Power in Flux
Likes Likes:  2
Page 1 of 2 12 LastLast
Results 1 to 10 of 20

Thread: BMS Confusion

              
   
   
  1. #1
    Junior Member
    Join Date
    Aug 2020
    Posts
    10
    Post Thanks / Like

    BMS Confusion

    I am currently building an ebike with a curtis pmc 1231c controller and a battery pack consisting of 26650 batteries. I'm wanting to create my own pack with the configuration of 26s19p for a 96v system and having a good amount of range with the 19p ( I believe 5ah per row, at 95 ah? correct me if I'm wrong on that.) I am also guessing the battery pack configuration should be around 380 A continuous and 570 A peak that the motor would see.

    As far as the BMS, there's confusion on the rating of the BMS's and what it should see. What would be some low cost solutions to this? I've also read about some relay bypassing or? I'm honestly not entirely sure how to choose the right BMS.

  2. #2
    Member
    Join Date
    Jun 2020
    Posts
    34
    Post Thanks / Like
    Quote Originally Posted by Csecrist12 View Post
    I am currently building an ebike with a curtis pmc 1231c controller and a battery pack consisting of 26650 batteries. I'm wanting to create my own pack with the configuration of 26s19p for a 96v system and having a good amount of range with the 19p ( I believe 5ah per row, at 95 ah? correct me if I'm wrong on that.) I am also guessing the battery pack configuration should be around 380 A continuous and 570 A peak that the motor would see.

    As far as the BMS, there's confusion on the rating of the BMS's and what it should see. What would be some low cost solutions to this? I've also read about some relay bypassing or? I'm honestly not entirely sure how to choose the right BMS.
    The bms is really not a low cost device.
    It all depends on what you're building and how long you want your batteries to last.
    If you want to have everything be safe and last a long time, an orion 2 bms would be your best bet at those power ratings.
    You might have issues fitting that onto an ebike though.
    An ANT bms (search aliexpress) would be a lower cost option (around 150) but make sure you get one rated for the amperage you require.

    Sent from my GM1915 using Tapatalk

  3. #3
    Junior Member
    Join Date
    Aug 2020
    Posts
    10
    Post Thanks / Like
    I've seen the orion 2 and those are a bit pricey, but they have a lot of controlling features. I have read in a few forums where you can bypass the bms for discharge purposes but have fuses and other relays to sense when the batteries drop just before you're wanting to. Not sure if that's possible or safe to do?

  4. #4
    Member
    Join Date
    Jun 2020
    Posts
    34
    Post Thanks / Like
    It's definitely not safe or reliable. You lose any balancing ability except while charging, and if one of your cells individually goes too low, it has no protection.

    People do many things, and many of them are bad ideas. If you're just building a dirt bike that you're going to use for an hour or two at a time and then do all the proper maintenance afterwords each time, you don't need a BMS at all, and you can just balance charge them.

    But if you want it to be reliable or you plan to ride it longer distances, you really should go with a proper BMS.

    Sent from my GM1915 using Tapatalk

  5. #5
    Senior Member Stevo's Avatar
    Join Date
    Nov 2014
    Location
    Behind the Redwood Curtain- REDWOOD ORIGINAL!!
    Posts
    901
    Post Thanks / Like

    My Social Networking

    Add Stevo on Google+
    Solid State batteries should make life easier for all of us. How do you manage so many batteries cheaply? Tesla uses a Can Bus method. That's got to be an expensive software and Tesla specific. I don't know what's available for us DIY'ers. That's why I'm following this thread to see what you come up with. This is a great subject.
    Last edited by Stevo; 03 October 2020 at 0834.
    Current rides: '96 Honda Ohlins VFR, '03 Cannondale C440R, '03 Cannondale Cannibal, '06 Yamaha 450 Wolverine 4x4
    Current builds: eVOR.v3.4
    WORX.VOR.v3.2

  6. #6
    Junior Member
    Join Date
    Aug 2020
    Posts
    10
    Post Thanks / Like
    This is why I'm reaching out to anyone who has came across this. Not sure where to go. I've reached out to a company called Bestechpower for one of these: HCX-D170V1 with Relay. It mentioned to have a continuous amp rating of 500 amps and peak of 2000 amps, but can't get them to reply. Seems to be the only one I can find.

  7. #7
    Senior Member
    Join Date
    May 2013
    Location
    Kildare, Ireland
    Posts
    357
    Post Thanks / Like
    Quote Originally Posted by Csecrist12 View Post
    As far as the BMS, there's confusion on the rating of the BMS's and what it should see.
    Can you elaborate on this please?


    Quote Originally Posted by Csecrist12 View Post
    What would be some low cost solutions to this?
    Quote Originally Posted by biothundernxt View Post
    The bms is really not a low cost device.
    ^^^
    There aren't any low cost BMS solutions out there worth having in my experience.
    Zeva and Orion are pretty much the baseline.

    Quote Originally Posted by Csecrist12 View Post
    I've also read about some relay bypassing or?
    "Shunting"
    I can work in a couple of ways but what you're describing is where some distributed (card based) BMS solutions allow you to "bypass" or partially bypass a cell which is choking the pack and limiting either charge rate or max charge on account of being weaker and/or out of balance.
    The benefit is that you can continue to charge the rest of the pack to nominal capacity and ultimately end up with a top-balanced result.
    That weak cell is still going to limit the degree to which the stronger cells can discharge however and should be removed if there's a significant difference in capacity.

    Quote Originally Posted by Csecrist12 View Post
    I've seen the orion 2 and those are a bit pricey, but they have a lot of controlling features. I have read in a few forums where you can bypass the bms for discharge purposes but have fuses and other relays to sense when the batteries drop just before you're wanting to. Not sure if that's possible or safe to do?
    The Orion kit is excellent and very well support by the folks at Ewert - I've worked with them for several years now and they're quick to respond, knowledgeable, and enthusiastic. Couldn't recommend them highly enough.
    I've also had dealings with Zeva although not to the same depth of detail, but I've found them to be similarly engaging.
    Not sure why you would want to bypass an Orion system (or indeed how you would even do it), they're a centralised model, not distributed so there are no series elements barring the current sense.

  8. #8
    Senior Member
    Join Date
    May 2013
    Location
    Kildare, Ireland
    Posts
    357
    Post Thanks / Like
    Quote Originally Posted by Stevo View Post
    Tesla uses a Can Bus method.
    By that are you referring to the integrated BMS in each module reporting to the BUS? (This method isn't uncommon) .. or do you mean that the module based BMS itself uses some for of polling rather than full time tap connections?

  9. #9
    Senior Member Stevo's Avatar
    Join Date
    Nov 2014
    Location
    Behind the Redwood Curtain- REDWOOD ORIGINAL!!
    Posts
    901
    Post Thanks / Like

    My Social Networking

    Add Stevo on Google+
    I know its too complex to easily be utilized by a DIY'er. I haven't found anyone that has tapped into it to use it for there own project. If you have, please post a link.
    Current rides: '96 Honda Ohlins VFR, '03 Cannondale C440R, '03 Cannondale Cannibal, '06 Yamaha 450 Wolverine 4x4
    Current builds: eVOR.v3.4
    WORX.VOR.v3.2

  10. #10
    Senior Member
    Join Date
    May 2013
    Location
    Kildare, Ireland
    Posts
    357
    Post Thanks / Like
    Quote Originally Posted by Stevo View Post
    I know its too complex to easily be utilized by a DIY'er. I haven't found anyone that has tapped into it to use it for there own project. If you have, please post a link.
    That very much depends on the skills of the DIY'er.
    Although tbf you're right, nobody has managed to utilise one yet but it won't take long before that changes

    https://www.youtube.com/watch?v=TP57bOstNGc

    Damien there releases most of his material though the openinverter forum and has made some outstanding contributions to the community - definitely a guy worth watching.
    Last edited by Spoonman; 05 October 2020 at 0936.

  11. Likes Stevo liked this post
Page 1 of 2 12 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •