Another question that haven't seen in this discussion. What battery charger do you need for this type of battery? My charger has setting for flooded, sealed and AGM, and I haven't seen many chargers that mention LiFePO4settings.
On Fri, May 27, 2022 at 7:19 PM Joe Della Barba via CnC-List < cnc-list@cnc-list.com> wrote: > Quick battery facts: > > > > An ideal battery is like a water tank. It holds X amount, can be filled as > fast as you want or as slow as you want, and likewise for emptying the > water. No matter what, you get 10 gallons out of a 10 gallon tank. > > How all types of lead-acid batteries fail in being perfect: > > 1. Peukert Effect – A 200 amp hour battery might last 250 hours if > only drawing one amp and maybe one hour at 100 amps. > 2. Charge efficiency – Not all the electricity that goes in gets > stored, some amount is converted to heat, off gassing, etc. > 3. Cycle life – A 200 amp hour battery eventually declines to a lot > less than 200 and then is dead. Battery manufacturers supply graphs of > depth-of-discharge vs. lifespan of the battery. A battery discharged to 80% > and recharged carefully to 100% might last well over a thousand cycles. One > discharged to 0% and recharged might last 10 or 20 cycles or maybe 1 cycle > if it was a starting battery. Most cruisers figure on 50% > depth-of-discharge as the limit for a good lifespan. > > > > What this means is a 200ah lead battery is good for 100ah if you want it > to last AND have a way to get it all the way back to 100% easily. Many > people figure on cycling between 50% and 90% or so. The fuller a lead > battery gets, the slower it charges. > > > > In contrast, a lithium battery is a lot closer to the ideal. The charge > efficiency is high, the Peukert Effect doesn’t really exist for them, you > can charge them fast if needed, and their lifespan is good to 80% > discharge. A 200ah lithium battery is good for 160ah useable capacity, not > the less than 100 that is the practical useable capacity of lead battery of > the same nominal rating. > > > > > > Joe Della Barba > > Coquina C&C 35 MK I > > Kent Island MD USA > > > > > > > > > > > > *From:* Bill Coleman via CnC-List <cnc-list@cnc-list.com> > *Sent:* Friday, May 27, 2022 4:27 PM > *To:* 'Stus-List' <cnc-list@cnc-list.com> > *Cc:* Bill Coleman <colt...@gmail.com> > *Subject:* Stus-List Re: Batteries again > > > > So Dave, would the SOK Battery 206Ah 12v LiFePO4 Battery Solar Battery be > an equivalent swap-out for a Lifeline GPL-8DA 12 V 255 AH Battery? > > This is a little confusing (and intimidating) for the non-initiated . . > > > > > > Bill Coleman > > Entrada, Erie, PA > > > > > > > > *From:* Dreuge via CnC-List [mailto:cnc-list@cnc-list.com > <cnc-list@cnc-list.com>] > *Sent:* Thursday, May 26, 2022 3:24 PM > *To:* cnc-list@cnc-list.com > *Cc:* Dreuge > *Subject:* Stus-List Re: Batteries again > > > > Dave, > > > > As I mentioned in previously replies to the list, it no longer makes any > sense to buy lead acid batteries(i.e. flooded, gel, or AGM) for a house > bank. For lead acid, the AH capacity is highly dependent on the current > load due to the Peukert Effect. Deep cycle lead acid batteries are rated > at C/20. For a 100AH rated battery, this is 100AH/20H = 5A. This is > often called the 20H rate, i.e. 5A * 20H = 100AH. If the actual load > is 20A, then the same 100AH rated lead acid battery would only provide 60AH > (or 10AH at 100A). And worse, one should only use 50% of a lead acid > battery’s capacity as going below 50% substantially degrades the battery > lifetime. This means that a 100AH lead acid battery has an effective 50AH > @ 5A (or 30AH @ 20A). > > > > Let’s assume a 100AH lead acid battery price of $264 (the average of the > Amazon prices), then 2 batteries would cost one $528 and one would get an > effective 100AH (50%*200AH) at 5A loads. > > > > Now, the price of LiFePO4 batteries have come way down in the last few > years and their performance and lifetimes are a magnitude better. A 100AH > LiFePO4 battery is typically rated at 1C. That is they can deliver 100AH > at 100A for 1H(or 5A at 20H or 20A at 5H). They can also charge at amps up > to 100A which is impossible for a lead acid battery. And LiFePO4 > batteries live 5 times longer. That is, one would expect to replace 5 > sets of lead acid batteries before replacing a LiFePO4 battery. Yes, > LiFePO4 batteries are more complex as they require a battery management > system (i.e. BMS), but there are companies which provide 12V drop in > replacements with the BMS built internal to the battery. Top companies > like Battle Born sell a 100AH LiFePO4 for $874 and provide a 10yr warranty. > Renogy sells a 100AH LiFePO4 for $765. A company, CurrentConnected.com, > sells > a SOK 100AH LiFePO4 battery for $569 and it has a 10 yr warranty! > YouTuber Will Prowse rates the SOK as the best value LiFePO4 12V drop in > replacement (see https://www.mobile-solarpower.com/lithium-batteries.html). > There are a plethora of cheaper 100AH LiFePO4 batteries that can be found > on Amazon, Ebay, AliExpres, …, but one gets little service and limited > warrantees, so I would recommend avoiding these. > > > > Rather than buying 2 100AH lead acid batteries for $528 at a total weight > of 140lbs(70lbs each) , one could just buy 1 100AH LiFePO4 for $569 > weighing only 28lbs and get a better performing battery. That is basically > the same price. If one takes into account the increased lifetime, the > saving is HUGE! > > > > If one builds their own DIY LiFePO4 battery, the savings is much much > greater. Last year I replaced 2 100AH lead acid batteries with one DIY > 560AH LiFePO4 battery for a little over $900 (see my blog link below). The > DIY LiFePO4 battery occupies the same location and physical space as the > previous 2 lead acid batteries, it weighs much less (95 lbs vs 125 lbs), > but has 5 TIMES the capacity. > > > > I recently gave a talk on off-grid solar systems a local amateur radio > society meeting. The discuss the battery as the heart of the system and > make the case for LiFePO4 batteries. My slides from the talk are available > on my blog: > > > > > https://svjohannarose.blogspot.com/2021/10/solar-off-grid-system.html > > > > > > Also, the details of my DIY 560AH LiFePO4 are posted at the link below > which includes details about alternator charging. > > > > > https://svjohannarose.blogspot.com/2021/06/adding-new-lifepo4-to-house-battery.html > > > > > > > > >
