Making my own portable AC power supply

[Locksmith]

No longer valid

[jimlongley]

EDIT: Here's the cheapest 2000W True Sine Wave inverter I could find:
http://www.invertersrus.com/sk2000-112.html" onclick="window.open(this.href);return false;

The BETTER option is to find a 12VDC Air Conditioner. They exist, mostly in a roof-mount setup, for RV's and such, but I have seen them in standalone. These use a DC motor, and will not require any inversion, and therefore, no efficiency loss!!

If he had been talking about Air Conditioning, I might agree.

I have the sk2000, but have only just turned it up to check it out.

[dicion]

Sorry, yea, I saw "AC Power Supply" and Immediately thought 'oh, he wants a power supply for his AC!' My bad
Probably because it's not ever called an 'AC power supply' when you make AC from a DC source, but rather, an AC Inverter :)
Totally my fault for assuming wrongly haha
Now I feel like an idiot... even though What I said was correct, He wasn't talking about Air Conditioning... Doh!

But yea, for powering things like cell phone chargers, etc. a battery or two, plus a small inverter will be fine

Basically, just add up all the things you'll want to power simultaneously, most of the plug-in transformers have a max wattage or amperage rating on them.

I'm gonna go crawl back into a hole now

A car battery will power consumer electronics devices (Cell phones, laptops, etc) for a VERY long time.

Its even more efficient, however, if you get 'car chargers' which use the DC directly instead of having to use AC though. Making AC from DC, You typically lose 20% or so on the inversion, then you'll lose another 10-20% on each wall-wart/plug in transformer to convert it back to DC. Thats a lot of lost power to convert DC->AC->DC again.

[KD5NRH]

If the main battery gets low or goes completely dead, I can flip a switch on my dash and combine my backup bettery and instantly can crank the engine (no jumper cables needed).

Can you not set that model up to isolate the starter circuit on the Yellow Top, and have it always and only powering the starter? It eliminates the switch, while still guaranteeing you the power to start the engine and charge both.

Considering some of the high drain stuff I use from time to time, I've thought about a manual approach: two batteries with marine quick-disconnects on them. When using the extra stuff without the engine running, I could just take one out of the loop until I'm done.

[ninemm]

Judging by the OP's original attempt, it would probably be best to KISS it.

[Locksmith]

No longer valid

[lrb111]

Ok, you guys are mixing up Air Conditioner and Alternating Current.


I'm talking about my own portable alternating current system. Not air conditioner. I just want to run cell phone chargers, laptops, and a small box fan.

It's not camping if you have an air conditioner in your tent!

I realize you are planning to use the "wall wart" ac chargers for your cell phones and laptops. But it gets way simpler if you buy the DC cig lighter style plug ins for your devices. Then you need no conversion, and subsequent extra loss of storage. A small solar panel can then be your constant charger.
You will just need to figure out what voltage your laptop batteries need.
12 volt fans are at every truck stop in the US.

[stevie_d_64]

As long as we are talking about generator efficiency and other "emergency" electrical power issues...I want to see what the experts recommendations would be for "our" situation...

After Hurricane Ike, we learned a lesson...18 days without power really stinks...So...

My wife and I are not too picky...We cold have toughed it out the entire time, but it was beginning to wear on us after the first week...

We also do not anticipate running a lot of "things" on whatever power supply we finally get...Here's the short list...

2 fans, at night, to keep the air moving in our bedroom...

1 surge protector/power strip to keep our cell phones charged up (overnight)

And on that power strip, I would still like to be able to run the laptop on power and to keep the batteries on this thing peaked...

As far as house appliances, I do not believe we will ever want to run the fridge (because we cook most everything as quickly as possible, and throw the rest away) I know that sounds bad, but it gives us the chance to clear out "stuff"... And we'll wash at a laundrymat...

So considering we do not have a great personal need for a lot of power, any recommendation for something that is big enough to bother with, easy to secure to keep it from walking away, and one that maybe on an occasion power a circular saw and power drill, along with the nightly power needs mentioned above...

We want to get something that is rugged, can be rolled on its own base, be fairly quiet...We'd get it...There are just so many out there I'd probably get something stupid...

When I saw the absolute waste of gas and what the nieghbors spent and powered 24/7/365 during that crisis, I kinda thought it would be smarter to not go that route...

So thats our story, and we're sticking to it...

BTW, the generator a co-worker did let us borrow for the next week and a half was a 2500W output (it had a higher cranking amp output, but I forgot those numbers) 7-8 gallon tank unit...It worked great for being a new unit, and he said we needed it worse than he did...I think that unit was too much, but it seemed to work well for us, and had room to spare for other things...

If there is a high quality unit out ther that meets these requirements in the $400-$600 range...We'll stand by for recommendations...

Much appreciated...

[FlynJay]

Your best bet is going to be to get a second heavy duty deep cycle battery, heavy duty alternator for the truck, and a power switching box that isolates the main engine battery (that way you can start the truck when your accessory battery is drained). If you don't want to go with a heavy duty alternator capable of charging both batteries simo, you can get a power managment system that will charge the lowest battery first and then switch to the other battery once the first is charged (very common for cabin cruizer boats).

I would not power DC devices with their AC-DC plug in converters, there is a large amount of energy loss in the conversion; both from DC to AC in the inverter, and AC to DC in the wall warts.

You can go a step further and get a 12V fan for the tent and try to eliminate the DC to AC inverter all together.

Keep everything DC an your battery will last alot longer.

[dicion]

2 fans, at night, to keep the air moving in our bedroom...

1 surge protector/power strip to keep our cell phones charged up (overnight)

And on that power strip, I would still like to be able to run the laptop on power and to keep the batteries on this thing peaked...

So.. first you'll need to find the wattage requirements of the fans. This is harder than it sounds. Consumer electronics are required to be rated to the MAX amount they will ever pull. Since these fans are AC motors, the rating on them will more then likely be their start-up surge rating, not their running rating. If you have a current clamp to measure how much its using while running, that's the best way, or even plugging it into one of those kill-a-watt things will work too.

My guess is that a standard box fan, on high, would pull maybe 100-150W, once its running. On start-up, however, it could easily hit a few hundred more watts.

Cell phone chargers etc are usually like <50W each.
A typical Laptop charger is ~100 watts.

Generators:
You could probably do fine with a small 750-1000W Generator.

As far as reliable generators, Personally, I've always seen good results with Honda ones.
No-name ones sometimes are name-brand motors, re-branded, but sometimes they are just that, no-name brands.
Briggs and Stratton, I would consider about mid-range for generator usage. I wouldn't consider one for any sort of long-term use though.

Also, Home generators require frequent maintenance. Most people completely skip this fact, and this is why they break down.

Generally, oil changes on generators are required a lot more often they you would think. Most of them recommend an oil change after the first few hours of operation (sometimes ~5-10) , then another one after another, smaller then usual number (~50-100) , and then finally you get to a repeating number, usually a few hundred hours. (~100-400) depending on generator

Another Option would be 100% Solar!:

Buy and store some large multi-hundred watt solar panels. Then, once the storm hits, and you're out of power, mount and use the solar panels to charge a few large 12VDC Deep Cycle Batteries during the day, and use them to run some 12VDC Fans at night.

Required matereals: I'd say 2 or 3 100 Watt Panels, A solar Controller, and some batteries. There are batteries specifically made for Solar Power usage, that are designed to be frequently charged and discharged.
Benefits: It's Completely Silent, requires no fuel, and very little maintenance :)

Ill see about getting some links to local Texas sources of solar solutions.


Personally, I am looking into getting a backup standby generator for my home, that runs on natural gas.
We were out of power for 3 weeks after the Hurricane. I eventually got a nice 3000W Generator, wired it into my electrical panel, and powered most of my house with it (just no AC) but the first 2 weeks definitely was not fun.

[longtooth]

I guess I am too old or just missin something. I thought "camping" was roughin it.
That is the reason we quit.
When I statred needing the fan & ac I also needed the firm matress.

[Drewthetexan]

Hondas run forever. I used to work in a tool rental shop and those things took all sorts of abuse and kept on going.

Generators and load requirements are a really complicated thing, especially when it comes to inductive loads like fans, or circular saws. In reality their power usage can't be measured in pure wattage, but everything is rated that way to keep things simple.

http://www.cumminsonan.com/residential/select/ has basic appliance ratings for determining your power usage needs.