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diesel
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# Posted: 27 Dec 2015 04:49pm
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I have an opportunity to build a cabin on a friend's property. This property is powered by a micro-hydro system installed in a nearby creek. There isn't enough extra amps/watts in the system to run my home, but certainly enough to keep a battery bank on constant trickle charge.
Most information on battery banks is about charging via solar panels or wind mills. I've not found any information regarding putting together a grid-charged battery bank. Any help out there?
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MtnDon
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# Posted: 27 Dec 2015 04:53pm
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Quoting: diesel ....a grid-charged battery bank
Why would you want to do a grid charged battery bank?
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Nate R
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# Posted: 27 Dec 2015 07:34pm
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I'm assuming the OP is saying they'd run 120V from the friend's place to run a charger for theirs?
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MtnDon
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# Posted: 27 Dec 2015 08:45pm
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OK.
I get stalled by the statement, "There isn't enough extra amps/watts in the system to run my home"... If there isn't enough for the hydro to run the second home directly, how is there going to be enough power to recharge whatever gets used out of the battery? A charger + battery + inverter setup has inherent losses that would need to be made up and still have enough hydro power to recharge. Perhaps a further explanation of what is expected to be powered in the second home would help sort this out.
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diesel
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# Posted: 27 Dec 2015 09:49pm
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Thanks, folks.
Pardon my lack of clarity. Yes, I would get approx. 250 watts all day, year round. Not enough to run the home, but I'm hoping enough to keep a battery bank charged. It must be possible, as I know of people who are doing it...I just don't know which type of battery/inverter/charger set up is suitable.
This would be a year-round home, not a summer cabin or cottage. Heat would come from wood, hot water from wood/propane. I'll need electrical power for fridge, small chest freezer, laptop, stereo, lights. I'd have a back-up generator wired into the system should the micro-hydro shut down for any reason.
Anyway, mostly wondering if there is anything I need to keep in mind that wouldn't be a concern with solar or other alternative power source. In other words, is there anything uniquely required of the system if it is on a constant trickle charge versus the varying charge that would come from the sun.
R
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MtnDon
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# Posted: 27 Dec 2015 10:35pm - Edited by: MtnDon
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OK, let's take a step or two back to the beginning. Just like you would have to if you were designing a PV solar system, how many watt-hours a day would be needed to operate your home power needs? (or amp-hours @ what voltage) That needs to be determined to see if the plan is feasible. Refrigerators use more power than any other single item; the energy rating should include the kilowatt hours on an annual basis.
What is the distance from the source of the power to your planned home?
What is the voltage of that available 250 watts? That is needed so together with the distance we can calculate the required wire size.
Some hypothetical... 250 watts, every hour all day / night long. IF the battery system was 12 volts, that would be 250 watts divided by 12 volts = 20.8 amps. Not exactly what I would call a trickle charge. Of course that is a theoretical 100% efficiency which will not happen in the real world.
So calculate the estimated use of all the items you wish to power. Plus get that length of wire run and the voltage; it would be best if it was "house power", 120 VAC. Then some educated guessing can happen. And don't call that available power a trickle charge; in a 12 or 24 volt battery system a trickle would be more like 20 to 30 watts. That's what I was having a problem with.
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MtnDon
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# Posted: 27 Dec 2015 10:51pm
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The average refrigerator has a start up surge that is many times the running watts. That can be hard to estimate but is important as the inverter used must be able to easily and reliably start it. Ditto for the chest freezer. Try and find the running watts / amps for both.
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diesel
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# Posted: 27 Dec 2015 11:24pm
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Thanks, MtnDon...
Okay...it's not a trickle charge. I meant to indicate a constant charge. Pardon my ignorance of the proper jargon. I know squat about electricity.
Thus, I'm not sure what the voltage will be; I'm guessing 120. I do know that there is 600 volts coming into a switch box about 200 feet from the planned house. There's also a 120 outlet coming from this switch box. I'm not sure whether I'll be required to run 600 volt tech cable to a battery shed near the planned house and converting it there OR if I'll be running 120.
I understand I'll need to look on the labels of any appliances to find out what kind of load (watt/hours, amp/hours, etc.) they require. I haven't collected the actual appliances yet...still in the early stages, so just guessing at rough numbers at this point.
So, it seems to me that it's all doable with some math and prudent battery/inverter/charger selection...and a bunch of money. No particularly unusual needs as compared to a solar charged system...just a little different. Is this correct?
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MtnDon
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# Posted: 28 Dec 2015 01:03am
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Quoting: diesel o particularly unusual needs as compared to a solar charged system...just a little different. Is this correct?
The use end, your end, is the same as for a PV system. The difference is in the section that charges the batteries and where that power is coming from.
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pizzadude
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# Posted: 28 Dec 2015 01:06am
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There's no 600v....?
The switchbox might have a 600v rating on it, but should only have 120/240vac.
Nothing more than that for a residential dwelling.
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rockmtn
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# Posted: 28 Dec 2015 08:45am
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250 watts from a hydro (assuming you do get year round production) is ~ 6 KWH/day or 186 KWH/mo. Totally possible to run a small off grid home on this power production;
What you need in the most ideal scenario is a small battery bank (really only 12-24 hours of storage, enough to "even out" your usage patterns).
As it relates to the equipment selection, it depends:
(1) Does this Hydro produce 120 Ac directly, which you would be tapping into? (2) Does it produce High Voltage DC (which presumably your friend is using to charge a battery bank, then run an inverter)
(3) Some other combination?
I'm going to assume you are just getting 250 watts delivered from a black box for now. If so , this is roughly the balance of system components you would want:
(1) 48 V battery bank;~ 6 kWh/storage (120 AH).
(2) Inverter, size based on your biggest load(s). Anything from 1-2kW is likely fine for the usage you describe.
(3) Charger for 48 Volt bank; This will depend on if you have AC feed, DC Feed, or some other combo.
Without understanding the rest of the set-up its impossible to make a efficient recommendation, but taking a "stead" supply of 250 watts hydro, and running a small full time cabin is very possible.
If you get the details from your friend about whats available (or what he is making available power wise) then some components could be recommended.
For comparison: At our place we have a median output of about 250 watts from our microhydro. This is combined with a solar array to charge a single battery bank, which then provides all the AC power for the property. On cloudy rainy days the hydro can often be turned up (doing about 500 watts right now~ 12 KWH/day) and in the summer when then stream drys up, we get plenty of sun.
So keep in mind a few solar panels could balance such a system very nicely.
Good luck
E
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diesel
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# Posted: 28 Dec 2015 05:14pm
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Thanks, E...
I know that I haven't provided a lot of detail...mostly because I don't know all of the terminology. I'm an electrical dunce.
What I do know is that there is a micro-hydro system in a nearby creek that is generating approximately 30 to 35Kw. This is a year-round creek that not only supplies water for power generation, but also drinking water for dozens of homes and field irrigation for crops.
A dozen homes are being comfortably powered by this grid directly (AC...no battery banks), but the system is nearing its limit and another home getting full power would be too much. Therefore, I plan to build my home around a battery bank and use minimal draw from the grid to simply keep the battery bank charged.
Hope this extra info helps.
R
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rockmtn
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# Posted: 28 Dec 2015 08:15pm
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Cool!
That is certainly micro-hydro from a utility stand-point, but large for most off-gridder standards!
That means you likely have a lot of options...
The fact that is comfortably supplying power to the neighborhood homes indicates there is likely capacity in the system, but not enough to add "another home". Trickle charging (or a constant "small" load) makes sense.
Basically, you are going to need three components:
(1) 120 V AC charger that you will tie into the switch box you mentioned. @120 volts and 200 ft of wire you don't need a huge cable to handle the ~2 amps or so it will be crying
(2) A battery bank sized to provide the peak amps needed for your biggest load / longest draw period above 250 watts (say 12 hours). (4 of these, in series)
(3) An inverter sized to your biggest house load.
I've linked to example components above; you could find components that are less expensive, but if you plan to use this as a full time place I would recommend the investment in a quality charger and inverter.
note that for (3) its listed as an inverter/charger; but you can't really use it that way in your application as it only does one or the other (inverts, or passes through AC and charges). You would connect your back up generator to this device. It would then both charge your batteries while on genny power and "pass through" the AC power to your home from the genny. (I recommend a honda 2000)
Keep in mind that your daily energy budget needs to net out to 6 KWH or less in this scenario. Totally feasible, but tight. (Fridge + lights + stereo) -- all possible, but you are going to need to invest in energy efficient components.
Adding a few solar panels to a system like this would really work well... or maybe see if the folks running the hydro will let you take a little more... like 300 or 350 watts... or take extra power at night when loads in the mini-grid are likely low and they are probably just burning it in a diversion load.
Good luck!
E
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diesel
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# Posted: 29 Dec 2015 02:28am
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Thanks for the tips and help, E...much appreciated.
Everyone in my neighbourhood is off-grid. About half the homes here are on this larger micro-hydro system, a couple of homes have their own smaller micro-hydro systems and the rest are on solar/battery-banks.
As you thought, this larger system is capable of dumping about 8 to 10Kw via baseboard heaters to "burn off" unused power. Kind of a waste, but it's just how the system is set up. You'd have to see it.
It's quite possible I may be able to access up to 500 watts...just not sure about that at the moment. Using solar panels to assist is a possibility, but where I'm building gets very little sunlight in the winter. For several weeks, there is no sunlight hitting my property. I'm hoping to avoid the extra cost of solar components.
I'm fortunate to have a neighbour and friend who is an electrician...and happens to manage a hydro power plant in the nearest town. He'll be able to sort me out when the actual ground breaking happens!
Thanks again,
R
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creeky
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# Posted: 29 Dec 2015 03:28pm
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You're lucky to get the hydro 24/7.
I would skip the lead acid battery tho. They're really inefficient. Especially if you're on a limited input.
Lithium batteries, I know, said it before. But longer lifespan. At least 15% more efficient charging/discharging.
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groingo
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# Posted: 30 Dec 2015 11:30am - Edited by: groingo
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First thing you need to do is get a KillaWatt Power meter and do a real time energy audit, test and log every appliance as you use it and for how long.
Now determine if you can trim power used by either eliminating or using an alternative method, the object is to lower electrical demand as much as possible but not sacrifice so much as to create a hardship...there is a balance to be found and it can save you a boat load of money if you are willing to make some changes in how you do things.
Best advise, start small and see what you need as you need it, you can estimate and scribble on paper for years but sometimes its best to just jump in and take baby steps, that way you will learn form real life as you go, just use good common sense and keep looking for alternatives.
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rockmtn
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# Posted: 30 Dec 2015 07:31pm
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hey Creeky, what kind of Lithium packs do you recommend? I have been looking around, but not seeing a lot on the market yet. I'm running an old used traction (fork truck) battery; pretty inefficient, but plenty of AH, and with care could have a long life yet.
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