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  • Post in thread: JBD Smart BMS UART Connector Type

    Thank you @mikefitz I found both of those but they weren't quite the same. Luckily, I realized I had overlooked something in the manual. Under each of the ports in the tag column there is a note "HY2.0-2P" and 4P for the UART connector. These are the part numbers for this particular connector...
  • Post in thread: Ok you win... Cell imbalance

    Try an active balancing BMS such as JKBMS if you get an opportunity to switch it out. Their 2A active balancer made a huge difference with my slightly mismatched 248ah 8s pack.
  • Post in thread: NodeJKBMS Published - JK BMS Remote Data Monitoring With MQTT Publishing

    Over the past several months I spent some time porting an earlier github project called NodeJBD to support the JK BMS. This is a node.js written application which polls active data parameters from the JK BMS and displays on command line, or the data can be published to MQTT and read by other...
  • Post in thread: 24v Inverter Recommendation

    I'm searching for an inverter that increasingly seems like a unicorn. After trialing a few I just cant seem to find the one. Anyone have any recommendation on an inverter that would meet these specs? - 24v/2000-3000w - NO low frequency transformer hum (its going in an occupied space) - Hard...
  • Post in thread: JK BMS: canbus AND/OR rs485

    Here is how I connected mine. This is a Heltec branded version of the JK B2A8S20P. The top heatsink is screen printed a little differently but its otherwise identical to the JK. The 3rd port over when viewing from the bottom is a 4-pin, Micro JST 1.25mm port. Some of the JK versions have this...
  • Post in thread: Battery Storage with Micro Inverter System

    I have an 8kw system with enphase microinverters installed about 2016. It is under a 20 year PPA agreement so I really cant modify the system. The system ties into my main panel via a 2 pole 40 amp breaker. The main problem Im trying to solve is I want to add a battery backup to the system that...
  • Post in thread: Writing Data to JKBMS USB-TTL / RS-485

    Thanks, super helpful, I got these cmds to work with my B2A8S20P, and I see that the byte at position 11 (Transport Type) must be set to 0x02 "BMS Active Upload" for the write command to work. Unfortunately I still havent been able to get the BMS to accept the password after trying about 250...
  • Post in thread: Amp Draw - Parallel Packs

    Thats great to know, thank you. Its definitely under 10%, most commonly 6-7% even at higher amperages under heavy load or 70a charging. I guess at the end of the day its never going to be perfect and they will constantly be evening out. I scotch-brited all the lugs, bus bars and battery...
  • Post in thread: What Causes a Runner?

    After struggling with the passive 150ma balancer on my JBD BMS, I decided to try the JK 8s 2a active balancing BMS (JK_B2A8S20P). Wow, what a difference. In only 40 minutes the JK active balancing BMS equalized a 125mV cell delta down to 15mV, something that would have taken many hours with the...
  • Post in thread: JK BMS: canbus AND/OR rs485

    First off all things JK BMS are rather mystifying due to multiple sellers and nascent documentation. The way I understood it, is that the JK BMS is manufactured to be capable of speaking any of those protocols, but it's activated in the firmware prior to shipping, only if you pay. It's kind of...
  • Post in thread: Writing Data to JKBMS USB-TTL / RS-485

    @pacman that’s great that is one of the things I’d like to be able to control remotely as well. I’m working on a mqtt loader for the jkbms to interface with my victron nodered ESS mode 3 implementation for the multiplus-ii. Could you share the command you used to switch charge/discharge on and...
  • Post in thread: 24v Inverter Recommendation

    @AustinMTB I hear you on the manuals, I feel like I have read at least 40 in the past month. I wish noise level was a spec on the datasheet for these units. There are many use cases where the unit will be in earshot of, maybe even directly in, a living area. The environmental specs should...
  • Post in thread: “Normal” Cell Delta at Charge Voltage

    One thing I’ve noticed about both of my 8s packs, is the JBD BMS really doesnt seem to balance at all when the charge current is zero. I can let them sit in absorb at 27.8v for 2 hours without the 44mV and 42mV cell delta moving more than 1 or 2 mV. So thinking balancing under current was the...
  • Post in thread: 24v Inverter Recommendation

    Wanted to add RE eco mode: Victron calls it AES or search mode. The way I understand it, is that below a certain threshhold, configurable on some units but defaulting to about 50w on most of the ones I’ve seen, the inverter goes into a low power mode that “searches“ for current demand every .5...
  • Post in thread: Writing Data to JKBMS USB-TTL / RS-485

    @NEEY Electronics if you have any insights here please advise!
  • Post in thread: Battery Storage with Micro Inverter System

    Thanks, I realize the importance of in anti-islanding (im not a line worker but i work with them). Any other options than going all Enphase? Although the existing system is Enphase, I really dont want to modify it in any way, or have to obtain permission from the PPA provider. The battery system...
  • Post in thread: “Normal” Cell Delta at Charge Voltage

    Is there such a thing as a normal, or acceptable range, for the cell voltage differential at top of charge? Strictly as an example, if a 230ah 8s pack stops charging at 27.8v, leaving it’s cells with a [min, avg, max] of [3.440, 3.475, 3.498] and thus a 58mV cell voltage delta/differential...
  • Post in thread: Writing Data to JKBMS USB-TTL / RS-485

    I think this is a question @Steve_S or @upnorthandpersonal may be able to answer. I'm trying to write a python script that can write data to the JK BMS via USB-TTL. I found the documents here, specifically "Communication protocol between monitoring platform and BMS.pdf". There is also a...
  • Post in thread: What Causes a Runner?

    Since installing my 8s2p 498ah LiFePO4 setup, I've had recurring issues with so called "runners". By that I mean, 1 or 2 cells in the pack will go to a much higher voltage than the rest of the cells whilst under charge voltage. For instance, when charging my pack to 28.00v, at 27.9v or higher...
  • Post in thread: JBD Smart BMS UART Connector Type

    Probably a long shot, but wondering if anyone has been able to identify the connector in the photos. This is the 4-pin Bluetooth module cable that connects into the UART port on my JBD 8s 100a smart BMS (SP16S020). I want to make some longer cables because my batteries are in a steel cage which...
  • Post in thread: JK BMS: canbus AND/OR rs485

    Mine is 3.3v on the rxout pin. Vout is full battery voltage so be careful with that one (i dont use it) I think in a few years we will see BMS with native wifi and built in web status. The industry just isn’t quite there yet.
  • Post in thread: Amp Draw - Parallel Packs

    I have a 498Ah 8s2p setup where the two packs were recently installed in parallel. I top balanced both packs and charged both individually to 28.00v before connecting them together. As expected the voltages are identical as measured by my dual JBD BMS's and current flow between them at idle is...
  • Post in thread: Battery Storage with Micro Inverter System

    What I ended up putting in was a 13.2 KWh 8s2p LiFePO4 battery pack coupled with a Victron Multiplus II 2x120v. I reconfigured my critical circuits to run on a dedicated critical loads subpanel fed from the Multiplus II. When grid power is available the MP-II can put out 40a (20a battery + 20a...
  • Post in thread: What Causes a Runner?

    They are JBD Smart BMS, 2 x 8s. I believe these are passive balancing the packs, and do so at a pretty low current. I'm going to try manually balancing as sunshine_eggo suggests and then I'm hoping the passive balancer will maintain the balance with daily charge/absorprtion cycles.
  • Post in thread: Amp Draw - Parallel Packs

    One thing still confuses me: why would i see the higher current in the longer round trip cable? It seems that with the higher resistance offered by the longer cable, the current on the longer cable would be lower compared to the shorter run pack. The other thing mystifying me is why i would...
  • Post in thread: “Normal” Cell Delta at Charge Voltage

    So far mine holds at 60mV between cycles, the balancer doesnt make much of a dent beyond that (20mv diff to balance, 3.4v or above only, and whilst charging and discharging). Prior to manually in place top-balancing to 28v (ie while in series formation, not on the bench and in parallel) I was...
  • Post in thread: What Causes a Runner?

    @sunshine_eggo this seems like a good idea -- when doing this I assume I have to charge them all individually (16 times), or is there a way you do them in parallel to speed up the process? And where should I stop the charge, under 1a or even lower than that? Are there any reasons you could...
  • Post in thread: Sanding Tin Plated Copper

    I have heard its recommended to use scotch brite or very fine grit sandpaper on bus bars, terminals, lugs and battery studs. What about tin plated copper surfaces like a Blue Sea Class T fuse holder, a battery switch terminal stud, etc. When sanding - at what point do you stop sanding? When...
  • Post in thread: Initial Charging of Parallel Battery Banks

    One thing I haven't been able to find much in the way of recommendations for, is how you should go about the initial charge and syncing of two batteries prior to cycling them in parallel. Is there a step by step process you follow to do it? I know some of the basics, like pre-charging both to...
  • Post in thread: JBD BMS Linux Utility

    Is it possible to control the JBD BMS via this or a similar linux based method, for instance to toggle the charge or discharge ports on or off programatically? Either USB or Bluetooth would work for this, just trying to find a way to remotely manage these without having to be near the BMS...
  • Post in thread: Recommendation: Off-Grid Emergency Backup

    Looking for a recommendation on a solar project Im thinking about. I have 600 watts of solar on a shed that has been converted into an office and have 12s lifepo4 230ah of storage as well. Ideally Im looking for an inverter/solar charge controller that can power the shed during normal...
  • Post in thread: JK BMS: canbus AND/OR rs485

    Yes, or half way around the world for that matter. But you have to work for it. JiKong not making it any easier for you. I view my battery status using a custom nodered dashboard i built as a single page web app from my ipad or phone. Some use grafana or other ways to display the data. But it’s...
  • Post in thread: Writing Data to JKBMS USB-TTL / RS-485

    I heard back from JiKong and one of their Alibaba sales partners — apparently the write function was disabled at least in the current revision of the BMS they sell such as the B2A8S20P and writing parameters via rhe GPS port is currently not possible. The information in the protocol spec is...
  • Post in thread: Top Balanced 8s Pack - High Volt on 3 Cells While Charging

    I'm in the process of building an 8s2p LiFePO4 12.8 KWh DIY Powerwall and I have assembled my 230Ah prismatic cells first in parallel, and top balanced them to 3.65v with a bench power supply. After assembling in series I'm seeing good balance between cells of around .003, never over .01 while...

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