Industrial Telecom AGM Battery cell construction question

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James
James Solar Expert Posts: 250 ✭✭
in Advanced Solar Electric Technical Forum #1
Hello Folks,
If I don't already have enough to think about, a new question has come up at the breakfast counter.
It involves the internal construction of a large capacity 2 volt AGM cell.
I'm involved in a small friendly debate regarding the internal construction of these batteries.

I must admit, I am not well versed in battery design, but I think I know the basics.

So here it is;
The cells in question contain two postive and two negative posts each.
When configured into a set, they interconnect with two negative cables going to the next cell postive posts and so on, as in any battery configuration.

The debate comes in at the point of the postive and negative terminals for connection to an inverter (or any load, for that matter).

I say that the two positive posts are electrically common within one cell, as is the negative posts.
I also think for proper loading, both positive posts should be bussed together in order to equally load the cell's internal plates.

My friend insists that you can load on post, leaving the other unconnected, with no adverse results.
I don't agree, however I don't know enough about these cell to defend my position.

Anyone here have intimate knowledge of cell construction to back me up?
I get a free breakfast if I'm correct :)
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: Industrial Telecom AGM Battery cell construction question

    Sounds like parallel cells.

    Want to know for sure? Get out the Voltmeter. If they are two separate parallel cells then the negative of one will only read against the positive of that one. If they are connected internally you will get the same Volt reading using one negative and either positive.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #3
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    Re: Industrial Telecom AGM Battery cell construction question

    My guess is they are internally connected with a lead buss bar at the top of the plates.

    If you are using huge amounts of amps, then I would parallel the outputs, just to reduce the IR loss across the internal lead buss bar.

    If you are looking at long duration, low amp drain, I'd just use a single terminal.

    That's how my NiFe bank is configured, cells are bussed internally, with 2 terminals.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #4
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    Re: Industrial Telecom AGM Battery cell construction question

    fwiw, my AGMs came with a bridging bar between two + and - terminals, at the cable connection points, so there is only one terminus for + or -.

    ps I have been wondering the same after being told I could 'split' my battery into 2 parallel sides for lower amperage per split. Not tested as there is 2 plus feet of snow out west right now... agree with Coot, just apply a DVM to each side
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • James
    James Solar Expert Posts: 250 ✭✭
    #5
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    Re: Industrial Telecom AGM Battery cell construction question

    Hello, the voltmeter confirms that they are internally connected, as I have assumed. My question remains however, as to how to know how they are connected. I would like to believe they are internally connected with a robust lead bussbar, but I have been using an external bar to connect just to be sure. By the way, I removed the postive busbar and cable for the photo to better show the terminals.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
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    Re: Industrial Telecom AGM Battery cell construction question

    Only the battery manufacturer knows for sure, but I'd hope the internal connections are capable of carrying the full operating current potential (whatever that may be).

    Trojan has 2 Volt batteries that are the same as their 6 Volt, only they are internally connected in parallel rather than series. This gives them 3X the Amp hour capacity of the 6 Volt, but you still have three cells to check (unlike most 2 Volts which are one large 2 Volt cell).
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #7
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    Re: Industrial Telecom AGM Battery cell construction question

    James, are those the Hawker batteries?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • James
    James Solar Expert Posts: 250 ✭✭
    #8
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    Re: Industrial Telecom AGM Battery cell construction question

    Yes, they are the old Hawkers. I'm told Hawker Powersafe cells are now made by Enersys
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  • rplarry
    rplarry Solar Expert Posts: 203 ✭✭
    #9
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    Re: Industrial Telecom AGM Battery cell construction question

    I was going to say they look very similar to my batteries, I have the enersys ddm 125-33. They are 2 volt cells with 3 positive and 3 negative posts per cell. When I bought them I asked why 3 positive posts and was told that to meet the potential current flow 3 posts were necessary. The positive and negative posts are common internally, I was told.
    Larry
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