posted ago by bluewhiteandred ago by bluewhiteandred +12 / -0

So I have some corded power tools and I was thinking, instead of buy new cordless ones with battery packs for certain applications, would it be possible for me to just buy a power bank I could plug them in to?

I assume it's as simple as just finding what amps / volts / watts each tool needs and then finding a power bank that can output to that?

Anyone done this or have simple tips, or has it been worth it to buy new tools, or what has been your view on this?

Comments (13)
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YouNeedVPN 7 points ago +7 / -0

Find out what your tools actually pull on startup. The first second uses the most juice and then it settles down, but if it never gets the big jolt it will never start moving.

House circuits are designed for 1800watts (or 2400w in newer construction), and if you have seen the lights dim during tool startup, you were pulling most of that 1800 watts.

Its probably worth the $20 to buy a kill-a-watt meter and see what your tools pull. Then add a bit for safety.

johnmic07 5 points ago +5 / -0

Pretty much all tools that plug into a standard outlet are going to be 120V. And ya you're going to want a power bank that can provide enough amps/watts to supply your biggest tool. Typically, you aren't going to be using five leaf blowers at once so it's not really necessary to have a power bank big enough for every tool you own. But if there is a realistic situation where you'd be using multiple tools at once, then look at the nameplate on your tool or the manual to find the amp rating or watt rating. Add that for all your tools that you'd be using simultaneously and then make sure that number is smaller than the amp rating or watt rating of your generator/power bank. Each outlet will also have an amp rating so make sure your tool doesn't use more than that. Finally, there will be a Watt-hour rating on an power bank, which is the number of hours it will run at that wattage. For example, if your bank has a rating of 1500Wh and you have a 150W tool, then you could run it for 10 hours on that power bank.

Husky 4 points ago +4 / -0

I recommend you buy some cordless tools, and not only can you charge the batteries on a large power bank, you'll have more capacity than if you only had the power bank, you'll have more energy efficient tools that were designed with battery life in mind, and you'll have redundancy in case of failure. Two batteries at half the total capacity are always better than one at the same capacity because if one dies, you still have functioning energy storage.

Its also possible to mod the battery chargers for some power tools to run off dc (solar power is dc)

80960KA 3 points ago +3 / -0

Number you're mostly concerned with is watts, just make sure the power bank/inverter generator/inverter (all the same thing in terms of how they work and what comes out) is rated for the combined watts of the number of tools you want to run at one time. I'd also add a 20-40% safety margin on top of the total of the tools because manufacturers often aren't 100% telling the truth in their advertised power ratings. Just because something can hit the number on the box doesn't mean it's happy running there.

I think in general you're gonna be looking at really light duty use, I wouldn't even try building a deck with this unless I had a pile of spare battery packs around, and at that point you might as well by cordless tools since battery packs are often a quarter to half or more the cost of a tool. If you want to run your corded tools well in the field but don't want to invest heavily, a gas genset is probably your best option.

bluewhiteandred [S] 2 points ago +2 / -0

ok so for example would something like this be enough power to run something that uses 1000 watts: https://www.amazon.com/Sungzu-417600mAh-Generator-Emergency-Generators/dp/B08NYVLGJZ/ref=sr_1_5?dchild=1&keywords=1500w%2Bpower%2Bbank&qid=1634845527&sr=8-5&th=1

but with the price it might be worth buying a few cordless tools instead

(I still just wanted to check the electric principles, I've been ignorant of them)

80960KA 4 points ago +4 / -0

Yeah, that should be able to run a 1kW tool, and with a watt-hour rating of ~1500 it should be able to do it for around an hour and a half (no doubt under the idealest conditions) of combined runtime. For small DIY jobs around the house that's probably adequate, but won't be enough for say building kitchen cabinets or a deck where you're running saws or driving long screws frequently.

I'd say just moving to a cordless platform is the best bet for your dollar, and if you want portable power for working out in the boonies a gas genset would be a great addition. You can run stuff like corded hammer drills from it direct, and it'll happily chug away all day charging up batteries on a few bucks worth of gas.

RogueCoyote 3 points ago +3 / -0

It's a little more complicated than purely matching the tool's running wattage to the generator's output. Nearly anything that has a motor in it will draw much larger peak-amperage as it jumpstarts the motor, so you need a powersource that can handle that temporary peak draw.

If you wanna go full on with it you could look into your tool's exact peak amperage and buy a generator/powerbank that exactly meets what you need (plus some safety margin). But probally much easier is to just get one that meets the same 15 amp standard that your home uses (or 20 amp if you're using more industrial tools). That way you know that if it can start up on your home plugs, it'll start on the powerbank.

Watts = Volts*Amps. So 15amp home amperage * 120v home voltage = 1800 watts that any home tool will ever peak at.

If you just want something easy and that'll work; get a Jackery 1000 (has 2000w peak output, 1000w sustained). Or an equivalent specc'd competitor. I would probally recommend a solar generator like that over a pure battery bank, as the solar functionality can come in a lot of use for remote/long work, or disaster prep.

BigOT 3 points ago +3 / -0

because all of your corded tools run off of alternating current you would need to buy an inverter of the appropriate wattage to be able to run them as well as batteries to draw from.

cordless tools use DC motors and are designed with their own battery microcontrollers built in.

I've never done the math on it but I wouldn't think it was worth the trouble and expense of buying a dedicated inverter and battery to run corded tool vs buying mass produced cordless. you would likely end up needing to buy a hand truck just to haul a huge stack of deep cycle batteries around

C5H5NNiO 2 points ago +2 / -0

Just a correction: Cordless brushless tools have a microprocessor.

Side comment- Many a tools "die" when too much dust collects on that PCB. Simply open up and dust and boom, good as new. I prefer brushed motors, reduced complexity.

bluewhiteandred [S] 2 points ago +2 / -0

does it really need that much power / there aren't powerful enough banks for it?

maybe it also depends on how powerful of tools I want to use?

this was from like 6 years ago, I figured there would be more options by now: https://toolguyd.com/bosch-mobile-power-unit-battery-bank/

exwhyze 3 points ago +3 / -0

Your best bet is to run cordless. I've been doing commercial/industrial construction for 14 years and have watched the "cordless revolution" and while they do have their limitations, Joe Homeowner or even the residential contractors will never see these.

The only tools still worth having a cord on still are 6" or bigger grinders, SDS+ hammer drills, and if you're lucky enough to have one, mag drills. Everything else, impacts, sawzalls, skilsaws, regular drills, the smaller SDS hammer drills, you're better off going cordless if you plan on using the tool for more than a few days.

I invested heavily in Milwaukee as their only true competitor is Hilti and I am not made of money. Milwaukee's main advantage is the fuel brushless line, and their absurdly long runtime on the HD batteries. You will pay out the ass for these batteries but you can occasionally score deals. I picked up the m18 fuel chainsaw & leafblower combo with a 12.0 battery for 450 bucks at Ace.

C5H5NNiO 1 point ago +1 / -0

I haven't come across a cordless recip saw that had any meaningful punch compared to corded. You can get away with circular saws if you're mainly cuting 2x4 or 1/2" plywood. Agree with the grinders and SDS's- you need that cord!

Having cordless drill drivers and impacts have been industry changing absolutely.

exwhyze 1 point ago +1 / -0

Honestly can't say i've noticed any lack of power with the recip saws, but we're typically using those to cut grating or on "sparks-free" jobs. I am rarely if ever using one for any consistent heavy use.

The most badass bar none cordless tool i've seen to date has been the milwaukee metal-cutting saw. I've personally cut a 1¼" plate with that thing faster than I could have with a torch. Utterly incredible.

C5H5NNiO 2 points ago +2 / -0

Great Post- enjoyed the replies!