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phutch85
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# Posted: 17 Sep 2014 05:58pm
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Hey all,
I know it gets talked about a lot on here, but I'd like to present my idea for some off-grid power. I see a lot of posts for set-ups that typically exceed my need or include extra complications like the ability to modify and expand the system, or the ability to run higher draw devices and appliances.
For my little 10x12 cabin, I would like to have the ability to run up to 6 lights which would each run a 5W LED bulb. In addition, I would like to be able to charge cell phones and other micro-USB devices (Kindle, portable bluetooth speaker, etc.) Any other devices I'd power, I plan on running directly from my generator, a Honda EU2000i. I only use the cabin on weekends, maybe once or twice a month. I estimate that the lights and charger would run a maximum of 15 hours for any given visit.
It is far too shady and protected for solar or wind to be an effective option for me, so I want to go the route of a small battery bank, using my generator as a charger. What I want to avoid is having a system where I have to run the generator for hours and hours on end to replace the charge I've lost. What would be ideal, is if I only had to charge the batteries every other visit or so.
After doing some research, I haven't found a comprehensive list of parts and a very straightforward plan for someone who wants a system as simple as mine. I'm hoping that this post will accomplish that and perhaps warn me from any mistakes I might be making. I am very, very new to electrical work of any kind. So, here's my plan. If you have any ideas for how to do it cheaper or easier, I'd love to hear your thoughts. Thanks everyone!
Generator: Honda EU2000i
Connected to Iota DLS30, 30 AMP Battery Charger (http://www.amazon.com/IOTA-Engineering-DLS30-Converter-Battery/dp/B00A0V5HPC/ref=sr_ 1_3?s=automotive&rps=1&ie=UTF8&qid=1410987561&sr=1-3&keywords=battery+charger#product Details)
This battery charger has an AC plug that will connect directly to my generator's AC outlet.
Connected to the Iota will be two 12V, 35ah batteries, wired in paralell to give me 12V and 70ah. This connection will be made using 8 awg wire. Here's a link to my proposed battery (http://www.amazon.com/DEEPCYCLE-SOLAR-ENERGY-STORAGE-BATTERY/dp/B008D5YG3G/ref=pd_bx gy_lg_img_y)
Connected to the batteries will be this 500w Energizer Inverter (http://www.amazon.com/ENERGIZER-Inverter-cigarette-lighter-compatible/dp/B00ATXERNO/ ref=sr_1_1?s=automotive&ie=UTF8&qid=1410989580&sr=1-1&keywords=inverter)
I like this inverter because it comes with battery cables and because it offers 2AC plugs in addition to 2 USB ports that I can use solely for charging cell phones and micro-USB devices, while the AC plugs will run to my lights.
All told, the system will cost under $350 (minus generator cost). My two questions: 1) Am I missing something? and 2) How long would you anticipate it would take to replenish charge? With lights and phones, I estimate at any time I'd use a maximum of 60W of power, for a total of 15 hours a weekend. These number are almost certainly too high, but estimating conservatively seems the way to go with these things.
If this is all legitimate, I'd like to post a step-by-step for the benefit of all those who want a super simple system but have no idea what they're doing.
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Steve961
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# Posted: 17 Sep 2014 06:26pm
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One problem I see is that you either have too big of a charger, or too small of a battery bank. Lead acid batteries should be charged at a maximum C/8 rate, which means that your battery bank would need to be 240 AH (Amp hours). Another other option would be to go with a smaller ~10 amp charger, but then you would not be using your generator efficiently. And yet one more option, you could get AGM (Absorbed Glass Mat) batteries which allow you to charge at C/2, but at a much greater cost for the batteries.
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MtnDon
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# Posted: 17 Sep 2014 06:35pm - Edited by: MtnDon
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My major question is about the batteries and the Iota charger. The batteries are sealed meaning you can't check or add water. The Iota may be too powerful for the small amp-hour capacity. It may overcharge, overheat the batteries and cause loss of water. May cause overheating and damage if not watched carefully. They say sealed but there has to be vents for safety sake, so they can lose water with overcharging. Loss of water = loss of battery.
At $150 for those you might be better off with a single RV battery. Those have caps so you can use a hydrometer or add water as needed. More capacity makes it a better fit with the 30 amp charger. Cheaper too. They are not sealed which is good in my book, except that also means they leak if they fall over... in case you are transporting back and forth. But you could carry it in an RV battery box. And if bought locally it's an easier return if you need to make a warranty claim.
If you don't have the EU2000i yet and don't need the 16.6 amps you could use a EU1000i... It would still run the Iota 30 amp charger and use less gas overall.
If the generator will be the only recharging source you don't need their IQ4 accessory. If you will be carrying the battery back and forth and maintaining the charge at home the IQ4 is great to have as then you can leave the charger and battery connected all winter and not have to worry about overcharging or having the battery deteriorate between charging.
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MtnDon
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# Posted: 17 Sep 2014 06:41pm - Edited by: MtnDon
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If you have no other need for AC power other than the lights and a USB port you might consider going DC only. Look at someplace like superbrightled.com for 12 volt LED with 400 or so lumens. Vendors on ebay and other places have usb port devices than can be connected to 12 VDC and provide the 5 volt power for up to 2.0 amps for recharging phones, etc. No inverter needed, no inverter losses.
And if you carried the battery back and forth you would not need the generator, just the Iota at home. Unless you start running more devices than just what was mentioned.
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razmichael
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# Posted: 17 Sep 2014 06:49pm - Edited by: razmichael
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Edit: I hate it when I draft up something and post - only to find that MtnDon beat me to it! Anyway - what he said ... and what I wrote... End Edit
I'm not going to get into a "I use this ..." discussion as everyone has a different set of criteria, but will make a couple of comments (and I'm sure you will get many more). I'm going to assume you really do want to keep this very simple and cost effective although many try to start this way and then find they need/want more!!
First, if you want to keep it simple then keep your lights 12VDC rather than running them off the inverter. The inverter you picked is a very simple and cheap on and will not be particularily efficient so you are eating up your power just by having it on. Maybe not an issue if you had more to spare but you do not.
If you do this then the next thing is to decide if you need an inverter at all. If your intent is to run the odd big stuff off the generator then maybe skip the inverter at this stage. I would be surprised if you could not charge all your electronics from 12VDC either through a car adapter into a "lighter socket" you can wire in (or use a USB adapter in the socket).
The battery charger is a very basic system. Even the IOTA site offers an upgrade to it to provide four way chargingIOTAIQ4 . Either add this to it or look for another smart charger. This is key to keep your batteries alive for any length of time. I cannot speak for the IOTA quality but the system you have selected is very basic and looks more like something that belongs inside a electronics system - might not be the best suited for a cabin?? There have been some discussions on the forum on battery chargers. There are some decent ones for not a high cost.
I suspect - but others from the U.S. can confirm, that you can find better batteries than these for the same or close price. Since the batteries are so vital to the system, this is an area that I would spend a bit more on.
Great choice on the generator!
Just my quick and dirty thoughts and opinions.
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phutch85
Member
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# Posted: 17 Sep 2014 07:08pm - Edited by: phutch85
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Thanks for the comments everyone. I'm also seeing in my calculations that I made an error and definitely overestimated my total power needs over a full weekend.
Looking now, I think I would only need a total of about 20 amp hours for the weekend. I'm not married to those specific batteries, just wanted to provide a concrete example for people to look at.
Revising the charge controller based on Steve961's comments, I think I would be better suited for a smaller charger.
Assuming I used a comparable battery source (12V, ~80ah), I could use this battery charger from Schumacher (http://www.amazon.com/Schumacher-SC-1200A-CA-SpeedCharge-Maintainer/dp/B000BQSIWK/re f=sr_1_1?s=automotive&ie=UTF8&qid=1410994127&sr=1-1&keywords=battery+charger#productD etails)
That would keep me within the C/8 requirements of standard battery charging. And, if I'm only using ~20 amp hours of power a weekend, I should only need to charge with the generator for about 2 hours. Let me know if I have that wrong.
Regarding the use of straight 12V lights and chargers and avoiding the inverter, it's definitely something I've thought about. However, I'm more at peace with the slight efficiency loss than with the loss in universality. I want friends and family to be able to come to the cabin and plug in their various low-draw devices and chargers without having to worry about 12V DC adapters.
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jaransont3
Member
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# Posted: 17 Sep 2014 08:54pm
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Your proposed system sounds very much like ours at our cabin in Minnesota. We have a Honda EU3000i generator, two 6V golf cart batteries and a Tripp-Lite inverter/charger.
Specifics are:
Tripp-Lite Inverter/ Charger APS750 750W Continuous/1500W Peak. Built in 20 amp charger and transfer switch. PWM Sine Wave when on batteries.
Two (2) Duracell CG2 6V/212AH Batteries wired in series.
We went with the larger generator because we use it as back up emergency power for our house in town and it has electric start.
The Tripp-Lite works great and has multi-stage charging. The cooling fan is a little loud, but completely tolerable. We typically run the generator for a few hours every day while we are using the power tools and such or if we want to use the window A/C or the ceiling fan.
We have gone 2 days with just the batteries and inverter and could have gone another maybe. That is running the lights in the cabin (CFLs), our compact fridge, and the the Shur-Flo pump for our water.
All the details of our system can be found on this thread:
URL
Good luck.
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groingo
Member
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# Posted: 18 Sep 2014 12:32am - Edited by: groingo
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Regarding your choice of power inverter, if you plan on using LED lights you may want to look at a Pure Sine Wave inverter, the Modified Sine Wave inverters tend to eat up LED lights, mine have lasted about 30 days then they go dim and give off a god awful stench and get super hot go fizz and lights out. Typically these same lights go many years until I started using this inverter.
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Steve961
Member
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# Posted: 18 Sep 2014 10:40am
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groingo makes a good point regarding the inverter. My usual recommendation for a small pure sine wave inverter is the 300 watt Morningstar SureSine for about $240. It is extremely efficient and has one of the lowest standby power draws of any inverter I know of. If money is tight though, Samlex makes a 150 watt one for about $115.
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phutch85
Member
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# Posted: 18 Sep 2014 05:24pm
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Ah, that's great to know. Thanks guys. Looks like I'll be going with a 300 watt pure sine wave inverter, a battery around 80ah, and a charger that will put out about 10 amps. I'll update everyone when I pull it all together.
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ChuckDynasty
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# Posted: 18 Sep 2014 06:51pm - Edited by: ChuckDynasty
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I'd be surprised if you needed 5-6 5w led bulbs in a 10x12 unless it's a dark cabin. Unless you needed to run power tools I'd go 12v, no inverter, 1000i gen to charge your battery.
I run a larger then 10x12 room on a 108ah 12v battery charged by a 50w solar panel. One 3w 12v led to light the room, 10" led tv, usb for cell phones & laptop charging, music listening, 10in 12v fan now as well. every day. Great small experimental system that I've been using for over a year. My fully charged battery is 13v has never been below 12.5v...usually at 12.7v in the morning. Good luck
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toofewweekends
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# Posted: 18 Sep 2014 11:59pm
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Our set up is close to Jaransont3. Two Costco golf cart batteries (heading into year 5), Iota 30amp charger, inverter and Honda 2kw.
I'd opt for the larger generator and higher capacity components as you may end up using bigger power tools or other items in the future. As long as they last, it might well be the last generator you buy. Also, it seems cabins have a way of growing power "requirements." (Really, honey, we should have an ice maker for happy hour...)
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