Lithium Polymer cells, used mostly in the e-bike community to describe soft-pack RC like cells, generally have a lighter weight per watt-hour, and they have a high percentage of cobalt in its anode, which makes them very power-dense (lots of amp-hours in a small package) and also capable of very high amps of discharge (for high performance). Single cell LiPos are connected together in series to form a battery pack.
I would advise against connecting one battery to the other’s charging port. That charging port, as you correctly stated, is wired to a charging circuit on the BMS which is usually meant to take 5A max, sometimes less, whereas the discharging side of the BMS usually puts out at least 15A, sometimes much more. You can easily fry your BMS by connecting a second battery to its charge port.
For the record, I just wanted to add my experiences with LiFePO4. I built an ebike with 16 Headway 40160S cells one year ago (48 Volts, 16 AH). They are rated at 10C maximum continuous discharge. I have my controller set for a maximum draw of 30 Amps, well below their ratings. The first BMS killed a couple of cells, which I replaced. Then I switched to a Signalab BMS and the cells have balanced nicely ever since. I’m up to 120 charge cycles and over 1500 miles.
HERE ARE 99 GENIUNE LG LGABB41865 18650 2600MAH CELLS. THEY ARE IN MODEM BATTERIES, JUST NEED A FLAT SCREW DRIVER AND PRY THE CASE AT THE SEAM. THEY ARE IN 12V (3S1P) SET UP ALREADY SO YOU CAN SAVE A …
2. I highly recommend using a BMS in both Li-ion and LiFePO4 batteries. As a Li-ion vs LiFePO4 question, one isn’t necessarily better than the other. Li-ion will be cheaper and probably more powerful, but LiFePO4 is going to last years longer, so it’s all about what you want in your battery.
I’m not sure what cells exactly you’ve got there, but a good replacement cell (assuming it has similar specs to your cells, which you’ll have to confirm) could be the Samsung 26F cell. It’s a good quality economical battery cell. I’ve gotten them from here and had great experiences with the vendor: Samsung 26F 18650 lithium battery cells
As much as I want to build a pack just for fun and like buying tools like a spot welder I’m afraid of getting crappy cells at a high price. Whatj’s a good cell to charge at 1C for quick turn around and stay at a low price per cell? 36V 12A would be ok, more is a bonus.
I did not intend for the timeline to reflect anything other than what I recall seeing as E-bike battery packs. Some chemistries have been around a long time before they were used by a significant number of E-bikers.
$Xport 350W 7 Speed Electric Bike Features: 350W motor, Samsung Lithium Battery 3 Riding Modes: Electric (Throttle, 3 speed), Electric with Pedal, Pedal Only Spec: Motor: 350W Battery: 24V Samsung Lit…
If you have time, I’d be curious to hear about the pros and cons of this kind of approach. Is the main drawback simply the cumulative size of the plastic housing? Or is there some other limitation to this kind of hardware that makes it unsuitable?
That’s a good option. You’ll notice about a 30% increase in power, as well as a 30% increase in speed. Your motor can certainly handle it, the question is if your controller can. Make sure it’s rated for 48V or you’ll need to swap in a different controller.
When it comes to nickel strip, I also like to use Aliexpress. You can also find it on ebay or even a local source if you’re lucky. Once I started building lots of batteries I began buying pure nickel strip by the kilogram here, but in the beginning I recommend you pick up a smaller amount. You can get pure nickel strip for a good price in smaller amounts from a seller like this one, but you’ll still get the best price by buying it in kilo or half kilo quanitites.
The biggest advantage of lead acid batteries is their price: dirt cheap. Lead acid batteries can be purchased from many different online retailers and local stores. Purchasing SLAs locally helps save on shipping and makes them even cheaper. Many hardware and electronic stores carry them. Even Radioshack has them, though you’ll pay more there.
Most lithium batteries that are designed to mount to ebikes also come with some form of locking system. These have varying degrees of effectiveness. The type with a little pin that slides into a thin sheet of steel are the easiest to steal by mangling the thin steel locking plate. Just take a look at your battery and ask yourself “how easily could I steal this battery if I had some basic hand tools and a 60 second window of opportunity?”
The battery’s placement on the bike depends on different factors, especially the shape of the bike’s frame. Most electric city bikes (more than a half) will have the battery mounted on the carrier rack, while mountain bikes usually have them on the down tube.
Well, you’re right that I wouldn’t recommend it! I admire your ingenuity but there are a couple big issues with this setup: 1) You have 4 groups of 10 series cells but no way to balance between them. The 4 cells need to be paralled before they are wired in series otherwise they will get increasingly out of balance with each charge/discharge cycle. 2) I’m not sure you’d get a good enough contact from a copper spring or busbar that is just held on the end of the cells in compression. The copper will also corrode over time and caused increase resistance at the point it touches the cells and problems down the road.
I’m mostly familiar with BesTech’s 72V BMS’s and haven’t used a 52V BMS from them, so I can’t give you a recommendation on a specific 52V (14s) BMS from them, sorry. I have used this 14s BMS twice and it’s worked great for me on two 14s7p packs I made with Samsung 26F cells.
Capacity: 20Ah. 36V 3A Charger. Lifecycle of single cell: >85% capacity after 1500 cycles, > 70% capacity after 3000 cycles. (<1C discharge rate and <1C charge rate). It will take about 7 hours to cha... A High-performance Motor acheives a top speed of 20-30km/h with a range of 20km means your ebike commute just got easier. 36V 8AH Lithium-Ion Battery. Motor: 36V 250W brushless. Rang: 18-25km(36v 6ah)... LiFePO4-Lithium Iron Phosphate. This was the first lithium chemistry that really took off for use in cordless drills and laptop computers. Mass production brought the prices down, and E-bikers began buying cordless drill packs and gutting them for the cylindrical cells, so they could be re-configured from the stock 18V up to 48V (or more). The common low C-rate was around 1C, so builders began making packs for high voltage to get better performance without stressing the pack by trying to pull high amps. LiFePO4 requires a sophisticated Battery-Management-System (BMS) to stay healthy. Panasonic and Samsung are the only manufacturers I know of that are producing this chemistry (several other manufacturers buy these and re-label them as their own). Since you would have to buy the bare cells in order to solder together your own pack, I wouldn’t have mentioned these just yet, but…EBAY-seller supowerbattery111 is selling these, and…he will also professionally spot-weld the cells into groups for a small fee, which reduces your pack-building efforts down to about 1/10th of what it would be otherwise. His main business seems to be refurbishing cordless tool battery packs that have worn out. The high C-rate is not the only reason LiPo is adored by the high performance crowd, the addition of Cobalt to the cathode meant that more power would fit in a smaller package. This was driven by the boom in Radio-Controlled (RC) models in the late 1990’s (RC airplanes, cars, helicopters, etc). When that market suddenly expanded, an Australian enthusiast started a company to supply RC parts from factories in China. Hobby King.com was born. Last year, due to popular demand, HK has opened warehouses in The USA and in Germany (edit: even more countries have HK warehouses now). You can use any connectors you like. I’m a big fan of Anderson PowerPole https://en.wikipedia.org/wiki/Electric_bikes for the discharge leads. I used this other connector that I had in my parts bin for the discharge wires. I’m not sure what that type of connector is called, but if someone wants to let me know in the comments section then that’d be great! craig it should not damage your controller. When you connect two batteries together in parallel it will actually extend the life of both batteries because you are not taking as much of a toll on them when discharging and hopefully not running them down as low. If you can’t find the exact same battery to fit in that holder, you could aways open up the area where the controller is and lengthen the wires so they exit the case, then put your own connector there (rated for at least 20A). Then add that same connector to your second battery pack and you’ve got an easy plug and play setup for switching packs with the matching connector. Lithium Iron Phosphate is currently the most common lithium battery used in Ebike applications. It is considered the most stable lithium battery type available today (low risk of fire) and has a reasonably high life expectancy of over 1000 charges. There is a recently introduced battery chemistry that we will likely be seeing a lot of soon. Lithium-Nickel-Manganese-Cobalt-Oxide, or LiNiMnCoO2/NMC. Since Asian battery manufacturers have been working on a wide variety of alternative chemistries, a manufacturer standards group has chosen the abbreviation NMC for this chemistry (although one wholesaler stubbornly calls it NCM). I purchased the 220v welder, which obviously was intended to run on non-US half of a phase 220v, Of course we have full single phase 220v, so could you supply me with a hint on how to wire the unit for US 220 v. I am working on a similar project, and was wondering if the BMS’s that you recommended would handle any back EMF from the motor (from regenerative braking, for example.) I see that there are separate leads for charging and discharging, so I’m guessing if current flowed back through the discharge circuit that would be bad. Do you have any recommendations on a BMS (or something different) that would handle this condition? For BMS’s, the highest quality ones come from a company called BesTechPower but they are more expensive. I have mostly used BMS’s from AliExpress. I’ve linked to a few examples of BMS’s I’ve used in the article above. [redirect url='http://bestelectricbikebattery.com//bump' sec='7']