Bms on a budget

H

happydaddy

New member
Joined
Feb 20, 2018
Messages
4
Hi all

Im almost finished with my 14s80p 18650 power wall. I really like the batrium stuff but Cant afford it right now. Can I buy it in parts. if yes what do I need as a bare minimum if I want to get started.i would like to make my batteries safe and not overcharge one pack because of bad solder joint etc. alternatively should I look at the cheaper stuff like smartbms and use that in the meantime until I can afford the full batrium kit?
 
There's several threads recently on custom bms units. There are a few different avenues they are taking and all are pretty much reachable. Most of the units are fairly inexpensive.
 
Cautionary tale - I ran 6 months on 14s 240p battery bank using a set of 7s meters to manually measure voltage while I saved for Batrium. Each cell was tested via OPUS BT-C3100 and all packs were initially matched at 580ah +/- 4ah. I set my Midnite Solar Aux1 to shutoff my inverter at 47.0v (e.g. 3.36v / s) which seemed very safe. Morning, manual checks showed 2 low packs at 3.15v and rest in 3.3 to 3.5 range. All seemed reasonable. However, once I got my Batrium and could log what was happening, I discovered that 2 of the packs had 'wild' voltage swings compared to the others and were going below 2.80v at the 47.0v shutoff and then bouncing back up to 3.15v. Yikes... I have added 10% more / good cells to each of the bad packs and they only go down to 3.05v now... but still have wild voltage swing compared to the others.

Bottom line - I think I damaged these 2 packs thru the 150 cycles by letting them go too low. I am now in process of replacing them and we'll see - but to me, it shows that a BMS / logger / automatic bottom (and top) cutt-off of each pack in series is important.
 
offgridinthecity said:
Cautionary tale - I ran 6 months on 14s 240p battery bank using a set of 7s meters to manually measure voltage while I saved for Batrium. Each cell was tested via OPUS BT-C3100 and all packs were initially matched at 580ah +/- 4ah. I set my Midnite Solar Aux1 to shutoff my inverter at 47.0v (e.g. 3.36v / s) which seemed very safe. Morning, manual checks showed 2 low packs at 3.15v and rest in 3.3 to 3.5 range. All seemed reasonable. However, once I got my Batrium and could log what was happening, I discovered that 2 of the packs had 'wild' voltage swings compared to the others and were going below 2.80v at the 47.0v shutoff and then bouncing back up to 3.15v. Yikes... I have added 10% more / good cells to each of the bad packs and they only go down to 3.05v now... but still have wild voltage swing compared to the others.

Bottom line - I think I damaged these 2 packs thru the 150 cycles by letting them go too low. I am now in process of replacing them and we'll see - but to me, it shows that a BMS / logger / automatic bottom (and top) cutt-off of each pack in series is important.
Click to expand...

Thank for the heads up. This is what I would like to avoid. Would the batrium kit without the SOC sensor handel all this or is it essential to have it?
 
The Soc sensor makes it easier to determine how much is left. With out it you are guessing
 
In my example, I reviewed the the pack voltages (shunt not needed for that). Batrium GUI has an option to save info every 5mins to a text file. It was this review of the series of text file data the showed me the drop below 2.8v at 2am when Inverter kicked off and then 3.15v at 6am after I woke up.

Here's an example of the cell (pack) info recorded every x interval that you can set in the Tools -> Snapshot reporting of Batrium.
----------------------------------------------------------------------------------------

Cell Node information

ID Bypass Initial Session Amp MinV MaxV MaxT BypT HiT HiBypT LoV HiV BypV BypA DatEr Reset CalV RepCV Serial HwVers

1 0.0 mAh 0.00A 3.67v 3.67v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 9 2 7 250 273936659 HW6.2 FW2.2 BL2.0

2 0.0 mAh 0.00A 3.68v 3.69v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 3 11 250 274013710 HW6.2 FW2.2 BL2.0

3 0.0 mAh 0.00A 3.68v 3.68v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 56 4 8 250 273940670 HW6.2 FW2.2 BL2.0

4 0.0 mAh 0.00A 3.68v 3.68v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 12 5 7 250 273948144 HW6.2 FW2.2 BL2.0

5 0.0 mAh 0.00A 3.68v 3.68v 13C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 98 6 7 250 273936132 HW6.2 FW2.2 BL2.0

6 0.0 mAh 0.00A 3.68v 3.68v 13C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 7 6 250 274032625 HW6.2 FW2.2 BL2.0

7 0.0 mAh 0.00A 3.69v 3.69v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 1 8 11 250 274012953 HW6.2 FW2.2 BL2.0

8 0.0 mAh 0.00A 3.68v 3.68v 14C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 1 9 7 250 273939092 HW6.2 FW2.2 BL2.0

9 0.0 mAh 0.00A 3.68v 3.68v 13C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 130 10 11 250 273936870 HW6.2 FW2.2 BL2.0

10 0.0 mAh 0.00A 3.68v 3.68v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 3 11 7 250 273938908 HW6.2 FW2.2 BL2.0

11 0.0 mAh 0.00A 3.68v 3.68v 14C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 18 12 9 250 274029715 HW6.2 FW2.2 BL2.0

12 0.0 mAh 0.00A 3.70v 3.71v 14C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 13 12 250 273942861 HW6.2 FW2.2 BL2.0

13 0.0 mAh 0.00A 3.67v 3.68v 14C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 0 14 10 250 274030877 HW6.2 FW2.2 BL2.0

14 0.0 mAh 0.00A 3.68v 3.68v 14C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 3 15 6 250 273942058 HW6.2 FW2.2 BL2.0

15 0.0 mAh 0.00A 3.64v 3.64v 14C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 5 16 7 250 274033258 HW6.2 FW2.2 BL2.0

16 0.0 mAh 0.00A 3.64v 3.64v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 94 17 6 250 274014472 HW6.2 FW2.2 BL2.0

17 0.0 mAh 0.00A 3.75v 3.75v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 132 18 9 250 274028345 HW6.2 FW2.2 BL2.0

18 0.0 mAh 0.00A 3.73v 3.73v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 19 9 250 274014670 HW6.2 FW2.2 BL2.0

19 0.0 mAh 0.00A 3.75v 3.75v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 130 20 10 250 274014008 HW6.2 FW2.2 BL2.0

20 0.0 mAh 0.00A 3.63v 3.63v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 21 7 250 273937878 HW6.2 FW2.2 BL2.0

21 0.0 mAh 0.00A 3.75v 3.75v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 66 22 9 250 274013977 HW6.2 FW2.2 BL2.0

22 0.0 mAh 0.00A 3.75v 3.75v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 130 23 8 250 274014037 HW6.2 FW2.2 BL2.0

23 0.0 mAh 0.00A 3.63v 3.63v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 17 24 9 250 273939392 HW6.2 FW2.2 BL2.0

24 0.0 mAh 0.00A 3.64v 3.64v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 23 25 5 250 273945225 HW6.2 FW2.2 BL2.0

25 0.0 mAh 0.00A 3.63v 3.64v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 133 26 8 250 273938843 HW6.2 FW2.2 BL2.0

26 0.0 mAh 0.00A 3.63v 3.64v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 85 27 9 250 273944577 HW6.2 FW2.2 BL2.0

27 0.0 mAh 0.00A 3.63v 3.64v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 5 28 7 250 274033152 HW6.2 FW2.2 BL2.0

28 0.0 mAh 0.00A 3.64v 3.64v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 133 29 9 250 274024435 HW6.2 FW2.2 BL2.0

29 0.0 mAh 0.00A 3.68v 3.68v 12C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 0 30 9 250 273942220 HW6.2 FW2.2 BL2.0

30 0.0 mAh 0.00A 3.67v 3.68v 12C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 20 31 5 250 274033665 HW6.2 FW2.2 BL2.0

31 0.0 mAh 0.00A 3.67v 3.68v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 1 32 6 250 274033529 HW6.2 FW2.2 BL2.0

32 0.0 mAh 0.00A 3.67v 3.67v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 33 8 250 274015568 HW6.2 FW2.2 BL2.0

33 0.0 mAh 0.00A 3.67v 3.67v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 0 34 7 250 273944918 HW6.2 FW2.2 BL2.0

34 0.0 mAh 0.00A 3.67v 3.67v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 48 35 8 250 273945250 HW6.2 FW2.2 BL2.0

35 0.0 mAh 0.00A 3.67v 3.68v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 1 36 4 250 273945473 HW6.2 FW2.2 BL2.0

36 0.0 mAh 0.00A 3.67v 3.68v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 37 5 250 274015150 HW6.2 FW2.2 BL2.0

37 0.0 mAh 0.00A 3.67v 3.68v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 34 38 8 250 274027408 HW6.2 FW2.2 BL2.0

38 0.0 mAh 0.00A 3.67v 3.67v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 20 39 6 250 274025293 HW6.2 FW2.2 BL2.0

39 0.0 mAh 0.00A 3.68v 3.68v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 40 40 6 250 273944185 HW6.2 FW2.2 BL2.0

40 0.0 mAh 0.00A 3.67v 3.68v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 41 10 250 274031284 HW6.2 FW2.2 BL2.0

41 0.0 mAh 0.00A 3.67v 3.67v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 128 42 7 250 274022085 HW6.2 FW2.2 BL2.0

42 0.0 mAh 0.00A 3.69v 3.69v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 128 43 8 250 273941202 HW6.2 FW2.2 BL2.0
 
If you want more detail you can use the software i have written and you get below 1sec resolution. No you dont need shunt for voltages but the shunt give you an indication of the capacity used and or left. Getting that data from the voltage is trickier.
 
SORRY - I reposted accidentally.

offgridinthecity said:
In my example, I reviewed the the pack voltages (shunt not needed for that). Batrium GUI has a Tools->Snapshot Reportoption to save info every 5mins to a text file. It was this series of text file data the showed me the drop below 2.8v at 2am (down to inverter cut-off)and then 3.15v bounce back at 6am after I woke up.

Here's an example of the cell (pack) info recorded every x interval that you can set in the Tools -> Snapshot reporting of Batrium.
----------------------------------------------------------------------------------------
Cell Node information
ID Bypass Initial Session Amp MinV MaxV MaxT BypT HiT HiBypT LoV HiV BypV BypA DatEr Reset CalV RepCV Serial HwVers
1 0.0 mAh 0.00A 3.67v 3.67v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 9 2 7 250 273936659 HW6.2 FW2.2 BL2.0
2 0.0 mAh 0.00A 3.68v 3.69v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 3 11 250 274013710 HW6.2 FW2.2 BL2.0
3 0.0 mAh 0.00A 3.68v 3.68v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 56 4 8 250 273940670 HW6.2 FW2.2 BL2.0
4 0.0 mAh 0.00A 3.68v 3.68v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 12 5 7 250 273948144 HW6.2 FW2.2 BL2.0
5 0.0 mAh 0.00A 3.68v 3.68v 13C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 98 6 7 250 273936132 HW6.2 FW2.2 BL2.0
6 0.0 mAh 0.00A 3.68v 3.68v 13C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 7 6 250 274032625 HW6.2 FW2.2 BL2.0
7 0.0 mAh 0.00A 3.69v 3.69v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 1 8 11 250 274012953 HW6.2 FW2.2 BL2.0
8 0.0 mAh 0.00A 3.68v 3.68v 14C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 1 9 7 250 273939092 HW6.2 FW2.2 BL2.0
9 0.0 mAh 0.00A 3.68v 3.68v 13C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 130 10 11 250 273936870 HW6.2 FW2.2 BL2.0
10 0.0 mAh 0.00A 3.68v 3.68v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 3 11 7 250 273938908 HW6.2 FW2.2 BL2.0
11 0.0 mAh 0.00A 3.68v 3.68v 14C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 18 12 9 250 274029715 HW6.2 FW2.2 BL2.0
12 0.0 mAh 0.00A 3.70v 3.71v 14C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 13 12 250 273942861 HW6.2 FW2.2 BL2.0
13 0.0 mAh 0.00A 3.67v 3.68v 14C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 0 14 10 250 274030877 HW6.2 FW2.2 BL2.0
14 0.0 mAh 0.00A 3.68v 3.68v 14C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 3 15 6 250 273942058 HW6.2 FW2.2 BL2.0
15 0.0 mAh 0.00A 3.64v 3.64v 14C 13C 40C 55C 3.10v 4.16v 4.15v 1.27A 5 16 7 250 274033258 HW6.2 FW2.2 BL2.0
16 0.0 mAh 0.00A 3.64v 3.64v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 94 17 6 250 274014472 HW6.2 FW2.2 BL2.0
17 0.0 mAh 0.00A 3.75v 3.75v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 132 18 9 250 274028345 HW6.2 FW2.2 BL2.0
18 0.0 mAh 0.00A 3.73v 3.73v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 19 9 250 274014670 HW6.2 FW2.2 BL2.0
19 0.0 mAh 0.00A 3.75v 3.75v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 130 20 10 250 274014008 HW6.2 FW2.2 BL2.0
20 0.0 mAh 0.00A 3.63v 3.63v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 21 7 250 273937878 HW6.2 FW2.2 BL2.0
21 0.0 mAh 0.00A 3.75v 3.75v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 66 22 9 250 274013977 HW6.2 FW2.2 BL2.0
22 0.0 mAh 0.00A 3.75v 3.75v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 130 23 8 250 274014037 HW6.2 FW2.2 BL2.0
23 0.0 mAh 0.00A 3.63v 3.63v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 17 24 9 250 273939392 HW6.2 FW2.2 BL2.0
24 0.0 mAh 0.00A 3.64v 3.64v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 23 25 5 250 273945225 HW6.2 FW2.2 BL2.0
25 0.0 mAh 0.00A 3.63v 3.64v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 133 26 8 250 273938843 HW6.2 FW2.2 BL2.0
26 0.0 mAh 0.00A 3.63v 3.64v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 85 27 9 250 273944577 HW6.2 FW2.2 BL2.0
27 0.0 mAh 0.00A 3.63v 3.64v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 5 28 7 250 274033152 HW6.2 FW2.2 BL2.0
28 0.0 mAh 0.00A 3.64v 3.64v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 133 29 9 250 274024435 HW6.2 FW2.2 BL2.0
29 0.0 mAh 0.00A 3.68v 3.68v 12C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 0 30 9 250 273942220 HW6.2 FW2.2 BL2.0
30 0.0 mAh 0.00A 3.67v 3.68v 12C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 20 31 5 250 274033665 HW6.2 FW2.2 BL2.0
31 0.0 mAh 0.00A 3.67v 3.68v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 1 32 6 250 274033529 HW6.2 FW2.2 BL2.0
32 0.0 mAh 0.00A 3.67v 3.67v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 33 8 250 274015568 HW6.2 FW2.2 BL2.0
33 0.0 mAh 0.00A 3.67v 3.67v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 0 34 7 250 273944918 HW6.2 FW2.2 BL2.0
34 0.0 mAh 0.00A 3.67v 3.67v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 48 35 8 250 273945250 HW6.2 FW2.2 BL2.0
35 0.0 mAh 0.00A 3.67v 3.68v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 1 36 4 250 273945473 HW6.2 FW2.2 BL2.0
36 0.0 mAh 0.00A 3.67v 3.68v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 37 5 250 274015150 HW6.2 FW2.2 BL2.0
37 0.0 mAh 0.00A 3.67v 3.68v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 34 38 8 250 274027408 HW6.2 FW2.2 BL2.0
38 0.0 mAh 0.00A 3.67v 3.67v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 20 39 6 250 274025293 HW6.2 FW2.2 BL2.0
39 0.0 mAh 0.00A 3.68v 3.68v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 40 40 6 250 273944185 HW6.2 FW2.2 BL2.0
40 0.0 mAh 0.00A 3.67v 3.68v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 2 41 10 250 274031284 HW6.2 FW2.2 BL2.0
41 0.0 mAh 0.00A 3.67v 3.67v 13C 12C 40C 55C 3.10v 4.16v 4.15v 1.27A 128 42 7 250 274022085 HW6.2 FW2.2 BL2.0
42 0.0 mAh 0.00A 3.69v 3.69v 13C 11C 40C 55C 3.10v 4.16v 4.15v 1.27A 128 43 8 250 273941202 HW6.2 FW2.2 BL2.0
Click to expand...
 
You must log in or register to reply here.
Back
Top