A BMS isn’t necessarily strictly required – it is possible to use the pack as is, without a BMS. But that requires very careful monitoring of the cells of the battery to avoid damaging them or creating a dangerous scenario during charging or discharging. It also requires buying a more complicated and expensive charger that can balance all of the cells individually. It’s much better to go with a BMS unless you have specific reasons to want to monitor your cells by yourself.
Regarding the cell question, its a mixture of both. Cheap ebikes use cheap cells. You can bet the Sonders ebike had the cheapest cells available. Name brand ebikes usually use Samsung cells, but sometimes LG and occasionally Panasonic cells can be found in name brand ebikes (the Panasonics are some of the most expensive and so they are rarer). That being said, I’ve seen some shadier internet sites selling high quality (and genuine) Samsung/Panasonic packs, and I’ve seen some nice ebikes with some no-name cells. You should always check with the vendor/manufacturer if you want to ensure you’re getting good cells. Unfortunately, it can be hard to verify the cells yourself though without voiding the warranty, as they are usually http://electricbicycletechnologies.com under shrink wrap. A good vendor will be happy to confirm the cells for you ahead of time and may even be able to show you some pictures of opened packs to verify.
A High-performance Motor acheives a top speed of 20-30km/h with a range of 20km means your ebike commute just got easier. Power: Under 500W. Load capacity: under 200KG. Material: Aluminum Alloy. Outdo…
$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…
Yes! We are hoping that is why you bought it! However, if your eBike has a Lithium-Ion based battery, it is best not to fly as Li-Ion Batteries are considered hazardous materials and can land you a $50,000 fine if you try to bring it on an airplane.
Believe it or not, most BMS’s can handle the current from regenerative braking in the discharge mosfets as its rarely more than 5-7A. Some BMS’s (called two wire BMS’s) actually use the same mosfets for charging and discharging. Those inherently should be more than capable of dealing with the load from regen.
To determine how much power you need, you’ll need to determine the voltage you want and the capacity you need to supply that power (voltage times current). Read this article to learn more about calculating your ebike’s power: http://www.ebikeschool.com/myth-ebike-wattage/
There are different models of welders out there but most of them work in a similar way. You should have two copper electrodes spaced a few millimeters apart on two arms, or you might have handheld probes. My machine has welding arms.
I like to use a wall-plug timer when charging – mine was intended to just control lights in the house initially, and I set it so that there is no power to the outlet during the night, and limits the length of time that the outlet is “on” to only 8 hours during the day time. This saves energy, saves me from moments of forgetfulness, and makes me look pretty professional to visitors.
Shenzhen Tianlihe Technology Co.,Ltd, founded in 2005, concentrate on design and manufacture lithium battery packs for over 10 years. Our R&D team are experts in lithium ion battery solutions and smart BMS development with communication protocols,like CAN Bus…We really love our job and work hard for your pleasure.
In my video reviews I often suggest that ebike owners store their batteries in a “cool dry location” to maximize the usable life of the cells and make charging convenient. In some cases this cold mean inside the house (either the entire bike or just the battery if it’s removable). So how can you charge these packs safely? What are some options for preventing electric bike fires? To help answer these questions I reached out to Edward Benjamin, Senior Managing Director of eCycleElectric LLC and Chairman of the Light Electric Vehicle Association for insight. Ed travels the globe doing consulting for large ebike firms, teaches ebike classes to shops (of which I have attended two myself!) and I consider him an expert but these tips are just that… the best information we have to help guide you towards making your own decision. Nothing can be truly guaranteed and some of the tips Ed shares below focus on what to do if a fire does break out.
What a great article! It has opened my eyes to lots of possibilities. Being new to this I had a couple of questions. I am interested in building a spare battery to give me more range on the Faraday Porteur. My question is how to connect the battery I would build to the bike. The main battery resides in the downtube and the connection is hidden. They offer an ancillary battery that plugs into the charging port which is what I would like to build myself rather than buy. Do you think this would be possible? Where could I find a connector that would match? Any concerns? If so, what other options do you suggest? Thanks so much for the help!!
A recent quote from ES member SamTexas on claimed max C-rates: “…I have in front of me Samsung’s own Nickel (Manganese) 18650 cells….I have tested these cells at 3C continuous and they do deliver full capacity at that rate. Push it to 5C and they become hot and capacity is greatly reduced…“
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.
I am planning on making a 6S2P LifePO4 pack that has a voltage of 19.2V. I have a 6 cell BMS that does balancing (and that is intended to work with 6 LifePO4 cells). I need some help selecting a charger to charge this pack, however, particularly regarding the charger’s voltage specification.
Now this step is very important: I’m going to turn the pack upside-down and perform this set of welds between the positive caps on the second parallel group and negative terminals on the third parallel group. Essentially, I’m welding on the opposite side of the pack as I did when I connected the first two parallel groups. Skip down a few pictures to see the completely welded pack to understand how the alternating side system works.
I see, so regarding the question about building backup batteries, applications where the existing backups are NiMH or NiCd and are already designed into a charging system should really get NiMH replacements rather than Li-ion. I didn’t realize older batteries used something other than CC-CV.
Capacity: 30Ah. output: 71.4V 5A. Lifecycle of single cell: >85% capacity after 700 cycles, > 70% capacity after 800 cycles. (<1C discharge rate and <1C charge rate). Lifecycle: > 85% capacity after 5…
40% grade hills? That’s huge! You’ll definitely want a cell that can perform at high current since you’ll be pulling peak power from those cells to get up those big hills. Something like the Samsung 25R would be a good choice for this application.
Most electric bicycle batteries fall into the 24V to 48V range, usually in 12V increments. Some people use batteries as high as 100 volts, but we’re going to stick to a medium sized 36V battery today. Of course the same principles apply for any voltage battery, so you can just scale up the battery I show you here today and build your own 48V, 60V or even higher voltage battery.
Now I’ve got all of my pack sealed in heat shrink with my wires exiting the seam between the two layers of shrink wrap. I could have stopped here, but I didn’t particularly like the way the shrink fell on the wire exit there, from a purely aesthetic standpoint. So I actually took a third piece of shrink wrap, the same size (285 mm) as that first piece and went around the long axis of the pack one more time to pull the wires down tight to the end of the pack.
The BMS is for 7S, I connect B1+, B2+, B3+, to the negative of the first serie. B4+ is connected to the positive of the first serie, B5+ positive of 2nd serie, B6+ positive of 3rd serie, B7+ positive of 4rd serie.
Thanks so much for all this great informating, Im going to purchase the ebook for sure! One small question first, though. I’m building a 13s8p 18650 pack from laptop batteries for my bfang 750w 25A pedicab. I already have 45V 15 Ah LiPo setups from china, but want to up my Ah.
Thanks so much for this excellent information. I was wondering how to calculate the total amps for the entire battery? I’m trying to determine watts from this as I have a 24V 500 watt Rayos electric bike and am working to build a 24V 20 Ah battery (7s7p) battery and would like to know what watts it is capable of providing.
Work in a clean area free of clutter. When you have exposed contacts of many battery cells all wired together, the last thing you want is to accidentally lay the battery down on a screwdriver or other metallic object. I once nearly spilled a box of paperclips on the top of an exposed battery pack while trying to move it out of the way. I can only imagine the fireworks show that would have caused.
I use my welders on 220V, though 110V versions are available. If you have access to 220V in your home (many 110V countries have 220V lines for clothes dryers and other high power appliances) then I’d recommend sticking with 220V. In my experience the 110V models seem to have more problems than their 220V brothers. Your mileage may vary.
Lithium batteries are not 100% fire-safe. Some batteries are more dangerous than others, depending on the chemistry, whether it has BMS or not, and what kind of casing the battery is in. If the battery is cased in metal its less likely to burn your garage down, than if its encased in plastic. Also be aware that all BMS’s are not alike, some are good and others are crap, just like anything else in life. [redirect url=’http://electricbikebatterys.com//bump’ sec=’7′]