Finding a 48V 20Ah battery at a cheap price used to be difficult. Now there are literally over a dozen of them on Amazon, and the SWQQWEI 48V 20Ah is regularly near the top of the price-per-watt-hour lists. At a decent price per watt-hour for 960Wh, it's a good deal, but there are reasons to be cautious before ordering.
This is a generic box-style lithium battery and not a downtube or shark/hailong form factor, which will affect fit strongly and is the single thing that causes the most buyers to trip up. The actual riding performance is decent for the price, but you have to approach it with full knowledge of range and compatibility expectations.
Specs and Value
The basics: 48 volts, 20 amp-hours, 960 watt-hours. The cells are 18650 lithium-ion, welded. The BMS can handle a continuous 30 amps discharged which covers the majority of 48V hub motor setups from around 500W up through 1000W in power.
Physical specs
Weighs 8.5 pounds and measures 10.4 x 5.1 x 2.75 inches, about the size of a thick hardcover book. The 54.6V 3 amp charger has a little cooling fan as a nice touch since even 3 amp chargers generate real heat. A full charge takes roughly 5-6 hours from empty.
For the money you're getting a healthy amount of capacity. If you put this up against the rest of the 48V 20Ah selections in the battery comparison table, this one always ends up in the favorable/value price per watt hour tier. The protections built into the BMS include low voltage cutoff, overcharge protection, short circuit protection, reverse polarity protection, all the things you'd expect from a good pack.
Cycle life and longevity
700-1000 charge cycles the manufacturer claims, which translates to several years of regular use. That's reasonable for good quality 18650 cells, though the actual longevity depends greatly on how you store and charge the battery, as we tackle in the FAQ section below.
Form Factor and Compatibility
This is the one thing to get right before you order. The SWQQWEI 48V 20Ah is a generic rectangular pack. It's not designed to tuck into a downtube mount, a shark/hailong carrier, back rack bracket, etc. You'll have to strap, mount, or bag it externally, or wire it into something of your own design.
One Amazon reviewer put it even plainer: "Real big, real powerful, not an eBike battery. It's just a great big battery, won't fit on a bike as a slide-in, slide-out battery." That's a fair assessment if you're wanting a plug-and-play replacement for a standard ebike battery.
Where it works great are DIY builds, custom electric bikes with no dedicated battery compartment, scooters, e-trikes, golf carts or pretty much any project where you see yourself mounting it externally. Readers report using it on hoverboards, go-kart builds, three-wheelers, etc. The connector is an XT60, common to the DIY battery world and also RC.
Nicely, it includes an XT60 pigtail connector with leads already attached, which is a thoughtful addition. A few reviewers mentioned it. It means you can hook your battery directly to a controller without splicing the existing connector or hunting for a different pigtail for the pack you got. One builder said they were immediately able to wire it in and made the battery removable from their project. This is what you want.
Voltage compatibility: you'll want any 48V control system for this pack. If your bike runs a 36V or 52V controller, this battery isn't the right match. Check your controller specs prior to ordering.
Real-World Range
The listing says 45-48 miles per charge, based on the formula: Wh divided by Wh per mile (say 20) equals miles. That math works out on paper for a very light rider on flat terrain using full pedal assist at the lower end of speed. Real-world is different.
Amazon reviewers paint a more realistic story. One 4-star review says "About 20 miles out of this battery on my e-bike if I pedal a lot." That's more like what most riders experience. A heavier rider, the presence of hills, throttle in use, or heavier pedal/assist settings will all eat into that number. A reasonable real-world expectation for a 960Wh battery on a standard ebike is somewhere between 20-40 miles depending on your weight, terrain, speed, and how hard you're working the motor. If you do most of the pedaling and have a lighter assist on flat ground you'll be toward the high end. Throttle heavy and/or climbing hills regularly, plan on the low end.
That's still a respectable range for the price. Just don't go in expecting a real-world 45-mile ride.
What Amazon Reviewers Are Saying
There are 91 reviews and the average is 4.6 stars, so the picture is mostly positive. The common refrains: good battery for DIY projects and custom builds, fast shipping, and holds charge well over months of usage. More than one buyer has said they "use this on a whole bunch of different projects not just one ebike", and that versatility comes up a lot in reviews.
The poor reviews generally fell into three categories. The first, and most troubling, is that several people said the battery quit charging after a few months of light use and the buyer suspected a failed internal connection or BMS issue. That's one report out of 91, so not a huge deal but something to consider if you plan to depend on this for a daily ride with no backup.
The second category is compatibility: two buyers ordered the wrong voltage or the battery proved incompatible size-wise on their bike frame. That's a sourcing issue, and not necessarily a product defect. Know your bike's voltage, and check the frame and mounting carefully before you order.
The third category is a fulfillment issue where a buyer ordered but for whatever reason didn't get their item. The charger fan gets some positive comments in more than one review, and the XT60 pigtail connector is a pleasant surprise since usually you have to pay extra for those or they're just absent. Check current pricing on Amazon since the price on this one seems to be stable.
Who Should Buy This
The SWQQWEI 48V 20Ah is an ideal battery for DIY electric vehicle builders who are looking for a 48V pack and are okay with an externally mounted battery pack.
If you currently have a 48V bike with an external battery compartment, rather than a removable downtube or rear rack slot, this is a great option for you as well. Or, if you're building a scooter conversion or an electric project such as a go-kart, and need a pack with a solid 48V source at a decent price, this is a great battery.
If you want a battery that slides cleanly into a bike frame slot, look at downtube or shark/hailong form factor ebike batteries. Use the battery comparison table to filter options by form factor to find batteries that fit your bike.
See all 48V 20Ah options on Amazon if you want to compare before committing.
Frequently Asked Questions
Will this fit my standard ebike? Probably not as a direct slide-in replacement. This is a rectangular box battery rather than having the standard downtube or shark mounting system. If you've got an external battery compartment this will fit just fine, as will a custom build, but if your bike has a standard integrated battery slot, look for a battery that has the right form factor.
What connector does it use? This battery ships with an XT60 pigtail connector with leads already attached, so you can wire it directly to a controller. If your bike has a different connector, you'll need either an adapter or to splice your own connector.
What charger is included? A 54.6V, 3-amp charger with a small internal cooling fan. The charging speed is fairly moderate so plan on 5-6 hours to charge it from fully depleted. Charging at speed will eventually shorten the battery life and for this reason it's not recommended.
Is 960Wh enough for daily commuting? For most daily commuters, yes, without a problem. At 960Wh you're looking realistically at 20-35 miles of range depending on riding style. As long as your round trip is less than 20 miles long, and you can charge it at either end of your trip, you'll be just fine. If you want a little more buffer, you could consider a 25Ah or even a 30Ah option in the same voltage.
How many charge cycles will I get from this? The manufacturer suggests at least 700-1000 cycles. But at one charge a day that works out to a couple years of use. If you're careful about storage too, keeping charge in that 60-80% range and keeping it out of temperatures too hot or cold, you can expect a longer lifespan.
Will this work with my 48V Bafang mid-drive motor? Yes, just so long as you stay within that 30A discharge limit. Most Bafangs in the range of 250W-750W draw well below the 30A limit at 48V, so you should be fine overall. Check your individual motor for its peak current draw just to know for sure.