Typical last mile battery runtime (protecting against power cuts)

Mark Tinka mark at tinka.africa
Sun Feb 5 09:20:29 UTC 2023

On 2/5/23 11:12, William Herrin wrote:

> Hi Roy,
> My guess is that your 20kw Onan isn't up to stably producing 20kw any
> more. Or perhaps the older transfer switch with its mechanical timer
> relays has gotten dodgy. The modern consumer gear is very reliable but
> the pre-2010s commercial/industrial gear (such as Onan) takes a lot of
> TLC to keep it working right.
> Another thing that can happen is uneven load. The utility won't care
> that 80% of your draw is on one side of the circuit but that'll stop a
> generator in its tracks.
> If you want to know for sure, get yourself an inductive clamp meter
> and start checking the amperages at the breakers. You can get a cheap
> one under 50 bucks. You just set it for AC amps, take the cover off
> your breaker panel and clamp the jaws around the "hot" wires coming
> from each breaker, one at a time.
> As John mentioned, unless you have a really large house or a tankless
> electric water heater, it's really odd to overwhelm a 20kw generator.
> Even with the auxiliary resistive heat.

Agree with this assessment.

20kW rated is plenty of energy for even a demanding home.


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