Segway-Ninebot External Battery Pack for ES1/ES2/ES4 Electric Kick Scooters

Short version: This significantly improves the performance of an ES2 and makes it better to ride, but also makes it harder to carry.Longer version: I bought the ES2 4 months ago, in part, because I knew I could upgrade it to an ES4 if I wanted to. I commute 1.5 miles to the office. The route is a bit hilly with one being particularly steep. I am at the higher end of the weight rating and so my experience with the ES2 was that it would slow a bit on most hills and couldn't make it up the last one. I left it in sport setting and would only get about 4.5 total miles of range before it became too weak to be useful. Even so, it worked well for my commute and since it was now a long-term solution, I decided to add some range and power.The battery is easy to install and I had it set up and charging in under 30 minutes. It does become noticeably top-heavy, but still seems stable. The battery adds significant acceleration and hill-climbing ability. The scooter is much more lively and fun. Performance is a little weather-dependent. I can now climb that one hill without having to give it a kick-assist as long as it isn't too cold out.My one negative comment is that the battery placement is a bit awkward for carrying-purposes. Before I installed it, I could carry it to my office with no issues. The problem is that the battery is installed over the balance point so now there is no good place to hold it. I've taken to rolling it on the front wheel, but may add a carrying strap in the future.Bottom line: the positives far outweigh the negatives. If you need more performance out of your ES2, this is worth it.

So far so good (went refurbished). Charged up fine and got error code off my scooter (finally!). Read further for error codes I was trying to correct if you’re in the same boat.Have Segway ES4 kickscooter. Was getting ready to send it back in for the 3rd time in 20 months (but probably only used for 10 months total because of weather). They were going to have me pay to ship/diagnose/repair it. After remembering the app, I connected it and it showed my external battery was unable to be charged (this was error code 46, 14, 41). Since I’ve had such a terrible experience with this scooter and it’s reliability I decided to go with the refurbished option to save some money (didn’t want to spend full price for it to die after a year). Swapped them out.. error code GONE. Segway was going to charge me hundreds of dollars and all they needed to do was tell me to swap the batteries.

I had purchased a Bird ES1-300 and I also have a Xiaomi M365. My M365 can be programmed to go 18 MPH. My Bird, which is basically a non folding version of the Segway ES1 300W, goes 16 MPH. I wanted it to go faster and get more range. I read that top speed increases automatically when you attach the battery to the Segway ES1 (effectively making it a Segway ES3) and the range nearly doubles.Well, 1 of 2 ain't bad. I definitely get more range. However, Bird has the firmware customized to only go 15.5 MPH max. So, the speed remained the same. However, the acceleration and the ability to maintain speed up hills did increase. You don't think an extra battery would affect acceleration, but somehow the motor sucks in more juice and it makes the whole scooter feel like the motor had been upgraded. The extra battery just makes it feel peppier and more responsive. I can't comment on the extra weight other than to say that I don't notice it.If you have a Segway ES1 or ES2, I would highly encourage you to pony up for this battery because of the extra speed and range. If you have the Bird Version, you won't go faster but you will accelerate faster and maintain speed better on hills, and nearly doubly your range.All in all, this is a worthwhile upgrade and I would do it again if I ever had another ES1.

11/1/21 Update. I actually bought two of these since my initial one star review-surprisingly, the $65 used one was a tad more reliable than the brand new $240+ with tax one. That newer one works fine for a few weeks but then kicks out error code 19 and error code 42 and failing to charge. More than anything I think it's a poor quality of connection between the heavy battery and the tiny port on the stem. No amount of tightening helps and you eventually strip out the impossible to reach Metric 3 bolts. Meantime, you can't charge the thing (i.e., use it like an ES2 instead of an ES4) because they stupidly blocked the regular charging port with this enormous battery you can't unbolt. Frustrating: I may do something to just snap/break the external battery off and keep it an ES2 forever. 5/10/21 Update. Yeah, it just keeps rattling itself loose and suddenly plunging the scooter to a top speed of 6 kph (which is actually slower than walking speed). The battery level lights don't work, and I'm not really sure if it isn't completely dead, like my original ES4 battery, after very little use. Everything with the ES line is cursed. Original Review: So, this is the latest version of the battery pack that makes a Segway Ninebot ES2 into an ES4. I bought the ES4 just a few months ago, and it is a poorly-constructed toy. In addition to awful delivery service both originally and returning from the repair shop (twice), it dilly-dallied at the repair shop twice as noted and I lost about 4 months of use with it. I decided to keep it as a spare. When the pandemic hit, it ended up locked in my workplace for 3 months. Just before that it had started giving Error Code 48, a code so "new" it was still listed as "reserved" in my owner's manual but the scooter still worked. It's actually the code for, "Your auxiliary battery pack is totally dead." A little tinkering, and, yes, the auxiliary battery was totally dead, the warranty had run out even though the problem dates from months before, and I bought this replacement. It, too, was crazily delayed (the UPS depot next door to me each and every day said they had it on-site, but it was delayed "due to weather or natural disaster"). This was news to me, living 1-1/2 miles away from the depot. What finally showed up is a little different from the product pictured. There doesn't seem to be any bright red bezel across the top but the little red side lights do come on when the headlight is turned on. Still, it seems an expensive replacement part to have to buy ($240 with tax). It definitely charges up and gives the ES4 a lot of zip. I just worry it will die as quickly as the first one did. Again, it seems a very expensive component to have to buy if it gets a less than one year old scooter back to operating capacity. With all the delays, the ES4 and this battery pack cost some outrageous amount ($5/mile?). And, of course, it started acting up right away. Apparently, the electrical connection is subject to being shaken loose. The battery lights will flash across the top and the scooter will act like it's an ES2 carrying a heavy dead battery. The only solution seems to be uninstalling and the reinstalling the battery. This would be after 50 miles of use. Just not good engineering. I recommend the Segway G30 Max original instead, a completely different machine that costs about the same but has taken me 3,000 miles+ without one single problem.