tom4416

I've done the searches to find out about power inverters but couldn't find out what size can safely be run from the 12V power outlet in the back of an 03 Runner for extended periods of time. It appears that limiting it to 150 or 400 watts is the only way to get the 12V plug on one and that is really all I need (basically to charge/power a laptop) but wanted to make sure that isn't too much of a continuous draw on the wiring for that outlet. I know it comes as a 120V outlet as an option (or standard on the LTD, not sure which) but have no idea what the output is when configured that way (or if the wiring is different). Any help appreciated.

Bob_98SR5

Tom,

there's a similar thread going on about this topic, though it has more to do with installation and the right equipment. You might want to keep an eye out on it too.

I'm sure others will speak up b/c I am definitely not an electrical expert, but I do know what was recommended to me by others and my local electrical/fuse supply shop.

My 12v plug outlet could only support a 400W power inverter. However, certain accessories like laptops could *not* be reliable supported. For example, I'd plug the supplied 12v power inverter plug into my 4runner's accessory plug and sometimes it would just cut out after booting. Not enough juice? That was the simple conclusion. However, a cell phone recharger (110V plug) could easily be supported---two in fact with a power strip.

So I followed what Corey did and did my own: http://www.4runners.org/articles/dist

It takes more work but its definitely worth it. It will handle everything. Even more so since I purchased a gel-cell battery prior to the installation.

Good luck,
Bob

Scottiac

Unless you're planning on dropping some serious change on a pure-sin wave inverter (300+$), you'd be much better off just getting the DC converter for your laptop. Laptops are sensitive little buggers, and don't like the barely modified square wave power produced by most economical inverters.

I ran mine off a cheapo inverter, and the laptop AC power supply got *hot* pretty quickly, followed shortly after by the 12v DC outlet cutting out entirely. There's another thread on that running around here somewhere, but that's my experience with it.

I'm gonna buy the DC adapter for my laptop... much cheaper, and I imagine a hell of a lot more efficient than going from:

alternator AC -> rectifier etc. DC -> Your Inverter AC -> Laptop power supply DC ...

Bob_98SR5

Scottiac,

Yikes, though my AC adapter never did get burning hot, you're freaking me out, bud!

Have you decided which DC adapter you purchased?

Bob

Scottiac

Bob,

Not yet... Probably the john-q-generic recommended-by-dell one that will no doubt be listed on their web site somewhere! :-)

"Hot" in this case meant a fair bit warmer than you'd want to hold on to, not melting-kind of hot. But when running off clean power, it never heats up nearly as much.

The other motivation is that I can't see going through an extra DC -> AC -> DC cycle can be all that efficient.

tom4416

Now I'm confused (well, I was already confused, now more so). My laptop is a Compaq with a Lithium Ion rechargeable battery and the instructions say it is fine to run off AC with the battery installed - basically running through the battery with a continuous charge going to it. In this case, since it's basically running off the battery, wouldn't any fluctuations be absorbed by the charging system, not allowing the computer to cutoff or reboot since it's power supply is constant? I understand that the charger wants a pure sine wave current also but still don't see how an imperfect electrical supply would impact the electronics of the computer itself. In the inverter thread, I noticed them talking about sine wave inverters at Costco and Sam's Club for next to nothing ($40.00?), are these not truly pure power inverters? I've heard horror stories of people installing aftermarket electonics (hardwiring) into the newer cars and totally screwing up the electrical system (alarms come to mind as the most common problem) so I really want to avoid a hardwire installation. Unfortunately, Compaq doesn't show a 12V converter on their website for this laptop so I kind of think that it is out. Unfortunately, I went to the dealer to ask these questions and no one there had a clue other than to say I should have bought the model with the rear 120V outlet (which no one knew the specs of anyway).

jharris2

I bought the Juice by iGo -- AC and DC adapter, works in car, on planes, and around the world. Also has the ability with optional cables to charge cell phones and PDAs. Cost is about $100 for the basic unit but has been well worth it.

Scottiac

Tom,

You are correct in that your laptops AC power supply takes the brunt of the abuse from the square wave power, not the laptop itself.

The battery being in-line or not really doesn't make much difference; by the time it gets through the PS to the laptop, it's DC anyway. If it's really ugly the laptop might heat up because it's not good, constant DC, but that's kind of an extreme case.

I'm just not fond of anything that makes anything (even power supplies) overheat... Means somethings ugly is going on.

If you do a web search on DC laptop power converter, you will find a couple million companies that offer computer specific DC->DC adapters. Dell (my laptop) doesn't offer one directly either.

One such (no recommendation, just first hit) might be:
here

The thing that went zot on me was the 4runners 12vdc outlet, which cut out for a while. The laptop was just warm. (Which, considering it was freezing outside the truck wasn't totally a bad thing! )

Laptop converters (I saw one I liked that had both car and airplane adapters) tend to run around $60 or $70. If you can find a true sin-wave converter for anywhere near that price, GET IT!

Or just let the beastie run warm. I've done it before, and if you're not making a huge habit of it, you'll be fine.

toy283

Most cigarette lighter fuses are 15amp, check to see what the fuse is for your outlet (I have no idea). Watts = volts × amps. For a 15amp circuit, you have 180 watts. No more. The max output of the inverter cannot be any more than the max input (it will actually be less due to various losses), 180 watts. This works out to 1.5 amps @ 120 volts.

Robinhood150

To be more precise the inverter can be as high as you want, but the appliance used should not draw more than 180 watts.

jharris2

Capacity for the front power port is 100 or 120 watts -- it's clearly marked on the cover. If you install the ashtray, the combined capacity of the cigarette lighter and power port is the same.

Since I'm away from the truck, I can't say for certain, but I believe the rear power port has the same capacity as the front.

toy283

True. If you plug in a 400watt inverter, you're still gonna get a max of 180 watts of available energy.

tom4416

Thanks for all the help. I think I'll got the 12VDC converter for the laptop since it's the only thing I would be running off the outlet anyway. Sounds safer and I don't want to destroy a $1500 laptop for the sake of a cheap power inverter.