A lesson in 12-volt power management. How much battery capacity do you need to make a cup of cappuccino?
Dear Readers,
Since the English language is simply too small to encompass my thoughts and discussions on the amount of battery and solar energy needed for common (and not so common) RV appliances, Iām introducing two new words into your vocabulary: CEUs and PREUs (pronounced like cues and prunes, but āprunesā without the ānā).
In the beginning, there were SPEUs
Of course, this is simply an expansion of my concept of SPEUs (pronounced like spew, as in spew forth), which I created to discuss the amount of energy required to make a sock puppet with a sewing machine. Hence, Sock Puppet Energy Units (SPEUs) were born.
In todayās article, Iām going to discuss the amount of energy needed to make a cup of cappuccino or coffee (hence, CEUs for Coffee Energy Units) and later Iāll cover whatās need to run a portable 12-volt Danfoss refrigerator (hence, PREUs for Portable Refrigerator Energy Units).
Study timeā¦
This sort of mind experiment will help you understand just how much battery energy is needed for any electrical appliance in an RV. Thereās a little bit of math involved (actually just simple arithmetic), but most of these calculations can be performed by counting on your fingers and toes. That means you can put away that slide rule for nowā¦ So please keep your arms and legs inside the ride at all times until it comes to a complete stop.
The Portable Solar Power Station
I hate to call them solar generators, since these are basically lithium batteries and a pure sine wave inverter in a box with plug-in solar panels, but a Portable Solar Power Station is a reasonable nom de plumeā¦ Thatās why a few months ago I asked for a Jackery 1500 Power Station with 1,500 watt-hrs of battery storage, an 1,800-watt pure-sine-wave inverter, and 400 watts of solar panels (200 watts shown here). Now, this portable battery / inverter will certainly not replace a hard-working generator to power your entire RV, nor do I think itās time to rip out your existing RVās converter / inverter / battery system. But as a supplement for boondocking without a generator itās a solid concept. So thatās what Iām using for these next few energy experiments.
How much energy does a Jackery 1500 store?
Well, the Jackery 1500 is listed to be able to provide 1,500 watt-hrs of battery storage, and my casual observations confirm this. So you can run a 1,500-watt space heater for 1 hour (because 1,500 watts times 1 hour of time equals 1,500 watt-hrs).
Or it could run a 100-watt light bulb for 15 hours (because 100 watts times 15 hours equals 1,500 watt-hrs). Now, there is inverter overhead (the fan) and inefficiency losses when it makes 120-volts AC. So, some of my tests includes powering a Vitrifrigo Portable Refrigerator both from 12-volts DC directly as well as the 120-volt AC inverter.
Spoiler Alert ā No surprises, since the portable refrigerator could run for nearly twice the number of hours using 12-volts DC compared to 120-volts AC.
How many CEUs does it take to make a cappuccino?
Okay, now itās time to answer the question I get asked every week on my various forums and blog. Just how much battery power will it take to make an espresso, latte, cappuccino, or mug oā joe in my RV? Iām thinking in Coffee Energy Units, or CEUs for short.
While there are old-school ways to heat water on a propane-powered cooktop, many of you still want your Nespresso machine. Apparently some of you made deals with your better halves that they could bring along their favorite caffeine machine, or they wouldnāt go boondocking in the woods with you. So now itās a deal breaker if you canāt deliver the javaā¦
The setupā¦
I plugged my Nespresso machine into a Jackery Explorer 1500 which has an onboard 1,500 watt-hr lithium battery and 1,800-watt pure sine wave (PSW) inverter. The Jackery has a very nice Power / SoC (State of Charge) meter, which makes it pretty easy to get both power and energy usage data.
As you can see in this short video HERE thereās 1059 watts of power draw from my Nespresso machine during the warmup cycle, followed by around 850 to 900 watts during the milk foaming cycle, followed by 550 watts down to 208 watts during the espresso pumping cycle.
The dataā¦
We can see from this short video that the peak wattage used is just over 1,000 watts, so a 2,000-watt inverter should easily be able to power this Nespresso machine, as long as you donāt have the microwave oven running at the same time. And the SoC started at 87% and ended up at 85% at the end of the cycle. Since this is a 1,500 watt-hr storage battery, all we have to do is multiply 2% times 1,500 watt-hrs and calculate 30 watt-hrs of energy needed. So Iām going to estimate that each CEU (Coffee Energy Unit) is around 30 watt-hrs of energy for a Nespresso machine making cappuccino.
Flipping the calculation, youāll see that if you have a single 100 amp-hr AGM or FLA (Flooded Lead Acid) battery, the 600 watt-hrs of available battery energy divided by 30 watt-hrs (1 CEU) needed per cappuccino cycle equals 5% of your available battery power, which is 20 espresso-making cycles on a battery charge.
More Calculationsā¦
If you have a 100 amp-hr lithium battery in your RV, thatās around 1,200 watt-hrs of available battery power (since you can discharge them down to 0% SoC). So you could make 40 cups of cappuccino on a single battery charge.
So, the Jackery 1500 should be able to make 50 cups of cappuccino on a single charge, which Iām not going to actually test since Iām pretty sure I canāt drink that much caffeine in a day. But the math indicates thatās how it should work.
And if you consider that 400 watts of solar panels can recharge around 1,200 to 1,500 watt-hrs of battery power in a day, it suggests that you could make 50 cups of cappuccino per day FOREVER, as long as the sun is shining and you donāt run out of coffee pods.
Part 2: More info to come next weekā¦
Iāll be posting the second part of this article next week where Iāll show much battery power was needed to run a portable Vitrifrigo 12-volt compressor refrigerator / freezer. You will be amazed. See you thenā¦
Please share this with every RV owner you know who loves & needs their caffeine. š
Letās play safe out thereā¦ Mike
