This is a nice part, but there are many of these (TI has several nice=20 ones), but most (not all) have overlooked temperature monitoring, which=20 is incredibly important. These chips do a good job of balancing, but if=20 the cell fails, its temperature will rapidly rise, and only if the load=20 is removed quickly can the stack be saved from fire damage. These chips=20 are not only incredibly expensive, but they are often made of "unobtainium"= .. I am looking at doing my own balancing and monitoring with a 1-cell=20 design, using a tiny PIC, dual DACs, and dual power FETs controlled by=20 a bidirectional opto-coupler connected to an overall controller. The PIC=20 watches each cell's voltage, and uses the DACs to control ea FET to=20 balance the cell. A cheap thermistor checks temperature. All cells are=20 controlled by the central overall controller (PIC16F1939) thru the opto=20 channel, using a Manchester code. Each cell has a small PCB mounted on=20 it, tied across the cell terminals. --Bob A On 9/26/2013 10:31 AM, Dwayne Reid wrote: > I read recently of a Linear Technology chip that is designed for > larger-size Li-type battery systems. The chip is the heart of a > little module that also includes a small SMPS transformer. Tere is > one module per series-connected cell. l cells at that particular > location are in parallel of there is more than one cell per series locati= on. > > What the module does is either remove excess charge from the cell and > distribute it to a common buss (tying all the modules together) or > steal power from that common buss if the cell voltage is too low. In > other words, the module does all of the cell voltage balancing. > > It looks as if the module can be scaled to handle several amps (or > more) of balance current. All that changes is the switch-mode > external FET and the size of the transformer. > > It looks like a compelling answer to the problem of balancing cells > in large Li-type battery systems. > > I don't have a part number handy but I read it in a LT magazine that > came in some while ago (fairly recent). > > dwayne > > > That it does is tie all of > > At 05:58 AM 9/26/2013, Luis Moreira wrote: >> Hi Guys, >> Looking at this pack, made me think again about this long term project t= hat >> I have of converting my mountain bike to a electric bike and the battery >> pack is one of the main components. I probably will need 36V or 48V, whi= ch >> will mean a "few" cells in series and a couple of strings in parallel fo= r >> suitable capacity. I found a lot of circuits for charging one Li-Ion cel= l >> using a charging and protection IC, but is it feasable to scale it up to >> lets say 12 series cells? How do you deal with it if cells are in parall= el. >> Please don't concentrate on how many cells I need for this project that= is >> not the issue, I am really just asking how are the individual cells >> protected. >> I know that these Chinese packs are protecting the cells in a >> price/protection optimum ratio but what if protection is the overriding >> factor and I don't mind spending a bit more on protection circuit? >> Best regards >> Luis >> On 26 Sep 2013 12:27, "Luis Moreira" >> wrote: >> >>> Hi Sean, >>> It is a 2S2P configuration 8.4V 6400mAh. >>> Thanks >>> Luis >>> On 26 Sep 2013 01:55, "Sean Breheny" wrote: >>> >>>> Hi Luis, >>>> >>>> Are the cells in series or parallel? >>>> >>>> Sean >>>> >>>> >>>> >>>> >>>> On Wed, Sep 25, 2013 at 10:52 AM, Luis Moreira < >>>> luis.moreira1575@googlemail.com> wrote: >>>> >>>>> Hi Guys, >>>>> The battery pack for my Chinese bike light as just failed and I decid= ed >>>> to >>>>> take it apart. It is made up of 4 x 18650 cells. They claim 6400mAh b= ut >>>> I >>>>> think not... Any way, I am not looking into repairing it but I find t= he >>>>> protection pcb on the pack very interesting but unfortunately I can n= ot >>>>> find any info on the ic's on it. I presume that they are two mosfet >>>>> packages and one supervising ic but can't get no info. The numbers on >>>> the >>>>> two packages which look like mosfets are 8205 and 14T1G and the >>>> supervisor >>>>> ic is a 6 pin package with 3Z98 on it. I am not sure of the last digi= t >>>> as >>>>> it is a bit faded it could also be a 9 or a 5. >>>>> Any info would be apreciated. >>>>> Many thanks >>>>> Luis >>>>> -- >>>>> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >>>>> View/change your membership options at >>>>> http://mailman.mit.edu/mailman/listinfo/piclist >>>>> >>>> -- >>>> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >>>> View/change your membership options at >>>> http://mailman.mit.edu/mailman/listinfo/piclist >>>> >> -- >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist > --=20 The only place success comes before work is in the dictionary. VINCE LOMBARDI --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .