How much electricity do household items use? Or specifically the ones I have?
The old bloke in the photo, is Alessandro Volta, he made the first basic battery. Volta and a few others back in the black and white days had a thing about naming physics discoveries after themselves. James Watt, Andre-Marie Ampere, Charles-Augustin de Coulomb and old George Ohm. These guys basically discovered electricity as we know it. Nikola Tesla, Thomas Edison etc and all that lot came later.
I’ve been doing a bit of research into this clever electricity stuff, inverters, shore power and AC in general and as part of that I’ve been measuring the real world amps/watts/volts of various household appliances. That’s how I spend my spare time… Anyway all this will help me get an idea of what’s possible and what I should be aiming for in terms of battery capacity and power.
The appliances I’m mainly interested are: a new Bush 50cm electric cooker (oven and hob), a new Russell Hobbs under-counter fridge freezer, electric heaters, kettles, a dehumidifier, my Macbook charger and a few other bits and pieces.
I already own most the appliances listed below, and I’d like to put a few of them in the boat (the hairdryer and GHD straighteners are obviously for my partner Lorraine… honest). It’s pretty obvious before I started that the oven and kettle were going to be the monsters but I’ve also learned that I want to stay away from what I thought was a fairly efficient ceramic heater.
I’d prefer to go all electric (DC mostly) with the boat and avoid gas entirely, purely down to preference.
The plan is to use many of AC appliances like the oven, when on shore power only. Most marinas are limited to 16 Amp connections, some allow you to pay more and get a 32 amp connection which I doubt we’re ever going to need in our little boat. The majority of the functions of the boat: lights, fans, water pump, bilge pumps, sound, radio, USB charging etc will all be 12v DC powered.
When we don’t have AC shore power, we’ll go to the pub instead. Or fire up Just Eat.
Little old Perdita will likely never be too far from electricity of one kind or another, and I’m aiming for a nice balance between little bits of AC comfort and DC efficiency.
Anyway, here’s the list of appliances and their consumption! You can see the old favourites like Ovens, kettles and hair dryers are the worst offenders.
I suppose the obvious thing to keep in mind looking at the table below is that 16 amps is the maximum for simultaneous use on shore power.
| Appliance | Amps | Watts | |
| Cooker | Bush 50cm Electric Oven & Hob | ||
| Oven top + bottom elements | 9.19 | 2248 | |
| Oven top element | 6.8 | 1667 | |
| Oven bottom element | 4.57 | 1135 | |
| Grill | 6.88 | 1667 | |
| Hob – 1kw small size – heat 4 of 6 | 2.4 | 592 | |
| Hob – 1.5kw large size – heat 4 of 6 | 3.52 | 874 | |
| Heater | Delonghi Ceramic Fan Heater | ||
| Cold fan and rotate | 0.23 | 29.5 | |
| Heat 1 and rotate set at 26c | 5.03 | 1247 | |
| Heat 2 and rotate set at 26c | 9.61 | 2330 | |
| Hairdryer | Small Black Travel Hairdryer | ||
| High heat and power | 7.33 | 1800 | |
| Low heat and power | 4.65 | 1135 | |
| Dehumidifier | Ecoair | 1.15 | 245 |
| Set for 50% and single speed fan | |||
| Kettle | Russell Hobbs | 12.03 | 3000 |
| Travel Kettle | Russell Hobbs | 4.57 | 1120 |
| Hair Straighteners | GHD | 0.5 | 0.5-100 |
| Mobile Charger | Samsung S6 Fast Charger | 0.065 | 10 |
| Fridge + Freezer | Russell Hobbs Undercounter Combi | 0.57 | 63 |
| Toaster | 4.15 | 1010 | |
| 13″ Macbook | Mac off – with charger | 0.155 | 21 |
| Mac on – with charger | 0.215 | 29.5 | |
| Nespresso Coffee Machine | 5.01 | 1200 | |
| Battery Charger | 20 Amp Maypole Battery Charger | 1.2 | 240 |
| Set on High Power (2) and Boost (high) |
Conclusions
I took all these readings using a little Energy Meter that I got via Amazon, they’re not the most accurate thing in the world, but the numbers seem to stack up ok.
It looks like with a bit of balancing, it should be possible to have the electric oven when on shore power. I’ll be looking for a really nice efficient electric kettle and a less hungry electric heater. I’ve already got a low energy Samsung Smart TV and a tiny little Microwave. I’m also going to look into a diesel heater, although they cost a few quid.
I’ve already looked into diesel generators, and I think having one is overkill for the size of the boat. I’d also have to deal with the noise even for a ‘silent’ unit. It’s unlikely we’ll run a generator.
So for now our setup will be: diesel engine alternator power, solar panels (about 300W ish to kick off with), 5 x 110ah AGM batteries + 2 x 110ah cranking batteries, which should be plenty for our planned usage of Perdita.
All this might change anyway, but messing about like this with a bit of research helps provide a better idea of our electrical requirements.
Thanks for reading!