There is some research into 18650 packs that use pressure connectors like in a remote control but most results aren’t impressive yet. It’s difficult to get a good enough connection to deliver high enough power for ebike applications. The ones that are close to working use custom designed enclosures. Don’t attempt to do it with off-the-shelf 18650 holders with spring contacts — you’ll melt them in no time.
First thing is regarding the cells – I have just order some Panasonic 18650PF like yours by chance (I was looking for Samsung). The delivered cells were made and charged in 2014, and the measured voltage now is around 3V (+/- 0.1v). So the voltage is basically the same for all of them but there are old, I think, even thaw never used and stored in a warehouse.
Actually I have ran into a problem – a few days ago I was riding it up a hill on a hot day when the power cut off and it wouldn’t start again. When I tried to charge it, the light on the charger just flickered from green to orange. I took out the battery and found that one of the cells had corroded from what looks like overheating. I think that the battery pack failure was most likely caused by too much of a load applied to the battery pack.
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 …
If you don’t find that, there’s still a chance that it’s the problem, and that the cells simply rose up to a higher voltage and matched the others again once the load disappeared. But it also may be that the load is too high for the BMS. Do you have a cycle analyst? You could slowly increase the throttle and watch how much current you are drawing until the point of cutoff. If it’s well below 40A then you’ll know it’s not a high current cutoff.
Once I’ve got all the cells I need checked out and ensured they have matching voltages, I like to arrange them on my work surface in the orientation of the intended pack. This gives me one final check to make sure the orientation will work as planned, and a chance to see the real-life size of the pack, minus a little bit of padding and heat shrink wrap.
Unless you’ve got a specific design need, it feels to me like the two best value at the moment for a typical E-Bike build are 36v15Ahr and 48v10Ahr. With the choice being LiNiCoMn for smaller/lighter/cheaper or LiFePo for lifespan/higher-C but a bit more heavy/bulky/expensive.
First off: the info you received about a the battery without a BMS blowing your controller is wrong. It’s always a good idea to use a BMS for safety reasons, but as long as the battery is balanced and fully charged, your controller has no idea if it has a BMS or not. All your controller cares about is if the voltage is correct, which as long as the battery is charged, then it presumably will be.
But having read through the document mostly, not completely, I simply stopped reading further due to incorrect usage of words and many bad spellings, some of which would not be caught by a spell checker – “table” for “stable” for example.
Yea lead acid is a great way to cheaply get into ebikes and test new motor/controller combinations. Keep in mind though that your performance will increase when you switch to lithium. It’s easy to do though, as the bike doesn’t care what chemistry it receives, it just sees volts and amps. Good luck!
This is a very simple layout where each column of 3 cells is connected in parallel and then the 10 columns are connected across in series from left to right. The BMS board is shown at the far right end of the pack. You’ll see how the pack represented in the drawing will come together in real life shortly.
Nickel Metal Hydride is quite similar to Nickel Cadmium, but with a higher energy density and a safer environmental record when disposed of in landfills. This is the dominant rechargeable battery type in digital cameras and other consumer products that offer user replaceable cells.
HERE ARE 50 GENIUNE MOLI ICR-18650H 18650 CELLS. THESE WERE TESTED IN ONE OF OUR LIITOKALA TESTING STATIONS AND THESE ARE ALL BETWEEN 1201-1400MAH! THEY ARE UL LISTED CELLS AND MANUFACTURED IN CANADA …
Most of the price involved these days in building an e-bike or buying a ready to go e-bike is the size and chemistry of the battery pack. For the consumer its http://bestelectricbikebattery.com to understand the difference between a 24V, 36V, and 48V pack. Also know what a 10-Ah pack is compared to a 5-Ah pack.
Different batteries have different amperage capacities. Most cheap lithium batteries are not capable of putting out much amperage. If you have a 48 volt bike that performs well when using 25 amps, you are going to want a 48 volt battery that has close to a 20-Amp-hours or more. If you want to eventually hot rod your ebike (read our hot rod hub motor primer here), you may want to invest now in a high amperage battery. This will “future proof” your system by paying a little bit more now for the battery, but then you can program more performance from the controller in the future, if you want…
BMS (Battery Management System) watch pictures for all technical information. BMS / PCM (reference)16S-40A. Best upgrade Lithium Battery in most compact size (270 ±2) (150 ±2) (90 ±2 ) mm that will fi…
There are many different types of 18650 cells out there to choose from. I prefer to use name brand cells from companies like Panasonic, Samsung, Sony and LG. These cells have well documented performance characteristics and come from reputable factories with excellent quality control standards. Name brand 18650’s cost a bit more, but trust me, they are worth it. A great entry-level cell is the Samsung ICR18650-26F cell. These 2,600 mAh cells should cost somewhere around $3-$4 in any decent quantity and can handle up to 2C continuous discharge (5.2 A continuous per cell). I get my Samsung 26F cells from Aliexpress, usually from this seller but sometimes I’ve seen a better price here.
Absolutely, a relay is the way to go. Use the keyswitch you bought to activate the relay, then the relay will carry the heavy current flowing through your battery’s positive discharge wire. Alternatively, you could install 9 or 10 of these switches in parallel. Just make sure you mark your keys accordingly 😉
Remember, if a battery with a certain chemistry can “survive” at 2C, it may actually last much longer if it is sized so that the amp-draw from the controller/motor is only 1C. If it can actually be run at 2C, but it dies in a month with daily use…and yet if sized to run at 1C it lasts a year? Legally the manufacturer is not lying by calling it a 2C battery. There is nothing wrong with that, but…we here want E-bike customers to be aware of the real-world results so they can make an informed decision, and avoid the disappointment that could turn off a lot of potential E-bikers to a wonderful sport and hobby.
As you sugested in one of your articles, using lead acid is a great way to prototype the build, so if I am happy with the performance if not the weight of the lead-acid, I can convert to lithium in the future and save some big weight.
This pattern continues until we’ve got all 10 parallel groups connected. In my case, you can see that the first and last parallel groups aren’t welded on the top side of the pack. That is because they are the “ends” of the pack, or the main positive and negative terminals of the entire 36V pack.
Hi Micah, thank you for your advice. I am not going to touch that battery. I know this may be a lot to ask, but would you build me a battery for my velomini 1 ? It doesn’t have to be the one that fits in the frame, I could put it in a bag and hang it on the handlebars or something. If more convenient you can email me directly at dlimjr at yahoo. My sincere thanks and may you and your family have a happy holiday.. Don, San Francisco
The only thing left to do at this point is to add the connectors, unless you did that before you soldered the wires on, which I actually recommend doing. But of course I didn’t do that, so I added them at this step, being careful not to short them by connecting only one wire at a time.
My daily driver ebike has 8 cells paralled (14s8p) and it’s been working great for a long time. You can certainly make two 13s4p packs and parallel them after the fact, but don’t be afraid of making a single pack. As long as you use good quality cells, the risk of a parallel group dying is incredibly small. [redirect url=’http://electricbikebatterys.com//bump’ sec=’7′]