Here Tom:
Hey, thanks for the message. Heres my parts list from an earlier post:
- Arduino UNO Wifi REV 2
2.Nema 17 Bipolar 1.8deg 13Ncm 0.7A
-
Adafruit 16-Channel 12-bit PWM/Servo Driver - I2C interface - PCA9685
-
Lithium Ion Polymer Battery - 3.7v 2500mAh
-
JST PH 2-Pin Cable – Male Header 200mm
-
4Pcs SG90 9g Micro Servos
-
Aoicrie 2pcs XL6009 Boost Buck DC-DC Adjustable Step-UP Down Power Converter Module
-
TMC2209 V1.3 UART Stepper Motor Driver Module VS TMC2100 TMC2130
-
Radial Electrolytic Capacitor, 100uF, 25V, 105 C
I included a Pastebin with all the links in the post:
As for diagrams/sketches, here are the two most recent ones, though the central wiring of the first one is a bit differnet now. Also, the second diagram is just a more detailed diagram of the bms on the first diagram.
My current issue is with the my BMS board not outputting the correct voltage. I gave details and pictures in the last 2-3 posts.
Thanks for any help you can provide!
Hi,
What voltage do you measure, with the batteries connected, between;
B+ and B-
B+ and BM
B- and BM
Thanks.. Tom... 
The batteries are 3.85v and 4.18v. The voltage readings i get from the connections you listed are:
B+ and B- : 2.98v
B+ and BM: 0v
B- and BM: 4.17v
Additionally, the output form P+ and P- reads 2.42v.
I just measured again, and the numbers are different. The batteires are currently at: 4.17v and 3.84v.
The connections show:
B+ and B-: 7.2v
B+ and BM: 4.18v
B- and BM: 3.04V
The output is currently measring 1.86v.
I assume that is with nothing connected to P+ and P-.
Your results mean your batteries are not balanced, the BMS is not doing its job.
Have you applied power to the P+ and P- terminals to charge them?
If not then charge them through the BMS and see what happens.
Measuring each of the batteries voltage as they charge.
Tom...
Both of them show charged when hooked up to an extern charger. I'll try charging throguh thr BMS.
What are the voltages that you measure on each of the two batteries when they are not connected to anything?
It sounds like your BMS is not working.
Thanks.. Tom...
The voltage on the batteries is showing up as 3.84v and 4.17v
Get the BMS to charge them, check the battery voltages ever so often.
Tom...
I've just tried twice to charge them, but their volatge does not change even after hours of charging. I am supplying 8.4v of charging current.
8.4V is not a current.
Are both cells same brand and same type?
The large difference may indicate that one is damaged.
To test: take a large 2 ohm resistor. Put it from plus to minus. Measure voltage over resistor. What do you see then? Voltage should drop a bit only...
Do not get burnt, the resistor will heat up quickly.
Also: do all this fast. The current will be large. This may damage your battery.
Yeah I meant a 8.4v charging volatge. Both batteries are the 2.5A 3.7V LiPos from Adafruit.
I dont have any resistors lying around right now, so I'm going to order some. Is there a specific wattage spec I should get or will any 2 ohm resistor work?
You will dissipate almost 4W.
Perhaps 2x1ohm 2W is easier to get.
Battery 1 is showing 0.0V,
Battery 2 is showing 3.98V.
Guess I'm going to have to get a replacement on battery 1.
Then it is really really broke indeed.
Funnily enough, this is the second defective battery I have received from Adafruit. At this point, I'm considering just using the power bank that has been my temporary power source as the actual power source for my project. There doesn't seem to be any benefit to LiPos and that BMS circuit isn't going to be working for at least another week.
Are you sure your circuit is good?
That you have plus to plus and minus to minus?
That your charger is good?
Maybe put the battery in the other charge position?
Adafruit generally is a trustworthy supplier. So you could also send them a complaint...
Maybe they have more people with defective bstteries from the same batch. They might send you a new one for free...
Yep, I have double checked all of those things. I've already gotten a free replacement from them, since one of two intial batteries I bought was defective, and this is that replacement. I am currently trying to process the same process with them for this battery.
Well, they're not replacing it either way. Apparently, these LiPos aren't meant to be wired in series (even though they the exact same cells) nor tested with the resistors.
https://forums.adafruit.com/viewtopic.php?t=208094
The Adafruit person just told me to get a pre-series-d LiPo off, which means I'll just be using my power bank.