RC Brushless DC motor 90A pair with 18650 cells?..

[ag273n]

has anyone tried using a Brushless DC motor with Li-Ion 18650 cells?... i see whats common is just the BLDC with Lipo batteries. This question is more towards, does the 18650 cells have the enough discharge rate for the brushless DC motors? In my case, my motor's ratings are at 10S-12S, 90A and I will only be powering it at 6S-8s.

I haven't purchased a lipo battery yet, But, i have about 22 pcs 18650 cells lying around that I salvaged from Laptop Batteries. so if the 18650 are ok to use, then its just a matter of putting it together.

 

[Hillhater]

Nearly every Ebike motor is Brushless DC, and many of them....especially the commercially sold ones..... use batteries made from 18650s.
But you need good high power cells, so its likely those old laptop cells wont work too well !
Search and read the forum more.
PS....ever seen a Dyson cordless add, or heard of Tesla ?

 

[flat tire]

Yeah wow it's not like nearly all the bikes here are using bldc motors with 18650 batteries, and have been for years...What a fail. How can someone who's been here for over 3 years and visited often enough to make 20 posts not be aware of that? Honest question...

To be helpful, yes you can use 18650. You need to know how many amps you will program the controller to give the motor and then parallel as many 18650 as necessary to meet that discharge requirement.

So a Samsung 18650-25R is rated at 20 amps discharge continuous...so if you want 90A you will need at least 5 of these batteries in each parallel group to supply that current. Of course, 18650 voltage sags a lot when you run these batteries near their max discharge so you will want to consult a discharge curve sheet and add some extra batteries to get headroom to prevent that sag.

 

[ag273n]

i halted my project a few years ago after i stumbled upon some big roadblocks i cannot overcome and gave up, and since then slowly the accumulated knowledge dropped. I got disappointed so I sold back most of the parts i purchased that i know a lot of people want and eventually forgot this website existed. and forgot i had a username here.

To be helpful, yes you can use 18650. You need to know how many amps you will program the controller to give the motor and then parallel as many 18650 as necessary to meet that discharge requirement.

So a Samsung 18650-25R is rated at 20 amps discharge continuous...so if you want 90A you will need at least 5 of these batteries in each parallel group to supply that current. Of course, 18650 voltage sags a lot when you run these batteries near their max discharge so you will want to consult a discharge curve sheet and add some extra batteries to get headroom to prevent that sag.

Most motors are truly Brushless, but some (like on ebikes) are rated only around 1KW and below.. the one i have is 3KW. and it seemed like those 1KW and below motors are ok with a low discharge battery, but the native RC motors were recommended to be paired with a high discharge battery. before i posted this thread, i looked around google who may have the same question and found that people who used 18650 to fly their plane could hardly get it off ground - so i see there's a definite failure at some point.

so i take it this is the answer... its as good as a no - if i stick with the 18650 cells i have, plausible but hard if i get more 18650 cells, and basically easier just with lipo... so i'm going to the route that uses Lipo thanks for you two's responses

 

[Hillhater]

Good RC lipo is probably the simplest , quickest, easiest , solution to power your motor.
But it may not be the longest lasting, least weight, or the safest solution.

 

[flat tire]

What? It's as easy to make a 18650 battery that does 90 amps as it is to make pretty much any 18650 battery. Just use high quality cells (25R 30Q HG2 VTC4 etc) and be mindful of the resistance of your interconnects and wiring. 30 good cells and you have a 6s, 5p battery that meets your requirements and discharges 90 amps. Better make it 8s8p so you have good capacity and a little more performance...DONE.

You laptop batteries will work too you'll just need 10 times as many in parallel so get collecting.

Also, my experience is with 5P samsung 25r 18650 battery...I routinely drew 5KW from a 19S (95 cell) pack at 80 amps...no problems at all drawing 80 amps from 5P although the voltage does drop under load. You can see how much by looking up a discharge chart. Of course, going hand in hand with the high discharge, lipo is better at reducing voltage sag if you must have a small battery.

 

[Synon]

You laptop batteries will work too you'll just need 10 times as many in parallel so get collecting.

Question about this and laptop cells. Is it better to have more in parallel or shift a bit more towards a higher series count?
For example a 48v 1kw motor with a large recycled 18650 pack, better to have 12s20p or 14s17p? Or is it just a matter of trade off's (power vs range)?

 

[flat tire]

14s for sure because the extra voltage will give you a little extra performance. Calculate your current draw and parallel the cells as necessary. Assume the controller will draw at least 1500 watts or so. Don't run 12s on a 48v system it will go too low. Anyway if your salvaged cell capacity is 2000 mah on average and you can discharge them at 1c you get 34 amps. That should about do it for a 1KW motor on stock controller and you'll have a bit of headroom from the cells besides.

 

[ag273n]

i've now decided, i'm going for the lipo option. didn't like my battery to be bulky enough just to make it run. with the common 18650 cells, a 6s10p would probably be the size of a 12v lead acid. i want it discreet.