Voltage Booster, Mark II

Back in 2009 we covered an off-the-shelf device that could boost the voltage going to a device. Designed to run laptops off a standard car supply, the product could raise the voltage to 15, 16, 18 or even 24V at a max output of 80 watts. It cost AUD$17 and worked pretty well – but rather than 80 watts, its max output was really more like 40 watts, absolute tops.

Well, now we’re back with another voltage booster – and this one is much improved.

It’s cheaper (unbelievably cheap at just AUD$7.65 including delivery!), has infinitely adjustable voltage output from 12 – 35V, and has a higher power rating. It’s also much better made.

Talking about the power rating, it’s rated at 150 watts (with added fan cooling), 100 watts without fan cooling (but maybe with bigger heatsinks), and we’d say on the basis of our testing, it’ll be very happy at 50 – 60 watts continuous… just as it comes out of the packet.

At the time of writing, the module was being sold on eBay by ‘bycoins’ and the vendor called it the “DC-DC 10-32V To 12-35V 150W Power Supply Boost Adjust Module Mobile Laptop Car”.

Using It

So if it will run items drawing up to about 50 watts, what can you use it for?

Another way of expressing that wattage is to say that the standard continuous current draw of the device shouldn’t be more than about 4 amps at 12V. In turn, that excludes high current fuel pumps that can easily draw up to 10 amps, and radiator fans that can take up 20 amps.   

So what can you run?

You can use the Voltage Booster to easily increase the pressure and output of windscreen washer pumps commonly used for intercooler water sprays.

You can use it to boost the output of interior lights, brake lights and reversing lights.

Depending on the measured current draw, you can use it to boost the flow of water/air intercooler pumps.

You could also use it with 50W headlights in order to brighten your main beam (one unit per light).

Finally, in non-automotive applications, you can use it to maintain the output of a nominally 12V lighting system, even as battery voltage falls. In testing, we found that the system would provide its boosted and regulated output down to an input voltage of 10V. To put that another way, there would be no change in light brightness from a fully-charged battery of 13.8V to a flat battery at 10V! That’s got major implications for camping and remote area lighting systems. 

Increasing Voltages?

But what happens to the device you’re powering when you increase the voltage going to it?

In short, not only will its performance improve, but its life will be reduced. In many cases, that’s of little concern – something like an intercooler water spray pump is used so little (in relative terms) that its life will still be fine. Incandescent light bulbs will have a shorter life, but as they’re a replacement item, again it’s no big deal.

However, you should select the increase in voltage with care. A motor (eg a pump) used infrequently in short bursts could be run at 18V without many issues, but a filament lamp being used for long periods shouldn’t be fed much over 15V. In general, make sure that items don’t get too hot!

Note that devices that use internal voltage regulators, or are current limited, shouldn’t be run at higher than normal voltages. Normally, there will simply be no difference in the performance of the device but in some cases (eg LEDs using dropping resistors), the device may be damaged by over-current. So LEDs and electronic bits and pieces like car radios and other electronic modules aren’t suitable for running at higher than their design voltage.

The module

The module comes as a built – but bare – circuit board. It’s about 65 x 50 x 30mm (L x W x H), has a heatsink along each long side, a four-terminal connection strip at one end and a multi-turn pot at the other end. It’s well made – in fact, a real quality item with clear connection markings (in English), good PCB design and four tapped metal spacers (on which it sits). Looking at it, it could easily sell for AUD$40 or more.

Connections are very easy – ‘IN’ positive and negative, and ‘OUT’ positive and negative. (Don’t get these connections around the wrong way, and make sure you don’t short-circuit the output.) Before powering-up, turn the pot many turns anti-clockwise to reduce the gain; turn it clockwise to slowly bring up the output voltage. The output voltage is easiest measured with a multimeter. Note that this diagram is the view from above.

Here’s an example wiring installation running a pump. When the wiring is complete, the board should be mounted in a ventilated box.

Efficiency? So how efficient is the module? Efficiency is important for two reasons. Firstly, the less efficient it is, the more heat it will have to dissipate. Secondly, the less efficient it is, the more energy it wastes – and if you’re running say a camping lighting system from a battery, you don’t want to waste much energy. The manufacturer claims an efficiency of 94 per cent when running with an input voltage of 19V, a 2.5 amp current draw, and an output of 16V. That’s not normally how you’d use it, though. In our testing, with an input voltage of 12.0V, an output of 14.7V and a current draw of 1.25A, the efficiency was 91 per cent. In other words, the power draw was 15.0W and the output power was 13.7W – an internal loss of 1.3W. That’s pretty good.

Conclusion

The real beauty of the device is that you can boost output without having to change what it is that you’re powering. So the original washer pump can stay in place – just alter the power feed to it. If you’re up-rating bulbs, you don’t need to find new higher wattage bulbs of the same fitting – just bump-up the voltage going to them. Cheap, simple and effective!