I think it is much better to use a purpose built CV-CC (constant voltage, constant current) ebike charger. I 100% understand the desire to complete the project on the cheap, but I think that sometimes it is worth a few extra bucks as insurance to protect your battery which is worth many hundreds of dollars.
Excellent, excellent, excellent (did I mention excellent) motor! So much fun, so much torque. I bought mine with 30q 52v battery, unbelievable power. Done about 300 km yet but absolutely no regrets. Get the 42 teeth Lekkie ring, makes worlds of difference. The new color display is also …
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.
I’m wondering, what do you do for 6V or 12V applications where the correct number of in-series cells is ambiguous? For example, if I’m replacing a 6V SLA battery, it seems like the existing charging system would set a 1s battery on fire, but wouldn’t be sufficient to charge a 2s battery. Are there BMS’s that have VRs to step up the voltage from the charging system to the battery, and step down voltage from the battery to the charging system to facilitate a 2s battery for the application?
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.
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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.
The battery maximum power = volts x amps, so if this 36V battery can deliver 30A continuous, that means it can deliver a maximum of 1,080 watts, though I would run it conservatively at a lower power level than that in most applications.
When you buy your battery, make sure you know what its maximum amp output is. Remember, by multiplying amps and voltage you get the actual current capacity of the battery. For example a 48-volt 25 amp pack can put out 1200 watts.
Thanks for the kind words! Unfortunately I don’t have access to a schematic. I got that BMS from a Chinese reseller and I would be surprised if even he has a schematic. I have seen people parallel BMS boards on a single pack to get higher current output but I haven’t tried that myself.
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.
36V 10ah Lithium battery (Included with the battery is the charger and mounting Bracket). Standard Fat Wheel 26 in by 4in Front Wheel 500w brushless motor hub (works with disc brakes). Pedal Assistanc…
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.
It says it is 110 volts (220 are available) but this welder needs a 60 amp circuit (breaker) to work properly so it is not advisable to use at home! anyway, have you found this is a certainty? that you must use a 110 volt (single phase) 60 amp circuit? is this what you are using? have you been having breakers flip when you use your welder on a smaller breaker? (most homes are 20 amp breakers) Or would it just be better to go with their 2 phase (220 volt) 60 amp breaker? I guess I could just pick up another breaker and run it directly from the panel.
20″ 250W 36V White Folding Electric Lithium Battery B ike. Motor: 36V 250W Rear Hub Motor. The 20” Sheep is a 36V 7AH Lithium Battery powered Electric Bicycle. This Folding Electric Bicycle is the per…
A high quality USA battery manufacturer by the name of “Allcell” constructs packs consisting of 18650 cells (cylindrical cells that are 18mm diameter and 65mm long) and uses high tech packing materials to spread out the cells and thus the pack gets a longer life. This is the pack of choice in many high end commercially available ebikes including the Optibike, the Picycle, and the Hanebrink. (click on each to see article on that electric bike). The 18650 battery cell format batteries for electric bikes mass-produced for laptop computers and cordless tools.
LiPo packs that are homebuilt (without a BMS) can be extremely dangerous if you do not approach your battery with a lot of knowledge and care. Be sure to research extensively before building such a pack. Many E-bikers construct packs with no BMS using Turnigy/Zippy packs, acquired cheaply online through the Hobby King company which is based in China. For those who risk running their batteries without BMS they still use sophisticated chargers to balance their packs and constantly monitor the health of their cells.
The only two ebike companies that sell LiPo to the public are Optibike and Pi-cycles, and both contain the battery in a strong metal box which makes up of the frame. The companies fire tested these enclosures and are confident that their frame are effective and safe vessels for LiPo storage.
Also, the best method for adding an auxiliary battery would be to connect it when both batteries are full, or at least at similar discharge states. That means the auxiliary battery won’t have to work as hard transferring energy to the internal battery, as they’ll be depleted together at similar rates. And the diode in the auxiliary battery will ensure energy only flows one way (towards the internal battery).