off grid batteries

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winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
An ideal battery is a device which will store energy with zero loss, and then release that energy with zero loss.

Zero loss implies that all the stored energy could be released _very_ quickly.

The closer real batteries approach ideal batteries, the more they resemble a bomb.

-Jon
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Are you saying there is not a real issue with lithim batteries burning up?

I would at least like to see some data on it. You can find a Youtube video of just about anything flammable burning up. That's what makes Youtube great as a source of entertainment. But I would not use that info to assess whether or not something is a 'real issue.'

(How many Teslas caught on fire last year while sitting in the garage? Zero? How many home fires started last year due to people storing gasoline or diesel in their homes?)
 

iwire

Moderator
Staff member
Location
Massachusetts
I would at least like to see some data on it. You can find a Youtube video of just about anything flammable burning up. That's what makes Youtube great as a source of entertainment. But I would not use that info to assess whether or not something is a 'real issue.'

(How many Teslas caught on fire last year while sitting in the garage? Zero? How many home fires started last year due to people storing gasoline or diesel in their homes?)

I store 100 to 250 gallons of diesel in my basement at all times and that does not worry me. A very long history of safety

I would want to know a lot more about lithium batteries before placing a connected stack of them in my basement. These do not have a long record of anything.

https://en.m.wikipedia.org/wiki/Plug-in_electric_vehicle_fire_incidents
 

iwire

Moderator
Staff member
Location
Massachusetts
An ideal battery is a device which will store energy with zero loss, and then release that energy with zero loss.

Zero loss implies that all the stored energy could be released _very_ quickly.

The closer real batteries approach ideal batteries, the more they resemble a bomb.

-Jon

This makes a lot of sense.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
I would at least like to see some data on it. You can find a Youtube video of just about anything flammable burning up. That's what makes Youtube great as a source of entertainment. But I would not use that info to assess whether or not something is a 'real issue.'

(How many Teslas caught on fire last year while sitting in the garage? Zero? How many home fires started last year due to people storing gasoline or diesel in their homes?)

I wouldn't store gasoline in the basement, but my 275 gallon storage tank for my diesel-fired steam boiler was right in the corner of the basement. Diesel fuel is actually difficult to ignite. If you drop a match into a puddle of diesel, it will extinguish the match. IIRC the igniter in my furnace had to be on all the time when it fired because the furnace design couldn't maintain the flame once started. Newer designs can.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
The same reasoning applies to compressed gas and supercapacitors.
Or almost any energy storage mechanism.
:)
Correctamundo. Any new technology has its risks as it emerges, but those risks diminish as the tech is developed. If you were to look at jet airliners' safety record in the early days of their development and assume that the risks then were still the risks today, you would never board a plane. For example, the tiny detail of square corners of windows brought down more than one plane, but aircraft designers figured it out and fixed it.

Lack of effective, efficient, and safe energy storage has always been the Achilles' Heel for renewable energy technologies, but that is rapidly changing.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Correctamundo. Any new technology has its risks as it emerges, but those risks diminish as the tech is developed. If you were to look at jet airliners' safety record in the early days of their development and assume that the risks then were still the risks today, you would never board a plane. For example, the tiny detail of square corners of windows brought down more than one plane, but aircraft designers figured it out and fixed it.

Lack of effective, efficient, and safe energy storage has always been the Achilles' Heel for renewable energy technologies, but that is rapidly changing.

As in "We've got financing to commercialize our product" or "Fusion is just 5 years away"? Examples please if it's the former.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
As in "We've got financing to commercialize our product" or "Fusion is just 5 years away"? Examples please if it's the former.
I'm not sure what your point is, but there have been major advances in electrical energy storage over the past few years, and like most other tech it will likely become safer, cheaper, and more efficient as it matures. Lead acid used to be the only game in town.
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
Therehas to be somebody who has dealt with this. I know we have one guy >70deglat right now but I don't know if he ever did solar. Come to think of it,that's not a good place for solar! (unless you have REALLY big batteries). ...

I've got a remote access cabin about 65 N Lat - generation (3.3kw gas), Solar(200W @ 24V), Batt (24V, 140AH, WLA Calcium, 1.215), inverter/charger (120/240,3000W, 30A charger). So, I have a bit of anecdotal information. All this stuff is 20 years old, except the batteries, I bought them used, they are 40 years old.

The solar is kind of a joke, I don't think I get much of anything out of it. But it was cheap. I got four 50W cells for a $100 each (around 1998). They were surplus from a railroad remote signal project and I was standing in the right place at the right time. I don't leave them connected when I am not there because I don't have any faith the controller will shut off and not overcharge. I recall the controller was $35 mail order.

And I deal with WLA, AGM, the occasional Lithium Ion, and very infrequentlyLithium Polymer for my work.

So some of this is informed opinion - some is just anecdotal. I'll list references where I can, and note what is anecdotal.

As already said, if charged, 1.300sg batteries don't freeze until -70F. 1.215sg freeze around -27F. https://mathscinotes.files.wordpress.com/2013/02/finalplot.jpg

Anecdotal: My 1.215 sg WLA don't freeze and break exposed to -40F. I don't go snomachining if it is colder than 0F, but the bats are okay when I get out in the spring. I clean the posts, charge fully every fall. Shut off the CB from the batts so the solar is disconnected. Couple of times I have been out in the winter, 0F to maybe 25F. Put the heat on the gen, started it up, charged the batts, and used them - all worked fine.

Lithium (any chemistry) and stationary storage applications:
My information here is based on applicaion papers, IEEE, battery mfg. Energy density is high, hence the comments about "bomb like". The following was delivered at a North American battery conference a few years back (no reference):
Lithium Ion batteries (used in laptops) energy density is approaching that of a hand grenade. The difference is the laptop battery is designed to give up it's energy over a few hours. The grenade is designed to give up the energy over a few miliseconds.​

All the papers I have seen on Lithium chemistry batteries show short life, few charge/discharge cycles as compared to any Lead Acid chemistry. (no reference)

Anecdotal: Lithium ion will survive .9 trips to -40F. I murdered one phone batt and one radio battery leaving them out in the truck over night. I haven't tried them at -20F. They survive fine at 0F and warmer.

For stationary applications, energy density is possibly the least worrysome spec. We are not dealing with drones, phones, cars, or airplanes. Unless one is dealing with a short term, high power UPS, power density doesn't matter much either - that kind of leaves out the AGMs.

Dollars per watt, WLA is by far the best return for stationary applications. And my research shows calcium, low gravity (1.215 - 1.225) give the best longevity. I certainly would not insulate. WLA do not like geting hot - especially while charging. And they generate plenty of heat while charging. AGM is worse. They are prone to thermal runaway (no reference)

Personal Opinion - Protecting WLA from cold ambient: (this response is for paid jobs, where I have to put a stamp on the dwgs)
For mainland America, anywhere the ambient worst case is warmer than -27F, don't worry about it. For upper penninsula Michigan (did I get that right?) and similar areas, don't buy low sg batteries.

Some data shows battery capacity decreases 1%/deg-C below 20C (not linear)
http://support.rollsbattery.com/sup...ature-vs-capacity-flooded-lead-acid-batteries
So, at -10F, the batteries are down to 60% of the 68F rating.

Interesting writing this. Don't know if it helped much

ice
 

Fulthrotl

~Autocorrect is My Worst Enema.~
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