Typical charging rate of a car battery (from alternator)



Until it catches fire and burns your house down. Every harbor freight tool I have ever seen has wound up failing in some way that got people injured, from the anvil that split apart leaving half of it to fall on my foot, to the spot welder that ignited in my friend's hands. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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On 11/1/2012 11:34 AM, Scott Dorsey wrote:

OK, so spend more money and get something better. Your choice. HF seems to be a good source for stuff you'll use rarely or never. Treat it like the cheap crap that it is and it will last longer... emphasis on the cheap.
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I've had a few HF tools which did good. But, not very many.
Christopher A. Young Learn more about Jesus www.lds.org .
wrote in message
Until it catches fire and burns your house down. Every harbor freight tool I have ever seen has wound up failing in some way that got people injured, from the anvil that split apart leaving half of it to fall on my foot, to the spot welder that ignited in my friend's hands. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."



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On Thu, 1 Nov 2012 09:08:47 -0400, "Existential Angst"

It's "sorta" right. The current is limitted. But you CAN still short one out, and overcurrent CAN damage them. A shorted battery can kill an alternator pretty quick
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On Thu, 1 Nov 2012 09:08:47 -0400, "Existential Angst"

Well, you can't "short it out" if it is connected to a battery. You could short it out if you connect the BAT. terminal to ground :-)
However... as I said, you need to worry about the temperature of the alternator. There are temperature limits. see http://www.newindo.com/delcoremy/20si-21si-26si-delcoremy-generators.htm for examples of alternator specifications.
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John B.
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On Wed, 31 Oct 2012 23:39:12 -0400, "Existential Angst"

AFAIK the alt regulator does that just fine by design, so just stay within what it was designed for, Find the particular alt specs. If you're still thinking about using the car and an inverter for home power during outages, think small watts, or get a generator. Cars alts aren't meant for continuous high watts at 120v. But 500-600 continuous 120v watts from an inverter is easy for a typical car alt, and so is a peak 1200w for starting a fridge. You won't hurt your alt or battery. So figure out what you want to power during an outage. I'd say if you want more than 600w continuous, get a generator. The multiple battery issue isn't normally applied to cars. Check out boat and solar power forums. I know they use isolator switches to handle loads, but that's just from reading. I don't even think about adding batteries to a car. Maybe if I had a truck... Back to 120v inverters running from a car, the main issue is the cables. You need something like what's found here. http://www.donrowe.com/cables/cables.html Look at the #1/0 AWG CABLES. That site has a lot of info about inverters. The cabling is what stopped me. Just didn't want to deal with the connection issue. Have to remove an engine brace to get at the battery. There's an easily accessed covered lug for the +, but I'd have remove the brace to get at the -, or set up a stud to ground on the engine. Too lazy to do that for something I might never need. If I ever decide to spend the 4 bills or so for a good set-up I'd do it. You also need to fuse the cable. Another thing is cable length. You really need to shelter the inverter from rain/snow. I figured 6' cables would get under the garage door to the inverter. Could run the car in the garage with doors open, but I don't like that. So inverter location has to be considered. Anyway. that's about where I stopped thinking about setting up an inverter. Not many power outages here. I do like the idea for emergency use.
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wrote:

Along the lines of isolator switches below, and "sparing" the alternator, I was thinking of having two banks of batts, one powering the house, and one being charged by the car alt, and switching off as nec. Is johnB correct, that the alternator limits itself to its max safe output?? Still, wearing out an alternator prematurely is no picnic either.
At any rate, it seems like an alternator for big backup power will be stressed, either by too many charging batts or too much house load. Unless I could finagle some kind of current limiter on the alt, so that the size of a battery bank wouldn't really matter.

Yup, that's how I started this, until it grew feet. Sam's Club BlackMax 8750 W (7500 continuous) tested out really well. Noisy, but you could load the shit out of it, and still have PC-stable power. I was going to do the tri-fuel conversion.

I found that site. He's serious about inverters!!

I would use a side/screw terminal batt, and mount the inverter directly to one battery, via bus-type bars, which you can make out of 1/2" copper tubing, crushing it flat. Wire gauge is now moot. If I used a second battery, I'd proly bus-bar that as well, mebbe use the main section of the copper tube un-flattened, for structural positioning of the batts in the truck bed.
Have to remove an engine brace to get at the

Well, I wouldn't really deal with the hood battery. I'd use that batt only in conjunction with the alternator, when charging the inverter batts. So cabling between the alt/car battery to the inverter batts could be much thinner, on the order of #12 housewire -- which is actually good for up to 50 amps (not code-wise, of course).
And this strat holds whether your batt/inverter is on the vehicle, or off the vehicle, as long as the inverter itself is "bussed" to whatever batt bank you are using.

As per the above, you can just leave the car outside, as the only cable(s) you now have to worry about are 1. the charging cable from the car alt/batt to the inverter setup, and 2. the AC wire from the inverter output to the house. Both are now pretty thin-ish.

I'm forced to do a lot of hanging out in my car/truck, in the cold no less, so there are many advantages to this system, many applications. Just one of them being, you'll never need a jump with extra batts!
Proly the *least* practical to all this is the power outage scenario (as I am realizing), but a cupla cars providing 600 W or so each is a whole lot better than nothing. Not many people appreciate the whole risk/reward, cost/benefit of this, re the probabilities.
But holy shit, people are going to be without power around here for weeks, and this is the THIRD time in just a cupla years. Funny, prior to all this, my power was truly erratic, but I lucked out during Irene, the Halloween snowstorm, and Sandy. But my luck can't hold out forever. But the probabilities are why I hesitate to go the whole generator route (again), bec that's no picnic either. But once it actually is set up, it's pretty seamless. Lotta work, tho.
Most of my neighborhood is without power. I'll see how long it takes them to get back up, and that will affect my prioritization for another genset. If it's more than a week, I'll be getting another genset by next summer, screw the probabilities.... :)
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On Thu, 1 Nov 2012 10:28:23 -0400, "Existential Angst"

Yeah, I haven't gone through that, just imagined it. My favorite idea is to get out of town for the duration, but that's not practical for many people. Only conclusion I've come to is if I bought a generator it would run off natural gas, and if I somehow ended up with a gasoline generator I'd work out a siphon system from my car gas tank. Most I went without power was 3 days. What did I miss most? TV and PC. A battery radio filled in, but I wished I had a TV and my PC. Damn, it was boring, waiting for the power to come back. A real good time for a fishing trip.
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During a power outage I want TV and especially Internet weather radar for the current weather forecast, to know whether to open up and repair or temporarily cover damage.
Recently I bought about the oldest widescreen dual-core laptop that can run Windows 7 + Media Center and added a USB TV tuner so it gives me both HDTV from an antenna and Internet from a cell phone modem, or the landline if it's still up. It consumes 30 - 40W which a truck battery and inverter will provide for a long time.
Of course, since I was prepared, Sandy didn't knock out power on this street. Usually here an ice storm means a week's outage.
jsw
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On Thu, 1 Nov 2012 14:17:09 -0400, "Jim Wilkins"

That's a good idea, a laptop that pulls in TV. I've resisted laptops, but you might have changed my mind. It could pull some double-duty for vacations too.

That's always the big question. Do I really need it?
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Chance favors the prepared. God does, too. I charged all my batteries, gassed up the generator. Got the generator to run (not easy). And no power out. I like it, that way.
Christopher A. Young Learn more about Jesus www.lds.org .
During a power outage I want TV and especially Internet weather radar for the current weather forecast, to know whether to open up and repair or temporarily cover damage.
Recently I bought about the oldest widescreen dual-core laptop that can run Windows 7 + Media Center and added a USB TV tuner so it gives me both HDTV from an antenna and Internet from a cell phone modem, or the landline if it's still up. It consumes 30 - 40W which a truck battery and inverter will provide for a long time.
Of course, since I was prepared, Sandy didn't knock out power on this street. Usually here an ice storm means a week's outage.
jsw
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On Thu, 1 Nov 2012 10:28:23 -0400, "Existential Angst"

And you would tear the batteries apart driving across town. You MUST have flexible connectors - for vibration as well as heat/cool expansion changes.

#14 house wire will NOT work to charge your batteries - and only a fool would use it in an automotive application due to vibration and work hardening, You NEED flexible cable - and the heavier the better. NOTHING less than a #8 - preferably a #6 - bigger if the cable is over 6 feet long.

The "sensible" way is the inverter in the car with heavy current cables as short as possible. Run extention cables out to the car for the high voltage low current.

You are going at it all backwards.

Idling the car with NO load burns as much gas as a good small generator set. Efficiency is pitiful

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On Thu, 01 Nov 2012 18:04:46 -0400, snipped-for-privacy@snyder.on.ca wrote:

I don't see it that way. My battery is near the grill. I don't want to hole my firewall for heavy cables and deal with having them in my car interior when I may never even need the inverter. Even if I was using the inverter with this car on job sites to power tools, I'd still have the cables under the hood, and rig a shelter for the inverter when needed. Lots of ways to do it, depending on needs and vehicle.
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On Thu, 01 Nov 2012 17:39:41 -0500, Vic Smith

You do not understand. The low voltage cables are heavy. The 115 volt cables are NOT heavy.
Do it your way - but there is a right and a wrong way - yours is NOT the right way.
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On Thu, 01 Nov 2012 20:40:07 -0400, snipped-for-privacy@snyder.on.ca wrote:

Right. I don't understand you want me unnecessarily punch holes in my firewall for the heavy low voltage cables. For an inverter setup that will be tested once, then rarely - if ever - used again. Think again.

Find a sap who will listen to bullshit. Wrong place here.
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On Thu, 01 Nov 2012 20:40:49 -0500, Vic Smith

I don't punch holes in firewalls to run heavy cables. If they are heavy like battery cables they go under the car and come up through the back using grommets - often through existing holes in the body that have factory installed covers. If it is a simple accessory battery charging wire (not using the SLA battery to power the inverter) - #6AWG stranded is 1/4" in diameter, sometimes it can be routed back through existing firewall grommets, and follow the chassis harness back along the rocker panel area to the back of the car.Then the inverter gets connected to the batteries with the shortest possible cables.
I've been doing this kind of installation since the late sixties - when an "inverter" was a motor generator unit. (Rotary Inverter). Google it. Coach batteries in motor homes and travel trailers use the same wiring techniques, but back then ran everything on 12 volts DC.
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snipped-for-privacy@snyder.on.ca wrote:

Sounds very familiar... Oh yeah that's basically how the rear battery in my vehicle is set up. Except I'm running #4 because I had it in stock. I run a modified isolator with remote sensing so the "house" battery gets a full charge. That batt. powers the extra lights and an inverter. Now that LED are finally throwing some light so they can be used as scene lights the current use is WAY down over the old 30W and 50W halogens. Wish I could find good 90 degree replacement LEDs for my mini bar though.
--
Steve W.

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On Thu, 01 Nov 2012 20:40:49 -0500, Vic Smith

However you do need to take the resistance of the wires into consideration.
#4 copper cable, for example, has a resistance of 0.253 per 1,000 ft at 68 degrees F. .308 at 167 F. 1 amp current through this "resister" results in a voltage drop of almost 1/4 volt. 10 amps results in a drop of 2.5 volts. or about 20% losses. Your 12 volt circuit suddenly becomes a 9 volt circuit. So at low voltage you require large, expensive, wires to avoid significant voltage losses.
A 120 VAC circuit using 1,000 ft. of #4 wire with 10 amps flowing through it would have a voltage loss of about 3 volts, or about 2.5% so with conventional AC circuits you can use smaller, cheaper, wires.
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wrote:

All good to know. And I always note wire sizes in inverter specs. Always considered wire costs to be significant to reduce losses going to the inverter. But I've booster cable jumped a lot of cars, and just naturally know that cheaping out on cables is a bad move. I was looking at cables in the 1/0 - 4/0 range and it looked to me that jumping a step in cable diameter would easily compensate for the resistance increase jump from 3 to 6 feet, and still meet a particular inverter's cable specs. I just disagreed about routing heavy cables to my car interior for an non-permanent, "as-needed" inverter setup.
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On Thu, 01 Nov 2012 06:39:12 -0500, Vic Smith

A GENERATOR regulator regulated both voltage and current. An alternator regulator controls only voltage. The current is limitted by the power ouput of the alternator and the internal resistance.

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