I’ve noticed when people are using generators to power a tool or appliance, they always directly plug into the generator. Then the generator is burning fuel reguardless of consumption.

How can that waste be reduced? A simple approach would be to plug your tool into a UPS (uninterruptible power supply) which is then plugged into the generator. This would help capture some of the excess energy when you are not pulling the trigger on a drill. Correct?

Possible flaw in this thinking: lead-acid batteries can only be trickle charged. So putting a battery in series only captures a small slice of the energy waste. Better than nothing, right?

I’m asking because I may need to install a generator for a whole house, and it’s not just for incidents. It will run daily in an off-grid house. So I’m trying to work out how to keep the fuel burn at a minimum and also how to fully exploit the available energy when fuel is being burnt (which should generally be during low sunlight times).

(edit) The UPS idea could backfire. IIRC, some UPSs are designed to always draw power from the battery while charging it at the same time. This is a superior design because it ensures that your appliance gets clean power that closely resembles a sine wave. UPSs that directly power the appliance from the mains and only tap the battery when mains go down have the disadvantage of sending potentially quite dirty wall power with surges and brownouts to the appliance. I think the always-use-battery design becomes self-defeating if using the UPS just to avoid generator waste. Correct? Though I’m confused because I don’t quite grasp how a lead-acid battery can charge as fast as it dissapates energy… I would think the charging would be slower than the consumption and power to eventually be lost.

  • CompactFlax@discuss.tchncs.deEnglish
    5·
    5 days ago

    The simple approach is a LiFePO4 battery bank with a charge capacity (A) and charge controller that is appropriately matched to your generator’s output. Fire up the generator to run heavy draw appliances such as electric stove, or when batteries are low.

    It’s somewhat frustrating to me when I’m running the generator to charge my laptop and run internet (150w) and the thing is rated to 5kw. Worse yet if you were running only lights. This can be mitigated, somewhat, by having an inverter generator which responds to load.

    There’s many problems with a UPS:

    1. UPS are designed to handle short term load. That is, a brief power interruption as a cable is relocated, or the time between an outage and the generators starting. Therefore, even if it has the capacity to run the home in current, it’s not likely to have the batteries behind it
    2. UPS usually charge very slowly after discharge.
    3. A UPS sized for a home - even off-grid cabin - is going to be obscenely expensive.
    4. UPS usually use lead-acid batteries which, while by far the cheapest option, lag behind lithium based alternatives significantly in terms of depth of cycle, cycle count, and charge/discharge current.

    Depending on your projected load, those “solar generators” may be a good fit. Ecoflow, for example, has a “smart generator” which hooks up to their inverter/battery pack and fires up when the battery is low. You can easily connect some solar panels as well. However, if you consider your money worth more than the ease of use or you need capacity exceeding what is readily available, there’s more affordable solutions.

    Personally, unless you have a strong need for it, I would strive to find a solution using solar generation as the primary source, with the generator only providing backup. It’s regrettably the “expensive” option.