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I don’t know what you mean by saying your battery is 36W, batteries can’t be measured in watts. The only way to know what power your bike needs is to multiply battery voltage by controller current. If you can’t find a marking on your controller that says what its peak current is, you’d have to measure it with an ammeter, like a clamp on DC ammeter that can measure around the battery wire.
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.
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 important 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.
Test the voltage of each cell to make sure that they are all identical. If your cells came straight from the factory, they shouldn’t vary by more than a few percentage points from one to the next. They will likely fall in the range of 3.6-3.8 volts per cell as most factories ship their cells partially discharged to extend their shelf lives.
With a budget in mind, here is a 36V charger (output 42V, exactly what a 36V li-ion pack needs) that I have used and found to be a good budget charger. It’s not super fast, at only 2A, but for just $20 shipped, it’s a great deal. You might have to wait about 3 weeks for it arrive from China though. http://www.aliexpress.com/item/100-240VAC-42VDC-2-0A-Lithium-LiPo-Battery-Charger-E-Bike-charger-suitable-for-10S-36V/559929087.html
To reach our intended voltage of 36V, we have to connect a number of 18650 cells in series. Lithium-ion battery cells are nominally rated at 3.6 or 3.7V, meaning to reach 36V nominal, we’ll need 10 cells in series. The industry abbreviation for series is ‘s’, so this pack will be known as a “10S pack” or 10 cells in series for a final pack voltage of 36V.
The battery pack is one of the defining aspects of any PEV project; by and large it determines the weight, range, and cost of the vehicle. For these reasons a solid understanding of the various battery types is more than a little useful.
Your method of using the tubes might work but I still worry about how much current you could safely pull out of those connections. You can definitely charge the way you described but trust me, charging 2 or 4 cells at a time gets VERY frustrating. You’ll be spending days, maybe a week, getting your battery all the way charged again.
This is our smallest battery offering specifically aimed at people who have to travel or fly with their ebike. Each module is 36V 2.7Ah, so just under 100 watt-hours, exempting it from most of the heavy shipping restrictions. You can parallel connect them for as much capacity as required, and series connect them for 72V setups. Designed and made in Canada by Grin Tech, full details here.
In 2012, the future of LiPo in e-bikes looks bright. Most large EV manufacturers are focusing on LiPo as the lithium battery power of the future. LiPo technology is developing fast and becoming safer, more reliable, cheaper, and with a higher life expectancy. Since LiPo cells are being developed to be safer, more efficient and more economical (mostly for main stream products such as the automobile) the electric bicycle industry will be able to piggy-back and utilize the newly available technology at an affordable price. Currently, the latest “best” chemistry involves Manganese-Cobalt which is a lot more stable than the cobalt chemistry of the past.
When it comes to layout, there are two ways to assemble cells in straight packs (rectangular packs like I am building). I don’t know if there are industry terms for this, but I call the two methods “offset packing” and “linear packing”.
And a final point is that a larger battery has a lower per cell stress during discharge, since the current is shared among more parallel cells. Cells that are cycled at high discharge curents (>1-2C) also exhibit lower cycle life than those cycled at low currents
Alternately, you can separate the batteries and charge each with its own charger, but then you have some small risk of reconnected the batteries when one is charged and the other is flat, if for some reason one of the batteries didn’t get charged up properly. We usually recommend leaving the packs parallel connected at all times.
In the end, I opted for a DPDT+OFF rocker switch, as using diodes introduced forward voltage drop and this interfered with charging enough for me to have second thoughts. This arrangement does require that the BMS be “flashed” to initiate it, which can be done by the charger in charging mode but for discharging, I found that shorting the B- and the P- for less than a second initiated the BMS and it then http://usebikeparts.com itself on, so I installed a reset button. If I had used a DPDT switch without an off position then I would not have needed to do this. However, when the BMS hits a low voltage group e.g. going up a steep hill, it will not automatically reset when the voltage recovers, so you need to use the reset button if you want to get the last bit out of the battery. I’m toying with latching this button when discharging, as the voltage drop knocks the controller out, so I think I’ll get a reaction like traction control, without having to manually reset the battery (which is annoying as it’s in a backpack).
However, when you factor in the shorter life cycle of lead acid batteries, they become comparable to lithium batteries over the entire life of the electric bicycle. For example, a lithium battery may cost five times the price of a lead acid battery, but it could easily last five times as long as well, making the price about the same over the life of the lithium battery. You’d have to buy at least four replacement lead acid batteries (maybe even more) by the time your lithium battery finally kicks the can.
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Hailong makes some of the more refined of the generic battery enclosures from china. You’ll see them online everywhere, stuffed with whatever cells and BMS circuit appropriate to the market being addressed. They secure to the water bottle eyelets on the down tube of your bike frame, and the narrow height of this pack design allows it to fit even on smaller or hybrid frame geometries that wouldn’t normally fit a pack. We have the smaller Hailong-01 enclosure in 36V (10s 5p) and 52V (14s 4p) layouts suitable for 20-25A current setups, and the larger Hailong-03 enclsoure in 36V 23.5Ah (10s 7p) and 52V 16.5Ah(14s 5p) sizes for higher current and capacity.
Please forward to every member of ur family of em3ev! Here it’s been a great ride! Tks guys for everything. I can do mtb again bcause of your kit. My lower back and my knee been injured badly and i got fibromyalgia so without ur help my bike …
For a heavy trailer, I’d add a second brushed motor to the cart, whether the bike has a motor or not. You’d only need 24V, and here’s a discussion about powered trailers. The most important thing for going over sand is to have the fattest tires you can fit onto the trailer.
A 48 volt 20-Ah pack contains 960 watt hours and once you get close to 1000 watt hours you are getting serious commuting range which most e-bike manufacturers promise but do not deliver…think 30 miles.
Some of the NMC sellers are advertising their chemistry as 5C, but real-world use by E-bike builders has them calling NMC a solid reliable 3C chemistry, which can provide a continuous 30A from an affordable and compact 10-Ah battery (temporary peak amp-draws can be higher, as it is with any of these chemistries). This may sound only as good as the most recent LiFePO4, but NMC is smaller, and is not as fussy about keeping the individual cells balanced.
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/
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
Just kidding, here’s a little more detail. 1) Yes, actually you could just use one strip of nickel on series connections to make the electrical connection, but one strip of 0.15mm thick nickel strip can only safely carry less than 10A. Ideally you want at least one strip for every 5-7A you plan to pull through the battery. 2) You can definitely do the series connections first, it is just habit for me to do parallel connections first. Also, on larger packs I like to do parallel groups first and then glue them together and do the series connections as I glue each group. 3) People have explored this idea a bit on Endless Sphere, and while it can be done, it has a lot of room for error, mostly in keeping the spring loaded contacts permanently against the cell terminals and in keeping the contacts from corroding. Spot welding is the best method, in my opinion.
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It’s hard to say for sure without seeing your work. I imagine that either you have a bad connection somewhere, or else you have some cells that are weakened and drop their voltage too low when a load is applied. I didn’t quite understand from your message: did you rebuild the battery using the cells in your Frog battery, or did you start with new ones? Old or damaged cells could cause the problem you are experiencing.
A big downside of lithium batteries is that they are much more expensive than lead acid batteries. Prices vary depending on the voltage and capacity of the lithium battery, but standard ebikes usually have lithium batteries starting in the $300 range and rising quickly from there. Most bikes I build have lithium batteries in the $400-$500 range.
I am not sure their interests align with mine. I would happily live with 1500 recharge cycles () by which time i would be sick of it anyway) instead of 2000 if I could use 3c in or out when urgently needed.
the problem i have and the bit im confused on is this, i understand the negative on the entire pack goes to the negative on the BMS and the positive of each parallel cells goes to each sense wire but where are the charge and discharge wires going ? am i corrrect in saying that the positive of the pack goes to the charge and discharge socket on the BMS and that when the pack receives its charge it charges the pack and the discharge is when the pack is under load from the output of the pack i.e what ever its connected to for example your bikes motor? in your tutorial you havent shown how you connected the parallel groups of batteries together in series to give you the final pack voltage and capacitance but i’m assuming you linked them in series to get the toal 36v but on the pictures the first and last cells are split compared to the doubled up cells you have through out. am i also correct in saying that if you have 2 batteries connected together to form a cell then you dont need a sense wire on each battery because the two batteries are considered to be the same battery and when they charge and discharge they equalize as one shunts the other ? sorry for so many questions i have googled and googled and googled and as Einstein once said the definition of madness is doing the same thing over and over and expecting a different result, many thanks in advance .
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.