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Thread: Connecting the charge controller

  1. #1
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    Default Connecting the charge controller

    My set up will consist of my battery bank set up outside my HAM radio shack. From the battery bank to the inside i am going to run 4 gauge wires(10ft run) to buss bars inside the shack. Now what i wanted to do was run the charge leads from the charge controller to the buss bar which the 4 gauge main wires are attached to. Would this be ok or do i need to run separate wires from the charge controller directly to the batteries?

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    [QUOTE=RussN9ZP;48294]My set up will consist of my battery bank set up outside my HAM radio shack. From the battery bank to the inside i am going to run 4 gauge wires(10ft run) to buss bars inside the shack. Now what i wanted to do was run the charge leads from the charge controller to the buss bar which the 4

    Theoretically, since the Charge Controller is sensing the battery voltage to regulate its output, you should connect as directly as possible to the terminal of the battery. In practice, depending on how large your bus bar is and whether there are any interconnections along it that will develop a significant voltage drop, you might not need to do this.

    There are two different scenarios that have to be taken into account:

    1. When there is no load and you are charging the batteries at full current, what will the voltage difference be between the charge controller terminals and the battery terminals? A large (.1 or .2 volt) voltage drop along the way will result in the battery being undercharged.

    2. When there is load and you are also getting output from the charger, will the current being drawn from the battery, through the busbar, cause the voltage seen by the charge controller to be less than the battery voltage, causing the CC to output more current than it otherwise would for the battery voltage? Easy to dispose of that one: if current is being drawn from the battery, that means the charger is unable to keep up with the load and is supplying some of the load current with nothing left for the battery. That will not hurt the battery at all and will get maximum output from the CC.

    And since I mentioned two scenarios here is the third: Filtering.
    The waveform output of the CC may be messy. If you connect directly to your bus bar, most or all of that noise will be on the bus. If you connect directly to the battery terminals, some of that noise will be filtered by the low impedance of the battery before reaching the bus.
    As a practical matter, you will want to put RF and maybe audio filtering at the output terminals of the CC anyway (depending on how well it is filtered already.)

    OK, looking at it again, I see that you may be talking about the bus bar which joins your parallel-connected batteries. That is another issue. You do not want to run separate wires from the CC to each battery. But you do want to equalize as much as possible the resistance from the attachment point on that bus bar to the different batteries. There is a good reference to charging parallel batteries in one of the sticky threads at the top of the off-grid forum.

    It is post # 2 here: http://www.solarpaneltalk.com/showth...p-Why-Tutorial
    Last edited by inetdog; 06-15-2012 at 09:49 PM. Reason: addition

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    Quote Originally Posted by RussN9ZP View Post
    My set up will consist of my battery bank set up outside my HAM radio shack.
    Why would you put your batteries outside? They need to be inside kept dry, cool, and treated with TLC. There is no danger from gassing especially if they are AGM. Leaving them outside in the elements will cuts years of life from them.

    You need to keep the distance from batteries to load buss as hort as possible

    KF5LJW

    73 to you.

    SK
    MSEE, PE

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    The third reason sounds like the best of all. I dont need any RF interference coming over my radios from the controller. The + and - buss bars will be inside the room and the 4 gauge main wires will run from the buss bars out to the battery bank. I wanted to run the charge control wires from the charge controller to the buss bars so i didn't have to run another set of wires back out to the battery bank.

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    Quote Originally Posted by Sunking View Post
    Why would you put your batteries outside? They need to be inside kept dry, cool, and treated with TLC. There is no danger from gassing especially if they are AGM. Leaving them outside in the elements will cuts years of life from them.

    You need to keep the distance from batteries to load buss as hort as possible

    KF5LJW

    73 to you.

    SK
    I have sealed lead acids and was concerned with keeping them in there current location under my desk due to gassing. Id much rather keep them inside.

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    4) charge voltage. May be as high as 15 or 16v when in a EQ cycle. Can your gear take that high? Maybe a couple, switchable diodes to drop it, or a DC-DC precision supply.
    Since the dawn of time it has been mankind's dream to blot out the sun.
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    spreadsheet based voltage drop calculator:
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    http://www.solarpaneltalk.com/showth...oss-calculator

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    Quote Originally Posted by Mike90250 View Post
    4) charge voltage. May be as high as 15 or 16v when in a EQ cycle. Can your gear take that high? Maybe a couple, switchable diodes to drop it, or a DC-DC precision supply.
    For the moment im only using HF panels and controller which doesn't go higher then 14.5 volts. Once i change over to a different controller and panels i will make sure to monitor the voltage before hooking up my gear. I have been looking into a couple different DC to DC supply's which will hold the voltage at the suggested 13.8V.

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    Quote Originally Posted by RussN9ZP View Post
    I have sealed lead acids and was concerned with keeping them in there current location under my desk due to gassing. Id much rather keep them inside.
    Russ I use 2 T-105RE Flooded lead acid batteries in my shack. There is no gassing issue for you to be worried about. I build DC plants for telephone offices. -48Vdc 40,000 AH plants with huge Flooded Lead Acid batteries in High Rise buildings next to office space. No special ventilation is required. Just a hydrogen detector and exhaust fan if detected. In 33 years not one alarm has gone off requiring ventilation.

    You said SLA batteries. they do not vent unless way over abused, and even if they did highly unlikely the room would ever reach 4% or more hydrogen saturation volume to ignite.

    As for RFI, then if you run into that means you have a cheap PWM controller, the batteries are huge capacitors that will filter out any line noise. Radiated noise can be a issue but battery location has nothing to do with that.
    MSEE, PE

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    Quote Originally Posted by Sunking View Post
    Russ I use 2 T-105RE Flooded lead acid batteries in my shack. There is no gassing issue for you to be worried about. I build DC plants for telephone offices. -48Vdc 40,000 AH plants with huge Flooded Lead Acid batteries in High Rise buildings next to office space. No special ventilation is required. Just a hydrogen detector and exhaust fan if detected. In 33 years not one alarm has gone off requiring ventilation.

    You said SLA batteries. they do not vent unless way over abused, and even if they did highly unlikely the room would ever reach 4% or more hydrogen saturation volume to ignite.

    As for RFI, then if you run into that means you have a cheap PWM controller, the batteries are huge capacitors that will filter out any line noise. Radiated noise can be a issue but battery location has nothing to do with that.
    Dereck, thanks again for answering my many questions. My system right now will consist of two or three of those 27 TMX's you recommended. For a couple weeks im going to continue with the HF panels/charge controller plus alittle help from the grid powered battery charger. My immediate future plans are a new charge controller and 200 watt panel when the hobby money replenishes. Its still hard to gauge my power needs at this point but i should be good with this set up. I really dont have a need for an inverter set up right now. All my systems are 12V.

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    Quote Originally Posted by RussN9ZP View Post
    Dereck, thanks again for answering my many questions. My system right now will consist of two or three of those 27 TMX's you recommended.
    No Sir please do not do that. When I made that recommendation I assumed you would only use a single 12 volt battery.

    You want to avoid parallel batteries at all cost. So if you want 2 or 3 times the capacity, buy cells that meet that requirement so as to only use 1 single battery string. The Trojan 27 TMX is a 100 AH 12 volt battery. If you want 200 or 300 AH you are going to want to use a different model. More then likely you will be looking at 6 Volt batteries using 2 in series.

    If they will be stationary and inside the shack please consider Flooded lead acid types because they cost considerable less than AGM. If mobile then yes look at AGM.

    For example the Trojan T-105RE is a 6 volt 225 AH Flooded Lead Acid battery. If you need some suggestions please ask but good names to look for are Trojan RE series, Deka, Crown, and Rolls. If you want AGM look at Concord and Deka.
    MSEE, PE

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