Looking to work with LiFePO4 battery, which has a range of 2.5V - 3.6V.
Correct me if I’m wrong, but I believe the balancing hardware should work fine after changing the balance voltage in the code. I may adjust the voltage measurement divider to utilize the full 2V scale and adjust the discharge resistor to 2.0 ohm to compensate for the lower voltage range.
For the controller board, 2.5v might be on the low end for esp8266. I may need to limit the discharge to 2.7v or add a buck converter.
JLCPCB now offers SMT service. I just ordered my boards 50% populated. I could probably order 80% populated boards if not for the “extended part” labor fees. (For each uncommon part number, they charge $3 for mounting the rail, may not be a big deal if ordered in large quantities)
We will see how the boards turn out
I’ve just used that as well, I’m looking to re-engineer the boards to use as many of their standard parts as possible and by the looks of it will mean shrinking the components to 0603 size (tiny!!)
Its not that difficult to do, this is also the first project I’ve made with SMT components - most are easy to solder and I’ve deliberately picked a larger “human friendly” size but each component is still the size of a grain of rice !
Stuart
I did send out the current V4 files for a quote and was considering ordering a few hundred. I don’t need them all but my arrangement is 14s10p clusters. Basically 48v 1.2kwh batteries that I can build and slowly expand the bank, 1 ‘battery’ at a time. However, if you will be offering them I may put this off until I see what the cost would be from you.
I also have 14 Nissan Leaf cells and I am working on a dual diyBMSv4 to bolt to the cells similar to the Batrium LeafMon. I converted your Kicad files to v5.1 and am getting ready to do the layout.
A small suggestion: Leave the version using 0805 as diyBMSv4 for those who want to roll their own and create a 2nd version diyBMSv4a for a manufactured version using 0603. You can hand solder 0603 but it requires a very steady hand.
I’m running mine powered from a cell bank using a LM2596 Buck Converter. I adjusted it to 3.3v and soldered the output to bottom of control board on the 3.3v and Gnd pins that the Wemos plugs into.
P.S. My battery charged up yesterday on PV, DIYBMSv4 shows 17mv range, that is almost perfect balance! Pretty cool for 1120 cells to be that close. Great program Stuart!
I’m trying to learn HTML so I can control my solar tracker remotely with my phone, your code is very high BAR to reach.
If you go forward with ordering, if you are interested, I’d be willing to share the cost/delivery of the order. I’m not sure where efficiencies in ordering are, but I’d be willing to carry spares for future BMS projects for others at board cost.
I am also working with Nissan Leaf batteries (7 modules, 14s2p at the moment) and plan to build up to 14s8p to 14s14p (depending on need) which also seems like your thinking.
I ordered 50 from JLCPCB and will see what they look like. There are a number of ‘missing’ components such as the connectors, 2.2ohm, ATTiny and thermistor. I see no problem hand soldering those. The price for the 50 boards including shipping to Canada was approx $77US. / 1.54 each. Add in the other items and I expect an assembled price will be <$5 each.
JLCPCB is having a December sale for pcb+assembly and i recommend people grab a few dozen at this price break. The commercial off-shore assembler I use for my business quoted me a higher price in 100-200 unit builds. JLCPCB is not charging for the stencil or setup which can run $200-$400.
George
Great project Stuart, This is just what I was looking for. I have ordered (hopefully) all of the boards and components required. It has been probably 20 years since i worked with microcontrollers lol and soldered (at that time) only through hole components… We will see how the smd stuff goes, probably have to stop drinking coffee 3 days before lol, the 1/4" oscillation in my fine motor skills should make it interesting :)
Does your jclpcb_assembly branch have the gerber file that will fit the 0603 components?
I am in the process of ordering with the SMT service from JLCPCB and they came back with 17 components that wouldn’t fit. They didn’t give any reason, but I had uploaded the gerber file from the master branch and the BOM and CPL files from the assembly branch. Was this an oops?
I just ordered from jlcpcb, 25 boards, 5 controller boards, and assemble for the 25 cell boards, total cost was about 60 bucks American including shipping. The version 4 files on GitHub had 4 errors in the parts placement. Q1 was upside down, D2, D3, D4 were reversed polarity. I will have to wait for final delivery to see what the quality looks like.
i have a question
how much space is requierd for influxdb to record a year bms data on 14s? does old data get overwritten if no free space is available or does it stop record then?
Describes how long InfluxDB keeps data (duration), how many copies of the data to store in the cluster (replication factor), and the time range covered by shard groups (shard group duration). RPs are unique per database and along with the measurement and tag set define a series.
When you create a database, InfluxDB creates a retention policy called autogen with an infinite duration, a replication factor set to one, and a shard group duration set to seven days. For more information, see Retention policy management.
