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Wikel's avatar
Wikel
Explorer
Jun 09, 2017

Gut check lithium 4S6P battery connections

Still working to figure out this whole solar battery thing. This is focused on:

1. The series interconnections between 3.2v lithium battery cells to create a larger 12v nominal pack.
2. The parallel interconnections between 12v nominal packs to create a larger AH battery array.
3. The link between the positive and negative connections and the upstream charging / discharging components using the battery array.



1. Would this be a correct setup and if not, what needs to change?
2. Is there a more effective way to arrange the battery configuration. If so, how and why?

Thanks for any feedback!
  • Wikel's avatar
    Wikel
    Explorer
    Jun 09, 2017
    time2roll wrote:
    Looks good to me. How do you keep the series connection balanced?


    There would be cell level monitoring in place but it didn't want to represent that here to muddy the discussion of the base electrical connectivity.
  • Wikel's avatar
    Wikel
    Explorer
    Jun 09, 2017
    2oldman wrote:
    That's a lot of wires.. wow.


    Actually the reds are just jumper bars for the series connections. Still have to be installed but not actual bendable wires persay.
  • Chris_Bryant's avatar
    Chris_Bryant
    Explorer II
    Jun 09, 2017
    The only way I could see to improve would be star wiring positive and negative- a lead from each 4 pack to a central point, instead of jumpering between packs.
  • MrWizard's avatar
    MrWizard
    Moderator
    Jun 09, 2017
    Have you been to one of the DIY electric vehicle sites
    Have looked at the battery packs involved
    As I remember it, there is more wiring
    The cells are Managed by the BMS, the battery monitoring system

    Your drawing is the basic hook up of the discharge path
    The charging system path is more complicated overlayed on top of this, more connections and wires directly from the bms
  • Wikel's avatar
    Wikel
    Explorer
    Jun 09, 2017
    Chris Bryant wrote:
    The only way I could see to improve would be star wiring positive and negative- a lead from each 4 pack to a central point, instead of jumpering between packs.


    Thought about doing a pos and neg bus bar for this parallele interconnect but need to do more research into that pro con wise.
  • Wikel's avatar
    Wikel
    Explorer
    Jun 09, 2017
    MrWizard wrote:
    Have you been to one of the DIY electric vehicle sites
    Have looked at the battery packs involved
    As I remember it, there is more wiring
    The cells are Managed by the BMS, the battery monitoring system

    Your drawing is the basic hook up of the discharge path
    The charging system path is more complicated overlayed on top of this, more connections and wires directly from the bms


    The BMS can be just monitoring with low and high cutoff or in combination with some type of balancing (debatable if that should be done with lifepo4 or not... i.e might damage they). This discussion is beyond BMS which is another topic in itself.
  • Wikel's avatar
    Wikel
    Explorer
    Jun 09, 2017
    mapguy wrote:
    Think you want to do 6p4s. What cells and BMS are you considering?

    Remember RV usage is similar to house battery systems on boats. Not really similar to EV battery systems due to the constant loads and multiple charging sources.

    Take a look at the following web pages:
    http://www.pbase.com/mainecruising/lifepo4_on_boats

    https://www.entropypool.de/engineering/

    http://nordkyndesign.com/category/marine-engineering/electrical/lithium-battery-systems/


    Clab batteries 180AH 3.2v.

    BMS I am still exploring but don't want to put that into this mix until the basic electrician approach is defined.

    I'll take a look at the 6P4S vs. 4S6P. That does change some things even though the output is the same. Thought I had read somewhere that do P first and then S vs. the other way. It also affects in and out boards for BMS cell/pack communications and monitoring (less in and out boards at a pack level (4 packs vs. 6 packs).
    Thanks

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