GoldenMotor.com Forum
General Category => General Discussions => Topic started by: dray on August 01, 2007, 05:38:33 AM
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I am thinking of trying out some of the 36V Lipo batteries has anyone tried them out? ;D
Wonder how many miles you could get out of the 50 AH?
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If you knew your business you would already know that no one except the factory has "tried out" the LiFePo4 batteries from Golden. However, there are builders in the UK who have tried them out and like them. Why don't you try and sell one to them?
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Lots of reports on Endless sphere about vendor confusion over the difference between LiFePO4 and lithium polymer. Apparently some have incorrectly marketed Lithium polymer packs as LiFePO4. I'll leave it up to you whether that was inadvertent or deliberate.
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Can't help you there... same enclosure as the one, however, now being tested by Golden.
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Endless sphere?
Are they mislabeling or selling under false pretenses?
I thought the lifepo4 were a typo for lithium polymer.
What are the differences?
I bought space in a container a few years back for lithium polmyer rc batteries. But soon after they came out with higher discharge models. Are the lifepo4's a high discharge or?
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Ahh endless-sphere.com, found it, thanx there is a wealth of information there!
I had been looking at the dewalt and other rechargables that are lipo, but lol I cant spare the batteries, I use them all day at work. If I were to fry them I would have to buy replacements immediately
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No, endless sphere wasn't misleading anyone. In fact the business owner doesn't even do much volume in e-bikes. From what I can gather, the business owner made the forum when the VisforVoltage forums took a nose dive after a major crash. It is an open discussion on e-bikes, e-scooters, e-motorbikes, e-whatevers. They have forums covering battery technologies, e-bikes, a business forum, etc. It seems like a pretty good resource. Of course, they have flame wars over there too ;D.
There is a lot of confusion among all the possible lithium ion chemistries out there.
Lithium Iron Phosphate is a newer chemistry which actually has a lower energy density than the older Lithium Cobalt and Lithium Manganese chemistries. It also has a lower specific cell voltage than other lithium chemistries. For a 36V pack you need 12 cells in series with it, instead of 10 cells in series for most other lithium chemistries. Its purported advantages are no/limited self oxidation, and a much higher cycle life. Most lithium ion chemistries self oxidize over time, and reduce their storage capacity. Often this leads to a battery with only 1/2 the storage capacity after just 1 or 2 years, whether it has been used or not! The cycle life of Lithium iron phosphate is thought to be equal to or better than the "emoli" chemistry (lithium molybdenium?) first introduced a few years ago. The emoli was one of the first battery chemistires to reach into the 2000 cycle life range. The iron phosphate chemistry also is very resistant to the catastrophic fires that prompted computer battery recalls in the last few years. Over on endless sphere there is a battery technical forum with a thread comparing the different battery chemistries.
Lithium Polymer usually refers to a polymerized version of Lithium Cobalt or Lithium Manganese battery chemistries. The polymerized version allows those prismatic cells rather than cylinders.
I don't know which vendors had sold Lithium Polymer packs as LiFePO4. You can browse over there and look into it more if you'd like.
-Mike
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Yeah, the DeWalt 36V packs are the LiFePO4 chemistry. Long cycle life, deep discharge. High up-front cost. The packs actually only have 10 cells in them, so they don't actually give you 36V. The fully discharged voltage is around 2.2V to 2.0V per cell, so a low voltage cutoff of about 22V is needed to get all the juice out of them. With the current Goldenmotor controller cutoff set at 31.5V you are leaving some capacity out of reach.
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According to batteryspace.com, they are two different types of batteries
Lithium Polymer
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3326
LiFePO4
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3071
I may be wrong in my assumption, but maybe they are the same and I am reading it wrong.
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They are definitely different chemistries. As I noted earlier, Lithium Polymer is usually a LiCo or LiMn chemistry.
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I've done research about lifepo4 since I read about them two years ago.
lifep04 is the chemical name for "lithium iron phosphate". The best known version is the used in the dewalt 36v battery packs. They buy them from a123systems, and the cell is called an M1 cell.
lipo stands for lithium polymer and refers to the encasement of the cell. The lipo's use a plastic bag to contain the cell, reducing weight. All of the lipo's I've seen are lithium cobalt something (I believe there are other materials in them besides lithium and cobalt), but there is no reason there couldn't be a lifepo4 in a plastic cell configuration.
Lithium iron phosphate have quite a few advantaged over the cobalt variety of lithiums. The largest being calender life. The lithiums currently used in cell phones and laptops have a 2-3 year lifespan whether you use them or not. Anyone who has used a modern laptop can attest to this. After two years, your supposedly 4 hour battery barely makes it 1 hour.
The second major benefit is that they don't explode like the cobalt cells do. Try going to video.google.com and look for "exploding laptop" or "exploding lipo" and you'll see some truely scary stuff. I personally wouldn't want to be going down a hill, have a cobalt cell overvoltage from feedback from the motor and have it explode... OR even worse, be in an accident with a car and be pinned to a ruptured cobalt cell.
The lifepo4 cells won't do these things. They have pictures of them being drilled without explosion, and individual cells have been exposed to 30 volt charges without explosion (I think the cells died... but they didn't explode)
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Thanks for the backup, dlantz.
EV Tech had a fire in their workshop a few months ago due to lithium batteries overcharging. Wiped out much of their bike inventory along with the building damage.
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Wonder if anyone has tied to use LiPo's (http://video.google.com/videoplay?docid=3690260570423705609&q=battery&total=20995&start=0&num=10&so=0&type=search&plindex=3) in place of gunpowder...? Hummm ...and for that matter I wonder if anyone has tried to build a battery with ammonium nitrate?
...and a Google search reveals:
Abstract
Plasticized chitosan-proton conductor polymer electrolyte films were prepared by dissolving chitosan powder, ammonium nitrate (NH4NO3) salt and ethylene carbonate (EC) plasticizer in acetic acid solution. The highest conductivity of the chitosan-salt with 40 wt.% NH4NO3 in the film at room temperature was 8.38 ± 4.11 × 10?5 S cm?1 and this increased to 9.93 ± 1.90 × 10?3 S cm?1 with 70 wt.% EC. Batteries with a configuration of: Zn + ZnSO4·7H2O/18 wt.% CA-12 wt.% NH4NO3-70 wt.% EC/MnO2 provided an open-circuit voltage of 1.56 ± 0.06 V. The discharge characteristics using a 1 mA constant current demonstrated a capacity of 17.0 ± 2.6 mAh. The internal resistance was 29.8 ± 5.1 ?. While the highest power density was 8.70 ± 1.91 mW cm?2.
Keywords: Chitosan; Ammonium nitrate; Ethylene carbonate; Polymer electrolyte; Proton battery
...next question is: do they explode...?
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Humm, let's take a look, Ammonium nitrate- a common fertilizer and also used in AMFO (Ammonian Fuel Oil) for blasting.
Ethylene carbonate- ethylene, a colorless gas that is highly flammable in concentrated form.
Yep, you could have a good blast off if conditions are right. I wonder what terrorist may do with a Lipo battery on an airplane?? :o :o
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I purchased a Li-ion 36v-13ah battery which the company built to my specs,they wanted to know discharge amps,etc.,and in 30 days shipped it to me. Cost was about $400 with shipping. It was very light and compact. However in about 6 months the charging circuitry failed in it,a costly experiment...
As wintnessed with the constant recalls of millions of laptop batteries from over-heating and fires during recharging I'm not convinced these batteries are reliable yet. Now I don't have any info yet on how reliable or durable the new Lifep04 batteries are yet,I would be interested to know. Has anyone out there tried one yet or have anything to report?
For now I think my next battery pack will be Ni-MH,no circuitry to fail or charging problems,and they are getting fairly cheap.
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Check out a123.com (http://a123.com). Maybe they could help you out with the new batt chemistry.
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Check out a123.com (http://a123.com). Maybe they could help you out with the new batt chemistry.
a123systems batteries are probably out of your price range. The 3.3V 1.1AHr cell costs $10@100pc with tabs welded on. It can deliver 30A continuous and 70A peak as I recall.
The 2.2AHr cell costs twice as much and can put out 60A continuous and 100A peak.
They have the side benefits of being intrinsically safe and only lose 10% of their capacity after 1500 100% discharge cycles.
a123racing.com (http://a123racing.com) has actual electric vehicle testimonials and youtube has safety test, electric dragster and electric motorcycle videos using the A123 cells.
Dan
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Well it doesn't look like we will have to wait very much longer. Gen.Motors is going to use a hybrid system in the next gen of Trucks/SUV to increase gas milage 20% or more using a123 technology as early as mid model year 2008. Then we just have to wait for totaled suv's and trucks at the local wrecking yards! ;D 8)
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::) humm... now where did I put the copy of "Praying for Sheetrock" ...by Malissa Fay Greene?
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Good one myelectricbike! LOL