Bank of Battery in serie, and why not in serie+//

Hi,
Sorry to ask you such stupid+nasty questions, but answers may interest folks and me.ç

I am planning a 48v bank of battery composed of 24 elements OPsZ of 2v.
http://www.hoppecke.com/produkte/anwendungen__1/it_telekommunikation/opzs
Thus each of them will be connected in serie. But in such a string, the cell connecting (+) will be very far away separated with the cell connecting (-) and I think the charge/discharge current may not be egal from the beginning element to the ultimate element.

¿ Is is a stupid thought to connect a double wiring in // for each element ?
¿ And what coult be the Amperage of this bank ?

jacques

Comments

  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Bank of Battery in serie, and why not in serie+//

    no it's not a stupid question because you are right that the extra wiring will introduce resistance to the overall internal resistance of the battery. you should go with extra heavy wires or use busses. doubling the wire if physically possible is good too.
    the capacity i didn't see listed, but i'm sure it heavy duty. look over their site more or email them. odds are they would have more than one to choose from.
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Bank of Battery in serie, and why not in serie+//

    Jacques,

    There's a simple way to solve this problem. After battery #12, run batteries #13 through #24 in another row back towards battery #1. You can then hook your equal-length main battery cables to batteries #1 and #24. It would be something like the lower right drawing below, but with 24 batteries for 48 V.

    2cea26110.jpg

    The battery bank capacity (Ah) will be the same as the rating for any one battery. Wired in series, battery voltages add up, but the capacity spec (Ah) doesn't change.

    HTH,
    Jim / crewzer
  • System2System2 Posts: 6,290 admin
    Re: Bank of Battery in serie, and why not in serie+//

    sorry crewzer,  :?  I have not caught the solution, for me it does not change weither I have 2 rows in serie or 4 rows in serie. The whole lengh is unchanged . No ?

    The what I thought was mere or more seemingly the Mid-Right wiring diagram, but with a complete serialing, to balance well the charge/discharge flows.

    jacques
    Bye the way, what is the translation of your abreviations STC, CEC, PTC ...
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Bank of Battery in serie, and why not in serie+//

    Jacques,

    For your planned 48 V configuration, you have no choice but to connect your twenty-four 2 V batteries in series. From an electrical perspective, there is no parallel connection option. Accordingly, there’s no alternative to the “long” series connection of the 24 batteries. It’ll be essentially the same physical distance if the batteries are lined up in a long single row or if they’re “folded back” in the middle to form two short rows.

    Your concern about the resistance of the long battery bank is valid. I’d suggest using short, heavy (~4mm x ~25 mm cross-section) copper bars instead of wire-and-lug cables to connect between the batteries. This approach should minimize the total electrical resistance and improve the reliability of the 23 inter-battery connections.

    The advantage of the “folded back” solution (the lower right drawing) is that the battery cables can be connected at the same end of the battery bank and the total battery cable length [(+) cable length and (-) cable length together] will be as short as possible.

    STC stands for Standard Test Conditions. It’s a laboratory test that, in part, is supposed to simulate irradiation of 1,000 W /m2, a PV cell temperature of 25 C and wind speed of 1 m/sec. Most manufacturers' power specifications are based on STC.

    CEC stands for the California Energy Commission, and PTC stands for PVUSA Test Conditions. The PTC specification is based on 20 C ambient temperature. This generally means the PV cell temperature would be ~65 C, so the PV voltage would be lower than realized under STC conditions. Since the PTC spec better predicts real-world operating characteristic, the CEC uses their numbers for baselining PV module performance.

    HTH,
    Jim / crewzer
  • System2System2 Posts: 6,290 admin
    Re: Bank of Battery in serie, and why not in serie+//

    tks crewzer
  • BB.BB. Super Moderators, Administrators Posts: 29,359 admin
    Re: Bank of Battery in serie, and why not in serie+//

    And CEC is: PTC Panel Rating * Inverter Efficiency = CEC Rating (not to exceed max. inverter rating).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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