[RE-wrenches] Portable power station for surge loads

Sat Mar 21 20:56:03 PDT 2026

Hi William,

Thanks for the summary.  I have been collecting information on 120-volt
induction cooking solutions, which are listed below.  Most of these are
probably too big for an ADU, but this is what I have so far

David

Induction cooktop info

The best portable one-burner induction cooktops:

https://www.nytimes.com/wirecutter/reviews/best-portable-induction-cooktop/

Copper induction range with a battery – only 120-volt outlet required:

https://copperhome.com/products/charlie

Impulse induction cooktop only with a battery – only 120-volt outlet
required:

https://www.impulselabs.com/

Electra stove with a battery

https://cleantechnica.com/2025/11/25/electra-just-made-switching-to-induction-as-easy-as-plugging-in-a-toaster/

On Sat, Mar 21, 2026 at 8:38 PM William Miller via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Thanks everyone for the input.  Here are answers to some of the questions:
>
>
>
> I have a heat gun that runs right at 1300 watts (10.8 amps).  I made
> before and after voltage measurements and got 6.5% voltage drop.  (124 VAC
> versus 116 VAC).
>
>
>
> My spreadsheet predicts 3.4% VD.  There are some Polaris splices that
> might contribute to the overall resistance.
>
>
>
> My plan would to power only the cooktop with the integrated
> inerter/battery/charger unit, if this becomes the decision.
>
>
>
> I like the all in one unit because I don’t want the complexity and
> foot-print of separate inverter and battery array.  This ADU is a rental
> and the owners are elderly and need plug and play simplicity.
>
>
>
> We could bump the circuit to 240 VAC, or higher, for that matter.  However
> there is an off-grid home in the middle of this feeder that taps off 120
> VAC very occasionally to get through cloudy/low hydro days.  Then we would
> need three transformers.
>
>
>
> I did recall that there are induction cooktops with batteries built in .
> I need to research that more thoroughly.
>
>
>
> Still pondering.
>
>
>
> William
>
>
>
> William Miller
>
> Miller Solar
>
> www.millersolar.com
>
> CA License C-10 77398
>
>
>
> *From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
> Behalf Of *Ray Walters via RE-wrenches
> *Sent:* Saturday, March 21, 2026 6:20 PM
> *To:* re-wrenches at lists.re-wrenches.org
> *Cc:* Ray Walters
> *Subject:* Re: [RE-wrenches] Portable power station for surge loads
>
>
>
> I remember doing some measurements on a long wire run, and being surprised
> that the actual voltage drop was much less than the calculations.  That's
> when I found a small note at the bottom of the NEC Table 8 conductor
> properties used for official VD calculations.   The resistance is listed at
> 167 F (75C), so if you use the adjustment equation in Note 2, it is much
> less VD, and corresponds to reality.  For underground conductors, I might
> use 25C.  Use common sense.
>
> The formula is R2=R1 (1+ a(T2-75))
>
> I made a spread sheet about 15 years ago, that uses that formula for doing
> wire sizing.  Happy to share, if anyone is interested.
>
> Ray Walters
> Remote Solar
>
> On 3/21/2026 3:21 PM, Jay via RE-wrenches wrote:
>
> Are you trying to run the whole house or just the burner?
>
> I’m also curious about how you calculated the VD. I ran it on a few
> programs and it came up much less VD. I’d go direct or try the load and
> measure the VD. It won’t use the full power for long. Or at least when I
> use my induction top it takes so short to bring anything to a boil, after
> that it’s turned down.
>
> Lots of options.
>
>
>
> On Mar 20, 2026, at 11:23 PM, William Miller via RE-wrenches
> <re-wrenches at lists.re-wrenches.org> <re-wrenches at lists.re-wrenches.org>
> wrote:
>
> 
>
> Friends:
>
>
>
> A long-time client has an ADU 755 conduit feet from the main house.  They
> started off-grid but they are now grid connected.
>
>
>
> In 1999 we pulled a 120 volt feeder of #1 aluminum to the ADU.  This
> provides about 10 amps at 5% voltage drop.
>
>
>
> This client wants to abandon a propane cook-top in the ADU in favor of an
> induction cook-top (indoor air pollution as a consideration).  A sample two
> burner induction cook-top is 1800 watts--too much power draw for this
> feeder.
>
>
>
> I was wondering if a portable power station rated at enough power to run
> the induction cook-top might solve this problem.  The 10 amp power feed can
> charge the power station at (hopefully) an acceptable amperage over an
> extended time period and the power station can provide enough surge power
> to run the cook-top intermittently.
>
>
>
> I see the Bluetti AC500, for example, can be adjusted to draw no more than
> 10 amps when plugged into AC.  Unfortunately this charge rate, when running
> at the full 10 amps, allows little overhead for other loads.  I presume
> this 10 amps draw is only 10 amps when the internal battery is fully
> discharged.  Maybe other units can charge at a lower rate.
>
>
>
> Have any of you tried this?  Any input is appreciated.
>
>
>
> William
>
>
>
> William Miller
>
> Miller Solar
>
> www.millersolar.com
>
> CA License C-10 77398
>
>
>
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