battery power station generator run times

Portable Battery Power Station Generator Run Times For Appliances

A portable battery power station generator. They are becoming increasingly popular. And for good reasons. You can run them indoors. Emission-free. They’re silent. And they can be recharged fairly quickly from a home wall outlet. Solar panel recharge too. In short, it’s basically a portable battery with an inverter that converts to 120 volts AC (i.e. same as in your home). But what can they actually run? And for how long before you need to recharge?

For example, a commentator here on the blog asked the following question…

Anyone have any experience with the Generac GB1000 portable power station? I’m looking for compact/storable solar power alternative with the primary use to power our pellet stove in a longer term grid down scenario. Already have a gas generator, so strictly looking for solar. We also do a lot of camping so could potentially take with us on trips as well. It seems like a nice option. Claims AC output running watts 1600, and max AC output starting watts 3200, which I believe should be more than enough to get the stove going?

I know Ken had posted a great article on building a battery bank for pellet stoves a ways back, just trying to find something a little more mobile, feel as if I’ll get a little more use out of it that way.

How To Determine Battery Power Station Run Times For Appliances

It’s actually fairly simple to figure this out. Hopefully it will help some of those who happen across this post.

Every battery power station generator has several ratings. The main specifications you’re looking for are these:

  • AC Rated Output Running Watts
  • Nameplate Capacity (Wh) Watt hours

Output Running Watts (W)

This is the load rating of the battery power station. That is, how many watts that it can put out in order to power your device or devices. Some power stations may specify both a running watts rating, and a peak watts rating (short term ‘start up’ burst). For the intent of this article, lets simply look at the output running watts rating.

In the example above, that particular Generac power station has a rating of 1600 watts. This simply means that the total load that you put on that generator should not exceed 1600 watts. Each device or appliance that you wish to operate will have its own (watts) consumption rating. But a quick way to measure this is to use a clever device-meter that measures this value. I wrote about this meter in an article linked at the end of this post.

P3 International P4460 Kill A Watt EZ Electricity Usage Monitor
(view on amzn)

You can also find lists of common devices and appliances and their ‘typical’ watts consumption on the internet to get you in the ball park, so to speak. But lets look at the pellet stove from the comment above. I have one, and for the sake of simplicity I’d say that on average mine may consume about 100 watts (depends on blower speed). The startup watts (the ignitor – which stays on for about 10 minutes) is about 350 watts. So this is not even a hiccup for the battery power station we’re looking at.

But how long will with the battery power station run it?

Battery Power Station Capacity (Wh) Watt hours

This specification is the total energy capacity of the battery itself. Most all of these power systems use Lithium ion batteries. And they can be discharged down to 20% (80% useful capacity).

Again, the Generac referenced above has a nameplate capacity rating of right around 1000 Wh. This means it has a useful capacity of about 800 Wh. Knowing this, we can approximate how long we can run that pellet stove before needing a recharge.

800 / 100 = 8 (hours)

See how it works? Pretty simple actually. Hopefully this helps the understanding of how to apply the ratings to real world conditions. That ‘Kill A Watt’ meter is really helpful in this regard.

[ Read: ‘Kill A Watt Meter’ — How to Measure Power Consumption (kWh) ]

[ Read: Jackery versus Gas Generator ]


  1. DO NOT charge them inside your living quarters or within 50 feet of anything flammable. We had a prototype go off in a lab at 0100 hrs. a couple of months ago. Fire department had to breach four doors to get at flaming shrapnel that punched through drywall. All the AC ducting and evap coils had to be replaced and the toxic stink is something you’ll never forget; if you survive the fire.

      1. I believe that Tmac is generically referring to charging high capacity Lithium ion battery packs, regardless of product or brand. Although one would presume that a reputable brand would ensure better quality BMS compared to others. Although that’s ‘inside baseball’ that I’m not privy to know…

        1. Ken –

          You are 100% correct, these events are almost always caused by a BMS failure; such was the case on that ugly night too. Contrary to the binary wonderings of another poster, this was neither a Generac product nor our own product, per my OP this was a prototype. For the record, Jackery is known in the industry as being top of their game. They are right up there with Bluetti and Goal Zero as far as quality. Jackery has come a very long way in a short time and I am not personally aware of any Jackery product suffering a catastrophic failure. This was a LiFePo prismatic array that cut loose, only a fourth of it actually. The takeaway here is awareness of the phenomenal energy density of these products and the potential for a defective or damaged BMS/PCB to cause that energy to be released at once.

    1. What battery chemistry was the prototype using?
      If it was NMC, then I would not be surprised, but if it was LiFePo4 then, in your opinion, are the claims of more safety with that chemistry bogus?

    2. Thanks, that’s the only reason I need to remove these things from my consideration.
      Possibly in years when they are more foolproof.

      1. Horse – Lithium is over the hill, new chemistries are in development that are intrinsically stable with even greater energy density.

        1. TMac,
          I’m liking the Sodium battery technologies, Prussian Blue anode/cathode, 50,000 cycles, fast charging!! No chance of self conflagration. Natron Energy is the company. Supposedly starting production this year, so I am hoping in a few years they will have batteries for solar systems.

        2. Minerjim – That’s 1 of 2 back in the skunkworks, I am impressed once more by the breadth of your knowledge.

        3. Too bad they’re still a private company – would love to steer some 401K dollars to this apparently groundbreaking battery technology…

      1. Cat6 – Theoretically, I suppose so; but practically speaking too many cheese holes would need to line up for a tool pack to blow like that. Most tool packs are still 18650 cells, each with their own vent. With big names like Makita, Milwaukee, etc., catastrophic battery failures are unheard of, I cannot recall a single instance. Even with cheap power tools the worst I’ve ever seen is some melted plastic and maybe a single cell overheat. I have charging bays indoors all over the place, not worried a bit. The kilowatt power stations are kept in a solid steel tool box.

  2. Oh, I just noticed the folding solar panels in the background. I have around a dozen different samples in another lab that I tested over the summer. A couple of things:

    1. Many of these panels collect IR more efficiently than UVA/B. +70C is the magic number where they universally shart the bed and output drops 80-90%. Good panels should never see a surface temperature above +56C. I’ve seen bad panels hit +70C with ambient of only +15C. That’s just nasty.

    2. Chinese math is a factor in the ratings, if you really want a 100 watt panel, buy one advertised at 120watts.

    3. Above 30 degrees latitude you will only see max potential for an hour or so either side of high noon. Incident angle degradation is not a straight line.

    4. Generally speaking, rigid folding panels are far superior to the flexi-canvas backed type.

  3. Awesome info Ken. Must say an above and beyond response to my original post. If I end up taking this route will certainly be ordering through your affiliate link. Thank you

  4. What do you all think about Inergy power station products? Been looking into one of those recently. They are a bit pricy.

  5. To Ken and Tmac: Thanks to both of you for sharing your expertise and advice in regards to purchasing, safe storage and use of such devices. It is a bit of peace-of-mind for me and my wife after purchasing a high quality unit last year. We have had several storms that resulted in hours long outages but nothing exceeding 24 hrs in my neighborhood. The silent power station kept the freezer going through those events.
    For the record, I purchased a Goal Zero 1000 kwatt unit. I already have lithium battery packs and charging units for power tools and my lawn mower. As time goes on, the technology on this things seems to get better/easier to use. In the coming year, next purchase will be solar panels. I am glad this info will be in the archives to reference for later.

  6. Call me old fashioned, but I would like to find something with a large AGM battery to power a CPAP overnight. Any suggestions?

      1. Thanks Ken, but all it says is 12V, and 6.67A. It is a Phillips Respironics Dream Station. I have several college degrees and professional credentials, so it is very humbling to admit that I don’t know anything about electricity. I am about to retire, and am developing a remote property, building my cabin, and enjoying the used bulldozer I recently purchased. I feel like I am pretty far behind the curve, but I learn a lot from your articles and the commenters. Keep up the good work.

        1. Old Alaskan, if you check the charger for your dream station it may have the info you are looking for. Good luck.

        2. Old Alaskan, it appears that several models of that device are sold with 80 watt power supplies, which would be consistent with the 12V and 6.67A that you note. It also appears that yours runs off of the 12V DC electricity that the battery could supply directly. That is, it doesn’t need an inverter between it and the battery to generate AC electricity. Big plus! Be aware that fully-charged batteries can run 13-14V, though, so you would want to test to be sure the device can tolerate the 10-15% higher voltage.

          With those figures, the device will draw about 54 Amp-hours (Ah) in eight hours of use. An AGM battery is typically used to no less than a 50% state of charge, so you would be looking for at least a 108 Ah battery to run the device for eight hours. 110 Ah AGM batteries weigh around 70 lbs.

          By contrast, a lithium iron phosphate (LiFePO4) 100 Ah battery weighs around 25 lbs and would provide nearly twice the runtime. Without getting into all the details, an AGM ends up needing to be twice the Ah rating of a LiFePO4 for the same amount of power. That’s according to a reputable source (Victron Energy). In other words, a 25 lbs LiFePO4 battery would run your device two nights between charges, where the 70 lbs AGM would last one night. Cycle life is also considered to be multiples better for LiFePO4 – 5-10x are claimed.

          Personally, I’m not sweating safety with the smaller LiFePO4 batteries that I keep around, though I’m probably more careful working with them. Lead-acid batteries convinced me long ago how much energy they can suddenly release. Lithium = More so.

        3. To Old Alaskan, ‘406Redoubt’ provided a good answer. To simply sum it up for your particular CPAP model, here’s what you need:

          Shielded DC Cord for DreamStation CPAP Machines

          12FT 12V Female Car Cigarette Lighter Socket Extension Cord with Battery Alligator Clips

          And of course, a 12 volt battery (and a charger for that battery). My current solar system battery bank is using 12 volt Trojan 31-AGM batteries. 100 AH (amp hour batteries). This would run your CPAP for about 8 hours down to 50% charge (that’s the max recommended dishcarge for a lead acid battery). I will be looking into newer battery technologies when it comes time to replace mine.

          LiFePO4 was mentioned. Energy density looks great. However I continue to be concerned about the quality of the built-in BMS (battery management system) for these batteries. If they’re not done right, well, they could catch on fire in a dramatic way… I’m sure some brands may be better than others, but I have not done any in-depth research yet.

        4. Old Alaskan, you could keep it real simple,
          A few panels and charge controller with an inverter from Amazon and a batch of 12v batteries,
          Ive got a battery on my fuel pumps that is about 10 years old, so thats pretty good,
          CPAP runs at nigh only right? So just need to lake sure you have enough batteries to keep it going. 6.6amp isnt much in 12voltese,

          You could also look into Goal Zero, they make excellent systems and i believe if you go to Steve Quayles website you will see a link to a backup power sourse supplier, also had some really nice hardware. It aint cheap but to keep you from flat lining in your sleep seems worth it

        5. Hi Old Alaskan
          Watts equal load current (6.67) x voltage (12), so your CPAP would use about 80 watts. So say you had a 12 V battery rated at 500 amp hours that battery in good condition would run your CPAP machine about 6 hours.

    1. One of the simplest solutions is to buy a High Efficiency inverter with from 500 to 1000w range and an an AGM battery. A CPAP uses about 350-400w on average ( I have been using one since 2007). I use a Solar Cube 1500W with inverter and built in solar panels as my quiet power supply. Too much for just the CPAP, but useful for other things. I also have a Windlily and Waterlily 12V DC 2.5 amp generators as back up for poor weather they both work in moving water or wind to provide charging current. Hope this helps. TTFN

  7. I bought a Jackery last year. I also have a generator. We won’t go out in the middle of a storm to set up the generator, we use the Jackery for the refrigerators or the wood stove fan if needed. Once the storm has passed then we hook up the generator.

  8. Peanut,

    Many of the new Jackery’s and similar products have USB-C PD (power delivery) capability which allows either 60 or 100 watts, in or out of the USB-C port, even while it is operating the inverter and in use. This is far from a pure parallel system.. But you can set up a second or even a third power station in a daisy-chain series via USB-C PD cables. Say unit #1 is running your fridge at 300 watts.. unit #2 is pumping 100 watts back in to unit #1 via the cable. Unit #3 feeds unit #2, etc. This can greatly extend your run times, say for example if you are in the northeast right now and just not in the mood to fart around with switching out boxes every few hours to keep essentials running.

  9. What an amazing wealth of information. You are all so knowledgeable and willing to share! Thanks to each one. I have a lot to go on based on all the responses. Once I achieve this goal, my next project will be to build a wood gasifier to run a generator (I can dream).

Leave a Reply