Cold Weather Power Batteries
Made the mistake of telling the wife that I'd look into electrifying (vs. "propane-ifying") the cabin lights and she's all over it.
So I'm looking into a battery/inverter system to power some lights maybe a few small appliances (radio, computer, etc), but in my situation, the cabin would be infrequently used during the winter and would be left cold and dark for weeks at a time.
Are there any power batteries out there that can handle winter without freezing and being destroyed?
(I'll go with a genny rather than have to haul batts in and out each year)
You're gonna wanna go with AGM batteries most likely for this application. They actually work well in the cold, and unless it goes below -70F, won't freeze if they are properly charged. In fact, the self discharge rate of deep cycles in cold weather is almost nil. This is because self discharge is a function of the chemical reaction taking place inside the battery, and those reactions slow at cold temperatures. This also reduces the capacity of production of the battery as well when it is being used in cold weather, so make sure you have a battery which produces enough amp hours in super cold conditions so you will at least have enough juice until you get things in the cabin warmed up for occupancy. I like 8d's for AGM deep cycle batteries. (8d is the size of the case, and is a very large battery)
As far as inverters/switches are concerned, I have had good luck with Xantrex units. I have one on my boat and one in my cabin. They both run off of four 8d AGM cells. Haven't ever had to do anything to them except connect them and turn them on. Very reliable and they produce a nice clean sine wave, which is good for your laptops, cell phones, i-pods, etc. The ones on the boat are connected to an AC battery charger and the engine alternators with an automatic switch for charging. The ones in the cabin get charged by solar. They are good for 3-5 years depending on use in my experience, and a set of four new 8d AGM cells is about 1200-1500 bux these days.
Its a lot to think about I know. I can't send you pics of the set-up in the cabin right now because I am wintering in the lower 48, but I can send you pics of a very similar setup in my boat here if you are interested in seeing it.
When it comes to batteries and cold temperatures as long as you keep it fully charged it will not freeze. Also the colder a battery is the less power it has until it warms up. A wet cell battery @ 0*f will have very little power compared to one @ 80*f.
we've used a pair of 6v golf cart batteries from Costco for a weekend place (Petersville area) to provide about 220ah of 12v power. They run lights, charge an iPad, powers a dvd player and little TV. All those run off an inexpensive 350w GoPower inverter. When we need the microwave, toaster, power tools, etc., we fire up the generator. A 100w solar panel keeps the batteries well charged from March to October, then it usually needs an occasional battery charger boost during winter visits since there's so little sun on the panel. Like others said, charged batteries don't freeze. It's a minimal set up, but we're going on Year 4 of the batteries and inverter and they were a whopping $120 total investment (more for the panel, but that should last 20 years).
Thanks all for the info and advice....will begin my search with the AGM batteries.
I'm with toofew, buy some Costco/Sams Club 6v golf cart batteries. Much cheaper than AGMs and they will do the trick. My battery bank is bigger, 6 batteries, and we have a larger inverter, but otherwise a similar setup as toofew. An 85W solar does the job Apirl-September (weekend use) keeping the bank charged up. In winter, a Honda 2000i gets them back to full charge at the end of the weekend. As long as they are charged when you leave, the cold won't hurt them at all.
There is definately nothing wrong with the 6v route. You just have to remember to buy in groups of 2 or 4 if you plan to run 12 or 24v respectively.
I just find it easiest to buy batteries in the voltage I want to ultimately use, and lately I have really been digging the performance and re-charge rates of the newer style AGM cells. Like most anything else, the options available to you will increase with the amount of money you are willing to part with. Also like most anything else a big price tag doesn't always mean quality.
I'm sure if you do your homework well you will find a solution that fits both your needs and budget.
Stop by AK Battery on Potter Drive or Renewable Energy on Dimond and have a chat. You DO NOT need AGM batteries. Flooded batteries are fine. After 15 years I have no issues when the cabin freezes up between visits. Surrette and Trojan are the premium batteries for alternative power systems. Golf cart batteries don't compare well. They work for low demand systems but there are better options out there. Your system will center around demand and storage/charge capacity. Solar is a nice but you'll probably need a genny backup. Your charge capacity will determine genny size, and so on. Email me if you want more info. You should still have my contact info from when you built your plane with Skup. :-)
By the way, when I arrive at the cabin in -25 temps, our go/no-go limit, the inverter runs everything just fine. The cold will reduce the duration but since we heat the place up right away the batteries gradually heat up to room temp so there's no problem. After 12-18 hours they're at full speed. If you run full loads and challenge your capacity in the cold you'll need to run a genny occasionally until the batteries warm up.
Nobody said you did.
Originally Posted by Mr. Pid
After 30 years of using flooded cells I just prefer the advanced technology of the AGM's compared to the old skewl is all.
A couple things which I like are the MUCH faster rate of re-charge as compared to wet cells, the much reduced risk of an accidental spill of acid electrolyte, and the much frendlier on the environment aspect of disposal when its run its useful life and needs to be replaced.
One thing I will say in defence of the lead/acid battery industry is that in recent years they have really answered the call to make their products as renewable as possible. Last I knew most major manufacturers of wet cells have about 98% reclaimation when it comes to lead, sulfur, and the plastic cases all that good stuff is housed in.
Saying you DON'T NEED AGMs is definately true, but at this point in time its akin to saying you DON'T NEED smokeless cartriges in your shotgun or that mom and dads old console color TV is a similar to a modern HD LED flatscreen. Wet cell technology is older than the crud under my toenails.
The problem I see with recommending using AGM battery in a cabin, is most people do not have a big enough generator or good enough charger to take advantage of a battery capable of taking a high current charge. Most people have no concept in the care and feeding of a battery. If there going to destroy a battery it better to replace a cheep battery every 2 years instead of having to replace an expensive battery at the same time.
So it seems to me.
Those are excellent points.
Thanks for the continuing input, appreciate all of the info.
SB....my plan was to go talk to Renewable Energy next time I'm in God's Country and outline my complete requirements; they have a class in a couple of weeks that would be helpful, but I'm stuck in Durance Vile at that time. I've got a guy that is willing to trade some construction work on the cabin next summer (including battery system) for some flying time in a -12, but I want to be able to hand him all of the kit so he's not designing on the fly, so to speak. I'm not set on AGM, but do want to build in the greatest amount of "I can leave it for a while longer" since I can't be certain of my Alaska time for at least two more winters. Will have a genny backup just 'cause I can't get comfortable not having one.
I've already recognized that I need to get a good charge controller.....cheap or not, I'd rather not hassle with replacing batteries any more than I have to.
My personal limit of going to the cabin is driven not so much by temps (in 30 years have only seen it below -20 once) but by wind: When the PA-12 takes 30 minutes to make the normal 10 minute hop from Palmer, that might be a bit too much wind to enjoy landing!
like most guys with fairly complex off-grid power systems I started basic and let my system evolve as needed. There's a huge difference between a cabin that uses a single battery and an automotive charger compared to an off-grid system with solar, generator, and inverter/charger with battery monitoring. The single best advice I can give a guy with an occasional use cabin that wants to add inverted power? Add some solar charging to the system. It'll keep your batteries healthy and charged while you're away. I get enough solar charging to eliminate the need for a generator for all but about 2 months in mid-winter, and that's only because snow sticks to the panels. If I cleared them I'd make electricity 12 months a year. I have no sulphated plate issues, either, with the solar contribution. You don't have to use solar as your primary charge source but adding a little will make a big difference in your battery life and performance. In advance of taking the classes google up Magnum Energy and Surrette Battery for some good information. Renewable Energy and ABS Alaska have some good reading and web links as well.