Battery Advice

BillT

New Member
I currently have eight L16 6 volt ...24 volt system. These batteries have lasted me eight years and need to be replaced. I do not use a whole lot of power. Should I replace them with lithium batteries or just more L 16s ?
Thanks
 

Hedges

I See Electromagnetic Fields!
Lithium, FLA, AGM each have their benefits.

Consider what DoD you need (or over/undersize to change DoD)
Temperature it will experience
Charge/discharge current ("C" rate)
number of cycles desired.
consequences of fire.

desired per $/kWh of use (if it matters)
 

BillT

New Member
what is DoD?
The temperature is moderate. Concrete basement never below 40 or above 60.
I do not know the charge rate. I have a outback system, with a slave unit.
 

Hedges

I See Electromagnetic Fields!
Depth of Discharge. How much of total capacity you want to use.
I have SunXtender AGM and expect to use 70% of capacity overnight. If every night, that might be 2 years or less, but my application is for occasional power failure.

Since never below freezing, don't have to address that problem for lithium.

How much charge current do you have available?
FLA probably prefers exactly 0.12C, e.g. 12A for 100 Ah battery.
AGM may like 0.2C, possibly accepts more.
Lithium typically accepts up to 0.5C, no problem at lower current. However, at 40 degrees F, 0.5C could cause damage.

For lithium, I would suggest determining what charge rate is OK down to 40 degrees, set BMS to cut out at that temperature, and adjust charge controller maximum. Or determine current available and adjust BMS to that temperature for charge cut-out.

Lithium may last 2000 to 6000 cycles, according to claims. But things fail, so don't count on it.
Cost is high if commercially made (only matches AGM if it lasts.) DIY or some "other" brands may be economical.

AGM is maintenance free but expensive and doesn't as many deep cycles.

Some FLA is quite inexpensive. Some premium FLA like Rolls Surette can last 15+ years if not cycled particularly deep. Requires watering and equalization, of course.

I think it's all a cost/performance/labor trade-off, so you have to pick what fits you best.
 

chrisski

Photon Sorcerer
If you see yourself doing not much different with your system, then why not swap out with new L16s.

If you want a deeper discharge rate or a higher charge rate, then maybe Lithium would work.

I’m swapping to Lithium’s now building my own battRey out of cells, and its more work than I thought and pricey, but for me will be worth it.
 

Hedges

I See Electromagnetic Fields!
My battery bank is 8x 6V 405Ah L16 size AGM from SunXtender.
18 months ago, cost me $5000
 

Steve_S

Offgrid Cabineer, N.E. Ontario, Canada
I started with 8x Rolls Surette S-550's which provided me with 24V/428AH Gross or 214AH Useable @ 50% DoD (Depth of Discharge).
The current selling price is $420ea X 8 = $3360.00 plus sales taxes etc...

I have now relegated that as my Secondary Battery Bank as I am now running with 1190AH LFP (LiFePO4) consisting of 3x 280AH & 2x175AH battery packs in Parallel within a Bank.

To make a 24V/280AH/7168Wh (7.16kWh), it requires the following:
8x 280AH LFP Cells ($1024 USD +500 S&H from Guesstimator) $1524 USD
1x 200A+ Capable BMS (Battery Management System) Average $250 USD
1x 200A Fuse Average $30 USD
1X Case/Box/Rack/Enclosure of your choice.
Estimated TOTAL $1804 USD Delivered to door.

NOTE:
24V/428AH Gross / 214AH Useable FLA Battery $3360
VS
24V/280AH Gross / 280AH Useable LFP Battery $1804

Supplier Used for this calculation link: * A Proper Quote requires a Chat/Messenger with Amy Wan of Luyuan Tech.

Download this PDF Resource which explains what you need to do to assemble an LFP Battery Pack.
Luyuan Tech Basic Lifepo4 Assembly Guide

Some HANDY INFO TO KNOW:
- LFP does not age/wear like FLA/AGM. You can ADD Packs in Parallel as Funds Allow, even 6, 12 or 24 months later without concern for degradation like lead.
- LFP does not need Hydrogen Venting, No Watering or Maintenance either.
- A 24V/280AH 8S Battery Pack weighs approximately 90 Lbs (pending on casing etc)
- LFP can Discharge at 1C Rate meaning a 280AH Pack can output 280 Amps for One Hour.
- LFP can also Charge up to 0.5C Rate which is 140 Amps for Two Hours for a 280AH battery.
** SOME TERMS ARE SIMILAR ~ BUT ~ The context is slightly different, this requires a learning curve to adjust to Terminology as used. With Lithium Based Cells, we talk about SOC (State of Charge) versus DOD (Depth of Discharge)
- LFP does like to charge below 0C/32F (pending on chemistry variation) so these must be kept at "Human Tolerable Temps", preferably between 10C-30C / 50F-86F.

There are many commercial pre-builts such as BattleBorn (12V/100AH = $900 USD +/-)

Or as Will has just Reviewed these:
24V 200AH LiFePower4 Battery by EG4 $1,499.00

OR you can go this route using 12V/100AH Battery Packs with 2 Batteries in Series for 24V "SETS" (Not the best option) and then with sets in Parallel to increase the available Amp Hours. Four of these in 2S2P would provide 24V/200AH Usable for $1400 USD

There is also AmpereTime & SOK prebuilts which Will has reviewed.

Hope it Helps, Good Luck.
 

BillT

New Member
Thanks everyone for the advice.
I think I will replace with new L 16s.. I only use them to run lights, computer and tv. I shut everything down at night. I have a separate system for a 12v refrigerator that works fine. I can get new L16s for $320.
Thanks again
 

OffGridEnclave

Solar Enthusiast
I currently have eight L16 6 volt ...24 volt system. These batteries have lasted me eight years and need to be replaced. I do not use a whole lot of power. Should I replace them with lithium batteries or just more L 16s ?
Thanks
i have made good experience sniping used forkliftblocks.
quality deep cycle lead acids never let me down, have my system running on them since 7-8 years.
if you looking for bigger sizes, say 1000Ah @ 24V and up, deep cycle lead acids still beat Li4Po on many specs..
specially for offgrid scenarios where frost temperatures are a thing,
You cant charge lithium below frost... you can charge lead acids until -40°C np .. if one needs to trust his life apon his electric setup those can be valid specs to consider.
i dont agree with this notion Will brings to the table a lot of " lead acid is outdated".
it still beats Li4Po in price and performance for bigger blocks..dont need Bms, has considerable less points of "possible failure", and are about 0 firehazard
 

OffGridEnclave

Solar Enthusiast
Acknowledging your points about fewer failure points & temperature sensitivity - But why do you say lead batteries work for bigger sizes over lithium?
combination of factors.
most obious, the price. the more Ah you need the bigger the price span gets.

a 1500Ah48V lead acid forklift battery will come as a "block" in a neat metal tub.
there is considerable less connectionpoints/small bms cables and such.. so much less points of possible failure. rodents are a thing for offgridlife outside in nature, a lead acid forklift block will provide MUCH less points for the little bastards to cause cautastrophic malfunction ( a mates house burned down because mice ate some cables,, fire is not a joke ).

reliability. if your bms dies you need to repaplace stuff, combining a bazillion Li4Po cells means some will die and one needs to maintanance more.
Lead acid requires less "tech "to be run in a offgrid scenario. (yes i am aware lead acid needs to be maintenanced too... ).
Combination of relilability... usually on bigger offgrid setups your heating relys on your electricity. now making that a chicken/egg problem by ALSO making the ability to charge your batterys only when you have heating can easely put one in a tuff place in a REAL off grid scenario.
It does snow in winter... solar panels will be coverd, cant rely on having enoth input for "electric battery heating" and such nonsense, if you leave house for a week or two in hard frost and house goes under 0°C relying on lithium can quickly teach one a dose of reality what "reliability" means if your life depends on it .

i am not talking about agm's or "car batteries" ...
proper deep cycle lead acid's with 650Ah and up per cell.

deepcycle-200x300.jpg
 
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solarsimon

Solar Enthusiast
Thanks. Some very valid points. Around me, whilst we we get frosts, long term averages are never sub zero, so a simple way to keep above zero is with thermal mass & insulation. Adding an IBC with 1 ton of water within a small insulated room is a good way to increase the mass. First principles over gizmos wherever possible.
 
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