Battery Backup For Laptop When Power Outage?

Discussion in 'Hardware Components and Aftermarket Upgrades' started by Drew1, Oct 3, 2018.

  1. Drew1

    Drew1 Notebook Deity

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    Hey all got a question. I have a dell xps 15 9550 laptop and i have it charged into outlet almost always. But if i disconnect it from outlet, i get around 2 hour battery life at the most it seem before i have to recharge it. The thing is when im doing certain things, i have to be connected for minimum 8 hours. Thus if i have a power outage and power doesn't come back, I lose money in what i do. I had this happen several times in the building where i rent from because power outages is very common.


    Most of the time, the power outage isn't that long like 15 minutes. But few times its been hours and rare times its a day or so. But my main issue is when im on the computer and i can't have this happen.


    I read online about ups etc. But im not sure exactly how that works. Does this mean if you have something like this and then your battery on laptop is running out of battery, you could connect your laptop to it and then charge your laptop like its an electric outlet? If so, could you basically use it like an outlet? Example say you charge it to your laptop at 10 percent battery. Say you have it charged to 100 percent and during this time, you used the laptop for another 45 minutes etc. Now you are suppose to unplug it right? Then now you get another 2 hours of it on battery? Then would there still be enough power in that device to plug it in again and charge it again? Thus it would be another 45 minutes and another 2 hours?


    I read that these devices only give you like 25 minutes or a bit more than that. So basically you could never get that much power?


    And can someone tell me what are examples of this on amazon?


    I saw these power banks on amazon. So is this the type of device that i would need for this? Im not sure if its power bank or UPS etc.


    https://www.amazon.com/MAXOAK-50000...=1538623206&sr=8-4&keywords=power+bank+laptop

    https://www.amazon.com/Portable-TSA...=1538623206&sr=8-5&keywords=power+bank+laptop

    https://www.amazon.com/Omars-24000m...=1538623206&sr=8-7&keywords=power+bank+laptop


    I know that the bigger the mAh, the more it last. But how many hours would it last? Example say you have 2 hours of battery on laptop when power outage happens. Now you have one of these on hand. How many hours could you get additionally with one of these devices? Thus when you plug it to laptop and use it while its plugged in... then unplug it when battery is 100 percent... then use laptop while on battery for another 2 hours... is there still enough power to charge it again or is that already way too much?
     
  2. John Ratsey

    John Ratsey Moderately inquisitive Super Moderator

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    UPSs are designed to temporarily maintain power supply in the event of power failure sufficient to enable an orderly shutdown. A UPS with a big battery may meet your needs.

    You don't say which (nominal 56 or 84 Whr) battery you have in your XPS15 9550. You can check this, and your power drain when running on battery, using BatteryInfoView. If that battery can keep your computer running for two hours and you want to run for 8 hours then you need extra capacity of at least 3 times the internal battery capacity. Make that at least 4 times to allow for power conversion losses. The only one of the external batteries you identified which comes near to that target is the first one which claims 185 Whr capacity (note that Watt-hours is a more meaningful indicator of capacity than mAh as batteries can have the same mAh rating but different voltages giving different power capacities). However, there's a note on that power bank about not supplying more than 90W so it might cut out if overloaded or the computer may throttle itself if it can't identify the rating of the power source.

    If your backup power supply is at a fixed location then a big automotive battery + charger + inverter could be the best solution. A 12V 60Ah battery could theoretically delivery up to 720 Whr (but assume less) and you can get a 250W 12V to mains voltage inverter quite cheaply. Just keep the battery on charge and if the mains goes off for a significant period then connect the inverter to the battery, unplug your XPS PSU from the mains outlet and plug it into the inverter. There should be enough spare power to run a light or two.

    John
     
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  3. Drew1

    Drew1 Notebook Deity

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  4. Grant B Gibson

    Grant B Gibson Notebook Deity

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    Can you explain more?
     
  5. Starlight5

    Starlight5 W I N T E R B O R N

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  6. RampantGorilla

    RampantGorilla Notebook Deity

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    The charger needs a 110 V AC power supply to function. The inverter turns the DC voltage provided by the battery into the AC power supply required by the charger.
     
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  7. John Ratsey

    John Ratsey Moderately inquisitive Super Moderator

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    The 18000mAh is meaningless by itself. The info here is that the capacity is about 65Whr so after allowing conversion losses, it's similar capacity to your internal battery. The convenience of Dell's Power Companion is that it is compatible with the computer and can be charged by the computer's PSU. The disadvantage is that you need several to run all day.

    The battery + inverter is explained here. Just add a charger to keep the battery topped up (best to have an intelligent charger which has a trickle charge mode). There's nothing automatic about this setup (unlike a UPS which switches automatically) but that's no problem as the notebook has a battery which acts as a UPS.

    John
     
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  8. Vathraq

    Vathraq Notebook Enthusiast

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    Depending on your budget and preferences a combination of several technologies may be best suited for you. You could look into small generators. Most of these require fuel. Depending on how long it takes your battery to charge/UPS to charge you could just run it until charged then turn it off.

    Something like this -
    https://www.amazon.com/gp/product/B00NHACROW/ref=s9_acsd_hps_ft_cr_x__a_w

    or even smaller using small propane bottles instead of gasoline
    https://www.homedepot.com/p/Ryobi-900-Watt-Propane-Powered-Inverter-Generator-RYi911LP/302703564

    Richard
     
    Last edited: Oct 7, 2018
  9. Drew1

    Drew1 Notebook Deity

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    Hi there. So you are telling me that getting this would mean i only get between 1 to 1.5 hours of battery only similar to my dell xps 15 9550 battery?
     
  10. John Ratsey

    John Ratsey Moderately inquisitive Super Moderator

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    It all depends on how fast your XPS guzzles power. Can you, for example, throttle back the performance when the mains power fails? Draining a 65Whr battery an hour implies a power consumption of around 60W. I prepared this graph for my Precision 5510 (essentially the same as your 9550) when I first received it in 2016.
    Precision 5510 speed power.jpg
    Limiting the CPU speed improves its power efficiency and the graph highlights the power saving which can be made by disabling turbo mode. This can be easily achieved by setting the maximum CPU state to 99% in the power plan advanced settings. Further reduction of maximum CPU state slows the CPU further although there's no simple and logical relationship. I can get 10 hours from my Precision 5510 with big battery under light usage with a moderately dim screen.

    However, if you want to have your computer doing a heavy workload all day on a battery then you will need a big battery. I would suggest something such as a 120 Amp-hr 12V automotive battery with an inverter. In theory this could provide 1440Whr but allowing for power conversion losses and avoiding draining the battery too far (not good for a lead-acid battery - the inverter may automatically cut out) the usable power may only be half (a guess). Given that you don't need portability it may be a viable solution. Get one 60AH battery and see how long it will last. If not enough then add another.... You will also need a mains to 12V charger.

    John
     
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