Power in Flux
Likes Likes:  0
Page 1 of 4 123 ... LastLast
Results 1 to 10 of 37

Thread: I see a Lithium battery dead end looming -- have you figured out the workarounds?

              
   
   
  1. #1
    Senior Member
    Join Date
    Aug 2010
    Posts
    137
    Post Thanks / Like

    I see a Lithium battery dead end looming -- have you figured out the workarounds?

    Sparky's saga mirrors mine. I'm going to Sealed Lead Acid "pure lead" high discharge rate AGMS's because I can see a total dead end with Lithiums of all types: Unless you have a cell-level battery analyzer (like the ones for lead acid), you can't measure Capacity. And, if you can't measure pack/cell capacity, you won't know which of the battery, or batteries, in the series is causing the entire battery bank to underperform.

    For example, right now, our Native Z6/Z6000 electric scooter shows 55-57 volts. But the bloated cells (damaged, read earlier thread) won't move the bike.

    I had a similar experience with my Montague electric bike, with SLA's two years ago: Full voltage on both batteries, but one had nearly zero capacity, as measured by a 12V battery analyzer. Although our investment in battery analyzers has been $1500, we've recouped some of that cost by charging $10 to test batteries in our town. Also, we're still riding electric 'scoots whereas those who don't have expensive battery analyzers have junked their bikes. Hence, I see a dead end for Lithium bike experimenters, or "paying Beta testers" aka some EMS electric motorcycle owners.
    http://www.gnbsystems.com/testers_rc300.php
    http://cpc.farnell.com/1/1/54466-sla...ct-meters.html


    Questions for people in this forum:

    1) How many miles have you gotten out of your Lithium pack, and please specify brand and model.

    2) Are you running with/without a cell-level battery bank equalizer? What are your conclusions?

    3) I read that the read-world range of a Zero electric motorcycle is only 26 miles; whereas, the Vectrix got 65 miles. Why would you buy a $10,000 Zero bike that is, according to some reviewers, not suitable for highways?

    4) If "battery doping" by the battery genius Deafscooter allowed him to get 45MPH from a 24volt bike, why can't some small company buy his knowledge and sell products/kits/chemicals to every electric moto owner?

    5) Does anybody know where I can get a 48V "bad boy" charger?

    Thanks for all replies.
    Last edited by NonPolluter; 09 February 2011 at 1941.

  2. #2
    SMPS Engineer BaldBruce's Avatar
    Join Date
    Aug 2010
    Location
    Cleveland, OH
    Posts
    487
    Post Thanks / Like
    Pretty simple rules for Lithium. Design your pack to be larger than you normally use in AH so you don't push them and keep the C rate reasonable. Monitor the per cell voltage so your system shuts down before you hurt them.
    I have not failed. I've just found 10,000 ways that won't work.
    Thomas A. Edison

  3. #3
    Not to be taken seriously DaveAK's Avatar
    Join Date
    Aug 2010
    Posts
    2,240
    Post Thanks / Like
    I'm not sure where you're getting your information, but I think you might be jumping to some wrong conclusions.

    1) Zero. My bikes not on the road yet, but I'm hoping for 50ish miles, and expect that to be a reasonable estimation, give or take. CALB 60AH LiFePO4.

    2) Not sure what you mean by battery bank equalizer, but I'll be using a MiniBMS for both cell level LVC and HVC. Not expecting any problems with it.

    3) I've heard nothing about the Zero range, but they make more than one model and have new versions out for this model year. As for the Vectrix I heard it was more like 30 miles, and had more than its fair share of problems mostly battery related.

    4) I bet I could get 45mph from a 24V bike without being any kind of genius, deaf, dumb or blind.

    5) eBay?

    A good BMS will solve your problems. A bad one will make things worse for you. You'll get plenty of opinion on what's good and what's bad, and that's where you're going to have to educate yourself. If you can't navigate that minefield then certainly SLAs are a safer option.

  4. #4
    o_O
    Join Date
    Aug 2010
    Location
    Austin
    Posts
    431
    Post Thanks / Like
    SLAs are inferior to LFPs in most aspects.
    • Leads are heavier for the same amount of stored energy (lower energy density).
    • Leads can only be discharged to ~50% before they suffer plate damage, so not only is the battery heavier to begin with, you can only use half its capacity. Deep discharge leads can go lower since they have thicker plates, but they will suffer damage with repeated deep discharges. The downside with deep discharge leads is they cannot deliver the high current of regular leads.
    • Leads have a cycle life of ~500 normal discharges (50% DoD). LFPs: ~2000 cycles at 80% DoD.

    The only significant advantage leads offer is higher discharge capability. Combine low capacity with high discharge and the pack won't get you far.

    There are a number of successful LFP packs in operation with many, many cycles on them. EMS doesn't have any despite their claims. They just don't know how to properly design packs for longevity. They push the cells too hard in every regard and it's no surprise your pack developed bad cells.
    My GPR-S originally came with a lead pack. I got less than 100 cycles out of it before it dropped to less than 50% of original capacity. EMS configured the bike to draw way too much current with undersized cells. That should have been a warning to stay away from any of their battery packs. The LFP pack I got from them lasted a couple hundred cycles (hey that's twice as long as the lead pack ). Hindsight 20/20...


    Quote Originally Posted by DaveAK View Post
    A good BMS will solve your problems. A bad one will make things worse for you. You'll get plenty of opinion on what's good and what's bad, and that's where you're going to have to educate yourself. If you can't navigate that minefield then certainly SLAs are a safer option.
    Well said. Unlike the motto "even bad sex is good sex", a bad BMS is much worse than no BMS. The Mini BMS is designed well and does a good job. There are ways to get by without a BMS on LFPs if you're intimately familiar with the specific manufacturer's chemistry. That entails sacrificing capacity and operating in the 20-90% range and periodic manual checkups. It's tough to sacrifice capacity on space-constrained 2-wheelers, but if I had to do it over again I'd gladly make that compromise and still have healthy cells.
    Last edited by chef; 09 February 2011 at 2254.

  5. #5
    Senior Member
    Join Date
    Aug 2010
    Location
    Pacifica, California
    Posts
    3,099
    Post Thanks / Like
    The only information that I can add is that my first GPR-S, with its 20-cell 50Ah Hi Power battery pack seemed to perform just fine for the first 300 miles - when the BMW melted down. The battery pack was able to get me the 35 miles home from my dealer with power to spare and voltage drop in the pack when I arrived home was still above the nominal 60 volts (it was 68 volts fully charged) for a 20-cell pack.

    My next sepex GPR-S, with its 24-cell 50 Ah Hi Power battery pack also made that initial trip with no problems, using 33 Ah during the 30-mile ride. I later ran it down once to 40 Ah before the pack sagged just to get a feel for the maximum range. I then typically would run the pack for 25 Ah (maximum) before returning home and recharging. The pack lasted for 1300 miles and maybe was recharged as many as 80 times, before it started to act strange. Up until the time the only symptom was noticeably less performance than my original RT-motored GPR-S, even when new. However, I still suspect that some of my batteries were damaged before I even took possession of my bike. It had about 200 miles on the clock when I bought it (even though the manufactured date of January 2010 on the headstock is a week before I the purchase date of January 10, 2010) and the voltage of the fully-charged pack was only 78 volts (I now know it should have been 81 volts). Later, when I inspected the batteries, I noticed that they were all covered with dust and were discolored as if they had been sitting around for some time before being placed in service.

    So my thoughts are that perhaps these batteries have lived a hard life traveling from the factory in China to the US distributor, to EMS and finally being installed into the vehicle. They may have been improperly stored and may also have been placed in service in some other application before being installed in my bike. I also note that the batteries were all built at the factory during the summer of 2008 and that the Hi Power importer says that the batteries are no longer available in the US any more. So my bottom line is that the problem may not be the LiFePo4 battery technology, but improper shipment, storage, initial charging and incorrect initial use of the batteries in the vehicles using these batteries.

  6. #6
    HighlanderMWC
    Guest
    6200 miles on a Brammo Enertia. So far no signs of any reduced capacity.

  7. #7
    Senior Member
    Join Date
    Aug 2010
    Posts
    137
    Post Thanks / Like
    Quote Originally Posted by DaveAK View Post

    4) I bet I could get 45mph from a 24V bike without being any kind of genius, deaf, dumb or blind.


    If you spend a few hours watching all of Deafscooter's achievements on many videos, you'll see that he is the "Dr. Werner Von Braun" (the rocket scientist) of lead acid battery doping.

  8. #8
    Senior Member
    Join Date
    Aug 2010
    Posts
    137
    Post Thanks / Like
    LIFEPO4, like the Electric Motor Sports GPR-S and Native Z6000 scooter, look good on paper. Real world experience is a nightmare, compared to just buying even a cheap 50cc Chinese scooter, like the one I had two years ago.

    Here is the real-world experience with Thundersky batteries, and the extremely time consuming data-logging, repairs, drilling bloated cells, hacksawing into battery trays, etc. necessary simply because consumers can't buy a cell-level battery analyzer:

    guity's gpr-s experience 1 2 ... 13 14
    Last edited by NonPolluter; 11 February 2011 at 1121.

  9. #9
    Not to be taken seriously DaveAK's Avatar
    Join Date
    Aug 2010
    Posts
    2,240
    Post Thanks / Like
    You seem fixated on a cell-level battery analyzer. What exactly do you see as its function, and what makes it necessary? You must be talking about something other than a BMS that will give you LVC and HVC protection and/or a datalogging cell-log that will track voltages, all on a per cell basis.

  10. #10
    Senior Member
    Join Date
    Aug 2010
    Posts
    137
    Post Thanks / Like
    Quote Originally Posted by DaveAK View Post
    You seem fixated on a cell-level battery analyzer. What exactly do you see as its function, and what makes it necessary? You must be talking about something other than a BMS that will give you LVC and HVC protection and/or a datalogging cell-log that will track voltages, all on a per cell basis.

    A Battery Analyzer is a diagnostic tool. You connect them to the terminals, and the readout tells you the Ah capacity, regardless of the State of Charge. In other words, you get the answer you need in minutes, without having to even turn the electric bike on.

    The drawback with most of them is that they need to rest, after doing three or four, because the tester gets a little hot, and inaccurate.

    Here are inks video clips to two models that I do not own:
    http://www.dailymotion.com/video/x6d...urate-bat_news
    http://www.youtube.com/watch?v=ezahuellCn0

    Note that these video clip are informercial by the sellers.

Page 1 of 4 123 ... LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •