Are LiFePO4 ready for 60v scooters?
I found these 30v 10ah batteries at Powerizer.
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4298
Is this a good price? Has anyone bought from them before? Can 6 on these be installed (2 series of 3 paralleled making 60v at 30AH) on the xm2000, z20, or zap scooter? What other venders are out there who sell something like this?
Great find. Has anyone tried them out and can I get some feed back?
http://www.electricmotorsport.com/store/ems_ev_parts_batteries_thunder_sky.php
Can I just wire 20 of them up in series with no problem (60v at 40AH)?
Electric Motorsport isn't selling BMS and for a charger I think they'd sell you a custom programmed Zivan. The battery they're selling is thundersky and there is a thundersky groun on yahoo!groups which has been there for years (and years and years) the the people there are very familiar with not just the thundersky batteries but other lithium batteries.
I was wondering if you could take those 20 LiFePO4 cells and group them into five banks of 4 cells each, and use five 12v Vector chargers to charge each bank of 4 cells. Would a Vector smart charger work to charge 4 LiFEPO4 cells correctly? I understand that each cell is 3.2v or so charged. What voltage do they need to have applied to reach full power when charging? I'm assuming no BMS.
Would the 4 cells in each bank get out of balance with each other? I am thinking about going this way, and also using the new PakTrakr for Lithium to monitor each cell. I think the PakTrakr would at least tell me if the cells were out of balance; not sure what I'd do with that info though.
If you pay more than a dollar a watt with BMS its too much.
Until it gets down to 50 cent a watt with bms it is not reasonably priced
Depends how you look at it:
Greensaver SP-27's $395 for 60v27Ah = 24c per Wh. Lifespan = 500
Thundersky LFP-40's $2000 for 60v40Ah = 83c per Wh. Lifespan = 2000
Cost of Greensavers for 2000 lifespan = 24c * 4 = $0.96
Cost of Thunderskys for 2000 lifespan = 83c * 1 = $0.83
Savings with Thundersky = 13c per Wh.
Of course, I'd certainly prefer 50c per Wh with a BMS, and yes, it all depends on the lifespan claims of both battery manufacturers.
Really, it's that I can never resist offering an alternative point of view when someone (usually usatracy) makes such a definitive proclamation without any sort of supporting data... :-)
I would disagree with usatracey. In some cases, free advice is worth less than you pay for it.
ThunderSky batteries need to have a BMS. There are some aftermarket BMS available for these cells; not too expensive. The charging solution varies with BMS. I can source the 40 Ah for $80/cell - no warranty.
As far as the upgrade to 72V - well, just add more cells. What's so tricky about that? I have run packs up to 96V nominal.
You should know how to use and manage these cells before buying them. You cannot (reliably) just group into 12 V packs and treat them like lead. However, they have been very good in the installs I've seen.
Good batteries are easy to find, cheap batteries are also easy to find. But good, cheap batteries are nowhere that I have found. I have seen one nice motorcycle conversion by Electric Motorsport and I liked it.
ThunderSky LFP-40s would be my choice for a motorcycle conversion. Any voltage.
revolt
Your "cost analysis" overlooks key points
1- When you sell the bike, you have to "convince" the person buying the bike that it is WORTH the extra 2,000 bucks because of "all the mileage" left in those great used batteries, after all, they'll go 100,000 plus miles
2- If you opt to pull them and reuse them instead of suffering the resale loss, you'lll be screwed when the new bikes go 72 and yours is 60 volt pack and your trying to figure out how to mod the pacj and BMS.
3- Now place those factors on the AVERAGE person out there and not the tech head, and the batteries are overpriced at more than 50 cents a watt.
Those have got to be the wackiest, impossible to measure factors that I've seen suggested for a cost analysis! But because I can't resist let's take a look at those points one by one:
1- We're not talking about LiFePO4 as a selling feature for a bike producer. We're talking about LiFePO4 as a buying feature. The question is "are LiFePO4's good value for money?" not "will LiFePO4's help me sell my bike?".
2- (a) resale loss when you sell is the same for any "early adopter" and equates more to the entire bike than the battery pack. (b) why is LiFePO4 any worse than lead when going 72v from 60v?
3- You still don't give any sort of hard data as to why 50 cents is the magic price? Why not 65c or 35c?
You're normally pretty fastidious when it comes to data to back up claims. At least help me out and explain the magic of 50 cents.
Patrick - are you a representative or do you have an affiliation with a LiFePO4 vendor? I agree with your basic position but in this discussion I think it would be reasonable to let people know
(translation: I'm pretty sure you work at ElectricMotorsport, right?)
Ah, yes, excellent point, i should have thought of that in these days of "full disclaimers".
I used to work at ElectricMotorsport with Todd; that tapered off last fall. I worked on that R1/E1 motorcycle conversion - amazingly, it had 28 LFP-90s! I'm still working on motorcycle projects, and there was a large purchase of LFP40 and LFP90 cells to get volume discounts. So I am not a vendor, per se, but there are more LFP40s than we will use. We have these in hand, in the San Francisco Bay Area; they arrived last September. Willing to pass them on for our cost, and shipping costs will be from the US, not China. Same warranty as ThunderSky gives - none. These are nominal 3.2V/cell, have a max of 4.2V/cell, but you probably shouldn't charge above, say, 3.8V. It all depends on the balance of your system components - there is very little extra capacity gained with higher voltages, and presumably this extends cycle life as well.
We are developing a BMS for the TS cells, although it is quite sophisticated, with per cell micro, and central controller. There is another guy who is building BMS for another lithium batt, but it would work well, and I think it's about $100 for a 16 cell unit, with an 8 amp charge limit. You can use almost any charger with enough volts - even a power supply will work fine. Both have LVC (low voltage cutoff) alarms - but it's up to you to hook that up.
So that's where I'm coming from. Not a vendor, and the deal is limited, as we only have so many extra cells. Interestingly, ThunderSky now has an exclusive distributor in the US, International Battery. The bad news is they are selling for $3.25/Ah, rather than the $2 or $2.50 that Everspring was quoting.
Yes, LFP is ready for 60 volt scooters, and 96 volt motorcycles.
I had a good talk today with one of the tech guys at FOXX Batteries and found him to be knowledgeable and helpful. I was inquiring about building a 120 Volt 100 AH pack for a small electric car project. I agree with a previous poster that when 50 cent a watt prices are reached, folks will start converting in mass. My above battery with BMS and a 25 amp charger at current prices would run over $11,000 !! I also found out they are going to be bringing in 200, 300 and 600 AH cells. I think prices will reach 50 cents a watt in the next couple of years. I'd purchase the 120 volt 100AH battery for $5500 right now if it was available at that price. It would weigh 700 pounds less than comparable lead acid batteries, and should last 2000 to 3000 full cycles instead of a few hundred. But $11,000 is just way too much money for fairly untested technology. That's 3667 gallons of gas at $3/gallon, or enough gas to power a relatively efficient car for 100,000 miles.
When I bought my solor panels for the house a few years back, California had a huge rebate on them, $4.50 a watt, that paid for more than half of my system. Anyone here have good friends in Sacramento? If I could get a rebate for 50% of the cost of the Lithium battery, I'd start building my electric car next month.
I'm working on a Honda Civic project now. I could go lead-acid and with a brand that is well used in EV conversions: Exide. In fact Exide Orbital XCDs are almost the standard performance battery of choice now. Sure, I'll spend about $3,000 for 18 of them (16 with 2 spares). Or, I could buy TS LiFePo4 cells. Even if they were cheaper than the Exide Orbitals, it would be a risk that I'm not prepared to take, and Thundersky batteries don't appear to have lived up to their specs in the past. Kind of like a $10 flashlight that I bought. The battery in it was total crap, and I had to spend twice as much as the cost of the flashlight for a good B&B battery ($20). But I trust B&B, and haven't ever known them to produce junk. So for me, the issue is quality not cost. I would be willing to find a way to get the money if I knew for certain that I was buying a well refined good quality LiFePo4 pack that I can determine will live up to its specs. But I can't do that yet. And I also don't know about the quality of a BMS or charger, or the potential of serious battery damage if these fail and potential fires or explosions. There's just too much risk, and for now I'll go with what has just been known to work.
I don't know the specs on the Exide batteries but the Trojan T105 is a 6-volt 225-ah battery that I use to run my house. These batteries are used on a daily basis and lasted me 7-years at a total cost of $1600.oo. You might consider them if they meet your requirements. Here is the set I bought last year.
Chas S.
To set the record straight, there is no risk of fire and explosions with LiFePo4 batteries.
Here is the set I bought last year.
*drools*
 www.BaseStationZero.com |
| THINKING X-TREME? - Do a Google search for "Alpha Products International" first! |
To set the record straight, there is no risk of fire and explosions with LiFePo4 batteries.
Can you reference any papers, or testing done? And, if they have any potential to vent hydrogen/oxygen gas than there is a risk of fire and explosions. This could happen with a charger/BMS malfunction. Although, I admit the Dewalt A123 batteries on the market seem to have a good safety record.
Chas,
I have no doubt that Trojan are high quality batteries. But I'm not really interested in flooded batteries, and the car was setup to have the batteries mounted on their sides. I see that Trojan is selling AGMs now though, and maybe I'll check into them.
Andrew,
You might want to look at the deep cycle Optima Yellow top batteries. Very high discharge current.
Food for thought,
Chas S.
I talked with Mark at electric Motorsport yesterday. He claimed that they are not using a BMS - just bulk charging with a programmable charger and carefully watching the cell voltages the first several charges. Then again, these are experimental setups - not bikes someone is using every day. Considering the cost and the need to get the advertised cycles for the project to be economical, a BMS seems very advisable. My understanding is that liFePO4's are tolerant of an occasional overcharge, but not tolerant of over-discharge, discharge them once below 2.5 volts and they lose have their capacity. So, a low voltage cutoff is needed at a minimum.
1. As far as the economic of lifepo4's some things not considered is that you can't really compare a 40AH lead acid pack with a 40AH LiFePO4 pack at the high discharge rates we need. The 40AH LiFePO4's are probably equivalent to a 70AH lead acid pack at high discharge rates.
At current, through-the-roof prices for good-quality lead acid batteries, the cost for a 48 volt pack in my e-max is about $700 when shipping is included. The LiFePO4's are $1650 including shipping
So here's the calculation:
At 1C discharge, usable kilowatt hrs = 28 (from BB datasheet)*48/1000 = 1.344 kwh for lead acid, but 40*48/1000 = 1.920 kwh for LiFePO4
Life cycle unit cost for lead-acid per watt-hour for 2000 70% DOD cycles = ($700*(500/2000)/(1.344*0.7*2000) = = $1.488 per kwh
Life cycle unit cost for LiFePO4 per watt hour for 2000 70% DOD cycles = $1650/(1.920*0.7*2000) = $0.614 per kwh
The LiFePO4's are 2.4 times cheaper!
2. Then, there is the utility and value factor. A lead acid pack will not give the range needed for some errands I use the scooter for. The LiFePO4's probably will.
Andrew,
You might want to look at the deep cycle Optima Yellow top batteries. Very high discharge current.
The car was set up specifically for Optimas. But, I heard from someone that the quality has gone down, and they are the same price as Exide Orbitals XCD, which can output more power.
I checked, and I can get 18 Trojan 24-AGMs (12v 80 ah) for $117/ea locally. Also, can get 18 Exide Orbital XCDs for $130.44/ea locally.
The price of lead-acid batteries has gone up, but with a large quantity order like this, the price increase isn't nearly as severe. This increases the cost difference for a very large battery pack. While LiFePo4 are becoming much more competitive for small scooters and e-bikes, they don't look as attractive for a very large battery pack. I think I'll stick with lead for now, and wait a couple years.
The following are with tax for me:
Trojan 24-AGMs Qty. 18:
$2247
Exide Orbitals 34XCD Qty. 18:
$2509
PJD - are you going to use Gary and Bob's BMS - it seems like an economical solution and seems very well thought out.
PJD - are you going to use Gary and Bob's BMS - it seems like an economical solution and seems very well thought out.
I think so. The max amps for the pair of FETs used for the LVC cutoff are a just barely enough - 50 amps each for 100 amps. That's uncomfortably close to the 95 max amps teh scooter runs at. I'll inquire about that.
I sent a PM to Patrick about the $80 LFP40's he mentioned above. No response yet.
Well with the kit form you should be able to swap out the FETs for higher power ones, right? I saw something posted in the thread about that (these bicycle riders just don't know what AMPs we really need, eh? ;-))
Something like this should be able to be setup to handle a 60v AGM pack too. Protects overcharge, protects overdischarge and all at a cell level. I know this one is not working in the 12v arena but the concept is the same. Of course if bank charging comes with the bike it is less of a problem too.
"Well with the kit form you should be able to swap out the FETs for higher power ones, right? I saw something posted in the thread about that (these bicycle riders just don't know what AMPs we really need, eh?"
The existing FETS are capable of handling 100 amps with a little extra solder, but actually even this isn't necessary. Instead of wiring the pack through it, one can simply wire the brake cutoff circuit, the contractor relay circuit, controller power circuit or other low-amp circuit that will cut the scooter off at low voltage.
Same warranty as ThunderSky gives - none. These are nominal 3.2V/cell, have a max of 4.2V/cell, but you probably shouldn't charge above, say, 3.8V. It all depends on the balance of your system components - there is very little extra capacity gained with higher voltages, and presumably this extends cycle life as well.
What do you think of the single cell charging schemes that some on endless sphereare using to charge a123 cells? Can the single cell scheme be applied to TS cells? The TS web site indicates a charge voltage of 4.25, but based on what Patrick wrote, that's too much. One single cell charger they use is by VoltPhreak. It's CCCV and made for LiFePo4, but it charges at only 2 amps, and may top out at 3.7 volts. Bank charging an LFP setup takes a lot of wires too.
I've heard mixed reviews of TS batteries, but if they are charged at a higher than optimal voltage then perpaps this has reduced their cycle life prematurely. TS shold lower they charge spec if that's true.
I can't think of a reason why the single cell charging schemes wouldn't work for a TS cell. However, I think the BMS/CMS solution that is coming out soon from Bob and Gary is better because it also has low voltage cutoff (LVC) protection for the discharge cycle. I think it's likely to be very cost effective as well - I think I saw $100 for a kit for 16 cells and the design is very modular.
boy you guys can go on ,,and on and as a newcommer .. none of you have realy answered the basic question !!Were is ustracy when we need um ? as for price , I found 2 mfg. one in china and one in india , at .51 usd per watt VxA == W 60x100=6000 x .51 = $3060.00 , plus the big one , SHIPPING !!! are there any US mfg.s ?? I to would like to see tests and comparisons on brands of lifepo4 batt.
boy you guys can go on ,,and on and as a newcommer .. none of you have realy answered the basic question !!Were is ustracy when we need um ? as for price , I found 2 mfg. one in china and one in india , at .51 usd per watt VxA == W 60x100=6000 x .51 = $3060.00 , plus the big one , SHIPPING !!! are there any US mfg.s ?? I to would like to see tests and comparisons on brands of lifepo4 batt.
I believe he is here: http://www.voltsrider.net/vr/forum_posts.asp?TID=9
But more confidence does not always mean more competence...
And for the newcomer in you: It's NOT a basic question, so there is no basic answer. It's complex.
Mr. Mik
boy you guys can go on
yes we can :)
.. none of you have realy answered the basic question
yes we did (see first reply) :?
!!Were is ustracy when we need um ?
Hmmph! ;)
I think they'd work - but 6 would set you back around $2673.24 so it's not a very good price.
You could get 20 LiFePO4 40Ah cells (for a 60v 40 Ah pack) from electricmotorsport.com for $2000 (33% more power for 20% less money). That's 83 cents per Wh.
Foxx (see another post on this board) are offering cells at $0.95 per Watt Hour - so a 60V30Ah pack would cost $1710. Unfortunately PJD didn't have very good luck with their responsiveness - but maybe that will change?
Not all LiFePO4 batteries are created equal - I don't know the relative quality of any of these three solutions.