The XISENY 48V 13Ah folding-bike battery is gone from Amazon, and if you own a NARRAK, APYEAR or EBKAROCY folding ebike and need a replacement, the useful thing left is how to find a pack that fits. Its listing called it a silver fish, which it isn't, and that name will send people to the wrong battery.
Sold as a silver fish, built as a folding-frame pack
The name on this listing was search bait, because a true silver fish battery slides onto a rail and sits on a base plate that carries the discharge connector. If you search for a silver fish replacement, you'll find rail packs that can't go inside a folding frame, and the reverse is just as true. Search by the frame type instead if you want a part that actually fits.
This pack is a long aluminium bar with black end caps that slides inside the frame of a folding bike. The listing's own images show the install in three steps: open the folding buckle and push the battery into the frame, turn the key to lock it in, then close the fastener. There's no rail and no base plate anywhere in that process.
The recorded title named three folding ebike brands it was meant for, NARRAK, APYEAR and EBKAROCY, and a motor range of 250W to 1000W. Treat that as a starting point rather than a promise. Folding bikes from one brand change frame shapes between models, and the listing itself told buyers to check the size and the port against their old battery before ordering.
Three numbers to measure: 420, 113 and 58mm
The images show this pack is 420mm long, 113mm tall and 58mm wide, or 16.54 by 4.45 by 2.28 inches, and they carried a notice badge that simply said "Battery Size". Measure your old pack against those three numbers before you order any replacement. An in-frame battery has no slack the way a rail pack does, so a few millimetres too long means the frame won't close over it.
Then do the checks that em3ev's folding-bike fit guide recommends. Fold the bike slowly and watch what moves into the battery space: the hinge, the crank, the cables and the latch. Make sure you can reach the lock with the key, and that the pack slides far enough to come out. A pack that fits with the bike open can still foul the hinge once it's folded.
We've covered other 48V 13Ah folding packs, including the Vodipower 48V 13Ah and the Cefito 48V 13Ah. Don't assume either one shares this pack's shape just because the capacity matches. Hold every candidate up against the same three measurements and the same port photo, and treat a listing without dimensions as a listing you can't check.
While the old battery is out, read its label. Write down the voltage, the amp-hours, and the full-charge voltage printed on the charger. A 48V lithium pack is full at 54.6V, so a charger rated for anything else belongs to a different battery.
The 5-pin port matters more than the voltage
The listing warned that the pack has a 5-pin discharge opening with ribbing around it, showed one right port next to two wrong ones, and told buyers to compare with the original.
Five pins is common, but the layout and polarity differ between makers, so a pack can match 48V and still not connect, or connect the wrong way round. Photograph your old port straight on before you shop, and compare pin count, shape and the ribbing around the opening with the listing photos of any replacement. If a seller can't show you a clear picture of the port, move on.
Use the charger meant for the pack. Similar-looking folding-bike batteries aren't automatically interchangeable, and that goes for the charging plug and the charger voltage as much as the frame fit.
What 624Wh bought you, and at what price per watt-hour
This 48V 13Ah pack held 624Wh. Two range guides, including em3ev's 48V range figures, put throttle-only riding at roughly 20 to 30 Wh per mile and pedal assist at roughly 12 to 18. That works out to about 21 to 31 miles on throttle, or 35 to 52 miles on pedal assist. Plan on the lower end if you lean on the throttle.
The listing's other option, a 15Ah version, would have held 720Wh. On the same figures that's about 24 to 36 miles on throttle and 40 to 60 on pedal assist, if a 15Ah replacement in the same size turns up.
At its last recorded price, this pack sat in the pricier third of the batteries we track by price per watt-hour, so it wasn't a bargain even while it was on sale. Several larger 16Ah and 20Ah packs we track cost less per watt-hour, though a silver-fish label tells you nothing about whether a pack goes inside a folding frame, as this very listing shows. You can compare them yourself in the ebike battery table. For a folding bike, fit decides first and price per watt-hour second.
The listing had a 4.3-star rating when it was live, but no review text was ever recorded, so there's nothing to say about how it held up. Search current 48V folding-bike packs with your measurements and port photo in hand.
FAQ
Can I still buy the XISENY 48V 13Ah battery?
No. The Amazon listing now returns a page-not-found error, and a search for the brand shows no live XISENY battery. You'll need a replacement that matches its size and port.
Will a silver fish battery fit my folding ebike?
Usually not. A silver fish slides onto a rail and sits on a base plate, while this pack slides inside the frame. Check the mounting style before anything else.
What are the dimensions of the XISENY battery?
It measures 420mm long, 113mm tall and 58mm wide. Measure your old pack and the space in your frame, then fold the bike to check nothing hits it.
What connector does this battery use?
A 5-pin discharge opening with ribbing around it. Five pins doesn't guarantee the same layout or polarity, so compare photos of both ports before you order.
How far will a 48V 13Ah battery go?
About 21 to 31 miles on throttle or 35 to 52 miles on pedal assist, based on general category figures. Your speed, weight and hills move those numbers a lot.