You're seriously considering a battery pack of 998.4 watt-hours. That's a huge amount of power packed into a rear rack battery like the Yose Power 48V 20.8Ah. And for many riders, that could be enough to fundamentally change the nature of their riding experience.
At 998 Wh (nearly one kWh), a rider using a 500 W or 750 W ebike will likely be able to make it home without needing to recharge, provided their controller doesn't max out at low voltage.
Specs and Build Quality
The key specifications for this battery include a nominal voltage of 48 V, a maximum discharge current of 40 amps, and a total energy storage of 998.4 watt-hours. Each of the 13 groups of eight lithium-ion cells used in the battery is connected in both series and parallel. 13 cells are used in series to provide the required voltage, while all eight cells in each group are connected together in parallel to increase the overall capacity of each group. Using eight cells in parallel increases the maximum current handling ability of the entire pack.
Instead of being mounted under the downtube or hidden inside the frame triangle, this rear rack-mounted battery attaches directly to the rack located behind the seat tube. While having the battery attached to the rack may change the weight distribution of your bike compared to a traditional downtube pack, attaching the battery to a rack provides freedom to attach additional accessories (like panniers) to your bike frame.
The Anderson connector output connection on the battery is designed to handle high currents. An Anderson connector is commonly found on large commercial devices such as power tools and industrial machinery. They are often used because they are reliable, easy to connect and disconnect and can withstand high currents.
The marketing materials indicate compatibility with motors ranging from 250 watts to 1500 watts. However, the user should ensure that the controller (which regulates the flow of electrical energy to the motor) can support discharges above 25A.
BMS and Safety Features
Yose Power specifies a 40A BMS with a max sustained discharge rating of 40A and a higher-trip-point cutoff of approximately 70A. A 40A sustained discharge rating would be about the upper end for a 1500W motor operating at 48V. The higher trip point protects against accidental spikes by limiting the time the battery remains under stress.
Each cell within the pack is rated as "Grade A." Grade A cells are typically made with higher quality materials and have longer lifespans than lower-grade cells. Yose Power rates these cells to last for over 1000 charge/discharge cycles. No one knows until you run a pack through several hundred cycles whether those claims are true. Still, using cells from a reputable manufacturer makes it easier to approach that claim.
The pack includes a small 5V USB port on the front of the pack. There aren't many reasons why someone might care about including a USB port on a rear-rack mounted pack. One possible reason is to let you trickle-charge your smartphone or another device while parked at a coffee shop.
Before shipping out each pack, the seller says they perform Quality Control (QC) tests on them. Although you wouldn't know anything about those tests unless you were inspecting the packaging yourself, you would presumably see evidence of such testing based on items included in the package itself. In addition to providing information on installing and removing the pack from your bike (and troubleshooting), the packaging includes spare fuses, an Anderson-to-Anderson adapter cable, two keys for locking the pack, and a 54.6V DC input 3A AC/DC converter (charger).
Since you'll never lose your keys (you'll always carry them with you), there's no better deterrent against theft than making sure thieves can't simply walk away with your power source when you leave it unattended at your local grocery store.
Range and Real-World Performance
Amazon currently lists the Yose Power rear rack mounted lithium ion battery pack as having a four-and-one-half star rating based upon eight customer reviews, although that is clearly a small sampling of customers who have purchased this product. Although Amazon ratings should be viewed with caution, given that there are thousands of products listed on the site, positive comments from customers appear to be generally positive regarding performance expectations.
Customers have stated that this battery produces as advertised, giving riders solid range estimates, which is precisely what you hope for from a pack of this size.
Some riders report that this battery matches their capacity expectations, allowing for extended afternoon rides on a variety of terrains.
As well as a substantial amount of capacity, however, this battery carries an associated price tag. The price per watt-hour of capacity is greater than what you'd pay for some bare-bones packs offered by lesser-known vendors. Your payment for this battery is essentially purchasing reliability and warranty from Yose Power (a recognized vendor in the industry), along with a high-quality 40A BMS, quality control testing prior to shipment, and the complete set of accessories that come with the pack.
Ultimately, whether or not you believe that additional expense is justified will depend entirely on what you consider to be important, price vs. peace-of-mind.
In terms of charging speed, the charger supplied with this pack is 54.6V DC at 3 amps. Charging time will therefore be approximately seven hours (from empty) when fully charged. If you prefer faster top-offs during shorter rides, then you'll want to look into using a charger capable of delivering more than three amps.
Who Is This Battery For?
If you're willing to spend money on high-end components and worry less about losing money later due to failed packs, this pack might represent a great option for building out your high-powered ebike. With respect to cost, keep in mind that even though there are less expensive options available, you get what you pay for, and in this case, you're paying for brand-name reliability and warranty along with a robust BMS and QC testing.
Installation on most racks is simple, just bolt-on. Installation can vary depending on your specific rack design, so measure carefully before placing an order. If you're comfortable installing racks on your bike, installation of this pack is unlikely to be difficult.
How much range you can reasonably expect varies greatly depending upon factors related to your motor(s), horsepower (watts), your body mass (kg), terrain, how much you use throttle versus pedaling, but users consistently report excellent ranges on typical setups of 750 watts or less due to its massive 998Wh capacity. Therefore, it's fair to assume this is truly a range-focused battery rather than a "quick hop" around-town battery. If you want to see how it stacks up against downtube and frame options from other brands, our blog has more battery breakdowns worth a read.
Frequently Asked Questions
Will this battery work with my 48V motor?
If your motor and controller run on 48V, the battery is electrically compatible across the 250W to 1500W range. The catch is matching the 40A discharge to your controller's limits. Check your controller's max amp rating before you buy so the BMS isn't tripping on you mid-ride.
How long does a full charge take?
The included 54.6V 3A charger takes around 7 hours to go from empty to full. It's not fast, but for overnight charging it's perfectly workable. If you want quicker top-ups you'd be looking at a higher amperage charger.
Is the rear rack mount easy to install?
Generally yes, especially if your bike already has a rack. The battery sits on a holder base and locks with the included keys. The exact mounting depends on your rack design, so double check the measurements against your setup before ordering.
How much range can I actually expect?
That depends a lot on your motor power, your weight, terrain, and how much you pedal. On a typical 750W setup, users report very long rides thanks to the 998Wh capacity. It's safe to say this is a battery built for big range, not a quick hop around town.
What does the 40A BMS actually protect against?
The BMS is designed to prevent damage caused by excessive charge levels, excessive discharge levels, excessive current flow through the cells themselves, and short circuit conditions. It prevents overcharging, over-discharging, exceeding maximum allowable sustained current, and short-circuits, with a 40A sustained discharge limit and a trip threshold around 70A for surges.
Is the extra cost worth it over cheaper batteries?
That's the real question, and it comes down to what you value. You're paying more per watt hour here than for some budget packs, but you're getting a known brand, a proper 40A BMS, QC testing, and the full accessory bundle. For a high-power build where you don't want to gamble on a mystery pack, a lot of riders find it worth it. You can check the current price and details on Amazon to see if it fits your budget.
The rear rack battery segment has a few strong options, and the Yose Power 48V 20.8Ah is one of the bigger capacity plays in it. If you want to see how it stacks up against downtube and frame options from other brands, our blog has more battery breakdowns worth a read before you pull the trigger.