Upgrading my E-bike. Building a battery pack
Good day folks. For a couple of months now, pretty much since summer has started and the weather allowed it, I've been trying to ditch my car as much as possible for an E-bike which I got a pretty good deal for at a local bike store because it had some cosmetic defects like some scratches and a broken metal piece holding up the rear rack. All these weren't enough of a dealbreaker to keep me from buying it and I managed to fix them myself eventually, so I now have a nice folding 20" E-bike. Getting more and more used to it, I started thinking of upgrading it, with one of these kits floating around on Ali.
It's currently got a 250W Bafang rear-wheel motor on there and a 36v rack-mounted battery pack which I've yet to actually open up because it's still under warranty. The way it functions though is unlike what you'd expect when you hear the term "E-bike": you can't just hit the throttle and let the motor do the work, you have to actually pedal to get this to happen. Yes, that's right, there's no manual throttle control on this: the motor starts spinning when the sensor located in the pedal shaft tells it to, so it's more of an electric pedal assistant than a full E-bike. Still, better than nothing and it DOES make a huge difference uphill. It's got a small control panel on the handlebar to toggle between three different speed levels, basically how hard the motor tries to help you out, or you can disable it entirely if you want to conserve battery or you simply don't need it, like when you're going down a hill. Pretty fun stuff overall, BUT...we can do better than that
I did a little research and found out that these motors are pretty universal and can fit every size tire and bike if you're careful and don't screw up the measurements. Of course I went for the most powerful one I could find, a 1500w one (though with this being China, you CAN expect that to be overblown by quite a bit, still...). Not the cheapest thing, but still cheaper than trying to source a new bike with an 1500w motor already on it, plus I still need it to be a folding type and I'll make up for some of the price by selling the current kit that's on it. These upgrade kits come with everything you need to get going, including the BLDC controller of course, but they don't come with one crucial item: the battery ! Some of them DO offer the battery as an option, but forget about it: too friggin' expensive ! I could buy a used car for the price of the battery ALONE !
So being the resourceful chap that I consider myself to be, I started looking into building one myself, hopefully saving some $$$. The motor calls for a 52v battery, so I coincidentally found this video where the chap is building just that, except mine will lay flat on the rear rack where the current one is. We'll think of the enclosure later on... Seems simple enough: get some batteries, a BMS like these and start wiring......what could possibly go wrong right ? The choice of cells is the most important thing the way I see it. Also, since I don't have a spot welder and I don't want to solder directly to the batteries, I'm trying to source the same mounting brackets the chap in the video uses which have a screw at the top and allow you to use lugs to connect everything up, but can't find them - much quicker and safer than soldering, plus it allows you to (semi) quickly replace any dead cells, as opposed to soldering...what do you guys think ? You game ?
It's currently got a 250W Bafang rear-wheel motor on there and a 36v rack-mounted battery pack which I've yet to actually open up because it's still under warranty. The way it functions though is unlike what you'd expect when you hear the term "E-bike": you can't just hit the throttle and let the motor do the work, you have to actually pedal to get this to happen. Yes, that's right, there's no manual throttle control on this: the motor starts spinning when the sensor located in the pedal shaft tells it to, so it's more of an electric pedal assistant than a full E-bike. Still, better than nothing and it DOES make a huge difference uphill. It's got a small control panel on the handlebar to toggle between three different speed levels, basically how hard the motor tries to help you out, or you can disable it entirely if you want to conserve battery or you simply don't need it, like when you're going down a hill. Pretty fun stuff overall, BUT...we can do better than that
I did a little research and found out that these motors are pretty universal and can fit every size tire and bike if you're careful and don't screw up the measurements. Of course I went for the most powerful one I could find, a 1500w one (though with this being China, you CAN expect that to be overblown by quite a bit, still...). Not the cheapest thing, but still cheaper than trying to source a new bike with an 1500w motor already on it, plus I still need it to be a folding type and I'll make up for some of the price by selling the current kit that's on it. These upgrade kits come with everything you need to get going, including the BLDC controller of course, but they don't come with one crucial item: the battery ! Some of them DO offer the battery as an option, but forget about it: too friggin' expensive ! I could buy a used car for the price of the battery ALONE !
So being the resourceful chap that I consider myself to be, I started looking into building one myself, hopefully saving some $$$. The motor calls for a 52v battery, so I coincidentally found this video where the chap is building just that, except mine will lay flat on the rear rack where the current one is. We'll think of the enclosure later on... Seems simple enough: get some batteries, a BMS like these and start wiring......what could possibly go wrong right ?
The choice of cells is the most important thing the way I see it. Also, since I don't have a spot welder and I don't want to solder directly to the batteries, I'm trying to source the same mounting brackets the chap in the video uses which have a screw at the top and allow you to use lugs to connect everything up, but can't find them - much quicker and safer than soldering, plus it allows you to (semi) quickly replace any dead cells, as opposed to soldering...what do you guys think ? You game ?
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