two lithium chemistry batteries for consideration

[Kbop]

for cabin/off-grid/RV/ATV/battery back ups.
two newish batteries are now available in the USofA and for that matter, most of the world. that are worth mentioning
 - the small cylindrical 18650 types have been around awhile - often used in electric cars.  the new types are bigger, better and can discharge at 2+C without damage.  As an example battle born uses a bank of small cylindrical batteries - just like your battery power tools.
- they don't last as long as iron/water batteries but you won't get a hernia trying to lift one.
- one will do about 20,000 charge cycles
- one is prismatic and very easy to use and balance.
the specs on these will beat the battle born brand -

so  new users or those not electrically inclined - battle born is really good.  they are nearly lead acid drop in replacements - and good quality control/QA. - popular with RV and boon-docking users.  i've used these at work.
https://battlebornbatteries.com/product-category/lifepo4-batteries/


if life cycle is your primary concern - look at Lithium Titanate batteries. Yinlong company claims 20k cycles.
-i've never used these but they have been used by people i know - powering remote RF sites.  good reviews all round - and no premature failures over the last year.  They are replacing the currently deployed fuel-cell setups with solar.

I like the Fortune brand prismatic 100ah batteries.  (my current favorites) easy to use and put together as a kit. balance the strings, add a BMS and you are done. i use a 24V w/ a 3k sine inverter on a cart now instead of a generator for local power - runs a small stick welder or my circular saw all day long.  if your curious i have a 8s2p setup.
https://www.electriccarpartscompany.com/fortune-100ah-aluminum-encased-battery

- a couple of notes on current lithium batteries - they don't like getting hot, sitting in a car in the sun hot.  they don't work below -10F without a heater.  They don't tend to explode anymore.   their life cycle and power density are now exceeding lead acid batteries of all types.  there are lots of good videos and books written at the HS grad level using typical hand tools.  the small cylinder batteries are best spot welded as an example - these newer batteries use a metric wrench.  IMHO worth considering.  And lastly - battle born batteries are balanced with a BMS built in, no fiddling or building needed.

[Jackalope]

     Yeah, the new lithium batteries are phenomenal.  I looked at the Battleborn 100ah lithium batteries for the photovoltaic system here, but went with the Renogy 100ah lithium batteries.  The Renogy batteries were about $100 less for each one, and they weighed about 5 pounds less for each battery too.  The nice thing about the Battleborn batteries is they can be set up in series, whereas the Renogy batteries can only be used in parallel, with a maximum of three in a string.  Our system is 12 volts, so it wasn't a major factor for us, but if we were running a higher voltage, I would have definitely gone with the Battleborn lithium batteries.

[pkveazey]

     Yeah, the new lithium batteries are phenomenal.  I looked at the Battleborn 100ah lithium batteries for the photovoltaic system here, but went with the Renogy 100ah lithium batteries.  The Renogy batteries were about $100 less for each one, and they weighed about 5 pounds less for each battery too.  The nice thing about the Battleborn batteries is they can be set up in series, whereas the Renogy batteries can only be used in parallel, with a maximum of three in a string.  Our system is 12 volts, so it wasn't a major factor for us, but if we were running a higher voltage, I would have definitely gone with the Battleborn lithium batteries.

Whoa, hang on a minute. You can't just throw that 3 batteries in parallel thing out there and not explain why. I would have thought you could parallel 100 12 Volt Batteries in Parallel so the drain would be very slight. If there is a reason for it, I'm OK with it but enquiring minds want to know.

[pkveazey]

I'm glad somebody brought this subject up because after I replace the Side stoop and Back porch, my next agenda is to start building a Solar Panel, Charging Regulator, Battery Bank, and 12VDC to 240 VAC Inverter system just in case my generator quits or I can't get Gas for it. Yes... More.... More of this please.

[Jackalope]

Whoa, hang on a minute. You can't just throw that 3 batteries in parallel thing out there and not explain why. I would have thought you could parallel 100 12 Volt Batteries in Parallel so the drain would be very slight. If there is a reason for it, I'm OK with it but enquiring minds want to know.

    The battery parallel in a string limitation comes from Renogy, and I was wrong, the limitation is four batteries in parallel.  Here's a copy of the battery manual: https://www.renogy.com/content/RBT100LFP12S-G1/LFP100S-Manual.pdf   The limitation only applies if you plan on using the built in auto balancing feature, which I do use, as it prolongs the battery lifetime.  Renogy also emphasizes that the batteries cannot be connected in series.  Lithium batteries are very sophisticated, as each battery manages both charge and discharge rates.  So in addition to a special photovoltaic charger, each battery has its own individual controller.  Oh yeah, if you wish to charge a lithium battery from the grid, a specialized charger is needed too.  A regular lead acid battery charger is not suitable for charging lithium batteries.

      Battery longevity comes at a cost.  It's worth it to me, as no maintenance is required, and lithium batteries can be very deeply discharged.  Lithium batteries are an excellent example of the "buy once, cry once" philosophy.

      One major limitation of lithium batteries is they cannot be charged when the battery temperature is below 32 degrees F.  Our batteries are kept in an unheated area attached to my home, and thus far, haven't had any issues.   The same issue applies to portable radio lithium batteries too, but if I remember correctly, the temperature cut off was somewhat lower.  At my old job, field personnel kept their radios and extra batteries inside their parkas during winter months when temperature were below 0 F.  The cutoff in lithium battery chemistry is very pronounced, once the battery reaches a certain temperature, it's like an off switch.  We had a number of incidents where the batteries ceased functioning at sub-zero temperatures.  Field personnel usually carried an extra alkaline battery pack, just in case, because the alkalines kept functioning, though with a shorter life.  Usually everyone had extra AA batteries for flashlights, etc.  So lithium batteries have at least one weakness.

[Kbop]

RE cold weather ops using lithium batteries.
 
The battle born batteries (i'm used to) we keep in a typical battery box for mobile power.
we keep a seedling mat under them in the box - so they wont freeze.  it draws power from our inverter.
I've also heard of people using RV 'no freeze' water tank heaters for their lithium power banks too.

it is a weakness with lithium chemistry. 

a quick note here - the power shutdown in the battery is often done via the BMS (battery management system).  you could use the batteries below freezing - BUT, it wouldn't last very long and you could damage the battery due to lithium plating the anode during the charge cycle.