# Laptop screen goes dark on battery power. **URL:** \ **Category:** Factual Questions\ **Created:** [June 4, 2010, 4:32pm UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945 "2010-06-04T16:32:16Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![crazyjoe](https://avatars.discourse-cdn.com/v4/letter/c/f14d63/32.png) [@crazyjoe](https://boards.straightdope.com/u/crazyjoe)\ **Post date:** [June 4, 2010, 4:32pm UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/1 "2010-06-04T16:32:16Z")
I got me a laptop computer here, and the wierdest thing happens. On battery power, all of the backlighting turns off, so the screen appears almost completely black. Now, if I shine a birhgt light on the screen, I can actually see that the laptop is still running and doing stuff…I can navigate web pages, etc. If I put it in standby mode, plug in the AC adapter, and bring it out of standby, the screen comes back on. In fact, this is my work laptop, and I have been using it on the docking station for 2 weeks since this started happening (I have a new one on ordeer since this one is more than 4 years old and out of warranty). So, if I get my wish and am able to bid on buying this laptop when it gets put into “recycled service” what sort of problem should I be looking for to repair it? for the record, I have checked the power settings, it is set to “always on” so it is never supposed to turn off the screen on battery power. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [June 4, 2010, 4:39pm UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/2 "2010-06-04T16:39:54Z")
If you have “Always On” you might check the BIOS and see if that is overriding it (assuming it has some setting about this). Also, check to be sure you have all the latest drivers for that model laptop and do a Windows Update and get everything there. If it still does it then take it for repair. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [June 4, 2010, 4:49pm UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/3 "2010-06-04T16:49:34Z")
Laptops generally do dim their screen slightly when they go on battery power, just to save on battery usage. the key word there though is “slightly”. The screen is still supposed to be readable. You shouldn’t need a friggen flashlight to see it. I would check the laptop for a setting somewhere telling it how much to dim the screen when on battery. On my laptop, this setting is buried way deep in the display properties and ain’t exactly easy to find. I have a slider bar that I can move back and forth to optimize for performance or for battery life. This setting is different than the “always on” option, by the way. ---
**Author:** ![MsWhatsit](https://avatars.discourse-cdn.com/v4/letter/m/eb8c5e/32.png) [@MsWhatsit](https://boards.straightdope.com/u/MsWhatsit)\ **Post date:** [June 4, 2010, 4:53pm UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/4 "2010-06-04T16:53:01Z")
On my Dell Inspiron, you can adjust the screen brightness when on battery power by pressing the Fn key and then the up or down arrow on the keyboard, just FYI. I agree with **engineer\_comp\_geek** that it’s worthwhile to check to see if there’s some way to adjust the brightness-on-battery-power setting, just in case it accidentally got turned way down. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [June 4, 2010, 4:55pm UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/5 "2010-06-04T16:55:51Z")
By the way, to get to my settings (just on the off chance yours is similar), I right click on the screen and select properties. When that comes up I click on the settings tab. From there I make sure the internal display is selected, and I click on advanced. Then I click on the Intel Graphics Media Accelerator Driver for Mobile tab. From there I click on Graphics Properties, then select Display Settings on the side, then click on the Power Settings button on the right. And finally, I’m there, and I can adjust the laptop display properties for when it is running on battery. Simple, eh? :rolleyes: ---
**Author:** ![crazyjoe](https://avatars.discourse-cdn.com/v4/letter/c/f14d63/32.png) [@crazyjoe](https://boards.straightdope.com/u/crazyjoe)\ **Post date:** [June 4, 2010, 5:01pm UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/6 "2010-06-04T17:01:47Z")
I might be more inclined to think it was a setting if this didn’t just spontaneously start happening. At first, the screen blacked after about 15 minutes on battery power. Then 10, then pretty much instantly. If I bring it out of standby on battery power, the screen comes up to full (battery powered) brightness to display the login screen for about 10 seconds, and then goes dark. I have tried the brightness settings. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [June 4, 2010, 5:21pm UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/7 "2010-06-04T17:21:34Z")
Well, it is either a setting somewhere or it is broken. If it is broken, there is a very good chance it will cost more to fix than the laptop is worth. You may need to replace the display, or you may need to fix the driver circuitry on the motherboard (which is basically a motherboard replacement). ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [June 4, 2010, 5:32pm UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/8 "2010-06-04T17:32:48Z")
> [@engineer\_comp\_geek](#): > > Well, it is either a setting somewhere or it is broken. If it is broken, there is a very good chance it will cost more to fix than the laptop is worth. You may need to replace the display, or you may need to fix the driver circuitry on the motherboard (which is basically a motherboard replacement). Yip. The parts on a laptop aren’t nearly as easy to change. I know a guy who messed up the plug on the back, and had to get a new motherboard. I compare that with my much cheaper piano keyboard, which I was able to fix with soldering iron. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [June 4, 2010, 6:33pm UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/9 "2010-06-04T18:33:53Z")
> [@crazyjoe](#): > > At first, the screen blacked after about 15 minutes on battery power. Then 10, then pretty much instantly. I just had another thought. How is the battery life in the laptop these days? Maybe the battery is starting to go and the battery monitor circuitry is darkening the display in a desperate attempt to keep the computer running. Most laptops these days use lithium ion batteries. They store a lot of energy for their size and weight, but their long term longevity kinda sucks. Four years is probably about the time that I’d expect the battery to start to go south. Does anyone in the office have the same model laptop (or at least something with the same model battery) that you could swap batteries and see if that fixes it? ---
**Author:** ![srzss05](https://avatars.discourse-cdn.com/v4/letter/s/898d66/32.png) [@srzss05](https://boards.straightdope.com/u/srzss05)\ **Post date:** [June 4, 2010, 7:17pm UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/10 "2010-06-04T19:17:09Z")
> [@engineer\_comp\_geek](#): > > By the way, to get to my settings (just on the off chance yours is similar > \ > Simple, eh? :rolleyes: On my Sony, I simply open up Control Panel and click on Power Settings… ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [June 4, 2010, 9:56pm UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/11 "2010-06-04T21:56:50Z")
Dells have two screen settings. One for AC and one for battery. Fn up/down adjusts brightness. If your are on battery, then it remembers that setting for battery. Usually, you want less brightness to conserve battery power. Plug in your AC and adjust brightness. That setting is remembered. Try unplugging AC. You’ll see the brightness change to your battery setting. I think you need Dell Quickset installed for Fn up/down to work. It should be installed (by Dell) unless you’ve formatted the hard drive. ---
**Author:** ![AClockworkMelon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aclockworkmelon/32/10803_2.png) [@AClockworkMelon](https://boards.straightdope.com/u/AClockworkMelon)\ **Post date:** [June 4, 2010, 10:24pm UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/12 "2010-06-04T22:24:34Z")
On my laptop under power settings there are four power settings (with the ability to create more): Low performance, unplugged Low performance, plugged in High performance, unplugged High performance, plugged in For each of those settings (and the ones you create) you can adjust things like screen brightness. So if I unplug my laptop the screen dims. ---
**Author:** ![crazyjoe](https://avatars.discourse-cdn.com/v4/letter/c/f14d63/32.png) [@crazyjoe](https://boards.straightdope.com/u/crazyjoe)\ **Post date:** [June 5, 2010, 12:27am UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/13 "2010-06-05T00:27:52Z")
> [@engineer\_comp\_geek](#): > > I just had another thought. How is the battery life in the laptop these days? Maybe the battery is starting to go and the battery monitor circuitry is darkening the display in a desperate attempt to keep the computer running. > > Most laptops these days use lithium ion batteries. They store a lot of energy for their size and weight, but their long term longevity kinda sucks. Four years is probably about the time that I’d expect the battery to start to go south. Does anyone in the office have the same model laptop (or at least something with the same model battery) that you could swap batteries and see if that fixes it? I’ll try a battery swap…the battery has already been replaced once, but was down to only powering the laptop for an hour or so (instead of 2.5 hours) when this started happening. ---
**Author:** ![drachillix](https://avatars.discourse-cdn.com/v4/letter/d/48db29/32.png) [@drachillix](https://boards.straightdope.com/u/drachillix)\ **Post date:** [June 5, 2010, 12:54am UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/14 "2010-06-05T00:54:19Z")
> [@engineer\_comp\_geek](#): > > Well, it is either a setting somewhere or it is broken. If it is broken, there is a very good chance it will cost more to fix than the laptop is worth. You may need to replace the display, or you may need to fix the driver circuitry on the motherboard (which is basically a motherboard replacement). I cannot believe I am coming in here to school **E\_C\_G** turn in your geek card 😃 My first suspicion was a weak backlight inverter, the drop in juice from switching to batteries may not be enough to overcome whatever weakness is happening in the inverter. A backlight inverter is a $20-30 part easily replaced by a novice. A bad backlight can be repaired as well for a similar price point but requires a little more finesse. ---
**Author:** ![drachillix](https://avatars.discourse-cdn.com/v4/letter/d/48db29/32.png) [@drachillix](https://boards.straightdope.com/u/drachillix)\ **Post date:** [June 5, 2010, 12:57am UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/15 "2010-06-05T00:57:51Z")
> [@BigT](#): > > Yip. The parts on a laptop aren’t nearly as easy to change. I know a guy who messed up the plug on the back, and had to get a new motherboard. I compare that with my much cheaper piano keyboard, which I was able to fix with soldering iron. Motherboard jacks can be resoldered, it isn’t always easy. I can do it but I am not great at it. Honestly I take it to an electronics shop near me. I do the teardown and bring them the mobo and the jack to strip the old one and replace it. Most of the actual work is the teardown to get to the board. ---
**Author:** ![crazyjoe](https://avatars.discourse-cdn.com/v4/letter/c/f14d63/32.png) [@crazyjoe](https://boards.straightdope.com/u/crazyjoe)\ **Post date:** [June 6, 2010, 1:24am UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/16 "2010-06-06T01:24:31Z")
> [@drachillix](#): > > I cannot believe I am coming in here to school **E\_C\_G** turn in your geek card 😃 > > My first suspicion was a weak backlight inverter, the drop in juice from switching to batteries may not be enough to overcome whatever weakness is happening in the inverter. > > A backlight inverter is a $20-30 part easily replaced by a novice. A bad backlight can be repaired as well for a similar price point but requires a little more finesse. Interesting. Last night I tried a reboot, and all of the intro screens (HP logo, windows XP starting animation) worked, but at some point it crapped out. I don’t know, I will have to see if this even goes into the “employee resale” pile. If I can get it for 50 bucks, it would be worth fixing, but certainly not for much more than that. ---
**Author:** ![crazyjoe](https://avatars.discourse-cdn.com/v4/letter/c/f14d63/32.png) [@crazyjoe](https://boards.straightdope.com/u/crazyjoe)\ **Post date:** [June 7, 2010, 1:25am UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/17 "2010-06-07T01:25:08Z")
Woudl this inverter problem be accompained by a highh pitched whining sound? ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [June 7, 2010, 2:47pm UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/18 "2010-06-07T14:47:52Z")
> [@crazyjoe](#): > > Woudl this inverter problem be accompained by a highh pitched whining sound? It could be. The inverter board likely has one or more tiny high frequency transformers on it. When the transformers start to fail they can vibrate at their operating frequency, which is usually too high for the human ear to hear. You might be hearing some vibration sub-tones though, or you might just have really good hearing at high frequencies. ---
**Author:** ![drachillix](https://avatars.discourse-cdn.com/v4/letter/d/48db29/32.png) [@drachillix](https://boards.straightdope.com/u/drachillix)\ **Post date:** [June 7, 2010, 2:56pm UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/19 "2010-06-07T14:56:06Z")
> [@crazyjoe](#): > > Interesting. Last night I tried a reboot, and all of the intro screens (HP logo, windows XP starting animation) worked, but at some point it crapped out. I don’t know, I will have to see if this even goes into the “employee resale” pile. If I can get it for 50 bucks, it would be worth fixing, but certainly not for much more than that. probably the inverter then… It can still be a bad backlight or power problem from the motherboard, but we see alot of bad inverters. ---
**Author:** ![crazyjoe](https://avatars.discourse-cdn.com/v4/letter/c/f14d63/32.png) [@crazyjoe](https://boards.straightdope.com/u/crazyjoe)\ **Post date:** [November 17, 2010, 1:26am UTC](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945/20 "2010-11-17T01:26:59Z")
Well, I boutht the laptop out of the employee resale bin for $25, and got an inverter from ebay for around 10 bucks. Finally got around to replacing the inverter, and it worked great. Right up until it didn’t. About 1.5 days later, I am back to black screen. Have I likely blown another inverter? Is it worth trying to get another one, or a backlight, or something else? Interesting note: The first time the backlight went out was when I picked the laptop up while it was onthe table, and moved it to another table. As I set it down, the screen blacked out. I was able to get it to light up again by closing and then re-opening the lid, but alas, sometime after that (it was installing windows updates) it went down for good. Poop. [Next page](https://boards.straightdope.com/t/laptop-screen-goes-dark-on-battery-power/541945.md?page=2)