# Should 12 volt DC to 120 volt AC cigarette lighter plug inverters get very hot when not in use? **URL:** \ **Category:** Factual Questions\ **Created:** [September 21, 2010, 3:50pm UTC](https://boards.straightdope.com/t/should-12-volt-dc-to-120-volt-ac-cigarette-lighter-plug-inverters-get-very-hot-when-not-in-use/554542 "2010-09-21T15:50:23Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [September 21, 2010, 3:50pm UTC](https://boards.straightdope.com/t/should-12-volt-dc-to-120-volt-ac-cigarette-lighter-plug-inverters-get-very-hot-when-not-in-use/554542/1 "2010-09-21T15:50:23Z")
[I picked up one of these the other day](http://www.walmart.com/ip/Philips-Power-Inverter-DVDP32/4809766?wmlspartner=neQRQBqOKtQ&sourceid=20357198232049885240). I plugged it into the 12VDC lighter port in my vehicle in with nothing attached to it drawing current. I left it in for about 30 minutes and when I parked I went to pull it out of the lighter plug socket, and it was _very_ hot to the point it was almost impossible to handle with bare hands. Again, there was nothing plugged into the device. Is this normal for these devices? I have more bulky 150 watt 12 VDC \> 120VAC inverters that have a cord and separate box with a built in fan and they never got as hot as this device. It’s quite small and has no active cooling, just vents in the body of the device. Is this thing going to set my vehicle on fire or is running hot with no load SOP for these things? ---
**Author:** ![pericynthion](https://avatars.discourse-cdn.com/v4/letter/p/85e7bf/32.png) [@pericynthion](https://boards.straightdope.com/u/pericynthion)\ **Post date:** [September 21, 2010, 3:59pm UTC](https://boards.straightdope.com/t/should-12-volt-dc-to-120-volt-ac-cigarette-lighter-plug-inverters-get-very-hot-when-not-in-use/554542/2 "2010-09-21T15:59:31Z")
(EE) Doesn’t sound normal. ---
**Author:** ![pyromyte](https://avatars.discourse-cdn.com/v4/letter/p/d26b3c/32.png) [@pyromyte](https://boards.straightdope.com/u/pyromyte)\ **Post date:** [September 21, 2010, 5:46pm UTC](https://boards.straightdope.com/t/should-12-volt-dc-to-120-volt-ac-cigarette-lighter-plug-inverters-get-very-hot-when-not-in-use/554542/3 "2010-09-21T17:46:24Z")
I agree, something doesn’t sound normal if it got that hot. But some heat is probably normal while plugged into the 12VDC outlet, even if nothing is plugged into the AC side, because I am guessing that its electronics (IGBT, transistors, or whatever it has) are still switching on/off to make the AC. I’d probably take it back to Wal-mart and try another one. No one in the reviews mentioned anything about excessive heat. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [September 21, 2010, 6:06pm UTC](https://boards.straightdope.com/t/should-12-volt-dc-to-120-volt-ac-cigarette-lighter-plug-inverters-get-very-hot-when-not-in-use/554542/4 "2010-09-21T18:06:30Z")
IMO it’s either defective or poorly designed. In either case, if I were you, I would return it. ---
**Author:** ![Peremensoe](https://avatars.discourse-cdn.com/v4/letter/p/ce7236/32.png) [@Peremensoe](https://boards.straightdope.com/u/Peremensoe)\ **Post date:** [September 21, 2010, 6:09pm UTC](https://boards.straightdope.com/t/should-12-volt-dc-to-120-volt-ac-cigarette-lighter-plug-inverters-get-very-hot-when-not-in-use/554542/5 "2010-09-21T18:09:21Z")
Maybe you just got a bad unit and would be happy with an exchange–though getting a bad unit itself is indicative of the product line’s quality control, so a “good” exchange might go bad too. Personally, I wouldn’t get anything electronic or mechanical at Walmart, given the pressure they put on manufacturers to cheapify their designs. Is there a reason you need something in the dash, rather than set on the seat or floor, as with the cord-connected kind? ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [September 21, 2010, 6:19pm UTC](https://boards.straightdope.com/t/should-12-volt-dc-to-120-volt-ac-cigarette-lighter-plug-inverters-get-very-hot-when-not-in-use/554542/6 "2010-09-21T18:19:09Z")
something that is almost too hot to touch while in use or idling is unsafe. exchange it. do instructions say to not leave plugged in while not in use? even if the unit was a good working one if it produces heat while idling then you likely shorten its life by leaving plugged in, as well as drain your starting battery. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [September 21, 2010, 7:08pm UTC](https://boards.straightdope.com/t/should-12-volt-dc-to-120-volt-ac-cigarette-lighter-plug-inverters-get-very-hot-when-not-in-use/554542/7 "2010-09-21T19:08:18Z")
\*\*It was in use. \*\* If you had it plugged into the dash, it was working even if you had nothing plugged into the 120V side. Just like wall-wart power supplies are using electricity when plugged into the wall, even if the device they power is turned off. If you leave that plugged into the lighter in your car all the time, it will eventually drain your battery dead. But a well-designed converter should NOT get that hot. But is anything bought from Wal-Mart ever “well-designed”? You could try exchanging it, but I suspect that another sample would get just as hot. So you might just consider returning it, and buying one elsewhere.