Could I Damage My Chargers By Doing This?

rss2q
rss2q Solar Expert Posts: 75 ✭✭✭✭
in Solar Beginners Corner #1
General Information:
A 24v (2x 12v batteries) battery source will have the following components hooked up to it in parallel.

Again, all the components above are hooked up to the same 24v battery source in parallel.

My Question/s
If for example my motor controller is currently powering two 10A motors, my Solar Charge Controller is hooked up, AND my Tender 24v Battery Charger is hooked up and is powered, is it possible for me to damage my Tender charger or the solar charger as they are charging my 24v battery at the same time and while the motors are running? The motors are kinda insulated from the main circuit due to the motor controller, so there will not be issues with the EMF and etc.

Or if I wish to charge my battery with the Tender charger, do I need to disconnect all the other components (motor controller,inverter..etc.) in the circuit?

I'm thinking everything should be fine, but just want to confirm. :D
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #2
    Re: Could I Damage My Chargers By Doing This?

    In general, you have everything connected correctly (do you have a fuse/breaker in every + wire that leaves the + battery bus?).

    We have a few reports that several MPPT charge controllers have been confused by a "noisy" battery bus...

    One was that the 120 Hz current from a good sized inverter caused confusion (older charge controller design).

    Another was a battery desulfator caused a major brand MPPT controller to reduce its output significantly (10-30% or so?). When the desulfator was turned off--the MPPT controller worked fine (better than it had in years).

    So--watch the charging current from your solar array and that it makes sense (near rated power at noon on clear/cool days into discharged battery bank).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • rss2q
    rss2q Solar Expert Posts: 75 ✭✭✭✭
    #3
    Re: Could I Damage My Chargers By Doing This?
    BB. wrote: »
    In general, you have everything connected correctly (do you have a fuse/breaker in every + wire that leaves the + battery bus?).
    -Bill

    Well my main concern was that, two or one energy sources could charge the battery at the same time while large amounts of power is being drawn from the battery such as 2x 10A motors which are hooked into the motor controller.

    But no, I do not have fues on every + wire. How can I determine what size fuse to purchase for each?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #4
    Re: Could I Damage My Chargers By Doing This?

    You can start with the National Electric Code:

    Wire Current Ampacities NEC Table 310-16

    Basically, 14 AWG cable, 15 amp breaker; 12 AWG cable, 20 amp breaker, etc...

    And the wires (and breakers) should be sized for, at least, 1.25x the maximum continuous current:
    • 10 amps * 1.25 = 12.5 amps minimum, round out to 15 amp wire/breaker
    Many times, for solar power, we have heavier wires than required to keep the voltage drop low... You can size the fuse for either the wire gauge, or 1.25x the maximum continuous current you plan to carry.

    -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 ✭✭✭✭
    #5
    Re: Could I Damage My Chargers By Doing This?

    i'm going to give a simplified answer. the chargers (this is including controllers as chargers) most likely will not be damaged by paralleling their outputs if you wire them properly.

    fusing is a good precaution for most things electrical and if you figure a charger has xx amps deliverable to a battery that the fuse will be above this as bill pointed out. do not depend upon the fuses to make sure you did things correctly for under some rare unforeseen circumstances the fuse may not pop so always be sure of how you wire something. i've had my share of oops moments in the past to be able to say this and i can say that i have run into circumstances that a fuse would not insure against wiring errors.
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  • rss2q
    rss2q Solar Expert Posts: 75 ✭✭✭✭
    #6
    Re: Could I Damage My Chargers By Doing This?
    BB. wrote: »
    You can start with the National Electric Code:

    Wire Current Ampacities NEC Table 310-16

    Basically, 14 AWG cable, 15 amp breaker; 12 AWG cable, 20 amp breaker, etc...

    And the wires (and breakers) should be sized for, at least, 1.25x the maximum continuous current:
    • 10 amps * 1.25 = 12.5 amps minimum, round out to 15 amp wire/breaker
    Many times, for solar power, we have heavier wires than required to keep the voltage drop low... You can size the fuse for either the wire gauge, or 1.25x the maximum continuous current you plan to carry.

    -Bill

    Oh, so if I know in my system 15A for example is the max the system should ever have running through it, every negative wire connected to the battery should have a fuse connected to it?

    But what if say my Trend charge controller for example can only handle 8A...actually I don't even know if this apples to chargers (if not let me know)...but if so, if it has a certain limit what should I do then?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
    Re: Could I Damage My Chargers By Doing This?
    rss2q wrote: »
    Oh, so if I know in my system 15A for example is the max the system should ever have running through it, every negative wire connected to the battery should have a fuse connected to it?

    Positive wires, please. It's kind of standard to fuse the positive wires.
    But what if say my Trend charge controller for example can only handle 8A...actually I don't even know if this apples to chargers (if not let me know)...but if so, if it has a certain limit what should I do then?

    If the Trend charger is capable of a maximum 8 Amps and is fused accordingly, the fuse should pop before the charger gets seriously overloaded. Most chargers have internal thermal protection as well (check the manual).

    As long as the load doesn't not exceed 2X the lowest current capacity charger (16 Amps?) all should be well. If it does, the fuse on the lower output charger should pop first. If the higher capacity charger is then overwhelmed by the load its fuse will blow. Then you're running on battery power.
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  • rss2q
    rss2q Solar Expert Posts: 75 ✭✭✭✭
    #8
    Re: Could I Damage My Chargers By Doing This?
    Cariboocoot wrote: »
    Positive wires, please. It's kind of standard to fuse the positive wires.
    Yeah that's what I thought, I was just confused by BB's post on that haha
    Cariboocoot wrote: »
    If the Trend charger is capable of a maximum 8 Amps and is fused accordingly, the fuse should pop before the charger gets seriously overloaded. Most chargers have internal thermal protection as well (check the manual).

    As long as the load doesn't not exceed 2X the lowest current capacity charger (16 Amps?) all should be well. If it does, the fuse on the lower output charger should pop first. If the higher capacity charger is then overwhelmed by the load its fuse will blow. Then you're running on battery power.

    Oh, well the solar charge controller I'm using is the ProStar 15 which allows 15A from the solar side but I've never been sure how people knew what fuse type to use to protect the controller from the amount of amps flowing through the circuit.

    Meaning, if you have an inverter for example, that can draw 200amps, first, how can you determine how many amps your charger can handle (is it usually on the website/manual?), and second, I'm guessing whatever the max it can handle is the fuse you want to go with?

    My options at this point are, either disconnect everything that's using the battery but the chargers, or learn what you guys are trying to teach me regarding my previous questions. :D
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
    Re: Could I Damage My Chargers By Doing This?
    rss2q wrote: »
    Yeah that's what I thought, I was just confused by BB's post on that haha



    Oh, well the solar charge controller I'm using is the ProStar 15 which allows 15A from the solar side but I've never been sure how people knew what fuse type to use to protect the controller from the amount of amps flowing through the circuit.

    Meaning, if you have an inverter for example, that can draw 200amps, first, how can you determine how many amps your charger can handle (is it usually on the website/manual?), and second, I'm guessing whatever the max it can handle is the fuse you want to go with?

    My options at this point are, either disconnect everything that's using the battery but the chargers, or learn what you guys are trying to teach me regarding my previous questions. :D

    Think of them as separate circuits with a common element: the battery. The battery can handle the inverter if everything is wired right. The circuit protection on the charge circuit(s) is there in case something goes wrong. Normally the inverter does not "draw from" the charge controller, even though it may be using all of the current the controller is providing to the battery and then some.

    My fuzzy memory tells me the NEC requirement on fuses is 1.2X the rated current, sized up to the next available fuse. So on 8 Amps that's (8 * 1.2 = 9.6, round up) 10 Amp fuse on 12 AWG wire. The 15 Amp circuit would be (15 * 1.2 = 18, round up) 20 Amp fuse on 10 AWG wire.

    Either Bill or Niel will correct me if I started remember a biscuit recipe instead of fuse sizing. :roll:
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #10
    Re: Could I Damage My Chargers By Doing This?

    Hmmm... Biscuits...

    And, it is 1.25x 1/0.80) for the NEC fudge factor.

    Sorry about confusing you with fuses and where to put them.

    Treat the battery like the "Heart" of your system... Current flows, voltages, etc.... Are between the Battery and the Load (or Source) of current.

    In a way, this is no different than your car's automotive electrical system.

    The Battery controls the voltage (between 12 and 14 volts) in the system... You can run your accessories/lights/etc. with or without the alternator running (at least, until the battery goes dead). If your loads exceed the output current of the alternator, the battery will supply the additional current (for a limited time).

    And fuses/breakers are (for the most part) there to protect the wiring--not the device on the end (obviously, a 2 awg cable with 150 amp fuse connected to a 1 watt LED is not right either--Check manuals, they usually tell you the maximum rate branch circuit they can connect to).

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