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Small Cabin Forum / Off-Grid Living / Best current batteries?
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NorthRick
Member
# Posted: 11 Jan 2018 16:33 - Edited by: NorthRick
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Quoting: offgridjunkie
I love the talk about the new Lithium battery packs for off the grid. After reading some of the posts, I am hearing that they should be warmed up before charging. So my cabin in the winter gets down to below 0F fairly frequently and I leave my solar connected to my charge controller and my AGM Battery so that it always remains topped off. If I were to go with a Lithium, would I need to disconnect the solar in the winter when I am not at the cabin to make sure I do not damage them due to it being too cold?My system is very small, and meets all my needs, but my battery is at the age it is going to need to be replaced in the next few years. Any info on this would be great.


I've also read where they shouldn't be charged below freezing and our cabin situation is similar to yours. For us, the problem of disconnecting the solar to protect the batteries is that we rely on solar to finish charging up the battery bank AFTER we leave. I know it won't hurt lithium to leave them partially discharged, but I want them fully charged when we show up the following weekend.

Kamn
Member
# Posted: 11 Jan 2018 17:33 - Edited by: Kamn
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I had a thought but now that I think about.......not a good thought

KinAlberta
Member
# Posted: 11 Jan 2018 18:58 - Edited by: KinAlberta
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All I know about this kind of stuff is that the more research I do the more unexpected tidbits of critical information I stumble across. It’s like buried treasure.

Moreover the more I read on any given technical subject, the more I come to a realization that half the people posting (like myself a lot of the time) really don’t know half what they should know.

KinAlberta
Member
# Posted: 11 Jan 2018 19:36 - Edited by: KinAlberta
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Charging Batteries at High and Low Temperatures – Battery University

http://batteryuniversity.com/learn/article/charging_at_high_and_low_temperatures


Possibly helpful advice: “By not safe, I mean it will work fine until it randomly explodes...”




Why charging Li-Ion batteries in cold temperatures would harm them? - Electrical Engineering Stack Exchange



“...


“Do not charge lithium ion batteries below 32°F/0°C. In other words, never charge a lithium ion battery that is below freezing.
Doing so even once will result in a sudden, severe, and permanent capacity loss on the order of several dozen percent or more, as well a similar and also permanent increase in internal resistance. This damage occurs after just one isolated 'cold charging' event, and is proportional to the speed at which the cell is charged.

But, even more importantly, a lithium ion cell that has been cold charged is NOT safe and must be safely recycled or otherwise discarded. By not safe, I mean it will work fine until it randomly explodes due to mechanical vibration, mechanical shock, or just reaching a high enough state of charge.

Now, to actually answer your question: why is this?

This requires a quick summary of how lithium ion batteries work. They have...”





https://electronics.stackexchange.com/questions/263036/why-charging-li-ion-batteries- in-cold-temperatures-would-harm-them




Borrego
Member
# Posted: 11 Jan 2018 21:54
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After all.... I ended up buying today 8 of these:
Leoch DTA6224 224ah 6V Sealed AGM Deep Cycle Battery

I couldn't justify the cost, at this time, of the Lithium batteries...new at least. My research and anecdotal advice on the used ones showed some concerns with sparking and fires so even a slight risk of that made them out of the question for me.. I figure I will run these for the 5-7 years they are estimated to last and by that time, I will hope that the cost of Lithium batteries has reduced quite a bit

These are supposed to be first rate batteries, I will let you all know how they actually do.......

offgridjunkie
Member
# Posted: 12 Jan 2018 16:19
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Quoting: NorthRick
now it won't hurt lithium to leave them partially discharged, but I want them fully charged when we show up the following weekend.



Exactly my concern as well, and in the winter, I have less sun to charge them when I am at the cabin.

NorthRick
Member
# Posted: 12 Jan 2018 17:49
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Quoting: offgridjunkie
Exactly my concern as well, and in the winter, I have less sun to charge them when I am at the cabin.


Yes, we run a significant deficit between solar power produced and power consumed while at the cabin in winter. I will run the generator some on Sunday morning to get our lead acid battery bank back up to 80% or so but that's where the efficiency of charging the batteries off the generator goes down hill. Once we leave on Sunday, power consumption drops to 0 and the solar power trickles in and brings the bank up to 100% charged while we are in town.

The heat also goes off when we leave and winter time in Alaska is nearly always below 32F.

ICC
Member
# Posted: 12 Jan 2018 18:25
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Quoting: NorthRick
The heat also goes off when we leave and winter time in Alaska is nearly always below 32F.


You can store lithium below freezing. You can discharge below freezing. Just no charging.

I put a small LiFePo4 set in the range cabin last winter. They're inside. Cabin and batteries, etc. all drops to whatever it gets to someplace between -10 F and +20 F December through March. The solar controller has the input breaker flipped off when I leave. The batteries might be anywhere between 30 to 80% full when left. They remain there till someone returns. We light a wood fire. In a couple hours the batteries warm enough to charge no matter how cold.

Lithium also charge faster than any lead acid with the same solar input. A little bit of sunshine does more work. I've never had a problem with not having enough stored energy before the solar can kick in. But I am blessed with more sunny days than much of the country in the winter. All in all lithium beats the pants off of lead acid. But the up front cost the day you go lithium is higher than lead.

creeky
Member
# Posted: 13 Jan 2018 00:17
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Careful what studies you link to and what conclusions are drawn kinalberta. The originating study did not say anything would explode. The original study looked at lithium at -20C. Real cold. And charged at a high rate. And then said, yup, the anode is plating. And then said, at lower charge rates rates there is less or no plating. And then said the plating is partially reversible.

At no point did the original, actual research say anything like "NOT safe."

Nissan Leaf batteries don't start heating until -20C. If you can find even 1 report of a leaf car bursting into flame... but you won't.

Lithium is like chocolate. There's a lot of different flavours.

Some may want their batteries fully charged. But I went 30 days on a 9kw lithium pack without being fully charged. Who cares. I still had 6 kw of usable power. On lead I would have been running the genny. Because you have to be fully charged or you kill the battery. This is the mind set alteration that has to occur.

Ya. With some chemistries (mine) you have to be above 0 for longest life. I used 1kw every day heating my batteries recently (-30c/-22f). What do I care. With my 15kwh lead acid battery I had 2 kwh of usable power. At -30 I had 0. I had to heat those batteries too. With my lithium batteries I have 6 kw on hand most days. 1 kw. Meh. It's the price of playing the game.

And the sun I did get. It went into my batteries. Have you tried charging a lead acid battery at 0c/32f? You're in for a special surprise!

With lithium it's not about being fully charged. It's about having the power you need.

Mark your calenders folks. Borrego says he's going to get 5-7. I look forward to his real world results.

I had my 5 years on lead. After 1.5 years on lithium. 2nd winter. Lead is dead.

Notes
Member
# Posted: 13 Jan 2018 09:14
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Check out DIY powerwalls on Facebook and search Terry Arner for his Chevy Volt powerwall project.

NorthRick
Member
# Posted: 13 Jan 2018 11:47
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Quoting: ICC
You can store lithium below freezing. You can discharge below freezing. Just no charging.


For my situation, that's the part I can't live with. We don't have a lot of sun this time of year and I want to take advantage of charging the batteries while we are gone and the batteries are cold.

FishHog
Member
# Posted: 13 Jan 2018 13:04
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Quoting: NorthRick
For my situation, that's the part I can't live with. We don't have a lot of sun this time of year and I want to take advantage of charging the batteries while we are gone and the batteries are cold.



I'm in the exact same boat. If I had better sun exposure it might be a different story, but for now I'm going to make due with lead.

I agree that in the large majority of the situations lithium is the way to go, but not 100% of the situations. So lead is 90% dead, but until there are a few more improvements in battery technology it's not quite dead.

creeky
Member
# Posted: 13 Jan 2018 15:41
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Okay. The post title is "best current batteries."

I understand. Lead is relatively cheap in the short term. It appears to offer charging while cold. However, cold lead has very little usable power. So there is a line there. Heat your batteries and have more power. What I do with lithium and what I did with lead.

Remember. Your efficiency with cold lead is miserable. As low as 50% charge efficiency and 0 kw available at -17C. If you really need power at the camp/cottage you have to heat your batteries. Period.

Lithium has flavours. And you can use lithium titanate if you want to be able to charge and discharge down to -40C/F.

https://en.wikipedia.org/wiki/Lithium%E2%80%93titanate_battery

If anyone wants more info on LTO.

Also, there's a fellow on ebay selling the LTO batteries. He sells mostly 12 and 24v. Smaller packs. Perfect for weekenders. I think his name is barbjb. Iffen I remember.

Now that's the best battery.

FishHog
Member
# Posted: 14 Jan 2018 13:41
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good info, LTO batteries are quite interesting, although pricey.

offgridjunkie
Member
# Posted: 15 Jan 2018 00:00
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Creeky, when we are at the cabin, the batteries are heated, nice and warm. But when we leave for the week, there is no heat. What are you using to warm your batteries?

I use AGM and they are kept inside, but have seen temps while I am away get below 0F inside.

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