One of the useful developments in battery operated power tool systems of recent years is that manufacturers have woken up to the merits of having a universal battery system that powers a large range of different tools, ranging from power tools for the workshop to garden tools and even some general domestic devices for home or home-away-from-home. Added to this is the welcome benefit of being able to buy the batteries for these systems at a reasonable price, instead of the common former practice of manufacturers charging an enormous markup on these items to force people to purchase complete new tool kits. The number of manufacturers producing universal battery tool ranges keeps increasing in the marketplace, but we have chosen to focus on Makita and Ryobi as the preferred manufacturers of choice for range or quality. Makita tools tend to be robust and the higher range models suitable for professional use; Ryobi tools are intended only for domestic use and therefore cheaper, but still of reasonable quality for the price. Hence in the future this blog will carry a series of reviews of different Makita and Ryobi universal battery products. Today we are getting a look at the Ryobi OB18150 150VA 240V inverter, and future products likely to be evaluated could include the soldering iron/station, power scrubber and bluetooth speaker products.
The idea behind this device is to generate 240V power from a One+ 18V battery at approximately 150 watts. The actual correct capacity description is 150VA, which means in practice 150 watts only if the voltage and current are in phase, typically the case when driving resistive loads such as incandescent light bulbs. For other types of loads, if the voltage and current are not in phase, then the actual output will be less than 150 watts. Essentially, the maximum current that can be supplied at 240V is slighly over half an amp. This is still enough to run some useful loads. Apart from the mains socket outlet, there are two other functions built into the OB18150: a pair of USB sockets at the rear can supply a total of 2.4 amps to one or two devices, and a LED light on top can be switched on to one of two brightness levels, or off.
This inverter is a useful device to have in out-and-about or home-away-from-home type situations, for example on a worksite or camping, where one may be away from regular power for a while and need to charge a laptop or another battery powered device, especially those that can’t be charged with a USB port. Here we are thinking of various cameras we have owned that have to have their batteries taken out and put in the charger that they come with to charge up. So this means the typical USB power bank is of little use because unless a special battery charger is obtained, USB charging is simply not an option. So that’s where a device like this comes in handy, and especially so if we have other devices in the Ryobi One+ system we can use the batteries in for most of the time when the inverter is not needed.
The OB18150 comes without its own battery or charger, so we separately purchased a One+ 18V 4.0Ah battery and 2 A charger kit to power the inverter. The inverter, somewhat controversially, produces a modified sine wave output. This means that the waveform of voltage/current, whilst rising and falling in a similar manner to the sine wave we normally see on mains power supplies, which is what is typically produced by mechanical generators, achieves this output not by smoothly varying the voltage or current, but by rapidly switching these on and off with simpler electronics; thus the waveform could be described as a stepped square wave, with the steps making the waveform somewhat more rounded and less square. There are inverters around that produce pure sine waves, such as the more expensive Ryobi 36V 300VA inverter, which also uses a different battery type from the One+ and so would create incompatibilities with other Ryobi One+ battery system tools. Hence we elected to stay with the OB18150 despite its admitted limitations in the quality of the output power. As it turns out, none of our battery chargers tested with the unit had problems with the output waveform, but it is important to note that some devices, particularly of an audio nature, are sensitive to the waveform quality and may not work well. However many such devices such as those that use a compressor are likely to require a greater capacity unit that can supply more power than 150VA in any case.
So we feel confident that having this device available in the household will prove useful in a range of situations and we are planning to purchase a second 4.0Ah One+ battery to allow for greater usage on a charge. Our unit came from Bunnings at a cost of NZ$129.00. The One+ 18V 4.0Ah battery and charger kit cost an additional $179.00 from the same supplier.