BMS vs controller vs overload vs noob. Fight!

General Discussion about electric bicycles.
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laerciohj   10 mW

10 mW
Posts: 24
Joined: May 25 2019 1:47pm

BMS vs controller vs overload vs noob. Fight!

Post by laerciohj » Jul 30 2019 9:28pm

Hello people.

I would appreciate your help in mastering my e-bike kit.

First I would like to know if a BMS is usually able to control the current consumed by the motor. My BMS is specified as capable of 30A discharge. But my kit came to consume 35A. Watching current above 30A, I quickly stops accelerating to drop current, fearing overheating and short circuit in the battery, resulting in explosion, I suspect.

My controller 40A is programmable, it seems to be able to control the current level supplied by the battery and the current level sent to the motor, yes there are these two options and this is odd since both features are pretty much the same. However, I can't make it work on these controls. I put it at 50% in both modes, but the current in the tests is still well over 50% of the total (30A instead of 20A). Actually I don't know the app very well. I left it at the default settings and only lowered both current controls to 50%, but it had no effect. I even thought of putting a dimmer to limit the maximum current to 30A or less to protect the BMS, which is a protective device. I know, it sounds crazy, but lay people think so until they learn.

I mount a Cyclone 3kW kit, with controller YKZ7240JN-B 0001de 40A continuous and 100A peak, with a 48V battery, 19Ah, with BMS ANN086-13S-30A-02N22-1504BXX discharge 30A.

I used this display to analyze the current: https://banggood.app.link/pZQLNcY8KY

Cyclone Kit: http://sickbikeparts.com/electric-shift ... ble-3000w/

BMS: https://vruzend.com/product/48v-13s-bat ... ystem-bms/

Controller Application Demo: https://youtu.be/-SsbX_XhFaA

Awaiting precious help from you, thank you! 🇧🇷

flat tire   1 MW

1 MW
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Joined: Feb 26 2014 12:20am

Re: BMS vs controller vs overload vs noob. Fight!

Post by flat tire » Jul 30 2019 11:00pm

Don't worry about motor current just battery current. The BMS shouldn't explode if you overload, just turn off.

The controller is the only thing actually doing current limiting. Keep playing with the settings until you are comfortable it is restricting battery current to 30 amps or under.

Finally, for your next build try to plan everything before you buy parts.

laerciohj   10 mW

10 mW
Posts: 24
Joined: May 25 2019 1:47pm

Re: BMS vs controller vs overload vs noob. Fight!

Post by laerciohj » Jul 31 2019 7:07am

Thanks for the feedback!

With regards to BMS, so I should not worry about over load, but only if I turn it off? I expected him to cut the current automatically when his limit discharge was reached. Your explanation seems to say that it is not so. I am trying to make the settings of this set work effectively, but I still can't. Maybe I do not realize some necessary configuration in app.

I did some planning before buying this second kit. The battery and BMS are from the old kit, a 1.2 kW hub motor. Not being able to handle slopes, I bought this new kit. Since the controller is programmable, I should be able to limit the current up to 50% by app, which equals 20A.

My battery has Panasonic cells with discharge of 4.6A. In 8p totals up to 36.8A of current. This exceeds the capacity of the BMS, I came here to understand what problem I would have in combining this battery with this BMS.

I am preparing another battery with 72V and BMS bluetooth over 40A to let off. The new cells will be at 8p and each has more than 6A of discharge. But I would not want to discard my current battery as I have a programmable kit.

I am talking to you through machine translation. Strange things may appear to both parties, but overall works well!

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thundercamel   100 W

100 W
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Joined: Jul 23 2018 2:58pm
Location: Round Lake, Illinois

Re: BMS vs controller vs overload vs noob. Fight!

Post by thundercamel » Jul 31 2019 10:16am

You and Flat Tire are both saying the same thing. The BMS will cut power temporarily if too much current is drawn from the battery. I greatly prefer a smart BMS to verify that the voltages of each cell group is behaving. Might as well go straight for the 60 amp version, as these are programmable as well, but like Flat Tire said, the motor controller should be where you set your maximum current. The BMS is just a backup protection. The PC adapter gives you access to a few parameters that are not available in the Android app, like minimum and maximum temperatures from the two included sensors.
My Ebike builds - Existing bikes, affordable motor kits, self built 14s6p batteries - Now with more recumbent!

laerciohj   10 mW

10 mW
Posts: 24
Joined: May 25 2019 1:47pm

Re: BMS vs controller vs overload vs noob. Fight!

Post by laerciohj » Aug 01 2019 7:39am

One more confirmation, thanks!

Then we have two current controls: the controller (main) and BMS (reserve) that also acts on the discharge.

As I understand it the controller works by limiting the current and the BMS is more rigid, cuts the current.

My set operating at most is inappropriate. With a maximum current battery of 36.8A and a 40A controller, the BMS will constantly work by cutting the current. In addition, the controller above battery capacity forces cells above maximum capacity.

I need to program the controller to make everything flow safely, I thought it would be as simple as advertising. The idea is good, but this controller seems to have something beyond just opening the app, syncing via bluetooth and activating the option of interest. I don't know for this model PC control, as you suggested. Exist?

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thundercamel   100 W

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Joined: Jul 23 2018 2:58pm
Location: Round Lake, Illinois

Re: BMS vs controller vs overload vs noob. Fight!

Post by thundercamel » Aug 01 2019 8:44am

The PC adapter I mentioned only applies to the smart BMS that I linked in my last post.
My Ebike builds - Existing bikes, affordable motor kits, self built 14s6p batteries - Now with more recumbent!

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