Before you buy anything else about this pack know that it has seven reviews and is rated at 3.4 stars. That tells you more than most spec sheets will ever tell you. A 874 wh pack for less than 300 dollars on amazon seems almost laughably good. But, the question really is does that low review count and middle of the road score mean you should be cautious about buying this one or is it just a solid cheap option with not enough people yet to have bought it.
I'm going to cover all of the specs, the safety features, the real world math behind how many miles you'll get on a charge, and exactly who should take a chance on this product.
Specs and Build Quality
First the numbers. This is a 48v battery that is rated at 18.2 amps/hours (ah). That works out to 874 watts/hour. To put that in perspective, that's a bunch of juice... Equivalent to what many stock 48v packs say they're capable of carrying on a long trip. The math is easy enough. Voltage x amp hours = watts/hour, so 48v x 18.2 ah = 874 wh. More wh = more miles before you find yourself looking for an outlet.
Size matters more than you think. The dimensions of the rack portion of this battery are listed as 476mm wide x 165 mm tall x 380mm deep. That's approximately 18.7 inches wide x 6.5 inches tall x 14.9 inches deep. So you'd best make sure your rack is large enough to support this massive piece of battery prior to purchasing.
It is built using an aluminum alloy casing. Aluminum is excellent for both the weight and the heat dissipation characteristics of this product. The entire unit is designed to attach to your rear rack via the included rack attachment pieces.
As for the individual cells within this pack, Varstrom doesn't list a specific cell manufacturer within their amazon listing, which warrants mentioning. As previously stated, the chemistry type is standard lithium, the same chemistry found in most of the 48 v ebike batteries currently available on the market. However, "no name" cells are why budget packs often sell for so cheap. Without removing the casing and verifying each cell individually there is no way to determine the quality of those cells. Therefore, you are relying solely upon the reputation of the brand and the integrity of the bms to ensure your safety. That doesn't necessarily preclude it from working just fine for years to come, however it is something you should be aware of prior to making a decision.
BMS Safety and Design Features
This battery comes equipped with a 30A bms, which is the actual component that prevents you from having your garage burn down. In addition to protecting against fire hazards due to electrical shorts or overheating, the bms protects against overcharging and overdischarging. Since we are discussing a 48v system capable of drawing significant amounts of current (up to 1500w from a motor), these protective measures matter. If you've ever seen a low-cost pack swell up after being completely depleted, you understand precisely why a reliable bms is worth every penny.
There is a 6-pin connector on the discharge end of this pack, which is something to double-check prior to buying. Rear rack batteries are very seldom compatible between manufacturers on the connector alone. Prior to buying this pack, you need to check that your bike's connector matches this.
According to the listing information, this battery is compatible with motors ranging from 200W to 1500W operating at 48v. That encompasses virtually all types of configurations possible, but the connector pinout will be the actual showstopper regarding installing this pack.
In addition to the pack itself, the packaging contains a spare set of fuses, a safety lock and key so nobody can walk off with your electricity source while you step away for a cup of coffee, an aluminum rear rack, a free 3amp fast charger, and a taillight for nighttime riding.
The warranty details aren't published anywhere in the seller's description or in amazon's description either.
Range and Real-World Performance
Finally, everybody really cares about this stuff, how far will it go?! Real world range is determined by your motor wattage, weight, terrain, assist level and how much you pedal. A cyclist on a medium-sized motor utilizing moderate assistance levels can fairly expect a respectable amount of riding distance from 874Wh. A rider on a high-wattage motor, using primarily throttle input with a very hilly commute will drastically reduce that range.
Throttle-only operation on high-power motors eat watt-hours at roughly double the speed compared to pedal assist in most scenarios.
Here is the harsh reality about claimed capacities: nobody delivers lab range in real world riding scenarios and budget packs underdeliver relatively more often than premium ones. The reviewers posting thus far fall into two camps: cyclists happy with their capacity and cyclists who encountered problems doing so. Exactly what you'd expect given a 3.4 star average and such a tiny number of reviews. One great review combined with one terrible review can quickly bring down that average significantly. So don't try to draw too much conclusion from that metric one way or the other. It tells you nothing other than this isn't a proven, high volume item.
One thing you might want to check before planning to depend on this pack for daily commuting purposes is that the tail-light and rack mounts work properly on your particular frame. Riders report that fit can be finicky depending on bike model. Due to its size, this pack extends farther outwards past your rear wheel than most downtube packs would. Thusly, the additional force caused by poor-quality pavement causes increased stress on your rack mounting points. Therefore verify your rack meets these demands. You can browse through what others are saying about this product in our latest ebike battery reviews page to see if their concerns relate to your particular bike configuration, and click here to view the latest specifications for this pack on amazon.
Who Is This Battery For
This pack is best suited for DIY riders who already have a controller for their ebike rated at 48 volts, who know their connectors (since rear rack packs rarely match connectors between brands), and who desire a large capacity rear rack pack without breaking bank.
If you are replacing a dead pack and your ebike has already been configured to utilize a rear rack form factor, then this is a relatively straight forward option.
At around 220 dollars it appears to be one of the most cost effective ways to obtain 874Wh in a bolt-on package as well as a nearly complete kit (with rear rack, charger, lock and key, and taillight).
While I feel compelled to be forthcoming about the fact that it holds only 7 reviews and an average rating of 3.4 stars that is certainly a warning sign that you should seriously consider prior to making a purchase. An otherwise solid product with dozens of reviews and an average rating of 3.4 stars would be viewed as vastly different from one that has only seven reviews with an average rating of 3.4 stars. When the reviewer base is this small, one irate customer who received a lemon or had compatibility issues can depress that average down considerably and conversely one positive review can elevate it similarly. You are assuming substantially greater uncertainty about reliability than would exist were you to choose a highly reviewed pack from an experienced manufacturer. The advantage is price. Disadvantage is uncertainty.
You may prefer to pay more money for a reputable brand with a long history of reviews if you don't wish to troubleshoot your own ebike or want a pack that won't give you grief when running low.
If you're handy, you've confirmed the connector type utilized by your ebike and you're willing to assume some degree of risk in lieu of saving substantial cash, this is a logical gamble.
However, please keep in mind you are wagering on fitment as well as reliability.
Whether or not the reduced pricing represents sufficient justification for accepting said risks are decisions that only you can make, and you can compare it against other rear rack options before deciding.
Frequently Asked Questions
Does the Varstrom 48v 18.2 ah battery fit my ebike?
Whether or not it fits depends upon three factors: your motor voltage rating. The connector type utilized by your ebike. Your rear rack dimension.
Since it is intended for use with systems rated at 48v it requires an ebike controller with matching voltage ratings. The connector type utilized on the output of this battery is a six-pin connector so verify your ebike utilizes an identical connector type.
Lastly, since it weighs roughly twenty pounds and has an external dimension measuring approximately eighteen point seven inches wide x sixteen point five inches tall x fourteen point nine inches deep, please verify your rear rack is sufficiently sized prior to placing an order.
How long does it take to recharge the battery using the included charger?
Your new Varstrom ebike battery includes complimentary shipping with a free three amp fast charger. Recharging from empty using this fast charger should take multiple hours (depending upon charging time based upon remaining wh capacity), which is typical for any battery in excess of fifteen hundred wh capacity.
All packaging materials include complimentary fuses (spare). A safety lock & key (to prevent unauthorized access). Aluminum rear rack. Free three amp fast charger. And led taillight for nighttime riding.
Is it irresponsible to purchase an ebike battery with only seven reviews that averages three-and-a-half stars?
That could be considered reckless behavior but not immediately. Weigh the savings provided by this product against the added risk posed by the limited number of reviews.
With only seven total reviews, regardless of whether they are all positive or negative, one unhappy reviewer could negatively affect that average greatly, even if he was wrongfully upset with his experience with his new battery. Conversely, one extremely satisfied customer could positively influence that average equally rapidly as well.
Therefore, when comparing an ebike battery pack with numerous reviewers averaging three-and-one half stars versus an ebike battery pack with seven reviewers averaging three-and-a-half stars you're taking on significantly more uncertainty about its performance than you would be with an ebike battery pack from an established brand that has hundreds of reviewers.
Ultimately it will be your decision whether or not you believe that difference in uncertainty justifies the savings offered by this pack.
How far will this battery allow me travel before needing recharged?
Real-world distance traveled prior to needing recharged varies greatly based upon several variables including. Motor wattage. Rider weight. Terrain difficulties. Level of assist utilized during pedaling. And finally, how frequently you apply force during pedaling.
An average rider traveling moderately fast (using moderate assistance levels) on moderate terrain using a hub-motor with approximately four-hundred fifty watts maximum power should be able to achieve considerable distances using an eight-hundred seventy-four wh ebike battery.
A commuter using extreme throttle input exclusively on rugged terrain utilizing a motor producing greater than twelve-hundred watts maximum power will likely significantly shorten that range.
Generally speaking throttle-only usage consumes watt-hours approximately two times faster than pedal-assisted usage in most common real-world situations.
Do generic lithium cells warrant confidence in their ability to provide satisfactory service life?
Many inexpensive ebike batteries contain generic lithium cells and have operated successfully for years without incident.
But there's no guarantee without physically inspecting each individual cell inside the case, and even then there's still no certainty, therefore trust must be placed in the manufacture's branding and bms design choices for ensuring your safety while utilizing this ebike battery.
If that makes you uncomfortable then it may be wise to spend more money for an established brand whose products have been thoroughly vetted through thousands of user reviews.
For more information about lithium-ion safety failures, particularly how they occur and what signs you should watch for, please visit batteryuniversity's lithium-ion safety guide.