Move to off grid home

[Kurt]

As far as covering the fear of a large home battery pack wearing out in 7 years,...and then the cost of lead has gone up 10X...and the money has inflated (diluted?) 2 or three times...

You can order a spare set of identical batteries now, just special-order them from the factory as dry/never-filled units. With the electrolyte in sealed drums. I've heard they can last over 20 years that way. Then they work just fine once you pour in the electrolyte...

That is something to think about but at $15,000 to just have them sitting there for 10 years even at 6% interest I think that money would be better in the bank and would grow to over $30,000 by then. There is then hope that new tec and battery's are available in 10 years are better. Its a gamble if price will go up or down . If only we all could read the future.

At this stage I just got the quota last week for the proposed workshop at $38,000 so I need to put cash towards that.

Time will tell how long the pack lasts It's had a very easy life over the last 2 years as the old owners were not there full time. Spec sheet said something like 4500 cycles at 10% DOC and thats about what they see now .10% is around 6kwh and to be using that from the pack I would have to consume that 6kwh from 4pm -6am I am lucky to use 4kwh over that time period. So they should have another 10 years in them at least. When you think about it most people are more than happy to pay 15k or more for a new car every 10 years so its not that bad.

Kurt

[dogman]

Man, 4kw on the roof is all you should ever need. Sweet!

[grindz145]

Kurt that place is a dream! Thanks for sharing!

[Kurt]

Over the weekend we had about 100mm of rain on sat then Sunday was overcast and light rain all day. I checked the battery's 9:30 am and they were at 96%. Even on a crappy day the pv are still feeding 10 - 20amps hitting float charge before 10:30am.

A small video from the weekend


Kurt

[Pablo_1985]

I have been thinking about this a lot and i keep not understanding why people doesn´t use LIFEPO4... just an example:
http://offgridnz.livejournal.com/
and token from here the numbers http://www.solarpaneltalk.com/showthrea ... tery-banks

So I'm comparing the cost of AGM deep cycle batteries with LiFePO4 batteries, and it seems that LiFePO4 will win out.

Hear me out...

Goal - Provide 1 kW of power.

Assuming 80% DoD for LiFePO4 and 20%DoD for AGM (Which will give us approximately 5 years for each type of battery), we will need:

x24 3.2V, 16AH of Headway LiFePO4 batteries for a 12.8V, 96AH pack (1.28kW) and

x2 12V, 255AH, Concorde AGM Groupe 8D batteries for 12V, 510AH pack (6.12 kW).

since 80% DoD of 1.28 kW = 1.0 kW and
20% DoD of 6.12 kW = 1.2 kW

Price for x2 Groupe 8D Concorde batteries ~ $1,200
Price for x24 Headway LiFePO4 batteries ~ $600

.. not to mention x24 LiFePO4 batteries only weighs about 30lbs.

I guess the price of the Battery Management System for the LiFePO4 cells and the complexity of the system far exceeds that of the AGM batteries for now. Perhaps the technology is still immature.

Are there any technical barriers from preventing the use of LiFePO4 batteries as solar battery banks? Maybe the discharge rate (100A)?

For me it makes perfectly sense

[Kurt]

Lifepo4 isn't out of the question but .....

Using my system as an example the pack is around 63kw 100% DOC or 30kw at 50% DOC 6.3kw at 10% DOC and so on .There are Large lifepo4 cells out there But that would take a lot of 16ah headway cells .

Lets use your 30% DOC for led and 80% DOC for life . Using 16ah headways you would need 400 cells to give 30% of my 1330ah 48v led pack. Not to mention if you really needed the capacity you could take the pack down double that on the lead and that would take 800 headway cells.

400 cells is one big BMS and a lot of balance wire's.


Now you can fix this issue with some big life cells . I have googled some 400ah 3,2v cells



This is the cycle life of a 400ah lifepo4 I found
2000 cycles 80% DOD
3000 cycles 70% DOD

This is the cycle life of my exide led battery's
1500 cycles to 80% DOD
2500 cycles to 50% DOD
3300 cycles to 30% DOD
4500 cycles to 10% DOD

So at the 80% DOC the lifepo4 is only 25% better than the led on the cycle life. There is a big difference between golf cart led battery s and large RAPS battery's. Not to mention a 5 year warranty on the Exide battery's and only 12 months on the lifepo4

Weight isn't a issue when your powering your home as the battery's just sit in a bunker on a concrete floor and get shifted once ever 15 years. Mine are are around 120kg each 1.4 ton but I can easily slip a trolley under one cell and move it around.

Yes the future isn't led but for now the advantages of lifepo4 for powering your home are not the same as a EV. Weight,C rating are not a issue.

As it stands in my 48v 1330ah pack using 12 cells is around $15,000 retail. it would be interesting what you could get for that in large life cells.

Kurt

[Hillhater]

Certainly there are 1000Ahr Lifepo4 cells available at ?? $$'s
...but also these 100Ahr , 48v LIFepo4 packs at $240 each !!
http://www.alibaba.com/product-gs/51002 ... lecom.html

[Kurt]

Certainly there are 1000Ahr Lifepo4 cells available at ?? $$'s
...but also these 100Ahr , 48v LIFepo4 packs at $240 each !!
http://www.alibaba.com/product-gs/51002 ... lecom.html

Most likely there is larger lifepo4 I haven't done much searching. $240 for 100ah 48v would only be $3200 for a 1300ah 48v pack that sounds very good. Not sure how reliable they would be at that price point.

To me the criteria is..reliability, service life, safety then price . the last thing I would want is to be eating by candle or generator because a BMS or Chinese cell had a fit.

Its just going to be a learning experience with the battery's i have now as to how long they last and how they perform overall. I might do some research into large life example's.

kurt

[jonescg]

Not sure if you've already considered it or not, but Ironcore does NiFe batteries. These things has amazing cycle life - like 5000+ and counting. They work out to be as expensive as LiFePO4, but will probably last far, far longer. Google Edison batteries.

[Kurt]

Not sure if you've already considered it or not, but Ironcore does NiFe batteries. These things has amazing cycle life - like 5000+ and counting. They work out to be as expensive as LiFePO4, but will probably last far, far longer. Google Edison batteries.

Interesting learn something new about battery's every day . Nickel is expensive and like you say they are about the same price as Life.

I am happy with my lead and they are ticking along nice considering they are absorbed into the purchase price of the house and only two years old unless something bad or unforeseen happens I would be looking at battery's for many years.

I will be looking into using excess solar output to drive a mono pump. Then have two water tanks and setting up a pumped hydro down the hill. this will be setup to drain back late at night to recover a few kw charge extending the battery s life.

Kurt.

[Hillhater]

..I will be looking into using excess solar output to drive a mono pump. Then have two water tanks and setting up a pumped hydro down the hill. this will be setup to drain back late at night to recover a few kw charge extending the battery s life.

Kurt,
i understand how this could be done ( and you are in an ideal situation to do it),.. but i would carefully review the ROI of this project.
IE,.. what will it cost you in time, equipment and materials to install, vs any payback you can estimate ?
I guess the tricky part would be estimating the payback,..extended battery life would be a real wooly estimate considering your excess capacity now, and could be completely eliminated by some other unplanned event (??)
But it sounds like the payback for you would be the satisfaction of building it anyway.. ?

[Kurt]

Well i need to purchase a tank to collect storm water runoff from the shed/workshop I am planing to build soon. I can purchase one big tank or two smaller ones. smaller tanks are less cost efficient than one big one but the cost difference isn't that big. The pump I can get at trade price and the small hydro unit made from a old FP washing machine smart drive motor is relatively inexpensive at around $600 AU for a complete turbine kit.




link to NZ company
http://www.ecoinnovation.co.nz/p-81-pelton-turbine-low-voltage-kit-set-1.aspx




I already have a good 100m of the 200m of 2" plastic pipe laying around.

Some would say just buy more PV's .The trick is a already have to much pv and I need more storage. Well actually I don't need more storage but if i can reduce the time that my battery's spend at anything but 100% that has to be a good thing.At night there isn't many options other then wind, diesel generator or hydro.

I have a local contact that is setting up the same hydro system for the same reasons I actually got the idea of of him. He has all the gear purchased and is just finding the time to run the 200m of pipe. So will sit on the idea until i see his in action and see how it runs.

Kurt

[Hillhater]

Hmm, .. neat kit, but wont you need huge tanks ? ( dams ? )
..looks like you need around 29 cu meters for 1 kWhr ?

[Kurt]

Two 20,000ltr tanks with 85m head over 200m. potential for 3kwh. The good thing about the pumped hydro is you can have the valves on a voltage-time sensitive relay so it kicks in when you need it late at night. Once you have installed the tanks,wire and pipework their isn't a lot of ongoing maintenance other than perhaps a new pump sleeve every so often. its a very robust reliable night time 3kwh of charge you can count on. Also the extra 20,000ltrs of fresh rain water is always handy.

Kurt

[Kurt]

I finally got a chance to ride my ebike for the first time at the new location. It's been about 5 weeks or more from the last time a rode my E trike. The Lipo pack was showing just under 60v so I topped it up and balanced the pack. The trikes tyres had lost some air and where on the soft side after sitting around. I didn't bother pumping them up, My thinking was a soft ride could be an advantage on the dirt.

What I found to my surprise was the trike with slightly under inflated tires handled the gravel road with very well. The road although dirt is very smooth with no pot holes and is graded regularly . The trike was actually more fun to ride on the dirt that a paved road. I could hold 50kmh while riding one handed.being able to apply little squirts of power and feel the rear end step out was fun. The trike at 60v is actually about the speed I drive the car down that road due to the width of the road and tight twist and short but steep climbs and large trees lining the edge of the road.

It's been raining but I plan to ride from the house to the local town but will take the tourist drive of around 10km (20km round trip) I will try and get some video when i do and post it up.

It's great charging the bikes of solar now.especially when charging them when the sun is up as the inverter is more or less running directly off the pv's

Kurt.

[Kurt]

Finally I now have a copy of the original remote monitoring program for my inverter.



I need to run a cat5 cable from the inverter to the house over the weekend and I can fire up the software. It's going to be great to be able to glance at the laptop any time day or night and know what charge level my Battery's are at. Among other things like Voltage, Amps IN-OUT, kw load, kwh consumed over 24hrs & average over 7 days, temp of battery bank, Temp of inverter at three positions- transformer,heat sink and ambient air temp internal external. All historical data can be downloaded and put into excel spread sheet. The generator can be started remotely to from the program.

I was getting fed up with having to walk outside open up the battery room doors then inverter cabinet while watching out for snakes that for some reason love the room. last weekend I had a huge goanna lizard in there sitting above the door when i walked in frighten the crap out of me when I wasn't expecting it .

This is what they look like . The one in the battery room was about 2 foot long without the tail. They get a bit cranky and have some nasty claws.





So rather than deal with the creatures Just to view the inverters lcd panel for simple reading like battery charge % and PV amps in the program will be great.It felt like I was driving a car with no dash board instruments, Not knowing what the fuel, battery voltage,temp level was without getting out of the car and measuring it a real pain in the a**.

My thinking was is would be great to use a cheap android phone or similar that could run the software and a blue-tooth or wifi adapter so I could run the program permanently on it and mount the phone on a cradle . The program gives you the option to emulate the keypad & LCD screen on the inverter so not sure how that would go with a touch screen phone.

Some example shots of the very basic program. It doesn't look flash but it gives you all the data you need.







Kurt

[Elliot]

Hi Kurt, I've been watching this local Brisbane company for a while http://www.redflow.com.au/. Some interesting battery technology when you need to turn over your batteries on the house.

[Kurt]

Hi Kurt, I've been watching this local Brisbane company for a while http://www.redflow.com.au/. Some interesting battery technology when you need to turn over your batteries on the house.

Very interesting thanks for that. Local to is a good thing. I had a quick read. looks like a nice option with some big advantages. I couldn't see all the data but would be interesting to see how they handle hi C discharge. Any improvement on cycle life has to be a good thing.


I have been shocked at how little energy KWH we use in this new house. We purchased all new appliances for the home. It took me many days researching on the net to find the most energy efficient appliances. Our 500ltr refrigerator - freezer uses 400kwhr PA The Asko front loader washing machine uses 180kwh Pa. the FP dishwasher draws use 134kwh pa. The tv samsung 40 inch led tv uses 180kwh pa. The lighting is LED and compact fluorescent home theater pc is a little asrock ion unit that struggles to consume 30w playing a blue-ray.

All of the sticker ratings on the appliances are over the top. For example the washing machine's rating assumes you are doing 7 wash cycles a week .The Tv's rating assumes you watch something like 6hrs a day . Its amazing how picking your products carefully can save you a lot of energy. Some refrigerators of the same capacity usually cheap and nasty ones used double the kwh to do the same job and it was the same for washing machines and dishwashers.

We are struggling to use 3 or 4 kwhr a day As the design of the home with cross ventilation and very good insulation(given the local climate) heating and cooling are eliminated all year. Its a 4300 square foot home using 1/3 the energy of our little suburban house.

Kurt

[liveforphysics]

Great job choosing appliances wisely Kurt.

Sounds like you're really "doing it right" for living. Much respect to you, and thank you for taking the time to share your experiences.

[Elliot]

Hi Kurt, Just guessing but I think your near here, and I highly recommend this place for a beautiful Sunday Morning breakfast http://www.walkaboutcreek.com.au/userfi ... t_menu.pdf, cheers, Elliot

[Kurt]

Hi Kurt, Just guessing but I think your near here, and I highly recommend this place for a beautiful Sunday Morning breakfast http://www.walkaboutcreek.com.au/userfi ... t_menu.pdf, cheers, Elliot

Elliot,
Our city house in the suburbs about 300 yards away from walkabout creek. My wife and I have had breakfast their a few times and it is nice(shame the dam isn't open to recreational use as its going to wast) I would love to use my electric kayak on it . My daughter likes the animals at walk about creek. As you would know its at the base of a very nice road that heads up into the hills and nation park.

My off grid home is about 100km north in the sunshine coast hinterland.

Kurt

[Elliot]

I know, maybe Campbell Newman will let us use the dam after the election I really like the aviary at walkabout, really relaxing.

I'm on the other side of the mountain in the valley.

[Kurt]

I now have some downloaded data from the inverter to see how the system is running. When viewing the data we are only using the system on the weekends at this stage hence the low consumption Mon - Friday as its just the base loads refrigerator,security and standby loads.

I downloaded 7 days as we had a shocking day last Monday with 236mm of rain over 3 days. The solar irradiation on that day peeked at only 75wm2 and averages around 40wm2 That said I almost covered 100% of my base load with solar that day. On the Tue I ordered the generator to start to do a 6 month Q charge just to shake things up a little. In the future I am just going to let the PV's do the EQ charge.

One thing with a RAPs system compared to a grid tied system is you never get to see your potential PV output as the Pv's only run to charge the battery and then just sit idle each day .

To date i am struggling to use 4.5kwh a day and the max DOC my battery's have been at is 92% so I am using 8% of them to run my home.Its just ticking along having a easy life. That said the last two two days on the graph we had a guest staying with us so had extra water pump time for showers and ran washing machine and dishwasher.Efficient appliances go a long way . when we are not there weekdays the refrigerator automaticly sets its self to eco mode and reduces the defrost cycle to conserve energy.

data and excel graphs.



battery's reach fload early in the day . Every day but monday.


you can see how the irradiation was super low on Monday with thick black cloud.


Weeks load in watts average.


battery volts






On another note I have a little 26hp 4wd diesel tractor to mow the lawns. After getting sun burnt last time riding on it I started looking at a fiberglass canopy that attaches to the rollover bar. They offer some sun and rain protection.

Something like this


I got a shock that they want around $400 for something so simple. It got me thinking I could do something different and kill two birds with one stone. The tractor also needs some heavy weight at the front to counterbalance the 400lb 200kg mower at the rear. So my new plan is to mount my 140lb - 75kg 200ah SLA battery to the front of the tractor. I will then purchase a large 200w solar panel that is about the same dimensions as the fiber glass canopy. I will weld together a bolt on support frame and use the solar panel as a canopy. The tractor sits out in the sun all week and would charge the 200ah battery. I can then charge my ebike from the battery on the weekends.This keeps my lipo charging outside safer and gets the big 200ah sla out of my way and adds weight to the front of the tractor so i don't do wheel stands up hills.The funny thing is I priced the panel-regulator and cable (i already have the steel for frame) and its cheaper than the silly fiberglass canopy LOL.

Kurt

[Kurt]

This weekend I started the job of changing over all the multiple 11w compact fluorescent spotlights with 6w led drop in gu10 replacements. We usually just have a 30w 4 foot long slim fluorescent tube running above the island bench. Given the main living area is one big open room this provides enough ambient light for watching tv and general lazing around in the evenings.

Task lighting for reading is a 20w halogen lamp neer the sofa. Task lighting above the Other kitchen benches came from two spotlight fitting that hold three 11w compact fluorescent gu10 spotlights. Each fitting was on a independent switch with a total of 33w - 66w when both on. The biggest issue I had with e compact F was the start up time..very slow and dim when starting. The 2nd issue was the light quality. Not very natural and the intensity was a little dull and not as focus as you would expect from a spotlight.

After some trial and error I have found some cheep e bay replacement led globes that are a big improvement. 6w LED warm wight. They start and give full output immediately and are brighter and more focus than the compact F. The tone of light is more natural or at least to me is nicer to work with. There is a total energy consumption of 36w vs 63w for the compact F .

I made a small u tube video with comparison test. I think i mentioned a total consumption of 9w its actually 18w I have 12 more of the globes to replace around the home. Then I will start on replacing the bigger ceiling mounted spotlights used around the house as there would have to be around 30 of them Most have 12w Phillips warm white fluo's in them now.

Kurt

[kevo]

Excellent data Kurt, glad for your success - hoping to join you soon!