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…
Hey, I’m about to build my 16S2P pack from 32 Samsung INR18650-25R cells bought from batterybro.com. How far apart can their voltages be when you connect the parallel packs? They seem to all be charged between 3.52V and 3.56V.
Great for DIY e-bike and powerwall builders, t ake them apart and put them all together in series in other projects and get extreme power out of what you build! These batteries are made with TWENTY (2…
One other unrelated question: Do commercially available eBike batteries generally use off-brand cells for their assembled batteries to bring cost down, or similar to the cells, do reliable eBike companies use name-brand cells and off-brand internet vendors use off-brand cells?
I also soldered rather than spot welded and used 1.5mm2 solid core copper between cells, pre-bent to zig-zag shapes on a jig (current is then distributed between them). Offtakes were 4mm2. Soldering technique to minimise heat on the cells was to paint the cells and the wire with flux, load the soldering iron tip with enough solder to make the joint and then, while holding the wire on with the back of a wooden pencil, touch the molten solder to the cell/wire interface and immediately remove the soldering iron tip. This worked really well in terms of soldering quality and the solder cooled very quickly indeed. I cleaned the flux off with a baby wipe and then dried it with some paper kitchen towel.
An electric bike battery is a power storage medium for use with electric bikes and electric trikes. An electric bike battery can be a lead battery, or a lithium type battery similar to those in laptops, or cordless power tools. A lead electric bike battery is usually of the type called SLA, which stands for sealed lead acid. A lithium electric bike battery may be one of several types. The most commonly used lithium electric bike battery types today are Lithium Iron Phosphate (LiFePO4 or Life) or Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2 or NMC). The E-Bikekit lithium electric bike batteries for electric scooters replacement is a Lithium Nickel Manganese Cobalt Oxide type battery. Considering the size and weight difference between LFP and Li-NMC, all lithium packs are Lithium-Ion, but not all are the same energy density – LiFePO-4 batteries are larger and heavier than Li-NMC.
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26\” wheels with Aluminum Alloy spokes. Opportunity: Outdoor Camping, Mountain. Speed up to 25km/h,High speed brushless shock. 36V 8AH Lithium-Ion Battery. Material: Aluminum Alloy. Mileage range: ≥40…
You would think they would help with cooling, but in reality there is little to no difference. They do create an air gap between cells but because that air is trapped inside the pack and can’t get out, it just turns into an oven. So you can glue your cells together and have them cook on a skillet or use those plastic spacers and have them bake in an oven 😉
As with any battery, you can get longer lifetime if you keep the power under the designated amp rating, avoid completely discharging the battery, and always fully charge whenever you can. Fortunately these batteries are rated for very high amps, so this means you mainly can focus on depth of discharge for long lifetime. These LiNMC cells are “deep cycle” meaning that they have the ability to be fully charged and discharged. However the life of the battery will significantly increase if the depth of each discharge is limited to 80% of the rated capacity.
I have built a few 13s lithium batteries in the past year following your instructions. Thanks. I have taken one of the batteries apart to check its condition as it is the middle of winter here in Winnipeg, Canada. Two parallel sets were out of balance with the rest of the pack. I was wondering if there is a way to use my imax b6 balance chargers to rewire the battery and keep each parallel pack in balance for sure! This way I will bypass the bms. Does this make sense?
SLAs come in 6V or 12V increments, meaning you have to build your battery pack by combining these smaller SLAs in series and/or parallel to get the specific voltage and capacity you’re aiming for. This can be both an advantage and disadvantage; it gives you more room for customization but requires some work to combine the individual SLA batteries together into a larger pack.
When you wire in series you only increase voltage, not amp hours. So you’d have a 48V 5AH pack in that setup. Not enough range, in my opinion. If you want my advice, the single best upgrade you can do to that bike is to replace the battery and controller for 48V units. It will give you about 30% more speed and power. You won’t need to drill vent holes or anything, that motor can handle 48V as long as you aren’t riding up any 5 mile long uphills with a 250 lb rider. Shorter uphills and flat land will be fine all day long.
Do you have any charts showing the different weights by voltage for lead acid vs lithium? It would be good info to be able to see the penalty paid for cheap lead acid in a mid level build when compared to the equivalent lithium setup.
In many situations, especially if you are replacing a battery pack on an existing setup, the voltage is defined by the controller electronics and cannot be readily changed. Otherwise, the voltage determines the maximum speed at which your vehicle will travel, and you have a degree of freedom in selecting the voltage to meet your performance expectations. If you know the volts/rpm for the motor, then it is straightforward to calculate how fast it will go for a given voltage. Select a value that gives an unloaded speed of about 20% greater than your desired cruising speed for best performance.
I buy that pink cells, Samsung ICR18650-26F. The cells have 3,9V, is a little too, only one with 3,82 and the other 3,87. I want to do a pack with 4parallel and 7serie (28 cells), it is acceptable conect them? Any sugestion is welcome.
Do you think it is the BMS or the controller that is cutting out beyond a certain load or something else completely? As far as I am aware the battery is fully charged and balanced (I even left it charging for 2 days once as I read that it can sometimes take this long to balance the cells!).
I have found this BMS which is cheap (necessary for my project) and it is shipped from the UK. Because it is so cheap do you think that it may not be balancing? http://www.ebay.co.uk/itm/400984825723?euid=0502c7e2b2c744ec8857879d65d46e08&cp=1
I’m glad you enjoyed the article. To answer your questions: I chose this type of battery instead of LiFePO4 mostly because of the cost and convenience. LiFePO4 is a bit more expensive and has fewer options for cells. These Li-ion cells are a bit less expensive and there are dozens of options with many different specifications for any power/capacity need. I’ve used and built LiFePO4 packs before and they have their own unique advantages, but for me they just don’t add up to enough.
You can also add a label or other information to the outside of your pack for that professional look. If nothing else, it’s a good idea to at least write on the pack what the voltage and capacity is. Especially if you make multiple custom batteries, that will ensure you never forget what the correct charge voltage for the pack is.
When we add the fourth parallel group, we’ll again hot glue it in place in the opposite orientation of the third parallel group (and the same orientation of the second parallel group) and then weld it on the opposite side as we welded between the second and third group (and the same side as we welded between the first and second group).
Since most welders have arms like mine, I’ll show you how I did it. I started by hot gluing two parallel groups together in an offset fashion, making sure the ends were opposite (one positive and one negative at each end, as shown in the picture). Then I snipped a pile of nickel strips long enough to bridge just two cells.
This is also why the common and affordable RC smart-chargers are powered by a separate DC power supply. Many RC enthusiasts spend a day at a park, and while flying an RC plane, they have several other battery packs that are charging from their cars 12V system.
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.
I have an old 12V DC Brush Motor which its consumption is around the 12A, 13 A and I built a Battery pack, with two groups of batteries, (4S6P)+(4S6P), which makes a total pack with 14,8V 30A. To make this battery pack I used 18650 Samsung Cells 2600 mAh.
The batteries can be paralleled at any charge level as long as they are all the SAME charge level, i.e. same voltage. If they are all 3.81 V then you can parallel them, or you can charge them all to 4.2V and then parallel them, both are fine options. But if you are putting many parallel groups in series then it is a good idea to get them all to the same charge level first. That will make the first charge of the whole pack much easier as the BMS doesn’t have to balance cell groups that are at very different charge levels. [redirect url=’http://electricbikebatterys.com//bump’ sec=’7′]