Conclusion by Max Fuchs, BIKE test editor
The Bosch PowerMore 250 fulfils its most important function with flying colours: it noticeably extends the range and, compared to many rival solutions, provides an above-average level of additional capacity. Anyone who regularly goes on long rides will find this offers real added value. Its weaknesses lie less in the battery itself than in the accessories. Particularly in the grubby day-to-day reality of mountain biking, the fiddly mounting system becomes a real nuisance over time.
Facts about the Bosch PowerMore 250
- Capacity: 250 Wh
- Size: 200 × 88 × 75 mm
- Weight: 1,497 grams, including the connection cable (BIKE measurement)
- Price: RRP €469 plus a Bosch PowerMore cable for €29
- Compatibility: Bosch Smart System, compatible bikes with PowerMore readiness
- Assembly: Retaining plate on the bottle cage threads
- Charging function: The spare battery is charged separately using the charger for the main battery
Range Extender: The name says it all
With the PowerMore 250, Bosch is taking a different approach to many of its competitors. Instead of a backup battery that’s as small as possible, Bosch is providing a genuine range booster with 250 watt-hours. Although this additional battery is consequently larger and heavier than many rival solutions, it offers a decisive advantage: it noticeably extends the bike’s range. Particularly on e-MTBs with 400 or 600 Wh batteries, this allows riders to gain numerous extra kilometres and metres of elevation gain, depending on the assistance level and terrain. In a direct comparison, Bosch thus offers significantly more additional energy than many rival models, which often provide only 160 to 180 Wh.
The PowerMore is particularly impressive on e-MTBs fitted with the 400 Wh PowerTube main battery. Combined with the additional battery, the total capacity rises to 650 Wh – which is even higher than that of many bikes equipped with the next-largest 600 Wh battery. This is precisely where the strength of the Bosch concept lies: the PowerMore is not just a small backup battery for the final few kilometres, but fundamentally expands the bike’s range of use. Whilst many other solutions merely provide a brief boost to range at the end of a ride, Bosch takes the bike into a whole new range category. This means a Light e-MTB remains light and agile for everyday use, yet offers sufficient reserves when needed for long rides, significant elevation gain and extended adventures.
How the PowerMore Range Extender works
Bosch has devised a clever solution for managing the PowerMore’s energy. If the auxiliary battery is connected before setting off, the main battery and the range extender battery share the load and discharge in parallel. As a result, both reach the end of their capacity at the same time. If, on the other hand, the PowerMore is only connected during the journey, the system initially uses only the auxiliary battery until the charge levels have equalised. Both batteries then switch back to operating in parallel.
The system operates reliably and ensures that both energy storage units are used as evenly as possible. There is, however, one small snag: when using the PowerMore exclusively, only around 80 per cent of the maximum motor power is available due to the different cell structure. It is therefore advisable to connect the range extender before setting off and to let both batteries work together from the outset.
What’s particularly exciting is the option to power a bike using only the PowerMore. On e-MTBs with a removable main battery, the large battery can stay at home or in the car. This opens up some interesting options, particularly in bike parks with lift access: The heavy main battery is removed from the down tube, making the bike noticeably lighter and more agile. For short transfers, climbs against the gradient or the journey back to the lift, the PowerMore still provides enough power so you don’t have to do without motor assistance entirely.
Criticism of the socket
Integration into the Bosch Smart System, on the other hand, works flawlessly. The system automatically recognises the PowerMore and integrates it seamlessly into the energy management system. The charging process, however, is less impressive. Although a single charger is sufficient for both the main and auxiliary batteries, they cannot be charged at the same time. After every ride, therefore, you have to switch the charging cable round. It’s made even more of a faff because the PowerMore usually has to be removed first in order to charge – and that’s often a real test of patience due to the fiddly mounting bracket.
The competition shows that there is a better way. On the Specialized Levo SL, the main battery and range extender charge in parallel via a Y-connector, without the need to remove the additional battery from the bike. Anyone who uses their range extender regularly will quickly come to appreciate this convenience. Bosch really needs to catch up here, as frequent riders in particular benefit enormously from hassle-free charging.
A difficult compromise
However, the high capacity takes its toll. Weighing in at around 1.5 kilograms, the PowerMore is one of the heaviest range extenders on the market. The 250 Wh battery is also rather bulky and takes up a fair amount of space on the down tube. Those who value every gram and the slimmest possible integration will find more compact solutions in other drive systems. Specialized, for example, packs the 180 Wh range extender for its Turbo Levo models into a water bottle-sized unit that fits into a special bottle cage. However, with its 250 Wh capacity, the Bosch unit delivers significantly more additional power and is in a league of its own when it comes to range.
A fiddly assembly job
Ironically, the PowerMore’s biggest weakness in the long-term test was its mounting system. Bosch uses a plastic plate that fits onto the bottle cage threads. The range extender is slid onto two plastic rails and then locked into place. It sounds simple – but it proved a constant nuisance in everyday use.
As soon as dust, sand or mud got in the way, the battery would regularly get stuck in the guide rails. Often, the only thing that helped was pressing firmly, shaking it or even tapping it gently until the PowerMore finally clicked into place. Removing it proved to be just as much of a test of patience – which was particularly annoying because the extra battery has to be removed every time for charging. Anyone who uses the Range Extender regularly is likely to find this process a nuisance very quickly.
As the months went by, the condition deteriorated further. The play between the plastic rails of the mounting plate and the battery mounts became visibly greater. After about half a year, the PowerMore was audibly rattling away on rough trails. Whilst this had no impact on its functionality, it did significantly detract from the overall impression of high quality. One would have expected a more robust and durable design, particularly from a premium system such as Bosch. Especially as the competition has long since demonstrated that range extenders can be fitted more easily and secured without any play in the long term.
A conciliatory ending?
All in all, the PowerMore 250 really comes into its own where it counts: it delivers noticeably greater range, integrates seamlessly into the Bosch Smart System and, in particular, turns Light e-MTBs with a 400 Wh battery into genuine long-distance bikes. There’s also a clever added benefit: on bikes with a removable main battery, the PowerMore can power the motor on its own – ideal, for example, for days at the bike park when a lighter bike promises more riding fun.
However, the overall positive impression is marred by the rather poorly designed mounting bracket and the fiddly charging process. Anyone who uses the range extender regularly is likely to find both of these issues a nuisance quite quickly. The PowerMore is therefore one of the most powerful and practical range extenders on the market – yet Bosch is squandering valuable potential with unnecessarily complicated peripherals.
Plus
- High additional capacity of 250 Wh
- A significantly greater increase in range than many competing solutions
- Turns 400 Wh Light e-MTBs into bikes with a total capacity of 650 Wh
- Smart energy management
- If the main battery is removable, the bike can also be powered exclusively by the PowerMore
- Reliable performance throughout the test
Minus
- Relatively large and heavy
- Difficult installation using the plastic guide rails
- Susceptible to dust, sand and mud
- Do not charge the main and auxiliary batteries at the same time whilst they are fitted
- Over time, play in the mount and rattling noises when off-road
Max Fuchs
Editor