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WY_mark
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# Posted: 5 Aug 2018 22:12
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Hi everyone, been a while since i posted but im back to trying to make progress on the cabin. Im a little stuck on a small dc solar system. Seems all i find are drawings for bigger things or inverters... heres what i have:
75ah deep cycle battery and a 100watt panel, charge controllwe and thats it.
Here is what i want to do:
Power my 2.5watt composting toilet fan 100% of the time.
Add a usb power block to charge a couple of iphones and/or power a couple of usb led lights.
Have a power takeoff for a little dc fan
The above would be within 4 feet of my battery (probably less)
Where im stuck- my charge controller has one dc power takeoff and it strikes me as unsafe to gang the wires into it. What do i need for a safe but inexpensive way to distribute the dc load? Just a fuse box? Something else? If fuse box, how do i know what size? In short, in this small application how do i get the power from the battery to a couple of things?
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Nate R
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# Posted: 5 Aug 2018 22:43 - Edited by: Nate R
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I have a similar system.
60 Watt panel (undersized, should be 100) on a 115AH battery. 1.4W fan 24/7 (Fan from a composting toilet, I use it in my outhouse.)
I have a Morningstar AC Inverter for a few small AC loads, and a DC setup with a fan and cell charger on it, as well as the outhouse fan.
As far as DC loads, I use a DC fuse block meant for boats, from Blue Sea. I can hook it into my battery with an inline main fuse, and then distribute to 6 circuits individually fused.
https://www.amazon.com/gp/product/B000THQ0CQ
What are you using for a charge controller? I'm using a Morningstar Sunsaver, which I use the "Load" Terminals for my outhouse fan. This way, if the battery ever gets low, the charge controller automatically disconnects the fan to keep it from draining the battery entirely.
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darz5150
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# Posted: 5 Aug 2018 23:10
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I run power off the load terminals of my charge controller (xantrex) to a fuse block. I run water pumps off the fuse block with the correct size fuses. And also from the fuse block I run power to power distribution hubs that have USB port, cig lighter type plugs, and 3,6,9, and 12 volt outlets.
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WY_mark
Member
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# Posted: 6 Aug 2018 09:11
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Thanks! I have the basic renology 100watt kit from amazon. The controller is the renology wanderer.
I also intend to hook the fan to the controller - i dont think ill hook up anything before it for the same reason, i just want stuff shut off if power runs low.
It sounds like perhaps all i need is the fuse block?
Why hook fuse block to battery and Why not wire the fuse block to the controller and prevent overdraw from everything?
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ILFE
Member
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# Posted: 6 Aug 2018 09:31
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Quoting: WY_mark 75ah deep cycle battery and a 100watt panel, charge controllwe and thats it.
Personally, I try to keep my systems at a 10% charge rate. You are considerably below that. On a 75 AH battery, my advice would be to run no less than a 140 watts panel.
Quoting: WY_mark Where im stuck- my charge controller has one dc power takeoff and it strikes me as unsafe to gang the wires into it.
Most controllers will have a DC load terminal, if we are on the same page here and that is what you are talking about.
You don't have to run anything from that terminal, honestly. You can wire all loads directly from the battery, if you wish. But, keep in mind that you will not have battery disconnect protection from the controller, if you do this. What that terminal does is allows your controller to distribute DC power to loads, and disconnect loads (typically rated no more than the full output of the controller), if the battery becomes too weak.
What you can do is, as long as your total loads do not exceed the rated capacity of the controller DC output, to wire a fuse / distribution block directly to that controller DC output terminal. I cannot stress how important it is, to not go over the total rated DC output of the controller, at that terminal.
Quoting: WY_mark What do i need for a safe but inexpensive way to distribute the dc load? Just a fuse box? Something else? If fuse box, how do i know what size?
It doesn't sound as though you have much of a total load drawing from that battery. Remember that volts X amps = watts. Apparently, all of your loads are 12volt DC. So, you just need to input the number of watts each load draws, to calculate how many amperes each load will draw, thus knowing what size fuse is needed. Then, add 10% to that number, to determine what size fuse each one needs - or go to the next higher fuse that is made. Say your LED lights are 20 watts. 20 / 12v = 1.6 amperes. So, run a 2 amp fuse for that particular circuit. (To my knowledge, there is no fuse size between 1.5 and 2.0 amps.)
Just wire a fuse block from the battery and add the appropriate sized fuse for each circuit. Nate posted a link to a perfectly suitable fuse block for you to use.
Quoting: WY_mark In short, in this small application how do i get the power from the battery to a couple of things?
That should have answered your questions. Do you have others?
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ILFE
Member
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# Posted: 6 Aug 2018 09:41
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Quoting: WY_mark The controller is the renology wanderer.
There are much better quality PWM controllers on the market, by the way. Have a look at Midnite Solar or Morningstar, two companies that immediately come to mind. Both make excellent controllers. Yes, they cost more. But, you want a good controller to look after your battery bank.
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WY_mark
Member
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# Posted: 6 Aug 2018 09:49
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Ilife, awesome reply. Thank you!
I like the idea of running a fuse box from the controller, not the battery for exactly the protection you mentioned. Only the fan will run 24/7 but i like having it all ave battery disconnect protection.
It looks (sadly) like people in reviews are saying my charge controller's dc load terminal is for powering a small nightlight and not much else. In that case, if i wire my fuse block to the battery directly is there a discharge protection device that goes between the fuse block and the battery to prevent going too low?
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ILFE
Member
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# Posted: 6 Aug 2018 10:00 - Edited by: ILFE
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Quoting: WY_mark It looks (sadly) like people in reviews are saying my charge controller's dc load terminal is for powering a small nightlight and not much else. In that case, if i wire my fuse block to the battery directly is there a discharge protection device that goes between the fuse block and the battery to prevent going too low?
Not that I am aware of? Someone else here may know of such an animal.
But, that's what I mean about buying cheap controllers. Buy one you will not have to worry about.
Personally, I would dump that controller, especially if you have much money invested in your battery, and buy something like either of the following:
Midnite Brat
Morningstar ProStar
I own both of the above PWM controllers. They are both rated for their listed capacities at the load terminals. Both have low voltage disconnect circuits, I assure you.
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WY_mark
Member
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# Posted: 6 Aug 2018 10:11
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I get that you get what you pay for, but i cant put a $130 controller on a $139 system, just dont have the cash. Are there any <$50 options you like?
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ICC
Member
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# Posted: 6 Aug 2018 10:16
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I wholeheartedly endorse the Brat as a very good charge controller. It is not MPPT but is reliable and waterproof . Great for a small system. I have one on a work trailer setup.
Re fuses: a fuse, or circuit breaker, is employed in a circuit to provide overload protection for the wire, not the device. You could connect a fuse block to the load terminal on the Brat and then distribute the power through fuses to different devices.
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ILFE
Member
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# Posted: 6 Aug 2018 10:18
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Quoting: WY_mark I get that you get what you pay for, but i cant put a $130 controller on a $139 system, just dont have the cash. Are there any <$50 options you like?
I understand. I don't like paying crazy money for them, either. I only paid $40 for each of my Brats, as they were first run controllers.
Um, nothing under $50 US that I like, no. But, in all fairness, I haven't looked for any, either. My Morningstar PS-30M, I paid something crazy, like over $300 USD for it, here in Cambodia. Stateside, it would have been tons cheaper.
Maybe look around on eBay for a used quality controller? I have purchased a ton of them off eBay, over the years, especially Morningstar units. I have yet (knock on wood) to buy one that was no good.
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WY_mark
Member
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# Posted: 6 Aug 2018 13:34
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So the MNbrat is $100 but it says 10a loat circuit - that means i can run a max of 120watts on a 12v system, right? Or am i screwing up how this works?
If i want to run the couple thigs i described and add a small pump to get pressurized water out of my sink will this do? Seems like my system is wanting to get bigger
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WY_mark
Member
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# Posted: 6 Aug 2018 13:45
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What about wiring my fuse box to the battery with this inbetween so the load isnt running through the controller?
https://www.amazon.com/Electronics-Salon-Voltage-Disconnect-Protect-Prolong/dp/B018TW 0KN2/ref=asc_df_B018TW0KN2/?tag=smacab-20&linkCode=df0&hvadid=241974774130&hvpos=1o2& hvnetw=g&hvrand=8155761763209422464&hvpone=&hvptwo=&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint =&hvlocphy=9028794&hvtargid=pla-395587908460&psc=1
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ICC
Member
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# Posted: 6 Aug 2018 13:53
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Quoting: WY_mark So the MNbrat is $100 but it says 10a loat circuit - that means i can run a max of 120watts on a 12v system, right? Or am i screwing up how this works?
You should be able to find the Brat for $85 to $90 with a search. Plus shipping of course.
IIRC, if the load control portion on the Brat is used that limits the charge amperage to 20 amps. I have never used the load control feature on it as I wanted to be able to use it for more than 20 amps charge and I recall needing to jumper two terminals to do that, which also removed the load control feature.
There are separate low voltage cutoff devices available as well. I have none, in particular, to recommend in the low budget range, but a search for 'low voltage battery disconnect, 12 volts" should find some. More $ to spend of course. I have one made by Blue Sea; $100 or so but can handle 65 amps
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WY_mark
Member
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# Posted: 9 Aug 2018 09:46
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I have purchased but not yet installed battery - is there much reason to purchase a second battery? We use the cabin 1-2 nights at a time with no less than 5 days in between. I will mount the panels to an adjustable rack so i can change angle monthly. We are in se wyoming usa and have 320+ days of sunshine per year, unobstructed by trees/buildings.
Im now contemplating the morningstar 30a controller and adding a rv pump for sink. Do i need more storage (e.g. Another 75ah battery?
Things i want to do:
Run toilet fan 2.5 watts
Charge phone 2.1amp
Power a couple dc lights 25-35 watts
Sink pump 7.5amp
Future use?
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cman47c
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# Posted: 9 Aug 2018 10:02
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The sink pump at 7.5 A is a large user. If the lights are on and the sink pump runs a lot, one 75AH battery may last a weekend. With a 100W solar panel you will probably be OK in daytime.
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FishHog
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# Posted: 10 Aug 2018 07:52
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Quoting: cman47c The sink pump at 7.5 A is a large user
typically they are run for such a short period of time, that it doesn't add up to much. WY_mark, no one can really answer your second battery question. You need to do a load estimate for a total day of what power you will use. Compare to how much your panels will make and see if its enough. remember Lead batteries like to work in the top 20% of their capacity, and shouldn't be taken below 50% and that only rarely if you want them to last.
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WY_mark
Member
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# Posted: 10 Aug 2018 10:04
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Can you help with the load estimate?
2.5 watt fan x24 hours = 60 watt hours
Couple lights maybe 2 hours = 120 watt hours
Phones = approx 288 watt hours
Pump even if it runs for an hour = 90 watt hours
Heaviest use looks like 588 watt hours in a 24 hour period
75ah battery = 900 watt hours total, 20% of that is
180 watt hours which makes it seem like i need three batteries but i just cant believe my uses need three heavy marine batteries to work....have i calculated wrong? A 8000 mah battery pack will near fully charge my phone. I feel like im off by an order of magnitude somewhere.
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Nate R
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# Posted: 10 Aug 2018 11:39
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My feeling is FishHog is going a bit overboard for what you want. You're not living on this setup, using more than 20% of an actual deep cycle battery is fine to figure things out.
http://www.trojanbattery.com/product/27tmh/ <-- 600 cycles at 50% discharge. That's a LOT of weekends. 5-6 years?
If you had 8 batteries that were $600 each, might want to be more conservative.
Phones should not be 288 watt hours. 12 watts an hour for 24 hours? No way. Phones will be charged in under 2 hours at that rate. Then it will go to near 0.
So, I'm thinking more like 300wh worst case. 25 AH/day.
75AH battery might be a bit small for that.
I'd have a minimum 100AH battery (or 2 75s), and while 10-13% charge rate (rate of c/20 capacity) is ideal for flooded lead acid, many seem to agree that 5% or so is a reasonable minimum for relatively inexpensive systems.
If it were my system:
I'd do a battery like the Trojan above, 115 AH or so. Or 2 of your 75AH batteries.
I'd get a Morningstar Sunsaver (~$60) w/ Low Voltage Disconnect. (10A Model, could get 20A if you have a lot of solar.)
I'd connect the fan to the load control on the controller, so it will shut it off if battery gets low.
I'd run the other terminals to a fuse block, and distribute the rest of your power that way.
I'd use 2 100W panels, or something more than 100w. 120W minumum if your usage is that high.
Done. FishHog isn't wrong, I just find and feel at this size/cost level, the payoffs from going to "optimum" aren't worth it. Maybe you get 8 years from the battery instead of 5-6? But what'd that cost in increased panel, hassle?
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NorthRick
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# Posted: 10 Aug 2018 16:06
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Quoting: WY_mark Can you help with the load estimate?2.5 watt fan x24 hours = 60 watt hoursCouple lights maybe 2 hours = 120 watt hoursPhones = approx 288 watt hoursPump even if it runs for an hour = 90 watt hoursHeaviest use looks like 588 watt hours in a 24 hour period75ah battery = 900 watt hours total, 20% of that is 180 watt hours which makes it seem like i need three batteries but i just cant believe my uses need three heavy marine batteries to work....have i calculated wrong? A 8000 mah battery pack will near fully charge my phone. I feel like im off by an order of magnitude somewhere.
As Nate R said, your number for the phones sounds too high.
Also, 120 watts hours for a couple of lights sounds like incandescents. Replace those with LEDs and you'll drop the needed power to a quarter of that for the same amount of light.
And, yeah, no more than 20% discharge is ideal, but you don't give up too much life going to 30%.
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WY_mark
Member
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# Posted: 11 Aug 2018 09:37
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Thanks all, so just to summarize....
Maybe i get another 75ah battery and the good charge controller and should be good to go?
If it isnt getting charged maybe a second panel since that can be added later?
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WY_mark
Member
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# Posted: 11 Aug 2018 09:45
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Also, on a sunsaver 20a...why not connect the fuseblock to the load terminals so it is all protected from over drawing the battery? That lvd can do the full 20a, no?
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cspot
Member
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# Posted: 11 Aug 2018 21:15
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Ok. My camp is in SE Ohio and I am in the shade for part of the day. I have a 50 Watt Renogy System. Like you though I am only using the cabin on the weekend (not every one) and for a solid week or 2 during the year. Since I am not there I don't want someone stealing an expensive system. I am not a professional so any advice below please check for yourself that it is adequate and properly installed. I did a lot of reading before I settle on this.
https://www.amazon.com/gp/product/B00E7NDMC4/ref=oh_aui_detailpage_o02_s01?ie=UTF8&ps c=1
For the battery I bought a deep cycle marine that I think was around 100 Amp hour from the local auto zone.
I added an inline fuse from the solar panel to the controller and also a fuse coming off the positive side of the battery. After the fuse I have a 3 way switch that one side goes to the controller and the other side goes to a fuse block. The 3 way switch allows me to kill all power or when away from the cabin I turn it so the power only goes to the controller so it charges up the battery, but kills all the power going to the cabin. Here are the links to the fuses and stuff.
https://www.amazon.com/gp/product/B00YG1DY20/ref=oh_aui_detailpage_o09_s00?ie=UTF8&ps c=1
https://www.amazon.com/gp/product/B01NAYZ3RY/ref=oh_aui_detailpage_o00_s00?ie=UTF8&ps c=1
https://www.amazon.com/RENOGY-20A-ANL-Fuse-Holder/dp/B01LXQWZ7L
https://www.amazon.com/gp/product/B06XK159QJ/ref=oh_aui_detailpage_o03_s00?ie=UTF8&ps c=1
https://www.amazon.com/gp/product/B001P6FTHC/ref=oh_aui_detailpage_o03_s00?ie=UTF8&ps c=1
https://www.amazon.com/gp/product/B000NV0DYE/ref=oh_aui_detailpage_o03_s00?ie=UTF8&ps c=1
The fuse block only came with a couple of fuses so I added additional fuses from the local auto parts store.
Then I put in standard electrical boxes with standard base light fixures and bought these 12V LED Bulbs. They are only 10 Watt and are super bright. Even though I control the lights with switches, I bought light bases with a pull cord, so that I can individually control the lights. I have 8 lights in my cabin, but seldom have more than 2 on at a time.
https://www.amazon.com/gp/product/B06Y1RYVC8/ref=oh_aui_detailpage_o01_s00?ie=UTF8&ps c=1
I also installed these to charge phones and stuff. They fit in a standard electrical box.
https://www.amazon.com/gp/product/B00SVVQHKW/ref=oh_aui_detailpage_o02_s00?ie=UTF8&ps c=1
I also have a sureflo pump and also a composting toilet with the fan too. I have had no issues with draining the battery too far down. I have 3 kids and a wife that stay at the cabin with me. Since we carry water in, our showers are very short and we watch about light use as much as possible. I am sure at times I may exceed the recommended drawdown on the battery, but I don't think it will be an issue with our limited use. We have been using it for 8 months or so now. I also purchased an automatic battery charger a few weeks ago that I can use with my generator if we are staying for a week and it would happen to be cloudy every day. Still this is far cheaper than really upsizing the system for an occasional use cabin.
I hope this helps.
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cspot
Member
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# Posted: 11 Aug 2018 21:24
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Make sure that everything has a fuse. That protects your system and also helps prevent catastrophe.
Make sure to get a fuse box with more than enough space as you never know what you may add down the road.
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NorthRick
Member
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# Posted: 12 Aug 2018 21:40
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Quoting: WY_mark Also, on a sunsaver 20a...why not connect the fuseblock to the load terminals so it is all protected from over drawing the battery? That lvd can do the full 20a, no?
If the load terminal is rated for 20a, and all of your loads won't exceed that, then yes.
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razmichael
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# Posted: 13 Aug 2018 07:16
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Quoting: WY_mark Also, on a sunsaver 20a...why not connect the fuseblock to the load terminals so it is all protected from over drawing the battery
be a bit cautious about using the Charge Controller to prevent battery run down as many of them (unless they can be adjusted) have a very low "low voltage disconnect" value. For example, the Sunsaver 20a lists the LVD as 11.5 volts - you don't want to be running your batteries down to 11.5 very often!
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Rooker23
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# Posted: 13 Aug 2018 09:48
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I have a small DC system. 1 100 hour battery on 200 watt solar. Here is my setup. Used the Blue Sea fuse block. Also have a switch panel for my lights and stuff and a couple 12V outlets. I'm a complete novice so I could be doing something wrong but its worked well for me for 2 years now.
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