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Thread: 48 Volt battery bank wiring

  1. #11
    Join Date
    May 2010
    Location
    Desert Southwest, USA
    Posts
    38

    Default Re: 48 Volt battery bank wiring

    This is what I have so far. Unfortunately, I haven't had time to do much testing.
    The volts shown under the picture are for each battery in that particular column.

    Bulk charge is set at 55.6v (13.9).
    Adding a couple of cables at each end of the bank didn't seem to make much difference although, they're the wrong size any way (#4) -all I had on hand.

    As you can see, the inverter cables are connected to the copper between the battery posts, not at the battery posts.
    Overall, (and with little testing) it appears the batteries are balanced better.
    Attached Images Attached Images  
    OB Flexware 500, 3648 inverter, two FM60 cc, eighteen Kyocera 135sx panels, sixteen Lifeline 105Ah 12v AGM batteries - off grid. (grid power available) 6800w diesel gen

  2. #12
    Join Date
    Mar 2006
    Location
    SF Bay Area (California)
    Posts
    21,256

    Default Re: 48 Volt battery bank wiring

    13.9 volt (12 volt relative) is pretty gentle charging... If you need to charge quicker (use more current from solar panels, less run-time on genset), you might want to double check with the battery vendor and see if you can crank those up to ~14.2-14.4 volts or so (at 77F).

    -Bill
    20x BP 4175B panels (replacement) + Xantrex GT 3.3 inverter for 3kW Grid Tied system + Honda eu2000i Inverter/Generator for emergency backup.

  3. #13
    Join Date
    May 2010
    Location
    Desert Southwest, USA
    Posts
    38

    Default Re: 48 Volt battery bank wiring

    Quote Originally Posted by BB. View Post
    13.9 volt (12 volt relative) is pretty gentle charging... If you need to charge quicker (use more current from solar panels, less run-time on genset), you might want to double check with the battery vendor and see if you can crank those up to ~14.2-14.4 volts or so (at 77F).

    -Bill
    I hear ya Bill.
    I reduced the charge because some of the batteries were getting up to 14.6-14.8 (probably higher, don't remember) and gassing. Maybe with this new setup, I will be able to bulk charge at or near the 14.2-14.4 recommended by Lifeline. I won't be able to test that until the weekend..
    OB Flexware 500, 3648 inverter, two FM60 cc, eighteen Kyocera 135sx panels, sixteen Lifeline 105Ah 12v AGM batteries - off grid. (grid power available) 6800w diesel gen

  4. #14
    Join Date
    Mar 2006
    Location
    SF Bay Area (California)
    Posts
    21,256

    Default Re: 48 Volt battery bank wiring

    You might try measuring the resting voltage of all the batteries... Any that are significantly below the rest, you may want to charge those separately with a 12 volt battery charger...

    Equalization involves overcharging some batteries in a series string to recharge those cells below 100% charge. You can charge individual batteries if a few are well below the rest (possibly from your previous wiring issues).

    -Bill
    20x BP 4175B panels (replacement) + Xantrex GT 3.3 inverter for 3kW Grid Tied system + Honda eu2000i Inverter/Generator for emergency backup.

  5. #15

    Default Re: 48 Volt battery bank wiring

    Quote Originally Posted by dhsola View Post
    I hear ya Bill.
    I reduced the charge because some of the batteries were getting up to 14.6-14.8 (probably higher, don't remember) and gassing. Maybe with this new setup, I will be able to bulk charge at or near the 14.2-14.4 recommended by Lifeline. I won't be able to test that until the weekend..
    dhsola,

    How old are your Lifeline Concorde batteries?

    I have 16 of the exact same batteries, and I also experienced some of exactly what you are describing with unequal battery charging.

    With mine, I know that they are sulfated to different degrees, so that has caused some of the imbalanced charging voltages. I bought my Lifelines at a low price as "NEW", but they had sat for a long time and were deeply discharged before I ever got them. I also ended up setting my charge voltages at the low end of Lifeline's recommendations, so that I wouldn't overcharge some of the batteries. Just like you described.

    Works OK for an emergency back up battery system that is seldom neeed, but they are definitely not what I'd want to depend on for daily off grid living. Some day, I hope to get a fresh set of batteries and get off to the right start (and take very good care of them).

    Edward
    On-grid with RE backup power. HY-2000 2kW wind turbine charging 48V 600Ah Concorde Lifeline battery bank. Wind power diversion heats water in an auxilliary 80 gal hot water heater. 2.1kW Evergreen solar panels & TS-MPPT-45. XW6048 inverter, Onan 6kW 6DJE diesel generator, and Yanmar YDG3700 diesel gen as backup.

  6. #16
    Join Date
    Mar 2006
    Location
    SF Bay Area (California)
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    21,256

    Default Re: 48 Volt battery bank wiring

    Here is Edward's "keyturbocars" thread where he did a bunch of research and testing a setup to recover Lifeline AGM batteries:

    Sulfated Lifeline Concorde AGM Batteries

    If the batteries in series (and parallel) are terribly mismatched (i.e., good battery in series with sulphated battery) could cause the unbalanced charging where one battery is charging at "low voltage" and the other at "high voltage"...

    Charging/recovering batteries separately may help... Also matching batteries by capacity ("high" capacity in one string, "low" capacity in a second series string) may help too.

    -Bill
    20x BP 4175B panels (replacement) + Xantrex GT 3.3 inverter for 3kW Grid Tied system + Honda eu2000i Inverter/Generator for emergency backup.

  7. #17

    Default Re: 48 Volt battery bank wiring

    I agree with Bill. Handling each battery separately is a good idea. I did it and it did help my situation. Even so, my batteries were so far gone to begin with that the situation is still not great. Things are better though.

    If your battery bank is newer and in better condition then mine, then trying to equalize each battery separately according to Lifeline's procedure might give you good results.

    Edward
    On-grid with RE backup power. HY-2000 2kW wind turbine charging 48V 600Ah Concorde Lifeline battery bank. Wind power diversion heats water in an auxilliary 80 gal hot water heater. 2.1kW Evergreen solar panels & TS-MPPT-45. XW6048 inverter, Onan 6kW 6DJE diesel generator, and Yanmar YDG3700 diesel gen as backup.

  8. #18
    Join Date
    May 2010
    Location
    Desert Southwest, USA
    Posts
    38

    Default Re: 48 Volt battery bank wiring

    Last I checked the resting voltage they were within .01 to .10 of each other. (Actually my batteries never "rest"). Just checked (7:25 PM).. Neg side parallel batteries at 12.75v, .07 to .10 higher than all other batteries with about a 150w to 200w load.

    I bought the first two batteries March '10 and the last string of four in Oct '10.
    (By the way, two of the strings had discharged batteries (12.5 - 12.7). I wasn't happy to have paid that kinda money for new batteries and then have to spend several days charging them before I could use them).

    All in all, I'm pretty happy with these little Lifeline batteries..

    I have another small 4-battery-12v-system of Costco wet cell batteries. Little bit higher in total amp hours than the Lifelines but of course, they just can't take much of a load for very long compared to the lifelines
    OB Flexware 500, 3648 inverter, two FM60 cc, eighteen Kyocera 135sx panels, sixteen Lifeline 105Ah 12v AGM batteries - off grid. (grid power available) 6800w diesel gen

  9. #19

    Default Re: 48 Volt battery bank wiring

    Your batteries were (and are) in much better shape than mine were. If memory serves me right, I think some of my batteries were reading as low as 11.5V when I took them out of the boxes. They sat for 2 YEARS before I bought them. Other batteries were higher, but they were all over the place. They were all very low!

    I thought I was getting a good deal paying around 1/3 price (getting 3 for the price of 1)!. In reality I was paying a lot for scrap lead! UGH! It is amazing at how well they have come around all things considering, but they are definitely NOT what they should be. One day I plan to do it right. For now, they are sufficient for what I need.

    In the future, I'd like to get a couple strings of the 6V Lifeline GPL-6CT (oversized golf cart size) that are rated at 300A/H each. This time, I'm going to make sure that they are factory fresh and all from the same lot. And I'm going to treat them like they are made from GOLD!

    Live and learn!

    Edward
    On-grid with RE backup power. HY-2000 2kW wind turbine charging 48V 600Ah Concorde Lifeline battery bank. Wind power diversion heats water in an auxilliary 80 gal hot water heater. 2.1kW Evergreen solar panels & TS-MPPT-45. XW6048 inverter, Onan 6kW 6DJE diesel generator, and Yanmar YDG3700 diesel gen as backup.

  10. #20
    Join Date
    Mar 2011
    Location
    Ontario, Canada
    Posts
    6

    Default Re: 48 Volt battery bank wiring

    Quote Originally Posted by n3qik View Post
    I would go with this:
    Greetings. After much experimentation and blown fuses, I have concluded that there is no other practical way to wire a 48 volt bank of 12V batteries than that shown by n3qik's most excellent diagram. Perhaps I should refer this to David Small, the author of the interconnection article?
    Cheers.
    Stand-alone system: 6 X Kyocera KD210, AirX 48V, Outback FM 60 controller, 2 X Outback FX3048 Inverters, FW-X-240 transformer, 20 X Sterling HA 140Ah 12V AGM batteries @ 48V.

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