Posted on March 13, 2023
By Bryony Harrison

From lights and playback to heaters and even a kettle in the production office: there are numerous electrical items on set that consume power.

But how can you calculate the power requirements of all of this equipment in order to know which generator or battery pack to hire? How many will you need? And what are the cleaner alternatives if you don’t want to hire a traditional carbon emitting generator? What’s better – a VOLTstack, a Bluetti, or the latest in greener portable battery technology: the Instagrid ONE max?

As the industry moves away from wanting or even being allowed to use petrol or diesel generators, film crews are having to consider more carefully their power needs and their power usage throughout the shoot.

Our battery power solutions

Adding up your power requirements or ‘calculating power draw’

In the UK nearly all domestic electrical equipment draws under 3kW. A kettle for example uses up to 3kW of power but only for a short time. And a typical fridge will only use 300Watts while it’s cooling but will turn itself on and off throughout the day.

The power requirements of every bit of kit will state its maximum power draw on a label, usually on the back or underneath.

To calculate the total power draw if every bit of kit was turned on at once, you can simply add these numbers up to give your total power requirement. However, in practice, you’re very unlikely to run every bit of kit at once, so there is usually a lot of flexibility in this total figure. Best practice is to make sure you don’t have everything plugged into the same power source, so you can more easily monitor where the power is being used the most and act accordingly.

Understanding power capacity

Batteries all come with two very important pieces of information: how much power they can store and how much power you can draw out at one time. For example:

Kilowatt hours (kWh) lets you know how much power the battery contains in total. The number tells you how many hours the battery can produce 1kW of power. For example, a 2.1kWh battery can produce 1kW for 2.1 hours. You can divide the number of kWh by your total power requirements to give you the number of hours the battery would last if everything was drawing electricity at once. The output or ‘draw’ tells you the highest amount of power you can take from the battery.

Some examples using the Instagrid ONE max 2.1kWh:

A 32” TV screen uses 40Watts continually whilst on, so we can simply use 2.1kWh ÷ 0.04kW = 52.5 hours

A fridge drawing a maximum of 350 Watts is more difficult, whilst we have 2.1kWh ÷ 0.350Kw = 6 hours which gives your ‘worst case’, in reality, fridges do not constantly draw power, they switch themselves on and off and try to maintain a steady temperature. So the real figure depends on other factors like the temperature of the environment and how often it is opened. We have run a large freezer for over 24 hours with an Instagrid ONE max.

A kettle and an urn both draw 3kW, so like a lot of heaters they are at the heavier end of electrical requirements. An urn constantly drawing 3kW would not last long on any battery but with a kettle being turned on and off, you could estimate how many cups of tea you could make!

It’s important to try and gauge how much electricity you will use over time when considering your requirements.

A kettle typically draws 3kW but only needs 5 minutes to boil water for a few cuppas. So only the 5kW Voltstack and the Instagrid ONE max will give you enough power output to actually use a kettle. Using a bit of maths, we can see how many times that kettle can be boiled. 

2.1kWh Instagrid One Max / 3kW = 42 minutes, which means that if the kettle were used constantly you could boil it 8 times.

Voltstack 5.6kWh/3kW = 108 minutes which would boil the kettle up to 21 times.

At the other extreme, a fridge that only uses 350 watts while cooling might only use 1kW in a whole day. But this very much depends on the outside temperature, how many times it’s opened and what’s inside it.

Remember there are other considerations too. The Instagrid ONE max weighs only 20kg whilst the 5kWh VOLTstack weighs a considerable 150kg, but does come with wheels. So, consider using the VOLTstack when you won’t need to move much, and opt for the Instagrid ONE max when you want easily portable power.

As a guide, the following table calculates the power required and the approximate operating time using the Instagrid ONE max for common on set electrical items.

Some extension lead safety

It’s also important to remember that typical extension leads, even the ‘four way’ types can only handle 3kW in total. So you can use the adding up method above to ensure that you don’t overload it. For example; if you plug a 3kW hot water urn into a four way extension lead, you should definitely not plug anything else into it because you will overload it. Which means you could melt the plug, damage the kit, the location, or even start a fire. You can also easily melt a drum type extension lead by not unwinding it fully when using it near its capacity. The drum extension lead should say on it the maximum power you can draw without it being fully unwound, typically 750 Watts.

The different types of portable battery power

So which portable battery gives you the energy you need to power up your electrical equipment?

Instagrid ONE max

The 2.1kWh Instagrid ONE max battery is a silent, small and portable battery that weighs only 20kg, it can be easily carried around, so is much more flexible than any 5kW generator.

It has a 2.1kWh capacity, with 3.6kW power output, takes 2.5 hours to charge from a normal wall socket (or even from another generator). It has both a 13-amp and 16-amp socket, with an output voltage of 230VAC / 50Hz, and a 3600W power rating.

Made from recycled aluminium, this greener battery power pack saves up to 97% emissions compared to a diesel genny. Plus, the Instagrid ONE max doesn’t have an inverter, so it’s totally silent with no fumes and has an IP54 rating meaning it’s splashproof too.

The Instagrid ONE max has been priced with a view to a production using 3 or 4 or more of these packs to power different parts of a shoot, rather than relying on one big genny. You can run your LED lights, your production office, your playback, tea table, each with an Instagrid ONE max (or two). The Instagrid ONE max is the future of silent battery-powered filming.

Coming soon the Instagrid ONE max will also have a docking station to enable two or more batteries to be linked together and an app to easily monitor electricity usage.

VOLTstack

One of the first battery power solutions on set, the VOLTstack 2kW or VOLTstack 5kWh can power many elements of your shoot. Both are silent and come on small wheels. They are considerably heavier than the other options, with the 5kWh VOLTstack weighing in at 150kg. So great for flat, smooth surfaces, but not so good for navigating rough terrain.

The 2kW option provides 2.4kWh of power for 1 hour with a continuous draw of 2.4kW. The 5kW option provides 5kWh of power for 1 hour with a continuous draw of 4.8kWh. Both batteries recharge in just 2–3 hours using a 13-amp socket.  The 5kWh VOLTstack is ideal for powering laptops, printers, LED lights and fans in your production office and will run a fridge for three days.

Bluetti power pack

This 2.4kWh Bluetti portable battery power pack is useful with lower power requirements. It’s small and weighs just 23kg, but provides just 1kWh power output. It comes with 2 x 13amp plug sockets and 4 x USB sockets. So it can easily power up a laptop and other USB C enabled devices. The downside? It takes 12 hours to charge.

So, what does it cost to hire a silent, portable battery?

For portability, flexibility, charge times and hire costs, it’s easy to see why the Instagrid ONE max is fast-becoming the production team’s favourite.

The 2.1kWh Instagrid ONE max costs £225 per unit to hire per week or £75 per day.

The 2.4kWh VOLTstack costs £355 per unit per week.

The 5.6kW VOLTstack costs £715 per unit per week.

Bluetti 2.4kWh battery power pack cost £225 per unit per week or £75 per day.

For more information on which generator or power pack to hire for your shoot, get in touch with the Get Set Hire team.  

Products that work well with a battery power solution