Uninterruptable farmhouse lighting

[JohanF]

Re: Uninterruotable farmhouse lighting

I would lean towards the 12V to inverter side of things if lighting is a critical element in your farm. However, the upfront costs associated with it is very high.
Can you give some extra information on your farm size, the amount of lamps that *MUST* stay lit during an outage, etc, and whether those lamps are incandescent or florescent. This way we have some idea of your intended load.

If rolling outages are very often, I would invest in something more than just a genny with a yanker and wheels, more along the lines of a standby genny permanently installed on your farm with a power transfer switch. They are usually liquid or air cooled and runs on either propane or gas. Generac, Centurion, and Briggs & Stratton comes to mind

Thanks for your reply - glad you are agreeing to my line of thinking! I cannot see that the upfront costs should be excessively high?? Its considerably cheaper than a generator (although much more limited). I think I did give an indication of minimum amount of lamps etc. in my OP:

...I worked on a maximum simultaneous use of only 6 lights for about 5 hours a day x 18W = 540 Watt Hr./day. I plan to replace the kitchen light with 2 x 18W fluorescent LED tubes and budget for another 4 hour per day usage of those - bringing my total Watt Hr./day up to 684.

Lights are all fluorescent (CFL) as mentioned.

 

[JohanF]

The easiest thing to do would be to keep your existing lighting and just buy a large UPS. It would help your battery runtime if you replaced the CFLs with more energy-efficient LEDs. Also, some LED lights and most CFL have a low power factor which will put additional demands on the inverter, so buying lights with a higher power factor may help too.

You could do a custom 12V system, but it would be a lot more work. 12V lights are going to be more complicated to obtain and install, and you'll need to make sure that the wiring you use is thick enough to handle the amperage without significant voltage drop.

Thanks Arilou for replying! In effect, isn't a large UPS and the "charger - battery - inverter set-up" I have in mind the same? What do you mean with a "low power factor"?

 

[JohanF]

UPS's, even large ones, have limitations, you need to either make sure large draw devices/equip are turned off, or set it up on a separate circuit line that only includes the items you need running during power outages. UPS systems don't like fridges, a/c, motors, ect, the startup surge often trips the internal breaker, and to get one that can power those devices requires a HUGE UPS/battery set up that costs thousands of dollars, if not 10's of thousands, and then there's the battery maintenance, a whole separate room that's sealed off from living areas, ventilation and cooling, ect..... Better to have a genny out side and tapped into the circuits you need.

I am not considering connecting other devices or equipment to the inverter/UPS It will only be lights.

 

[N8N]

yes, a large UPS is pretty much what you're describing.

I'm wondering if you could get a used UPS from a data center or something, use that to run a subpanel, and then move all your lighting circuits (and other mission critical circuits, like the furnace, possibly fridge/freezer, receps in your bedroom so your alarm clock still works, etc.) over to the UPS.

Power factor is important because let's say you have e.g. a light that draws 10W but has a power factor of 0.7. What that means is that the UPS' inverter will see 10W but 10/0.7 = 14.3 volt-amps so it would have to be upsized accordingly. If you have a power factor of unity than watts and volt-amps will be the same.

 

[JohanF]

It's quite doable and I think you mean 120 not 220 correct?

If you have 680 watt hours of load, I would suggest 2-100AH batteries. I would invest in a good inverter and watch out for the efficiency and static load. You are likely going to go with 1000W. It's efficiency should be 90%+ and static load maybe 5-20 watts depending on the model. That must be considered in your battery calcs which is why I suggest 2-100AH 12V units. I suggest having them in a cool part of the basement. The easiest thing to do is find a charger/inverter with a built in transfer switch. I know big ones exist (3-4KW) but not sure what is on the small end these days. If you have AGM batteries (and a good charger) you are "likely" safe to just have them sitting there in your basement. If you have regular flooded batteries (require more maintenance by you), then I suggest a box with a small vent stack for safety.


As others have said, a cheap generator puts out a lot more power and can for longer, but the battery setup is pretty easy.

Semiman

Thanks Semiman for replying - glad you reckon the battery setup will be pretty easy (I don't need the extra power a generator can put out, so I am not considering that route now.) I was also thinking in the line of two 100Ah batteries. Please tell me more about the inverters - efficiency referring to how much power is lost during the inverting process? And what does the static load refer to?

 

[JohanF]

yes, a large UPS is pretty much what you're describing.

I'm wondering if you could get a used UPS from a data center or something, use that to run a subpanel, and then move all your lighting circuits (and other mission critical circuits, like the furnace, possibly fridge/freezer, receps in your bedroom so your alarm clock still works, etc.) over to the UPS.

Power factor is important because let's say you have e.g. a light that draws 10W but has a power factor of 0.7. What that means is that the UPS' inverter will see 10W but 10/0.7 = 14.3 volt-amps so it would have to be upsized accordingly. If you have a power factor of unity than watts and volt-amps will be the same.

I like the idea of a UPS simply because it is a neat way of keeping everything together. I live in a small town however and I doubt if I'll get a used one still in working order.

How do one measure or determine power factor? I have just looked at the packaging of two different make CFL globes and could not see any indication of power factor under the specs.

 

[N8N]

UPS units rarely go bad. More often the batteries go dead. I'm using a Tripp-Lite rack mount UPS that cost over $500 new - it's a 1000VA unit I think, maybe 1500VA - double conversion, true online, full sine wave used for data center, security, CCTV backup, for my A/V equipment and wireless router at home. I paid $100 *shipped* (was about $50 plus $50 shipping) for it used on fleaBay, works great. Had to replace the muffin fan because the stock one was too damn loud; I think I'm going to get a thermostatic control for it to quiet it down some, but it works great, and now my TV doesn't hum and buzz if I happen to have it on when the power goes out. I moved my old one to the laundry room where the FiOS box is; the main point of this exercise was to maintain connection to the outside world when the power goes out. I've now backed up the router with the good UPS (I bought the good one because it needed to be good because the router is in the same location as my A/V gear - so now I know that all my gear will survive anything short of a nuclear holocaust) and am using cheap line interactive consumer grade ones at the FiOS box and two PCs. That does nothing for lighting or HVAC though... will have to see if I can salvage another one from somewhere to back up the furnace. At least one of the line interactive units is old enough that I've replaced the batteries in it once already and still going.

For a full house backup you will probably want at least 5-10 kVA though, so your budget will be much higher. If and when your batteries go that will hurt; probably you'll want to find a unit within driving distance and hopefully used and cheap without batteries but guaranteed working. Then just buy new batteries and be done with it. That's what I would do anyway...

I'm curious if any of the big data center type UPS units also offer any provisions for tying in e.g. PV cells or a wind generator... would be nice but not owning a house at the moment I have not seriously looked into this.

As for power factor, just measure it - a Kill-A-Watt is a brand of inexpensive meter available here (US) that will measure PF for you, don't know what you can get over there. It is disappointing that mfgrs. do not list it on their spec sheets but I guess it's not relevant to most residential consumers as they are typically billed by watt hours and don't get surcharged for low PF like industrial customers do.

 

[SemiMan]

The built in batteries in a ups are generally small and not suited to the extended storage the op needs. A big inverter like in a ups also has big static load which may further draw down the battery. The built in transfer switch for the low cost is quite nice. Having the batteries in the inverter is the worst place as they are normally hot which is bad for long battery life. Good thing is they normally just float charge which is easy on the battery. You could remote the batteries with big cables. A 100ah agm battery is 5-10 times the size of your typical 1000va inverters battery.

Semiman

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[N8N]

The built in batteries in a ups are generally small and not suited to the extended storage the op needs. A big inverter like in a ups also has big static load which may further draw down the battery. The built in transfer switch for the low cost is quite nice. Having the batteries in the inverter is the worst place as they are normally hot which is bad for long battery life. Good thing is they normally just float charge which is easy on the battery. You could remote the batteries with big cables. A 100ah agm battery is 5-10 times the size of your typical 1000va inverters battery.

Semiman

Sent from my Nexus 4 using Tapatalk 4

No doubt. I was using my little anecdote as an example, I'm assuming he would be scaling up considerably from my little setup, and that price even of a salvaged unit would scale up as well. And yes I was assuming a big unit with an array of car battery sized SLA batteries, most likely remoted to a safe (but conditioned) location so if they ended up not being so S'd they wouldn't take out the inverter as well.

 

[FRITZHID]

Ok then, you want something like what I have set up in my lab. Its a bank of 20 9ah AGM batteries, a 1400kva UPS, and charging setup. You will need a separate charging system due to the fact that the internal charger of the UPS will not have the amperage to charge that many batteries. A solar or wind charger and a 2A trickle charger will suffice, however you'll also want a 5-10A charger available to recharge the bulk of power when your Mains kick back on, the rest of the charging system will maintain. Then set up a lighting only sub panel that ties into the UPS output. Your lights will always run thru the UPS and there'll be plenty of power available during outages.

 

[SemiMan]

Except I would go with one or two bigger batteries to avoid charge mismatching as best as possible with parallel batteries. Not a big deal but not a 0 issue either. Bigger batteries are usually cheaper on a capacity basis.

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[FRITZHID]

Valid point, however, in my experience, several slightly smaller batteries have been more reliable then a couple large ones, and easier to replace, and if/when one goes bad, you still have 90% of your power available until you can get a replacement installed, but that's just my opinion.
My bank has served me well and other then 2 batteries failing due to age, I've had zero issues with it. Keep in mind that most UPS's over 800kva use 24 or 36v, not 12. And the very large ones actually use 10 12v batts in series for 120v DC.

 

[SemiMan]

I have found it tough to find cheap good quality small batteries. I am fortunate to have a source of good 100+ah AGM batteries for well under 200.

I have been picking up surplus telco batteries 50ah for $40. They all measure 46-49ah. These are the 12-15 year types and have picked them up with 3-5 years on them. Great for backup camping etc.

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[N8N]

Hmmm... 50Ah batteries for $40? What physical size are they and what terminals do they have?

Wondering if they would be a suitable alternative for an AGM automotive battery. Paid well more than that for a military surplus Optima for my Jeep, although I've had no problems with it other than having to make an anti-skid mat for it as it tended to slide around in the plastic battery tray (a silicone baking sheet works well for that use, and also for making liners for coin trays etc. to keep items from sliding around.)

 

[FRITZHID]

That's a great find semi-man! I'm fortunate that I have a supplier for 9ah AGMs new for about $8 each, heavy duty spade terminals. Originally I procured them for my Handsun lights and got a good deal cause I buy them in bulk.

 

[SemiMan]

M6 terminals.

They are the Enersys SBS60 in this data sheet: http://www.enersysreservepower.com/documents/US-SBS-RS-005_0908.pdf

Semiman

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[SemiMan]

That's a great find semi-man! I'm fortunate that I have a supplier for 9ah AGMs new for about $8 each, heavy duty spade terminals. Originally I procured them for my Handsun lights and got a good deal cause I buy them in bulk.

They come up once or twice a year and I pick up a couple.

I don't know how they would do for a car starter battery but I did start my car once with one when I had a dead battery.

Semiman

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[FRITZHID]

Yeah, I could see the repeated high draw being an issue. I've used mine to charge car batteries but not to start them. They have been used to start my genny however!
AGM are great for long term backup power, I've found them to be long lasting, reliable, and with fairly high power density. And much easier/safer then lipos. ....tho someday I would like to swap mine out with lipo packs, just have to figure out the charging issues.
another plus to the AGMs is even after the seem dead, in a pinch, leave them off for a bit and you can usually get a little reserve juice outta them!

 

[JohanF]

Ok then, you want something like what I have set up in my lab. Its a bank of 20 9ah AGM batteries, a 1400kva UPS, and charging setup. You will need a separate charging system due to the fact that the internal charger of the UPS will not have the amperage to charge that many batteries. A solar or wind charger and a 2A trickle charger will suffice, however you'll also want a 5-10A charger available to recharge the bulk of power when your Mains kick back on, the rest of the charging system will maintain. Then set up a lighting only sub panel that ties into the UPS output. Your lights will always run thru the UPS and there'll be plenty of power available during outages.

Exactly the setup I had in mind! Whilst looking around for a used UPS, I realised that I can get a new 2000VA UPS for under R2 000 (÷10.5 = $190). Then I started wondering if the modified sine wave UPS would be a problem with the CFL globes - it seems as if it could indeed be a problem causing humming/buzzing and even flickering. :-(

Eventually I discovered a very informative website of a local supplier of all kinds of power solutions - they sell (amongst other things) a range of small business/home power back-up systems which include a large charger, pure sine wave inverter and automatic transfer switch (and different battery and cabinet options according to your desired back-up time). Just awaiting their reply re pricing now...

 

[N8N]

yeah I would go for pure sine wave... it may or may not be an issue with your CFLs, but you never know what else you might want to add to your backup scheme in the future.

Just as a thought, if you communication to the outside world depends on AC power (e.g. FiOS box or similar, router, dedicated PC circuit) you might want to count those into your load calcs as well. Lights are nice but in an emergency being able to phone a friend is crucial. Also, having at least one phone in the house that does not require AC power is nice. (I've gone overboard, I've got an old Western Electric wall phone dating from 1949 in the kitchen, but allow me my eccentricities...)