batteries: Lithium vs. Pb-acid - Page 1
Forum section: electronics / projects

author: Clear as mud
author_rank: Regular Contributor
timestamp: June 09, 2014, 08:27:58 pm
content: I know lithium-based batteries can be more cost-effective for mobile applications because of the weight savings, but I had not seen this claim before:Quote from: electrodacus on March 24, 2014, 07:12:40 amThat quote is from a post from April about a new open-source hardware solar battery management system. In the past, I had heard that lead-acid batteries' cheaper cost makes them better to use for applications where size and weight are not an issue. I am interested in the solar battery charging system, but since the thread was two months old, and my questions are slightly off topic anyway, I thought I would start a new topic.Does anyone know of good references to read, regarding the cost-effectiveness of lithium batteries? Does the increased cost-effectiveness come from their higher efficiency? Are they more efficient because they have a lower internal resistance?Is there any real advantage to lead-acid in terms of availability? I mean, are there places in the world where you wouldn't be able to get lithium batteries, but lead-acid are common?From my observations, lead-acid batteries seem more common, but if Li-Ion and LiFePO4 really are more cost-effective, are they likely to be more common than lead-acid in the future? For instance, will manufacturers of cars, boats, emergency lighting, and UPSs start using lithium batteries to replace the traditional lead-acid ones?I suppose there is a safety issue too. Are lead-acid batteries inherently safer in case of accidental shorting, or in a fire?

author: cellularmitosis
author_rank: Unknown
timestamp: June 09, 2014, 08:50:33 pm
content: Don't have any references off the top of my head, and I don't know if the above claim is true today or not, but one thing which plays into this is the discharge depth capability of lead acid vs lithium.The deeper you discharge lead acid, the more you shorten its life. Battery banks which are speced for maximum lifespan (e.g. 5+ years) will never discharge more than 20% per charge cycle. The problem with that is you need to oversize your capacity by 5x, which is very expensive.So with lead acid, you can buy fewer batteries, discharge them deeper, and replace them sooner, or you can buy more of them, use a shallow depth of discharge, and extend their lifespan. "Pay me now or pay me later".I am not sure how lithium ion compares in this respect.

author: Skimask
author_rank: Super Contributor
timestamp: June 09, 2014, 09:01:40 pm
content: Another thing I rarely hear anybody talk about with respect to Pb-Acid vs Lithium batteries is the ability to recycle the material involved.AFAIK, Pb-Acid batteries are almost 100% recyclable.Lithium-(insert variety of technology here), not so much.Seems to me in situations where size/mass/weight doesn't really matter, Pb-Acid would be the better way to go. I'm not a tree-hugger by any stretch, but makes a bit more sense to me.

author: Stonent
author_rank: Super Contributor
timestamp: June 09, 2014, 09:02:57 pm
content: Sealed led acid batteries (SLA) can sometimes bloat from pressure inside. Car batteries and marine batteries (deep cycle) tend to not be sealed to pressure can vent off. Deep cycle lead-acid batteries are typically used in boats and motorized vehicles (like golf carts, ATVs etc) because they are designed to be drained completely without damage like the non-deep cycle batteries are.As far as lithium based batteries just to be clear, straight lithium batteries are not rechargeable. Li-Poly, lithium ion and LiFePO4 are.Li-Poly is more flexible (literally) than lithium ion since it is a polymer, so the battery can be shaped in a pouch and tucked into more places.Lithium Ion I think (someone correct me if I'm wrong) seems to need the most care when charging to prevent the battery from being damaged. I think it is also the most energy dense.The only place I've personally seen Lithium Iron Phosphate batteries is in use in solar based rechargeable devices. The ones that I've seen are shaped like a regular AA battery but have at least double the voltage. Typically I see them in rather low amp-hour ratings.

author: ScubaShan
author_rank: Contributor
timestamp: June 09, 2014, 09:55:56 pm
content: I guess like anything it depends on the application. I choose a 360Ah@24v LYP pack over LA for our expedition truck primarily because using LYP takes up less space and ~50% less weight. The extremely high discharge rate (3C) also allows us to run large appliances from a relatively small bank, with LA we'd need a much larger bank to support running the same peak loads. They're also able to charge much quicker than LA batteries which is important when you only have sun for 8 hours a day. Some also argue that because LYP are rated for more cycles (~2000 to 80% vs ~400 to 50% Depth of Discharge) that they work out cheaper in the long run, but its too early to confirm or deny this for our application, i'll let you know in ~8 years

author: mtdoc
author_rank: Super Contributor
timestamp: June 09, 2014, 10:13:48 pm
content: As stated it depends on application. LiFePO4 are starting to be used more in solar and other RE applications. They've been used extensively in electric vehicles (cars and bikes) for some time. They have the advantage over other Lithium chemistries in that they are much safer and will not burst into flames if punctured or overcharged. They are heavier though..LiFePO4 are much more expensive per Amp Hour than Lead acid but can safely tolerated 80% depth of discharge for > 1000 cycles if cared for properly. And they have better charge efficiency than typical Flooded Lead Acid batteries.Deep Cycle Lead acid batteries come in various flavors. Most are flooded (rather than AGM or gel). The most robust are the "traction batteries" used in Fork Lifts and some RE applications. They have pretty poor charge efficiency but can be tolerate more frequent deep discharge than most other Lead acid batteries. Generally you don't want to ever discharge a lead acid battery below 50%So as far as which is most cost effective - I think over their lifespan LiFePO4 could prove to be more cost effective since with a great DOD capability you can get the same energy out of a bank with a lower AH rating than what would be needed with Lead acid.LiFePO4 are still pretty new to the RE world but in theory you should be able to get more cycles out of them than typical lead acid batteries (though maybe not better than traction batteries) so that will also affect cost effectiveness.If charge efficiency is better then you also "waste" less of your precious renewable energy production.On the other hand Lithium does require have an active battery management system which cost moneySo despite the higher cost per AH - the factors above could make LiFePO4 cost competitive with lead acid though I have yet to see a thorough cost analysis of comparable battery banks.

author: max666
author_rank: Frequent Contributor
timestamp: June 09, 2014, 10:44:12 pm
content: The technology for lithium based accumulators is revolving quickly, so I don't know what's the status quo. But I heard lithium batteries degrade when they stay fully charged, in contrast to lead acid batteries which don't like to be fully discharged.So as others have suggested, it will depend on the application.Also the demand for lithium will inevitably go up, I'm not sure how the mining of lithium will keep up with that. Especially if you want to produce electric car sized lithium batteries en masse, also mining lithium is a very dirty business. So lead acid batteries may continue to be a cheaper alternative, but who knows.

author: rob77
author_rank: Super Contributor
timestamp: June 09, 2014, 10:57:12 pm
content: my 2 cents...check the LiPoFe datasheets for the number of cycles... it's usually 1000+ cycles when charging with 0.8 - 1C , but only a few hundred cycles when doing fast charging (solar energy = fast charging).

author: mtdoc
author_rank: Super Contributor
timestamp: June 09, 2014, 11:01:46 pm
content: Quote from: rob77 on June 09, 2014, 10:57:12 pmOff grid solar PV is generally sized to provide 0.1 C charge rate. (i.e. not fast)

author: saturation
author_rank: Super Contributor
timestamp: June 09, 2014, 11:02:08 pm
content: Other posters have summarized it well. But for an easy access reference regarding cost effectiveness and more, check Wikipedia and battery university:http://batteryuniversity.com/learn/article/is_li_ion_the_solution_for_the_electric_vehiclehttp://en.wikipedia.org/wiki/Electric_vehicle#Cost_of_recharge

author: cellularmitosis
author_rank: Unknown
timestamp: June 10, 2014, 04:18:22 am
content: Also note that deep cycle lead acid batteries are the same as car batteries, but the lead plates are thicker. They are still being damaged by deep discharge, it's just that the thicker plates can withstand more damage.Lead acid batteries used in railroad signaling can last 20 years, but that's sitting on a float charger for their entire life, so that won't apply to your application, but it's interesting to know the upper bound of what's possible.

author: G7PSK
author_rank: Super Contributor
timestamp: June 10, 2014, 08:16:05 am
content: You need to pop over to MJLorton's site he has been testing batteries for solar systems for some time, he has had some very impressive results from lead crystal batteries.http://mjlorton.com/forum/index.php

author: Unknown
author_rank: Unknown
timestamp: June 10, 2014, 02:24:01 pm
content: Quote from: cellularmitosis on June 10, 2014, 04:18:22 amTelco batteries too - outside of container failure / manufacturing faults, 20 years was generally considered a minimum lifespan for older larger flooded lead-acid cells, even when regularly discharged. When I worked for the Evil Empire, it wasn't unusual to be working on batteries older than I was that still had 90+% of their capacity @ C/5. I looked after several sites where 40 year old batteries were still going strong - until some idiot decided to replace the central flooded lead-acid batteries with SLAs in RPS or DPS systems ("10 year lifespan" my arse...).A big part of that was the use of pure lead plates & good stable separator materials - even stationary traction batteries have relatively high amounts of arsenic & antimony (to improve the physical strength of the plates, and occurring naturally in conjunction with lead anyway) and plastic separators which slowly leach chlorine & other contaminants.The quality of even telco-grade lead-acid batteries has been going downhill ever since the 80's though, mostly due to the use of recycled lead (higher impurities) & cheaper (less-stable) separator materials.

author: Rick Law
author_rank: Super Contributor
timestamp: June 10, 2014, 03:24:59 pm
content: Quote from: max666 on June 09, 2014, 10:44:12 pmFrom varies web sources, Lithium batteries last the longest when stored/charged to 50%.Mining lithium and nickel (for NiMH batteries) are both very dirty. Neither lithium nor nickel recharge is a power source. Recharge means they need a power source and I really doubt earth-based solar is a solution at all. How many woods and open fields are we going to destroy and turn them into solar panel fields. What happens to the deer, the rabbits, the birds, and crickets ... that call those fields home? I have seen too many beautiful road side woods and brush fields turned into solar panel eye sores, and I feel so bad for the animals I used to enjoy seeing.Where is the romance in carving you & your girl friend's name on a solar panel?In any event, I doubt either Lithium or NiMH is environmentally friendly. They are just feel-good stuff like the typical electric auto. More environmental damage will occur from their (re)manufacturing and frequent battery replacement than the gas the car would burned in its life time.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 11, 2014, 04:07:00 am
content: Lead acid likes to sit at or near full charge, while just about all other rechargeables like to stay somewhere in the middle. That means lead acid is better for standby applications, while NiMH and lithium are better in applications that are regularly used. There are LiFePO4 "ballast packs" that attach in parallel with an existing lead acid bank and and allow some extra "headroom" for storing alternative energy.

author: woodchips
author_rank: Frequent Contributor
timestamp: June 11, 2014, 09:14:04 am
content: One other thing to consider is the maximum cell size each battery technology can support. With lead acid there isn't any real maximum, telephone exchanges used ones 6' high and 5' square. Every extra cell means wiring, and also the reliability calculations can start to look sick.There has been much talk about electric cars, the Tesla for example, and I was amazed that it uses thousands, 7500?, of small cells to make the battery. Why? It seems that make a cell much larger than AA and they catch fire if you draw too much current. Like the lithium batteries on cordless drills, they turn themselves off if you are actually working the tool hard, not a problem with NiCd.The lifetime of lead acid cells seems to be tied with the plate construction. As has been mentioned the traction batteries, using effectively solid lead plates, last for tens of years. But they are heavy. The sealed batteries are much more convenient but have definite life span.If the battery is static so size and weight aren't problems then always go for lead acid.

author: dannyf
author_rank: Super Contributor
timestamp: June 11, 2014, 10:47:16 am
content: QuoteI don't know if they are the more cost-effective -> I would argue that they are one of the least cost effective batteries out there as they are of high prices typically.They do have the highest energy density, of the common batteries.

author: dannyf
author_rank: Super Contributor
timestamp: June 11, 2014, 10:51:03 am
content: QuotePlenty, I would imagine.Lead batteries are very cost effective, and can sustain high current deep discharging. The raw materials are easy to manufacture.Li-on batteries have the highest energy density, so naturally suited for portable applications.Both are environmentally a nightmare to manufacture, use and recycle.

author: dannyf
author_rank: Super Contributor
timestamp: June 11, 2014, 10:56:05 am
content: QuoteElectrode crystalization and thermo management, as you pointed out.The ability to manage individual batteries in such a configuration is still an unsolved issue.