Friday, February 3, 2023


Get more from your amps and watts

By Bob Difley

Stretch your power

Electricity. We take it for granted. Plug in an appliance and turn it on. What could be simpler. But when you take up boondocking, electricity is more like opening the spigot of a water jug. When it all flows out there is no more, unless you refill the jug.

Your rig’s 12-volt system is sufficient for satisfying your power needs as long as you avoid excessive use of 120-volt current. An inverter — which converts 12-volt into 120-volt — consumes huge amounts of power if you run your air conditioner, toaster oven and microwave oven. Leave your electric blanket and Mr. Coffee at home for the same reason. An extra blanket and a drip coffee maker will replace these necessities of modern living.

If you observe a few basic electricity conservation rules, you’ll be able to get the most out of your available battery power.

• Use lights only when needed and turn off when not used — even for a short time.
• Don’t leave the porch light on. Carry a flashlight in the dark.
• Use battery-operated reading lights and flashlights.
• Shut off the radio or TV when no one is listening or watching.
• Avoid lengthy use of appliances requiring high wattage to operate, even if they are 12-volt, like your water pump.

The amount of 12-volt electricity in your battery(ies) available to operate your systems is a limiting factor for your length of stay, or the time between recharges. A single deep-cycle 12-volt house battery will produce about 105 ampere-hours of electricity. By calculating the number of amps each of your electrical appliances draws multiplied by the hours used makes for an educated guess at when you need to recharge by subtracting the ampere-hours used each day from the total available.

Only about half of these amps (about 50) are actually available to run your electrical equipment. Take voltage readings at the battery terminals with a multi-meter and when the voltage drops to 12.2 volts, start your engine or run your charger/converter off your generator to recharge the battery. Installing a second house battery or switching to a pair of 6-volt golf cart batteries will increase the total number of available amps.

Practice. Take notes. Keep a log. Soon you’ll be able to accurately judge how long you can go before your system needs rejuvenating.

You can find Bob Difley’s RVing e-books on Amazon Kindle.



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5 years ago

Readers should also know the battery is only rated 100AH if used 5A for 20 hours at modest temperatures. So you can half discharge via 5A for 10 hours, but 10A for only 3 hours, or 1A for up to 20 (still 50%!). If you heat or chill the battery, the available energy changes as well. My BMS compensates for this effect, but simple amp-counters and voltmeters do not give accurate capacity measures.

As Tom mentioned, LEDs really do give 10x the runtime for the same light, so definitely invest in that easy upgrade!!!

Tommy Molnar
5 years ago

And if you install a proper solar array, your electrical worries are almost over.

5 years ago

Convert when possible all internal lights to LED, plus porch light. Reduces the load on the 12 volt system and additional heat in the RV.

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