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Electrical Ground Wire vs. Chassis

Solar Elecrtrical Battery 12V

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#1 Living The Dream

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Posted 17 May 2016 - 05:02 AM

Hi All,

 
I have a few questions about electrical systems I was hoping some people with expereince could offer advice on.   I am somewhat experienced with basic electricity, only in a sense that I have a multimeter, know how to use it, and can handle V=IR
 
 
I plan to instal a simple fuse box for my led lights and some USB charging.  I am not doing a fridge as all my trips are weekends which a good cooler can handle no problem and I have a wave 3 for electricity free heating.
 
I have a small 40Watt solar panel to keep the battery topped up. This will get me started.  If after more use of camper I find myself needing more I will upgrade. 
 
gallery_6274_1000_113308.jpg
 
On the the questions:
 
1. So I know from taking apart my old camper (84) would often run a single hot (+) lead to the lights.  Then the ground is simply bolted to the bare frame. I think this means back at the battery the ground terminal is also bolted to the frame, is that so?
 
 Also, I think in modern systems there is a ground wire back to the fuse box.  Is this true?  Since I have everything apart I can easily run the ground to my fuse box.  Are there any advantageous to either way?  The only disadvantage i can think of is a bit more money spent on wires.  But this seems pennies compared to everything else, so not a big deal.  
 
2. How many ports in a fuse box?  Do I want each light and system running directly from the fuse block to the individual light?  For example from fuse block channel 1 to the porch light.  From fuse block channel 2 to each interior roof light, etc.   Or should I do one fuse for all lights.  One fuse for all USB charges, etc.?  Either way I am going to make sure my fuse block has some room to expand if things change down the road.
 
3.  For a basic system like mine, do I need a all-off switch in there?  The only parasitic load I can think of for this would be if the USB charge has some sort of LED light.  But am I naive on this? Is it definitely needed that I have the all-off switch for when I am not using the camper and it won't drain my battery?
 
I think my three first questions are summarized pretty well in this my sketch here:
gallery_6274_1000_20302.jpg
Now moving on to the solar question.
 
4. Where does the fuse block go in relation to the solar panel, controller and battery.  I have a cheap harbor freight charger that came with the camper, again will upgrade if need be down the road, right not it should get the job done.  Anyways, I see on the controller there is a load channel.  Do I want to send that to my fuse block or not?  What is the advantage/disadvantage of running fuse block though  the solar controller rather than directly to the battery. I have one of the examples illustrated below.
 
gallery_6274_1000_35915.jpg
 
Thanks for any advice, comment, criticism anyone is willing to offer.  I posted this outside of my build in hopes it will reach more people and be easily searchable as a source of info for those that come after me.
 
Thanks.  Tim

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#2 K7MDL

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Posted 17 May 2016 - 05:36 AM

I prefer to run a gnd wire but the camper frame can and does work.  Where voltage drop under heavier loads is a concern, running heavy direct gnd and hot wires will be best.  For some loads like lighting mounted on cabinetry or the roof, there is no good nearby frame connection.  If is easier and better to run a pair of wires out to the load.

 

The switch is good to have to perform work on your wiring with power off.  Less important if you know your parasitic loads won't kill your battery.  You should consult the solar charger wiring instructions, but since it is a form of battery charger and usually has backflow prevention, it is common to connect directly to the battery via proper fusing.  Fuses should be near the battery as well for any wire coming off of it.  Some prefer the place the switch between the battery and all loads and sources.  FWC has the switch between the IOTA 30amp charger and the battery for example.  Can run off AC power and the battery will be isolated (and thus not charging). Many do wire their chargers direct to they battery though, in RVs and boats. If using a solar controller, it is good to check on what it requires. 

 

Other than fusing near power sources, your diagrams are correct.  You can put the switch on either side of the solar controller, I prefer to run chargers directly to my batteries, and only switch power to loads.  In my small fishing boat I add a dash mounted LED to tell me my battery switch is on or off, ensuring I do not forget to turn it off for storage.  My switch is located behind a locking panel so not easy to see at a glance. 


Edited by K7MDL, 17 May 2016 - 05:39 AM.

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#3 Living The Dream

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Posted 18 May 2016 - 02:24 AM

Thanks so much for the detailed response. Everything you said reassures me I am on the right track and up for the task. I think I will go ahead and run a ground wire on everything since I have the camper apart and it is very doable.

 

Last question if anyone can help me out.  Do I want to run a fuse for every single item pulling power, ie. light one, light two, usb charger, etc.  Or should I keep it simple and just have one fuse for all lights, one fuse for all 12V charger accessories.

 

Thanks again.  Tim


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#4 ntsqd

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Posted 18 May 2016 - 02:47 AM

FWIW I put the manual re-set breaker between the battery and everything else. I use the manual trip button to isolate the batteries (have to remember to trip the breaker at the truck batteries too!) whenever I need to work on dead circuits.


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#5 K7MDL

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Posted 18 May 2016 - 02:52 AM

Simple is good.  It mostly depends on how you run the power to the load.  If the wiring to a group of lights are at opposite ends of the camper, you could choose to run them on separate fuses.  Generally you can group similar items onto a fuse, and ensure the smallest wire size used will be protected by the largest fuse you need to run the entire load on that fuse. 

 

For example you have 6 lights drawing 2A each at worst case (halogens for example), you need to supply 12A, so a 15A fuse would suffice. You may run the wiring daisy chain and/or in parallel, in any case the minimum wire size used in any part of that circuit must safely carry 15A-20A fused current.   There are wire size charts easily found with recommended fuse ratings to protect them.  Ensure you account for surge/startup currents for motor type circuits.

 

Reasons you may use more fuses are to simplify future troubleshooting, or you have a long or a more vulnerable wire run then the rest of the group.

 

For a small camper like ours, I would put all interior lights on one fuse, and use LEDs.  The old halogen lamps create a lot of heat, drain your battery and can even damage your side walls when folded and left on.  Exterior lights on another fuse, and each major load like fridge, pumps, etc on their own.  If you are running out of available fuse positions in the panel size you can fit, then start consolidating strategically keeping in mind the above.  

 

Thom's idea on using a breaker is a great idea to save the cost of a large battery switch.  Get 2 functions in one.  I do the same thing under my hood for camper power.  Easy to see if it is tripped and manually trippable to work on things.


Edited by K7MDL, 18 May 2016 - 03:01 AM.

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#6 JaSAn

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Posted 18 May 2016 - 04:19 AM

 

1. So I know from taking apart my old camper (84) would often run a single hot (+) lead to the lights.  Then the ground is simply bolted to the bare frame. I think this means back at the battery the ground terminal is also bolted to the frame, is that so?
 
 Also, I think in modern systems there is a ground wire back to the fuse box.  Is this true?  Since I have everything apart I can easily run the ground to my fuse box.  Are there any advantageous to either way?  The only disadvantage i can think of is a bit more money spent on wires.  But this seems pennies compared to everything else, so not a big deal.  
 
Best practice is to explicitly ground all circuits.  Frame grounds are notorious for vibrating loose, corroding, and offering high resistance.  They work, but are very hard to find if you have a problem.  Since you have your camper apart, spend a little to save yourself headaches down the road.
 
2. How many ports in a fuse box?  Do I want each light and system running directly from the fuse block to the individual light?  For example from fuse block channel 1 to the porch light.  From fuse block channel 2 to each interior roof light, etc.   Or should I do one fuse for all lights.  One fuse for all USB charges, etc.?  Either way I am going to make sure my fuse block has some room to expand if things change down the road.
 
This is personal preference.  Fusing each individual light means running wires from each light to the fuse box.  One reason to wire lights separately is that is if one fuse blows all your lights don't go out (ditto other circuits).
 
3.  For a basic system like mine, do I need a all-off switch in there?  The only parasitic load I can think of for this would be if the USB charge has some sort of LED light.  But am I naive on this? Is it definitely needed that I have the all-off switch for when I am not using the camper and it won't drain my battery?
 
In your drawings I don't see your solar panel nor your batteries fused.  In my system I use my fuse (ANL-60 amp) to disconnect either the solar panels or the battery from the system.  A switch will work but not replace the fuse.  A circuit breaker will do both. ABYC specify a fuse within 8" of the battery.  
 
Now moving on to the solar question.
 
4. Where does the fuse block go in relation to the solar panel, controller and battery.  I have a cheap harbor freight charger that came with the camper, again will upgrade if need be down the road, right not it should get the job done.  Anyways, I see on the controller there is a load channel.  Do I want to send that to my fuse block or not?  What is the advantage/disadvantage of running fuse block though  the solar controller rather than directly to the battery. 
 
NO!  The load channel is to use excess solar output when your batteries cannot take all the current your panels are generating.  You will only power the camper when your batteries are full and the sun is shining, the battery in your diagram is not connected to the fuse box at all.  The fuse block should get (fused) power from the battery to distribute to your camper.
 
Thanks for any advice, comment, criticism anyone is willing to offer.  I posted this outside of my build in hopes it will reach more people and be easily searchable as a source of info for those that come after me.
 
Thanks.  Tim

 

 

Decide what you will possibly want to power in the future (refrigerator, heater, ceiling fan, outside lights, etc.) and run wires now while you have the camper stripped if you know where they will go.  I would also run appropriately sized wire for the amount of solar you think you might add in the future.  Easier now than later.  And label all your wires (both ends) to save headaches later.  If you can swing it use different colors for different circuits also (I use black exclusively for ground); but if you label well this is not necessary.

 

jim


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#7 Living The Dream

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Posted 20 May 2016 - 04:33 AM

Thanks you all for the detailed responses!  I truly appreciate it.  I need to sit down with this some more and sketch it up in more detail,  Figure out what my total loads will be, and what I might add on down the road.  Yes I agree I need to fuse the battery and solar.  I think Ill get a breaker like some of you suggested.

 

The only thing I am still confused on is if the fuse box (distributer panel) goes through the solar controller to the "load port" or if it just gets connected directly to the battery.  I have two conflicting suggestions on here. I have looked around on the internet and continue to see it both ways.

 

Here is my understanding:

 

fuse box connected to solar controller.

If my total load (all lights, charging ports, etc.) max amperage is within the max amperage of my solar controller, I could run them all through my controller and be good.  As in, if the sun is not shining, the battery will push charge through the controller to the loads.  For instance if I have a cheap 7Amps charger and only expect 5 Amp load at any time, I would be good.  Also I think some controllers stop providing charge if your battery is too low, to try to keep your batteries healthy.

 

fuse box connected to battery
However, if my solar going to provide much less amperage than my load will require (as in it just tops up the battery, never runs an actual load).  Then I want to run my loads directly off the battery as the solar charger can not handle it.  For instance if I have a cheap 7 amp charger and expect to pull 10 amps a some time, I would want fuse box directly to battery.

 

I know this isn't perfectly clear.  If anyone could chime in a bit more to try to sort me out I would be very appreciative.    Thanks again. Tim


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#8 K7MDL

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Posted 20 May 2016 - 05:19 AM

I think you have it right. Both have their place. I would opt to believe you will at some time soon enough exceed your solar controller of choice's capacity and thus use it as only a charger, so you would connect the fuse panel off the battery.

 

I think the idea of running the load through the solar controller is for small simple systems that likely won't change much, or for solar home situations where the battery is supplemental rather than primary.  They also come with large inverters and quite often higher voltages.   So much solar power material is out there but look at the scale of what they are talking about. That said, there are a few campers here that are powered up enough to look like a solar home design :-).  More power to them! (pun intended)


Edited by K7MDL, 20 May 2016 - 05:21 AM.

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#9 Beach

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Posted 21 May 2016 - 06:49 PM

Use the battery for the panel 12v supply,  fuse the positive lead going to the panel, or better yet use a switchable breaker.. By using the battery instead of the controller, you will not exceed the rating of the controller if you had a short some where that might cause a momentary high amp draw. Also, some controllers can/will induce some electrical interference into the panel circuit which may affect sensitive electronics.


Edited by Beach, 21 May 2016 - 06:54 PM.

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#10 Happyjax

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Posted 23 May 2016 - 01:01 AM

The purpose of batteries is to provide for a load, the purpose of solar is to charge the batteries. I would not deviate from that. I would ignore the "load" on the controller as it just adds confusion and possibility of damage to your controller.....


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