Precise granny charge cost

[PedroPhev]

I am fastidious about precisely costing every aspect relating to electricity and petrol useage. This allows me to understand the most economical configuration of EV / hybrid use in relation to the vide variety of journey profiles. Also, to accurately compare cost per mile in relation to my previous BMW 420d GC (which was an amazingly capable and economical car).
Pivotal in my accurate costing of charging costs is this plug-in power meter I sourced through eBay, It is ridiculously capable for only £6.89! You programme it with your energy suppliers tariffs cost per KWh (from your electricity bill), then plug your granny charger into it and it displays how many watts the charger is drawing and the total cost to date based on your tariff. I have one permanently installed in the supply to an outdoor three pin charger socket. And another one I carry in the car so if I need to use anyone’s else’s three pin socket away from home, I can show them exactly what it has cost so I can reimburse them. Here’s the eBay link:

Electricity Power Consumption Energy Meter Monitor UK Plug in Watt Kwh Analyzer | eBay

Find many great new & used options and get the best deals for Electricity Power Consumption Energy Meter Monitor UK Plug in Watt Kwh Analyzer at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

 

[Gadget Geek]

If you are taking the pence/kWh from your bill, don't forget to add 5% VAT. That caught me out once.

 

[PedroPhev]

Good point, I’ve just checked my tariff to make sure I hadn’t made a schoolboy error, thankfully the tariffs I’m using included vat, but thanks for the heads up.

 

[Jomarkh]

I have a similar device but I only used it to check the current drawn by equipment.
I would not use it on a granny EVSE that is constantly drawing 10A 2.2kW as it two more potential weak points that could get warm.

 

[PedroPhev]

Agreed, and I was very cautious when I first used it, but so far neither of the two I use have shown any heating at all. I’ll keep a eye on it.

In addition the power meter can also display amps and voltage, useful for diagnosing wiring faults indicated by voltage drop or excessive current draw.