist valuable Gas and is not as efficient as just using the battery in your car.
Hope that helps.