115 V car outlets

Most likely it is tripping out when trying to charge the bulk capacitor in the laptop power supply. These built in 115 VAC convenience outlets are only good for 120 to 150 watts. They will trip out very quickly when overloaded. You might try unpluging the supply from the laptop and then try to start it up. Once running, then plug it into the laptop.

Most of those are pretty wimpy. E.g., the AC/DC power supply for my HP laptop has a button that allows it to draw more power to charge the laptop's battery (instead of just *powering* the laptop). There is a warning printed on it NOT to place it in charge mode when on an aircraft, etc.

As a simple test, perhaps try removing the battery so the charger can't draw any power for that "load".

Jeeps are pretty much crap these days.

I tried that, the power supply seemed to hold up until I connected the computer again.

But, thanks for the thought.

Jon

An interesting idea! I will try that.

(Also, it seems there is a hidden 12 V outlet in the back of the car, so i can use my 12 V supply if the AC one doesn't work.)

Jon

Um, yeah, Chrysler products. Don't ask about the 15 passenger van we used to have. it cost Chrysler about as much as we paid for it in warranty work, then cost us a bundle to keep it running after that.

Jon

Both my car (Infiniti Q45) and pick-em-up truck (Frontier) have spare "cigar" outlets marked "12V Power". ...Jim Thompson

If "the computer battery was being used, at least partly" is actually the case -- and not a consequence of the outlet shutting down, momentarily, so that power was being delivered *solely* by the battery -- then you won't be able to power up the laptop; the power supply/outlet won't meet its basic needs.

Even there, you have to watch that you don't exceed the rating for that outlet. I think you can probably expect a dedicated 10A circuit (~120W) but not sure how much beyond that.

Keep in mind that many of these "inverters" are crappy and don't like driving SMPS loads. Plus, efficiency losses, wire losses, low battery, etc.

Wonder if you can still get the old way... a small DC-motor-AC-generator set? ...Jim Thompson

I think what would classify as a Rube Goldberg machine

There are tons of cheap DC-DC converters meant for powering a laptop in a car

-Lasse

I meant for some appliance requiring 120VAC _sine_.

My vehicles have multiple USB power ports + 12V for charging modules. ...Jim Thompson

Den mandag den 25. maj 2015 kl. 01.43.34 UTC+2 skrev Jim Thompson:

still, the connector is rated for at most a few hundred watt not doing that solid state would be crazy

I think most laptops take ~19V

-Lasse

ARRGhhh! A motor-generator? It sure would work, they used dynamotors to run the plate supply of WW-II radio sets. But, definitely OLD-SCHOOL! I found you could run Dell laptops directly off the 12 V power, as the internal battery was 11.4 V. It would not charge, but would run the laptop just fine, although it drove the on-board battery management a bit crazy, as the battery seemed to last forever.

At least this series of Dell laptops requires 19 V to charge the battery. I got a $4 car adaptor that has a boost regulator to provide the 19 V. But, it has a relatively short cable, so won't run a laptop in the back seat from the front outlet.

Jon

Poor efficiency, noise, vibration, no regulation, but it works.

NT

I think that's exactly gotta be the problem, it's not credible that the Jeep's design called for a completely-wimpy inverter, when a more powerful one is so cheap to make.

In particular, so-called modified-sine inverters are simple. Make a floating 170Vdc, and connect the AC output receptacle alternately one way or the other, using four 50-cent MOSFETs in an H-bridge, see waveforms and math in AoE-III, page 673. Here's my simplified schematic for a commercial unit, on sale for $19,

So I think it's likely the supplier failed to provide what was originally spec'd and they let it slide by.

Also the rotor inertia can help with transients, e.g. when you plug your power brick in.

Cheers

Phil Hobbs

Does the supply claim power factor correction (PFC)?

If not, charging the battery plus running the computer (depending on how much you're computing) could trip it due to power factor, which is going to be maybe 0.6 tops for a standard rectifier design.

Tim

A DC-DC converter with a boost regulator is always a better option for devices that need a low-voltage DC input. Inverters are often used in inappropriate applications.

is one example, but there are many of these available.