Need help wiring 12v solar project

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  • solarpowernovice
    solarpowernovice Solar Expert Posts: 135 ✭✭
    #62
    Re: Need help wiring 12v solar project

    Everything is in working order now, my solar panels charge my batteries and my batteries are providing power to my inverter/appliances. All I need to do is vent my battery box now. I cut a 4 inch hole in the top of my battery box and connected a 4 inch dryer duct to it and routed it to the outside. Now I need a relay and a fan to hook to my charge controller and I want to order them both on newegg so i can save on shipping. These are the two parts I'm looking at... can you please tell me if these will work?
    http://www.newegg.com/Product/Product.aspx?Item=9SIA1SR0H18740
    http://www.newegg.com/Product/Product.aspx?Item=N82E16835119035 The batteries absorb is 15.3v will this be too much for a 12v fan? Is it safe to put the fan in the box with the batteries?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #63
    Re: Need help wiring 12v solar project

    Some of those fans can take 17.5 Volts right from the panel without problem. Others will be more particular. The relay may not like the high V either. But it's pretty easy to knock it down with a couple of diodes in series - shave off about 1 Volt and it will be in 'automotive' range.
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  • solarpowernovice
    solarpowernovice Solar Expert Posts: 135 ✭✭
    #64
    Re: Need help wiring 12v solar project

    what do you mean by a couple of diodes in series?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #65
    Re: Need help wiring 12v solar project
    solarpowernovice wrote: »
    what do you mean by a couple of diodes in series?

    Just that: diodes tend to drop Voltage a bit. Put them in series on the positive line and current still flows but Voltage is reduced. So you get something like this:

    15.5 VDC ---->|---->|---- 14.5 VDC

    Do not use Schottky diodes as they reduce Voltage very little.
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  • solarpowernovice
    solarpowernovice Solar Expert Posts: 135 ✭✭
    #66
    Re: Need help wiring 12v solar project

    could you possibly link me to the type of relay i should purchase with the proper diode? If you were in my situation what would you purchase?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #67
    Re: Need help wiring 12v solar project

    Well my usual dependable host links don't work anymore. Hmm. Nice website upgrade, guys.

    Digikey has tons of diodes: http://www.digikey.ca/

    Basically you need one or two with a current rating that will handle the expected current of relay and fans. Probably not a full Amp required here. The ones used for blocking diodes on small solar applications would work for this.
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  • solarpowernovice
    solarpowernovice Solar Expert Posts: 135 ✭✭
    #68
    Re: Need help wiring 12v solar project

    If i buy the relay on the hosts website will it work without having to add any diodes? I can buy the fan on newegg and the relay from the host, if it will work. heres the link http://www.solar-electric.com/regest12vosi.html and heres the specifications of this relay http://www.solar-electric.com/lib/wind-sun/OBrelay.pdf Will this and a fan be all I need? I dont know how to go about adding diodes in series :cry:
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  • solarpowernovice
    solarpowernovice Solar Expert Posts: 135 ✭✭
    #69
    Re: Need help wiring 12v solar project

    I bought the relay on solar-electric.com and they told me on the phone that the battery voltage shouldn't be a problem. After I get my box vented I'll be 100% done.(at least for a while until i want to add extra stuff:p) Thanks to everyone who helped me.
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  • darren_t_johnson
    darren_t_johnson Registered Users Posts: 1
    #70
    Re: Need help wiring 12v solar project

    Hi,
    This was a very interesting thread to follow. I'm in the the process of upgrading my system with larger panels and more batteries, and now I need to consider venting for my batteries... I was going to do exactly what you are doing but read some articles in the last few weeks that lead me to this question.
    If you are venting hydrogen gas, don't you want to use a fan that is safe for ignitable gases? I'm pretty sure case fans are not rated for that. Or because the fan is always running, we can assume that the level of hydrogen will never reach a point where this will be a concern?

    And I have another related question :)

    My controller has a LVD (low voltage disconnect and reconnect) built into it which I would use to power the relay and drive the fan. If I ever ran into the LVD and reconnect scenario, my fan would shut off, and only turn back on after the batteries reach 12.6V, would there not be a build up of hydrogen gas at that time that would be concentrated enough for me to worry about it? Or do batteries only vent hydrogen later in the charge cycle? I think I read that before.

    And my last question (which is a more reasonable question). How much power does that relay you bought draw? Or if it lists ohms, what is it?

    Thanks
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #71
    Re: Need help wiring 12v solar project
    darren_t_johnson wrote: »
    Hi,
    This was a very interesting thread to follow. I'm in the the process of upgrading my system with larger panels and more batteries, and now I need to consider venting for my batteries... I was going to do exactly what you are doing but read some articles in the last few weeks that lead me to this question.
    If you are venting hydrogen gas, don't you want to use a fan that is safe for ignitable gases? I'm pretty sure case fans are not rated for that. Or because the fan is always running, we can assume that the level of hydrogen will never reach a point where this will be a concern?

    And I have another related question :)

    My controller has a LVD (low voltage disconnect and reconnect) built into it which I would use to power the relay and drive the fan. If I ever ran into the LVD and reconnect scenario, my fan would shut off, and only turn back on after the batteries reach 12.6V, would there not be a build up of hydrogen gas at that time that would be concentrated enough for me to worry about it? Or do batteries only vent hydrogen later in the charge cycle? I think I read that before.

    And my last question (which is a more reasonable question). How much power does that relay you bought draw? Or if it lists ohms, what is it?

    Thanks

    I bet as soon as the charge controller comes on the observed voltage would be above that 12.6 volts.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #72
    Re: Need help wiring 12v solar project

    Two things:

    1). Venting fans are usually set to come on during Absorb stage, which is when gas production is at its highest.
    2). Using PM DC motor fans means there are no brushes so no arcs that could ignite the gas even if it did build to a dangerous level, which is highly unlikely.
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