[meanderingthemaze]

So, by now, I think many of you know I've been perusing the boards for awhile now. I've heard a lot of fanatics on either side of the argument. But to me, after crunching real numbers, and unfortunately only having access to a lot of anecdotal case studies, the case is not clear. It's quite grey actually when it comes to the most important aspect of the DIYer's decision making process: ROI.

I know this has been discussed to death, but I am hoping that I can task the users of this forum to consolidate what they understand into USEABLE and ACTIONABLE information for other DIYers on the board since this is the perennial question in this subforum: Lead or Lithium?

I am hoping that this discussion will not be about ego or being right and wrong but rather an unbiased, fact-based presentation of information so that we can empower other converters to make informed decisions and quit posting the same darn question over and over. That means that you should provide facts and sources to support your claims and state your assumptions!

Here's a simple "Battery Calculator" I did for myself to make it easier to investigate a variety of pack configurations quickly. If someone has something better, please post. The $ figures in there are estimates, but based on real world market figures and the sources of the information are given.
https://docs.google.com/spreadsheet/ccc?key=0Ap66n8KpnbwudFAtUnk3MERWTGZkSUtLdEstQ040SlE
Or this may work better:
https://docs.google.com/spreadsheet/pub?key=0Ap66n8KpnbwudFAtUnk3MERWTGZkSUtLdEstQ040SlE&output=xls

Indisputable things Lithium has going for it:

1. Energy density - can pack more electrons into a lighter box leading to better potential range.
2. Power density - can release and absorb more electrons quicker leading to better acceleration/charging characteristics.
3. Lower Peukert constant - has lower internal resistive losses during discharge/recharge, which leads to better effective energy density and thus better potential range.
4. Useable life - higher cycle life and potential age
5. Labor - over the life of the vehicle, there would be less battery swaps and therefore less labor hours. also no maintenance.

Indisputable things Lead has going for it:

1. Initial cost - significantly cheaper upfront costs.
2. Simplicity - with no need for a BMS, the overall energy storage system is simpler, ie: less complex.

The grey area, but the most important point to most people:

1. ROI - Based on effective kWh, doing an apples to apples comparison. I'm seeing a 5-6 fold cost diff b/t the two. This means Lithiums would have to last for 10-12 years to break even, at two years per Lead pack, being conservative.

I'd like to see more thorough fact based analyses about ROI. Most of the ones I've seen before rely on some very ambitious and possibly dubious premises. Speculation can lead to even more grey area, so let's deal with what we really know right now.

Unless there has been recent information I'm not aware of, claims of the longevity of Lithium need an asterisk next to them because there is no realistic way to simulate the aging process. Cycling batteries gives some information, but until we see some real world examples, like we have with Lead, of Lithium packs lasting 15 years, then please accept and state your analysis is based on an unproven assumption of lifespan.

I look forward to a constructive discussion. Thanks

 

[Ziggythewiz]

It feeds into ROI, but cycle life should be in the list for pros of lithium.

Also, I'm not sure where you get that lithium costs 5-6x lead. Everything I've seen is lithium around 3x the cost of cheaper lead options, and only double or less that of the higher end lead options.

More anecdotal evidence for you: When my lead began to die it was one at a time. I wasn't going to throw away the old and replace with new, especially since they were under warranty, full then prorated. It took about 8 months to transition from one pack to the next, which saved over $700 vs dumping one pack and switching for the next, but is cost countless hours in circuit reconfigs to keep things running over that window.

 

[dladd]

So, by now, I think many of you know I've been perusing the boards for awhile now. I've heard a lot of fanatics on either side of the argument. But to me, after crunching real numbers, and unfortunately only having access to a lot of anecdotal case studies, the case is not clear. It's quite grey actually when it comes to the most important aspect of the DIYer's decision making process: ROI.

I would question your premise. I do not think ROI is the most important aspect of the DIYer's decision making process. I'm not sure it was even in my top 5! Hell, from an ROI standpoint, I'd be ahead driving around in a 15 year old 30mpg Saturn than spending 15k to convert it to battery power...

and fwiw, I have not heard from these lead acid 'fanatics' at all. In fact, it seems fairly universal. Even those who have lead would prefer lithium. No one with lithium wishes they had stuck with lead. Well, maybe I shouldn't say 'no one', I'm sure there's someone out there that will say that. Certainly the upfront cost is high, and prohibitive for some. BUT, if you can swing it, Lithium is clearly better. In the short, and in the long run.

lithium is most likely better on ROI, but as you say, how can that be guaranteed since lithiums haven't really been used for more than a few years yet? It does seem clear though, an EV in daily use of any decent range will ruin it's lead pack in 2 years. I've read about that happening time and time again. Some may claim 5 years on lead, but that's going to be occasional use, short trips, and intensive babysitting of the batteries.

I'm not sure where you are seeing a 5-6x increased cost for Lithium, i think it's more like 3-4x at most. Making the crossover more like 6-8 years. Initial data shows that lithium cells will probably last that long, but it's no guarantee. However, in the mean time you'll have better range, better performance, less weight, and higher efficiency. Plus, you won't have the hassle of swapping out battery packs every 2 years.

 

[meanderingthemaze]

I would question your premise. I do not think ROI is the most important aspect of the DIYer's decision making process. I'm not sure it was even in my top 5! Hell, from an ROI standpoint, I'd be ahead driving around in a 15 year old 30mpg Saturn than spending 15k to convert it to battery power...

and fwiw, I have not heard from these lead acid 'fanatics' at all. In fact, it seems fairly universal. Even those who have lead would prefer lithium. No one with lithium wishes they had stuck with lead. Well, maybe I shouldn't say 'no one', I'm sure there's someone out there that will say that. Certainly the upfront cost is high, and prohibitive for some. BUT, if you can swing it, Lithium is clearly better. In the short, and in the long run.

lithium is most likely better on ROI, but as you say, how can that be guaranteed since lithiums haven't really been used for more than a few years yet? It does seem clear though, an EV in daily use of any decent range will ruin it's lead pack in 2 years. I've read about that happening time and time again. Some may claim 5 years on lead, but that's going to be occasional use, short trips, and intensive babysitting of the batteries.

I'm not sure where you are seeing a 5-6x increased cost for Lithium, i think it's more like 3-4x at most. Making the crossover more like 6-8 years. Initial data shows that lithium cells will probably last that long, but it's no guarantee. However, in the mean time you'll have better range, better performance, less weight, and higher efficiency. Plus, you won't have the hassle of swapping out battery packs every 2 years.

You are right to question my premise as I am using anecdotal evidence from what I've seen on the boards. Most people seem to be most concerned about finances, even though there is a subset of people, like racing enthusiasts or wealthier individuals who can afford to play with their money more. Even if this thread is only for those that are concerned with ROI, then I think it's worthwhile to lay out the cards on the table for analysis.

I've updated the above Lithium pros list to include less labor, since you bring up a good point about the work involved in switching packs.

As to the 5-6x cost, check out the spreadsheet I've linked to to see the figures. I'm comparing kWh. However, I should be comparing effective kWh, so maybe it is closer to 4x. I'll double check that now.

 

[subcooledheatpump]

This goes along with the BMS thing, but what about safety issues? Lithium, as I understand because of it's high energy density, can be quite explosive if the cells overheat or are exposed to overvoltage/overcurrent. Lead batteries are much more tolerant to overvoltages. No BMS to worry about for charging, but also for those (like myself) with regenerative braking, it means you won't have to stress when the voltage climbs up during regenerative braking. Just my thoughts

 

[Ziggythewiz]

Lead I pay about $310 per useful kwh, lithium would be around $558.

Part of the expense with lithium is that if you're going to spend that much anyway, why not spend some more and get 50 miles instead of 30. I could get the range I need out of 60 AH cells, but I'd rather save up and get 100s.

 

[PTCruisin]

Here is another "data point" regarding ROI:

I spent $5600 for a 12kWh LiFePO4 pack nearly two years ago. I drive an average of 20 miles/day, 7days/week, 50 weeks/year. Annual driving = 7000 miles.

The cost to charge the pack after the 20 mile commute is approx 50 cents - based on 8kWh from the wall plug @ 6.5 cents/kWh.

When the vehicle was ICE-powered, I would use 1 gallon of gas for the same commute @ $3.75/gallon on average.

Annual fuel costs = $1300
Annual electricity costs = $175
Annual savings = $1125

$5600/$1125 = 5 years to pay off batteries with cost savings.

So ROI is at 5 years. Since I use about 50 to 60 % of the capacity, I expect to get around 10 years of service out of the pack.

I know this is not comparing Li to Pb but I expect you would have to replace the Pb after 2 or 3 years anyway.

 

[somanywelps]

$5600/$1125 = 5 years to pay off batteries with cost savings.

And then you have very low (no?) maintenance and HOV access and not having to stop at gas stations.

 

[meanderingthemaze]

Lead I pay about $310 per useful kwh, lithium would be around $558.

Part of the expense with lithium is that if you're going to spend that much anyway, why not spend some more and get 50 miles instead of 30. I could get the range I need out of 60 AH cells, but I'd rather save up and get 100s.

So, this is an area I'd like clarified with calculations. I think it's very difficult to gauge useful kWh in a pack given the number of variables involved. However, is there a rule of thumb for adjusting the advertised AH rating given by manufacturer to the effective useable kWh that you'll see in your conversion? If so, please share. I'm curious to see how you are calculating that. Someone else in another thread suggested at 1C discharge that Lead would decrease to 65% of the advertised 20 hour rate.

Also, your cost sounds ridiculously expensive for Lead. Are you using AGMs? I think we should talk about wet batteries as they are the most widely used and the best cost advantage. I'm not sure how AGMs would be used.

If you check the above calculator link, it shows that a 6V 232AH lead battery costs $90. That's 90/6*232 = ~$65/kWh. However, if we say they're 65% efficient, that raises the number to ~$100/kWh. If Lithium is @ $558/kWh, you can see how I'm getting the 5-6x difference.

You could argue that you need less Lithium than you would Lead because the vehicle is lighter, but by how much? Factor that in and again, I don't see how it could be better than 4x difference.

In my opinion, the difference between Lead and Lithium costs need to be closer to a 1:3 to make it feel like a good investment, or better yet, 1:2...IMO.

 

[evnz]

ROI mean what?

 

[MN Driver]

Only a couple states offer free HOV lane access for electric cars. In Minnesota there is no HOV sticker, you pay 25 or 50 cents(or more if that lane starts getting congested to a speed lower than 50mph) to access the lane if you aren't carpooling on the highways that charge the express lane toll for that lane if you aren't a carpooling vehicle, motorcycle, or bus. I've never been on those highways where it is busy enough to even think about buying the electronic unit though. IMHO, I've never really understood the point, it ends up becoming a political issue for people to attack hybrid and electric cars.

There are ROI points that don't include the batteries too though, the other components can be used in a different car. The battery could be too, if someone decided to swap cars, as long as everything is compatible.

I think its clear to go with lithium, it's about the only real way to get a higher performance system that is lightweight, much easier to fit with more cargo room, longer life, they don't need to be watered like a plant to prevent them from dying, you can go higher voltage without having the excess weight without the extra capacity like lead, peukert requires you to buy more capacity to cover for it, same with adding extra capacity(and weight) to cover the range you lose when the lead-acid pack starts to dig itself a hole, lower efficiency charging and discharging. These are a few of the extra costs that aren't as apparent when going with lead.

 

[meanderingthemaze]

ROI mean what?

http://lmgtfy.com/?q=roi

 

[MN Driver]

ROI mean what?

Return on investment. This thread is discussing the cost difference, over time, of using lithium instead of lead. It doesn't make money so it's not technically an investment, but the gains that we can get in reduced operating costs by using an electric drivetrain go together with the costs of buying and using the battery packs, there are some value calculations to it and that is what we are discussing.

 

[Ziggythewiz]

65% is close, I was going with .6, but then you also times by 50% for DOD, so your actual multiplier is something like .25 - .35 Compare that to .7 for lithium and it does seem pretty clear.

GC8s from sams for around $100 are 135 AH (20 hr) so using .3 as a multiplier gives ~$310 / kWh. Obviously 6v batts are cheaper/kWh but there's no way I'm putting that much weight in my bug.

It's already 1:3, with 5x the life

 

[DIYguy]

Its really not about ROI in my little brain. One thing I agree with JR about is;
Lead = science project
Lithium = viable car.

Sorry to all u pb users. I started there also. No shame in that. Once u have done both, there just is no comparison to make. Forget the ROI. One choice "works".

Also, just for the record. . regarding complexity I assume u r talking floodies because AGM's actually require a BMS, where lithium doesn't necessarily need one depending on some choices and abilities.

All the best.

 

[CrunchTime]

I do not think ROI is the most important aspect of the DIYer's decision making process.

I agree. My decision came down to this: according to my calculator, with Lead I could have a 40km, 1 passenger vehicle; with Lithium I will have a >100km, 3 passenger vehicle (in NZ we cannot go over the manufacturer's weight limit (GVWR), and have to allow 80kg for each passenger)

In fact the Li cost distracted me from the real point: without LiFePO4 I wasn't going to be happy with the car, so there would have been less than no point in doing the conversion.

Personally, the ROI is not a factor - the conversion is for "fun" and to be a bit different, not because it's green, or cheap, or cool. (Well maybe a bit because it's cool ) (It is cool, right?)

 

[Frank]

I didn't look at the numbers in your link but if they say a 6V 232AH PbA battery is $90 I suspect it's a little out-of-date. At least to get a quality battery. Last year around here, a single T125 was $175. Pallet pricing would be cheaper but not by that much.

A significant factor is weight and terrain: my pickup has a 120 volt system (i.e. 20 6V batteries) that weighs 1320# (batteries only.) An equivalent amount of useable energy would be contained in about 300# of lithium. A weight savings of 1000# is very significant! My truck goes well enough on the flat but is a pig when climbing hills. A real pig.

With lithium you're not relegated to pickup trucks. With PbA you need the load-carrying capacity and pickups were the traditional conversion candidate. Anything will work with lithium. Prismatic cells really are a game changer.

 

[rtcaldwell]

I can understand how ROI may not factor in to many different applications, but it does factor in for me. I am still in my infancy of building a conversion and will be using a 1962 Ford Fairlane (an old american classic) which could carry both Li or Pb.

ROI is a major factor for me and I appreciate
meanderingthemaze brining up this as a post. If good information gets generated, possibly even creating a sticky. I would love to see a sheet worked out that was 'fairly' accurate when it comes to ROI. Possibly where one could even put in current figures/cost in their area.

Question, how much does recycle/core charge fit into this ROI idea? after 2-3 years when you return your lead batteries, don't you usually get some money back? or is that only if you purchase MORE batteries?

From what I have discovered, I am most likely going to go with Lithium because I have a few extra $$$ I can spend in an upfront investment, but a calculator like something that is being suggested would help people make informed decisions if they decided that Return on Investment was important to them.

 

[evnz]

I agree. My decision came down to this: according to my calculator, with Lead I could have a 40km, 1 passenger vehicle; with Lithium I will have a >100km, 3 passenger vehicle (in NZ we cannot go over the manufacturer's weight limit (GVWR), and have to allow 80kg for each passenger)

In fact the Li cost distracted me from the real point: without LiFePO4 I wasn't going to be happy with the car, so there would have been less than no point in doing the conversion.

Personally, the ROI is not a factor - the conversion is for "fun" and to be a bit different, not because it's green, or cheap, or cool. (Well maybe a bit because it's cool ) (It is cool, right?)

The ROI is not a reason to build an ev, you and i need to change the way people think of ev's.
I am regularly asked why i am doing it i tell them if people put a V8 in a mini why not put a electric motor in a j1 bedford
I am doing it with lead for the first set then lithium after that.
I have a 15 km round trip to work and back

 

[Ziggythewiz]

The ROI is not a reason to build an ev

Maybe not for you, it certainly is for me. It all depends on your alternatives. If you would otherwise spend $15K to purchase a vehicle, your conversion instantly pays for itself, along with saving $1-3K / year on gas.

If you don't get any additional utility from the car, I would expect the ROI to be around 8-10 years whether using lithium or lead. Maybe in a good economy that would be a bad investment, but right now can you tell me anything else (other than raw materials) that would have fared as well over the last 8 years?

More than anything though, I consider it a matter of national security and energy independence. We wouldn't have to keep 2 carrier groups in the middle east if oil weren't the lifeblood of our country.