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FUTURE SHOCK Outside Broadcast
battery for the technical power supply wasn’t quite as straightforward as they had hoped. “The manufacturers of the vehicles won’t release the information you need in order to connect directly to the vehicle battery system. Because of issues with safety and managing the battery capacity, they’re very reluctant to make that power source accessible to third parties. So our technical power installation had to remain separate from the vehicle installation. “But what we could do is use the same charging port as the vehicle battery. The vehicle plugs into the mains for charging, and we can intercept that current by putting an intelligent box behind where the vehicle connects to the charging point. We can then tap off some of the current to charge our technical batteries powering the broadcast equipment and leave the rest for the vehicle.” In addition to solving the problem of using the vehicle charging port to power the technical batteries, the Megahertz team was also able to adapt the vehicle’s in-built 12-volt system which powers things like lights, wipers and fans, to be able to top up the technical batteries. “The vehicle has a huge lithium iron battery that drives the traction and drives you around. But out of that system is the equivalent of a vehicle alternator that powers a 12-volt system in the vehicle, with a 12-volt battery, 12-volt wiper motors, 12-volt fans and so forth. We can attach to that because our technical system is also 12 volts. We isolate it and can switch it on and
off via a DC to DC converter. That means we have the ability to take 20 to 30 amps out of the vehicle system and put that into our technical system. “If you are coming towards the end of a job and your technical batteries are depleted, and you need to just run a bit longer to finish something – and your vehicle charge is relatively healthy – you can turn this switch on and suck current from the vehicle system. The system is set to 20 to 30 amps, but tests showed it was capable of producing 70 to 80 amps, about the same amount of power available in a petrol or diesel engine alternator. “It’s not enough to run it forever - and, of course, as you’re doing it you’re depleting your range to get home – but at least it gives you the option of just topping it up if needed.” identical to the two petrol-fuelled vehicles Megahertz previously made for the BBC, so about the only real training that crews required was in how to configure this charge allotment. Setting it incorrectly might result in a fully charged technical battery with no power to drive anywhere. In fact, during development, the internal converter was set to automatically top up the technical batteries, which threatened to steal power from the main drive batteries without anyone knowing. “We didn’t know quite what happened. The vehicle battery was fully charged – and MANNING THE SWITCH Internally, the ev-SAT was virtually
GREEN MACHINE Megahertz’s first green vehicle is a Nissan e-NV200 electric van fully kitted out inside like a standard OB van.
then it wasn’t. Afterwards we realised that the system was too clever. It decided by itself that it was getting low on technical battery and so started pulling charge out of the vehicle batteries. It was a setting in the touchscreen controls which we easily fixed. Those are the kinds of things you learn when you start testing.” NOT ROCKET SCIENCE There’s no question that electric vehicle development is the future – if we’re to have a future – but Burgess points out that it’s not rocket science. “It’s actually all relatively straightforward. What we’re doing is not particularly clever, really. There’s a clever bit under the bonnet that mimics the charging point. But because these charging points have to be used by the public they have to be very robust. You can’t have sophisticated electronics talking serial protocol and all this kind of thing. It’s simply voltages and pulses.”
STEVE BURGESS “We thought, ‘Wouldn’t it be nice if you could actually use an electric vehicle and share the power system?’”
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