Not that much, it is off by a few miles in the end, depending on how hard you ride, but it gives you a fair idea of what's left in the pack.
It works on all 4 of my BMS. The LCD needs power. Connect it across batt+ to batt -. It also measures total pack voltage via it's power wires.
The shunt value is settable in the BMS. More than likely the default value in the BMS's is a generic value that may or may not be right. I've ran into this too. Of course I'm modding all my BMS, but never the less, a micro ohm meter will get you close to the right resistance for the shunts. Dropping in a shunt based watt meter temporarily so you have a comparative value will let you see which way to adjust the shunt on the BMS to get it dead on.trazor wrote: ↑Sep 06 2018 3:15pmI was thinking about these BMS and their concept of "capacity" and "state of charge". I think the implementation is very poor. For example, the JBDTools and the protocol ( https://drive.google.com/file/d/0B3UXpt ... ZGTTQ/view ) show state of charge in Ah, taking into account an user set capacity and extrapolating to a voltage curve (which you can set 6 points: CellFullVoltage, CellEndVoltage, 80%Capacity,60%Capacity,40%Capacity,20%Capacity). Of course, the electric charges returned value can be totally fake. The proper state of charge to return only can be a ratio, percentage, etc.
So, I was thinking if using the protocol and an attached arduino, we can read the pack voltage and amperage in very frequent intervals and calculate the real charges that are being output by the BMS. I mean, to make something like this https://www.amazon.com/10-100V-Battery- ... coulometer without needing another shunt in the circuit.
What do you think?
As a side note, on my boards, the voltage readings seem very good, but the amperage is way off. Using a multimeter and a lab power supply I got the real values and re-calibrated the BMS. Mine by default was around 20% off on each direction (charge and discharge)
Also, the temperature sensors are all reading different values, so it is good to re-calibrate them using an ambient thermometer and setting all to the same value.
Just don't do that!Mikebike wrote: ↑Sep 07 2018 6:06pmNext challenge.
Went to extend the factory presoldered wire coming off the BMS so I could have 2 seperate longer negative leads coming off the C- pad. One for charge and one for discharge as shown for the single C- pad method (in other words both charge/discharge leads connected to the C- pad only).
How are u guys connecting the wires?
Is this black colored wire that came from the manufacturer presoldered to the C- pad aluminum wire?
If yes, then my 10 gauge wire that I have for this is copper and I didnt think you were supposed to connect/solder aluminum and copper wires together? See picture below.
If I cant join these 2 different wire types, then who sells the similar 10 guage wire in aluminum that I need? The place I went to for wire only has copper.
More than likely, IF you really do have it all wired correctly, then you have a setting wrong. Also, in the PC app you can make changes you can't do in the android app. Make sure everything is set correctly. I'm not accusing you of anything, but I have yet to have one of these BMS NOT work right out of the box. Of course before I ever connect my pack to the BMS, I've tested my balance cable multiple times to be dead sure I wired it correctly. Mistakes are easy to make. 2 crossed wires will cause all sorts of weird behavior.Ultraclearance wrote: ↑Sep 09 2018 8:45pmHi, hope someone can help!
I got a 20S Bluetooth BMS from https://www.lithiumbatterypcb.com
I built a 20S4P pack with New LG cells, but i cant get it to work, goes into "IC" status. Front end error. I have checked the wiring, and its correct, anyone know what the problem can be?
please put the metal plate back on. the balance board need this for cooling. that is what the thermal band is for.Mikebike wrote: ↑Sep 15 2018 3:21pmThanks for the suggestions.
Almost home. Battery pack complete except for the outside heat shrink. Made some acrylic ends for it to keep it all bolted together. Want to use clear shrink if I can find it cause I think it would be cool to see the battery.
Everthing seems to be working so far including the VBMS app that was provided. Bluetooth connects and charging also seems to work.
Does anyone have the latest version of the VBMS app? The version I have seems to be an older one and is missing some features I would like to have. Is there a way to upload the lastest .apk versions of these bluetooth apps somewhere so the latest versions can be downloaded by anyone?
There are at least 4 different bluetooth apps (.apk) I am aware of:
MaYi, VBMS, Huayurui, Xiaoxiang
Prolly spelled some of those wrong.
If anyone needs a link I will put (.apk) on google drive and enable share if that method will work to share (.apk) files?
ANT BMS and battery.jpg