Charging with a smart plug on a extension lead

I have just got a Twizy and loving it! Currently I am charging on a extension lead (reel completely out) connected to a plug in the garage. Was wondering if it’s possible to connect this to the extension lead safely? So then I can set a timer.

Many thanks

Welcome! In the world of extension leads there are various levels of quality and construction. The extension lead needs to be rated for 13A (some are rated lower!). The socket should be weatherproof if it’s left outside for any period of time as well.

Always check the plug on the Twizy and the plug inside the garage whilst the twizy is charging, to make sure the plug is not getting hot. Some cheap sockets and plugs tend to get too hot after a few hours pulling a continious load, so it is worth being wary of.

Lastly - I would personally avoid plug top timers as whilst some claim to handle 13A, many are poorly constructed and might not be able to take the 2kW the twizy pulls for 3+ hours for a full charge.

In the long term, it’s better to arrange for a proper Masterseal 13A weatherproof outside socket to be installed where you intend to charge up.

All sorted with the extension lead. It is waterproof and 13A. Seems to be working well and doesn’t get hot which is good.

It’s whether I can connect a smart plug to it? This would be handy in winter so I can charge the car just before I go to work where the battery would be warm.

Just like any plug top timer - personally I would avoid smart plugs for any heavy loads like charging a Twizy. The risk of them overheating and burning out is real. A lot of them have relays in them which are not really rated for continious high current draws. You might be fine and find a smart plug timer which can cope - or you could luck out and it burns out and melts. Not worth the risk in my opinion.

Do have a socket on an immersion tank timer. Worked well for last few years on my Twizy

That’s a better solution. Immersion element timers are typically rated for 3kW for prolonged periods of time.

I have a meross smart plug that works a treat. Shows how much energy the twizy is pulling - and can switch it on and off via smartthings or the app. :+1:

Cool. I think your right. I won’t risk it. Thanks for ur help.

I use a sonoff pow r2 since the beginning (one year and a half) without any problems. Its main purpose is to allow me to start charging as late as possible to avoid keeping high charge in the accumulator, and to disconnect before it is fully charged, thus extending battery life. 1.5 years and ~25k km since purchase and SOH is still 100%.

also rocking a few of these around the house , no issues yet :slightly_smiling_face:

I would avoid the cheap timers my twizy melted mine ,it was rated at 13amp but in reality more like 3amp

next time i’m charging i’ll grab some themo images to see just how hot it gets , I know the plug socket can get up to 60C in the sunlight.

this was on friday during the day time temperature of 31C

my sonoff is on the otherside of the door in a aircooled garage.

took my sonoff module apart , been charging the Twizy over one year.

looks great , no issues with this smart module.

Word of warning, they are not all the same. Maybe mine was a fake? It is not the latest version but sold as max load of 16 amps. I had about 2.2kw load (pool heater) and after a long while I noticed it had melted.

The is an old thread here:

I look at the first Sonoff and thought those tracks look thin for that current. Then saw the second and they are even thinner. I was going to swap my Immersion timer but will need to reconsider.

Mine was to be the Biitzwolf (BW-SS1) tracks are thicker than the burnt out Sonoff, but longer than the good one. Supposed to be rated at 3.3kW (15amps) which doesn’t work out (13.75a). But as the Twizy only needs 10amps there is some headroom.

mine is the 2018 version that has the track tinning to beef up the current and it probably only gets used once a week for a three hour charge in the summer and less in the winter.

i’ll get some themo pictures next time i charge to see the heating effect from the current draw.

also it only draws 10A , I can see that from my charging history.


I have been using a Z-wave Wall Plug from Fibaro for more than a year without any issue. It allows me to measure the real kWh consuption and create charging schedules if I want, although I am only using it for measuring the kwh. if you have a Z-wave controller, you can use it safely.


The issue is manufacturing inconsistency and endurance testing. A product might say its rated to 13 or 16A but not all manufacturers test to that maximum load (cheap Chinese made stuff often don’t) and those that do, probably don’t test for extended run times into several hours and test for contact longevity making amd breaking that maximum rated current.

I work for a manufacturing company that makes high current appliances. There’s a lot of research & testing done to ensure switchgear can withstand the loads and high currents for extended runtime. I’ve also seen my fair share of melted plug in timers that just aren’t up to the task of prolonged heavy current use.

I wonder if Kenneth will ever update Powerbox to allow different charging speeds / enable disable charging commamd or a timer on the phone app so a spare mobile can be left in the car to trigger charging at the right time? Bit like what OVMS can do…

I thought the powerbox could limit the charging speed? Maybe I’m confuzzled though. It happens :dizzy_face: