Do batteries get hot ?

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prince_77
prince_77 Solar Expert Posts: 31 ✭
in Solar Beginners Corner #1
i have a new solar system DIY that i manage to build with tristar45
everything is set up, and charging and set the parameters according to the tristar tech support/

after a 2 days work, i went to check the charger in the night, i got yellow light on charger and the 4 batteries are pretty worm

is that ok ?

the batteries are 12v parrallel +2serial making 24V system
and 24tmx trojan batteries

thanks
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
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    Re: Does batteries get hot ?

    Batteries can get a little warm, but not much more than 100*f

    can you tell us the panels, volts, amps,

    battery size v & A

    and your loads ??
    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 ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
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    Re: Do batteries get hot ?

    Yes it is normal for batteries to get warm when charging.
    But there is "warm" and then there is "something is wrong".
    This is one of the reasons remote temperature sensors are recommended: they tell the charge controller how warm the batteries are, allowing it to adjust its Voltage level accordingly. The warmer the battery, the lower the Voltage set point. Putting too much current or Voltage to them or sustaining the Absorb stage too long can heat them up quite a bit too, but we'll go with your having set the parameters on the controller right.

    Also, your description of how the batteries are wired is a bit worrying. They should be wired as two parallel strings of two in series. In other words, you put two in series to make a 24 Volt 'string'. Then you connect the two strings in parallel. If you do it the other way you can create alternate current pathways that aren't good for operation. Or more simply put: things can go wrong.

    I don't remember what the yellow LED on the Tristar indicates. Check the manual.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
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    Re: Do batteries get hot ?

    Mike;

    Trojan 24MTX are 12 Volt 85 Amp hour. So this would be a 24 Volt 170 Amp hour bank.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #5
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    Re: Do batteries get hot ?

    And do you have a remote battery temperature sensor?

    Hot batteries need lower charging voltages--In worst case situations, it is possible to get thermal run-away. Basically, batteries get very hot, their charging voltage falls, the charge controller thinks batteries need more charging current, batteries get hotter and can fail.

    A RBTS will reduce the chance of that happening. Especially where battery bank and charge controller(s) are in different rooms/environments.

    Will a small array on a largish battery bank cause thermal run-away? Probably not unless the battery box is well insulated.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #6
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    Re: Do batteries get hot ?

    in addition to what everybody else has said you can allow for some space between the batteries to allow good airflow preventing needless heat buildup. at least 3/4 to 1 inch i would think.

    also note that charging isn't the only time batteries heat as they will also do this while discharging too. as such, one should avoid currents that are excessive in either case that could cause needless extra heat if you can.
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  • prince_77
    prince_77 Solar Expert Posts: 31 ✭
    #7
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    Re: Do batteries get hot ?

    Thank u all for your help, i will add more info
    i took a graph from another discussion and chage it
    Attachment not found.

    I do have RTS sensor connect to the minus but i discover that one wire was out in the charger.

    is that the correct way to create 24V system from 4 Batt ? (24tmx trojan - 12V each batt)

    my solar array is 2 190W (total 40V - 9A )
    my charger is tristar PWM 45- and set according to the tristar setup and battery setup

    So im doing something wrong ?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #8
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    Re: Do batteries get hot ?

    You should move one cable (+ or minus) to the opposite end of the battery common bus bar (not both wires connected to the "top" of the left and right bus).

    That we better balance current flow.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • prince_77
    prince_77 Solar Expert Posts: 31 ✭
    #9
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    Re: Do batteries get hot ?
    BB. wrote: »
    You should move one cable (+ or minus) to the opposite end of the battery common bus bar (not both wires connected to the "top" of the left and right bus).

    That we better balance current flow.

    -Bill

    Thank u very much bill for the info

    i also have a power inverter to transfer the power, so i need to connect it to the opposite way on the batteries so it wont be as same as the charger?

    thanks again
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #10
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    Re: Do batteries get hot ?

    You can attach the inverter and charge controller to the same points--In theory, the ideal connection point is the same for both charging and discharging your battery bank. In practice, there are many installations that have "mirrored" optimum connection points.

    In this case, it would not matter if you connected the inverter to the opposite points. Which ever is easiest to wire. An article about balancing wiring for battery banks.

    http://www.smartgauge.co.uk/batt_con.html

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • prince_77
    prince_77 Solar Expert Posts: 31 ✭
    #11
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    Re: Do batteries get hot ?

    Thanks again bill for your help.

    i hope the RTS sensor will solve the issue now it will be connected and i will change the minus wire to the other bank


    Thanks
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