Lithium vs Lead; the Great Cost Debate. - DIY Electric Car Forums
Go Back  

DIY Electric Car Forums > Blogs > mattW

Register Blogs FAQ Members List Social Groups Calendar Search Today's Posts Mark Forums Read

Rating: 9 votes, 5.00 average.

Lithium vs Lead; the Great Cost Debate.

Submit "Lithium vs Lead; the Great Cost Debate." to Facebook Submit "Lithium vs Lead; the Great Cost Debate." to del.icio.us Submit "Lithium vs Lead; the Great Cost Debate." to Digg Submit "Lithium vs Lead; the Great Cost Debate." to Reddit Submit "Lithium vs Lead; the Great Cost Debate." to StumbleUpon Submit "Lithium vs Lead; the Great Cost Debate." to Google Submit "Lithium vs Lead; the Great Cost Debate." to Yahoo! Submit "Lithium vs Lead; the Great Cost Debate." to Newsvine
Posted 02-03-2009 at 01:21 PM by mattW

I've decided to try and work out the cost comparisons for a Lithium pack vs a Lead pack for a set range and a set number of years. Is Lead Acid actually cheaper or does is just seem that way up front? This article aims to find that out. The method is to get 10kWh of usable energy, Iíll try to get that with Lead and with Lithium and see what we find is cheaper in the long run. Assuming an efficiency of 250Wh per mile (a compact car) we should get a range of 40 miles (65km) with either pack. Iíll be using Australian prices since Iíve already researched them, but the comparison is probably close in other countries too.

Click image for larger version

Name:	Battery%20Debate.JPG
Views:	880
Size:	54.2 KB
ID:	26

The first step is to source a lithium pack with 10kWh of usable energy. The Lithium batteries I have chosen get 2000 cycles to 80% DoD and I estimate that at the 1 hr rate they will deliver 95% of their rated energy due to the Peukertís effect. So to give our total energy we multiply our usable energy by 1.35 meaning we need 13.5kWh to get out 40 mile range with lithium batteries. If we assume a 120V conversion this means we need 112.5Ah. The cheapest Lithium batteries I have seen in Australia are Thundersky LiFePo4 LFP prismatic cells $2.50 per 3.2V per Ah. So our 13.5kW pack would take 38 3.2V cells at ~110Ah and would cost $10450 at normal prices (no group discount), without shipping or BMS.
For a Lead Acid pack we also need to keep the batteries at less than 80% DoD and at the 1hr rate we can only expect to get 55% of the rated energy of the pack back due to the Peukertís effect. That means we need to multiply the usable energy by 2.25 to get our total energy, in this case its 22.5kWh. Trojan T605 batteries could make up a 22.5kWh pack with 18 batteries (108V, 210Ah) at $225 each or $4050, it didnít say how many cycles it would take on the website but letís guess around 650 to 80%. That means weíll need to replace our lead Acid pack around three times for every lithium pack we buy, meaning our total cost for the lead packs goes up by a factor of 3 to $12150 over 2000 cycles.
Now I must admit that I didnít look very hard for the cheapest batteries and I am only guessing the cycle life of the Trojans but even if itís not precisely accurate it does show that the myth that Lead is clearly cheaper than lithium is not well founded. Lithiumís greater efficiency and cycle life makes up for its higher initial cost. I didnít know what the results would be like before I started. The10kWh number was chosen just to make it easy to calculate, it has little influence on the result one way or the other. I thought the results would be close but not this close. Please note that the Lithium pack would require a BMS, which would cost $1270 but that still means you are going to pay around $12k whether you go with Lithium or Lead. It would also be worth mentioning that you would be paying for more electricity over that time with Lead; 36MWh costing $3600 compared to 21.6MWh $2160 @ $0.10 per kWh and recharging 80% of capacity. You would also need to water the batteries if you went with the Trojans, while the lithiumís would be maintenance free. Itís also worth mentioning that there are apparently disputed copyright issues with the thundersky cells and their previous record with customer support apparently not good, but this was just a cost comparison and the number look pretty convincing.
The total cost per km for the 2000 cycles is $15 750/ 130 000km = 12.1c per Km (19.7c/mile) for Lead Acid and $13888/ 130 000km = 10.7c per km (17.4c/mile) for the LiFePO4. These would obviously increase slightly when factoring in tire and brake wear. Just for comparison a the cost per km of a bunch of small ICE cars are listed here the cheapest being 41.44c/km but only 33.5% of that cost was for fuel and servicing (the rest being common cost for EVs as well) so thatís 13.9c/km for the cheapest ICE using fuel at $1.25/L. Clearly then EV have a price advantage over ICEís especially now that normal unleaded is averaging $1.48/L.
In summary, while Lead Acid may be cheaper up front new lithium packs are more cost effective in the long run as well as being lighter, smaller and maintenance free. Obviously battery choices are highly dependant on individual conversions and budgets but it should not be assumed that Lead is the budget option, since itís just not true anymore.
Views 42038 Comments 154 Edit Tags Email Blog Entry
« Prev     Main     Next »
Total Comments 154

Comments

  1. Old Comment
    Quote:
    set number of years
    For lithium this is not a know thing. For lead it's pretty much a given but it still depends upon how well you care for your batteries and how deep you discharge them. I know that for me even changing out lead every 4 years would be far cheaper than lets say one pack of lithium for 10 years. My lead pack only costs me about $800. So $800 times 4 equals $3200 for 4 packs of lead vs one pack of lithium for around $15,000 for the same size pack. Pretty easy to figure out the cost. That assumes that you can actually get 10 years out of a pack. Shelf life vs charges are totally different. I may get to charge and discharge thousands upon thousands of times but I my only get to do that in a short time frame. I have heard that the shelf life of lithium is not so hot. So shelf life is the real factor here and not how many times I can charge and discharge. I'd still rather spend $3200 for a few packs of lead than $15000 for one of lithium. Still a big difference. Granted the lithium would be lighter but still not worth the expense yet. Soon! Maybe something better will arise that has not been spoken about. : )
    Posted 05-23-2008 at 07:03 AM by
  2. Old Comment
    mattW's Avatar
    But are you comparing the same range for the two packs? You can buy lithium without getting a 100 mile range, people seem to overestimate their lithium sizing and payback time. It doesn't bother me if you go with lead, that your choice, I just want people to look at the actual comparison not just 100Ah of lead costs this much 100Ah of lithium costs this much. There is more to it than that...
    Posted 05-23-2008 at 07:20 AM by mattW mattW is offline
  3. Old Comment
    I think one of the main things you left out of the article was a weight comparison. 18 lead batteries at about 50lbs each would weigh 900lbs. Not sure what the carrying capacity of a compact car is, but you would probably not have the ability to carry much of anything else without a suspension upgrade. What would the cost of upgrading the suspension be? What are the effects on the cars handling by adding this much extra weight? What is the weight of the Lipo's? We can't discount these factors.
    Also, as someone else said, I agree that shelf-life (as well as total cycles) should also be taken into account.
    Posted 05-23-2008 at 10:22 AM by namyzarc namyzarc is offline
  4. Old Comment
    JRP3's Avatar
    Quote:
    Originally Posted by mattW View Post
    But are you comparing the same range for the two packs? You can buy lithium without getting a 100 mile range, people seem to overestimate their lithium sizing and payback time. It doesn't bother me if you go with lead, that your choice, I just want people to look at the actual comparison not just 100Ah of lead costs this much 100Ah of lithium costs this much. There is more to it than that...
    Yes that's a good point, you don't need the same amount of Lithium as lead since lithium has more usable energy, plus the fact that you are dragging around less weight with the lithium.
    Posted 05-23-2008 at 11:55 AM by JRP3 JRP3 is offline
  5. Old Comment
    Qer's Avatar
    Quote:
    Originally Posted by JRP3 View Post
    Yes that's a good point, you don't need the same amount of Lithium as lead since lithium has more usable energy, plus the fact that you are dragging around less weight with the lithium.
    Or you could drag around LOTS of Lithium but get a serious range. 100 km or more would be VERY nice, but doesn't seem very realistic with led, at least not if you want to go at highway speed too.
    Posted 05-23-2008 at 12:07 PM by Qer Qer is offline
  6. Old Comment
    onesojourner's Avatar
    My 2 cents
    is 2000 really a realistic number? what if you start having cells die after 500 or 1000? then what?
    Posted 05-23-2008 at 01:28 PM by onesojourner onesojourner is offline
  7. Old Comment
    JRP3's Avatar
    Quote:
    Originally Posted by Qer View Post
    Or you could drag around LOTS of Lithium but get a serious range. 100 km or more would be VERY nice, but doesn't seem very realistic with led, at least not if you want to go at highway speed too.
    I've seen a number of conversions on EValbum.com that got 60 mile range and 70 mph top speed.
    Posted 05-23-2008 at 04:14 PM by JRP3 JRP3 is offline
  8. Old Comment
    david85's Avatar
    Quote:
    Originally Posted by onesojourner View Post
    My 2 cents
    is 2000 really a realistic number? what if you start having cells die after 500 or 1000? then what?
    The cycle life is similar among many different companies using the same LiFePo4 chemistry. With the proper BMS, 2000 cycles should not be a problem as that assumes 80% DOD every time.
    Posted 05-23-2008 at 10:44 PM by david85 david85 is offline
  9. Old Comment
    saab96's Avatar
    Quote:
    Originally Posted by david85 View Post
    The cycle life is similar among many different companies using the same LiFePo4 chemistry. With the proper BMS, 2000 cycles should not be a problem as that assumes 80% DOD every time.
    What would that proper BMS be? While we have standardized controllers and motors and chargers for EVs, I have yet to see a true BMS "product" out there that has a published pricetag that you can just buy. It's really the missing link.
    Posted 05-24-2008 at 12:14 AM by saab96 saab96 is offline
  10. Old Comment
    The BMS is the core of the debate. The issue with lithiums is they need to have a closely coupled battery management system which is quite complex since it needs to monitor the batteries on a cell by cell basis and therefore expensive.

    Over time the cost of the BMS and the lithiums will clearly reduce while the cost of oil and lead-acid batteries will clearly increase. However right now we need a good, proven BMS for lithiums to progress putting them into cars. Does anyone know of a good BMS out there?
    Posted 05-24-2008 at 12:24 AM by Weka Weka is offline
  11. Old Comment
    mattW's Avatar
    The BMS was included in the calculations. There is a link to it in the blog. The cost for a 10kW pack was AU$1270. $350 for the master module and $24.20 per 3.2V unit.
    Posted 05-24-2008 at 12:41 AM by mattW mattW is offline
  12. Old Comment
    Quote:
    Originally Posted by mattW View Post
    The BMS was included in the calculations. There is a link to it in the blog. The cost for a 10kW pack was AU$1270. $350 for the master module and $24.20 per 3.2V unit.
    Good point Matt and quite true however I guess we are changing the argument on you from cost to availability. Can you describe your BMS supplier please, how it works, and why you think it is reliable? Don;t get me wrong, I would be delighted if you can point me to a good Lithium BMS solution
    Posted 05-24-2008 at 12:51 AM by Weka Weka is offline
  13. Old Comment
    david85's Avatar
    If you go to the metric mind website you can find a good BMS system. I don't believe that prices are on the website, but you can drop Victor a line and find out.

    Most contacts I have located in china supply the BMS with the battery. All it has to do is cut off voltage and amps above and below certain parameters, not very complicated.
    Posted 05-24-2008 at 01:09 AM by david85 david85 is offline
  14. Old Comment
    mattW's Avatar
    I haven't looked into it that much specifically- you can email him if you want more info. To be honest I just trust the person who recommended them to me. I can't really comment on how good they are because I haven't got mine yet.
    Posted 05-24-2008 at 01:10 AM by mattW mattW is offline
  15. Old Comment
    Matt, I have to take issue with the most critical item in your discussion:

    Quote:
    Now I must admit that I didn’t look very hard for the cheapest batteries and I am only guessing the cycle life of the Trojans but even if it’s not precisely accurate it does show that the myth that Lead is clearly cheaper than lithium is not well founded.
    You picked a situation that severely confounds your results. Your use of Australian Trojans at the extreme price of $225 AUS makes your comparison easy.

    Trojans are expensive. Lead Acid in Australia is extremely expensive.

    Let's try some US based Trojan T-105s from here:

    http://www.thesolar.biz/Trojan_batteries.htm

    Same voltage. Same Ah rating. Price USD is $127 each. So your pack price is now $2286 for 18 batteries. 3 sets cost you $6858 USD.

    See? Just by shopping around your argument kind of falls apart.

    And in the US I haven't gotten to the Eveready GC2 golf cart battery from Sams that only $75 USD each. That's a full 1/3 of the price of the T-605s that you originally quoted. Same voltage and same Ah rating as your T-605s.

    From a technical standpoint Lithiums are better. There's absolutely no dispute about that. However at least in the US lead acid is definitely a fully available option on the table because lead acid packs are available at a small fraction of the cost of lithium.

    ga2500ev
    Posted 05-24-2008 at 01:21 PM by ga2500ev ga2500ev is offline
  16. Old Comment
    Does anyone have a 10 year or even a 5 year old laptop with original batteries that hold a charge anything like they did when they were new? Or how about a rechargeable drill? Just curious since I have always seen a huge drop off after just a couple years. Norm
    Posted 05-24-2008 at 01:59 PM by ngrimm ngrimm is offline
  17. Old Comment
    hardym's Avatar
    As a Lead-acid EV owner who's joined the ranks of realization that their EV does not provide the distance that that they would like...

    I've tried to create a wiki page of all the alternatives to lead-acid on this site, and for each specific option, detemrine the cost of a 10KWh pack. (10KWh is arbitray, but it would get me to work and almost back.)

    The link is at
    http://www.diyelectriccar.com/forums...ad.php?t=13351

    This has been a disappinting collection of research until i found the latest lithium entry, which is:
    Ebay Ping is only selling on ebay, but offers a pack with BMS: 48V 20AH for $840 (10 packs = 9.6KWh @ $8400) Ping doesn't recommend series/parallelling of pack. Not sure of who manufacturers the cells, and no cell data. Here is a testimonial on a bike.

    Note the price point: $8400 for a 10 KWh pack, which is a good price point. Lithim is the holy grail EV batterys. The problem is paralleling these packs for EV use. I'm working on trying to find someone who has successfully done that. If you know of any... please pass info along.

    Mark.
    http://www.evalbum.com/1352
    Posted 05-24-2008 at 09:21 PM by hardym hardym is offline
  18. Old Comment
    saab96's Avatar
    Quote:
    Originally Posted by hardym View Post
    As a Lead-acid EV owner who's joined the ranks of realization that their EV does not provide the distance that that they would like...

    I've tried to create a wiki page of all the alternatives to lead-acid on this site, and for each specific option, detemrine the cost of a 10KWh pack. (10KWh is arbitray, but it would get me to work and almost back.)

    The link is at
    http://www.diyelectriccar.com/forums...ad.php?t=13351

    This has been a disappinting collection of research until i found the latest lithium entry, which is:
    Ebay Ping is only selling on ebay, but offers a pack with BMS: 48V 20AH for $439 (10 packs = 9.6KWh @ $4390) Price point is best I've found. Ping doesn't recommend series/parallelling of pack. Not sure of who manufacturers the cells, and no cell data. Here is a testimonial on a bike.

    Note the price point: $4390 for a 10 KWh pack, which is about 1/3 of other Li-ion prices. This has the greatest promise of the holy grail EV source. The problem is paralleling the packs for EV use. I'm working on trying to find someone who has successfully done that. If you know of any... please pass info along.

    Mark.
    http://www.evalbum.com/1352
    Do the math again. That's a 10khw pack of 20ah cells. You'd need 5 of these to get good EV range which would be about double what you can find elsewhere with 100ah bricks.
    Posted 05-25-2008 at 04:08 PM by saab96 saab96 is offline
  19. Old Comment
    Manntis's Avatar
    Quote:
    Originally Posted by david85 View Post
    If you go to the metric mind website you can find a good BMS system.
    He still hasn't fully completed it yet, and hand-makes each module. I enquired about 98 of them and was told it'd be months before he could ship them.
    Posted 05-25-2008 at 05:11 PM by Manntis Manntis is offline
  20. Old Comment
    Manntis's Avatar
    Quote:
    Originally Posted by mattW View Post
    The BMS was included in the calculations. There is a link to it in the blog. The cost for a 10kW pack was AU$1270. $350 for the master module and $24.20 per 3.2V unit.
    If you're referring to Rod, making them for TS batteries, his are limited to a relatively low voltage - but from what I've seen his quality control is excellent and he comes across as an extremely knowledgeable and easy to deal with fellow.
    Posted 05-25-2008 at 05:13 PM by Manntis Manntis is offline
 
 
Support DIY Electric Car
Sponsors

All times are GMT -6. The time now is 08:56 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.

Ad Management by RedTyger