R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Reply
 
Thread Tools Search this Thread
Old 03-04-2007, 01:02 PM   #781
Tech Master
 
sportpak's Avatar
 
Join Date: Oct 2006
Location: Ft Wayne, IN
Posts: 1,314
Trader Rating: 26 (100%+)
Default

People on this thread will tell you they live by the hard shell. I can't comment much on actual cell construction, but I do have some real experience. I had a MaxAmps battery that was dented by a small accident. The battery seemed fine, but a $60 battery isn't worth my real scale truck, house, and family. The extra 30% is worth the insurance. A touring car is a hostile place.
__________________
-Tamiya TA05-R - Tamiya M05 - Summit Raceway Ft. Wayne, IN

www.summitrcraceway.com
sportpak is offline   Reply With Quote
Old 03-05-2007, 04:22 PM   #782
Tech Master
 
linger's Avatar
 
Join Date: Aug 2001
Location: Retired
Posts: 1,132
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by 1shnot
......
orion 4800...3200.... and many companies, could some one tell me a st8 answer.. what is the diff between orion 3200 vs other company like maxamp?
just saw on other tread that hard case is "waste" and price diff is very min, but yet capacity is greater...
1shnot - you are asking a loaded question that does not have a simple answer. Let me bore you with too much information. First my rant about how a hard case is not a "waste"
__________________
I used to be a spitter, now I'm a swallower. I graduated.
linger is offline   Reply With Quote
Old 03-05-2007, 04:25 PM   #783
Tech Master
 
linger's Avatar
 
Join Date: Aug 2001
Location: Retired
Posts: 1,132
Trader Rating: 1 (100%+)
Default

HARD CASES ARE GOOD FOR LIPOS!
The internal construction of the high discharge type lipo that we use in RC cars/planes are essentially a bunch of little lipo batteries stacked together in parallel. These batteries are constructed with layers of copper graphite coated anodes and aluminum metal oxide coated cathodes and they are separated by a very THIN polyethylene film. Itís extremely important that the seperator maintains integrity or some of the cathode/anode layers will short out. A LiPo cell is MOST vulnerable at the edges where the seperator is not continuous. A dent on the side of a Lipo may move the seperator and cause an internal short. Sometimes the short burns off a little material, creates a little gas, and you have a puffy cell with less capacity. Othertimes, the short can melt enough of the seperator which causes shorts in other areas of the cell and the chain reaction causes a flame situation. A hard case prevents dents, which prevents internal shorting, which prevents a dangerous situation.
__________________
I used to be a spitter, now I'm a swallower. I graduated.
linger is offline   Reply With Quote
Old 03-05-2007, 04:26 PM   #784
Tech Master
 
linger's Avatar
 
Join Date: Aug 2001
Location: Retired
Posts: 1,132
Trader Rating: 1 (100%+)
Default

I canít make general statements covering all Lipo distributers, since itís usually impossible to find out exactly where each distributor gets all their cells (sometimes from multiple sources and judging from MaxAmps pricing, they get most of their cells from China), but I can share some insight over the price difference:

ďWhatís the difference between an expensive Lipo from a top tier manufacturer and an ďinexpensiveĒ Lipo (usually from China)Ē

Iíll address three areas: Quality, Performance and Safety
__________________
I used to be a spitter, now I'm a swallower. I graduated.
linger is offline   Reply With Quote
Old 03-05-2007, 04:26 PM   #785
Tech Master
 
linger's Avatar
 
Join Date: Aug 2001
Location: Retired
Posts: 1,132
Trader Rating: 1 (100%+)
Default

QUALITY CONTROL:
Quality control is a joke in most China factories. Incoming material inspection, statistical process control, in-process measurements, Hi-Pot testing, six sigma etc are completely foreign concepts. In a lipo cell, the main source of failure is from internal shorts. In most cases, an internal short burns off a little material, creates a little gas, and you have a puffy cell with less capacity. Othertimes, the short can melt enough of the separator which causes shorts in other areas of the cell and the chain reaction causes a flame situation. These shorts may be prevented in manufacturing with good control over contaminants and manufacturing burrs. All the top tier manufacturers will have automated Hi-Pot testing where a large voltage is applied (200-300 volts) before the electrolyte is applied and the resultant current is measured - high current means that something is shorted out. The China factories donít do this. The top tier factories will have specialized equipment to transfer material without exposing it to the environment thus reducing contaminants. The China factories literally use cooking pots and scoop them out manually. I could write a whole book about what the China manufacturers do wrong with respect to quality control, like how they measure coating thickness on a moving roll with a micrometer!!!, but I wonít bore you guys with that.
When asked about their failure rate after manufacturing Ė the China sales rep was proud to say that 0.3% of their cells swell up just sitting on a rack after manufacturing due to internal shorting Ė who knows how many cells are close to shorting out internally. Out of only 1 million cells Ė thatís 3000 failures. I asked a top tier manufacturer the same question Ė they produce 4 million cells a month Ė in 1 year, or 48 million cells later Ė they had a total of 0 cells swell up by themselves after manufacturing. 3000 cells out of 1 mil failure or 0 cells out of 48 million cells failure Ė thatís what you are paying for.
__________________
I used to be a spitter, now I'm a swallower. I graduated.
linger is offline   Reply With Quote
Old 03-05-2007, 04:26 PM   #786
Tech Master
 
linger's Avatar
 
Join Date: Aug 2001
Location: Retired
Posts: 1,132
Trader Rating: 1 (100%+)
Default

PERFORMANCE:

Current Rating Ė Most of the top tier manufacturers are fairly close to their published current rating. I find that most all the manufacturers are a little optimistic in their C-rating. Some of the China cells do live up to their C-rating, but Iíve tested some 20C rated cells from China that are virtually destroyed at a modest 10C discharge rate. Basically, there is no guarantee that a 20C cell from China can really do 20C. Some of the cells from China actually can do 20C and they hold a higher voltage than the top tier manufacturers - due to more volatile cathode chemistry, but at the expense of safety (see the safety section).

Cycle Life Ė the cycle life of the top tier manufacturers is stunning. Iíve tested many cells that perform just as good on their 400th cycle as they did their first. For whatever reason Ė every China cell has a degrading profile, where the capacity drops slightly every cycle. The rate of degradation varies depending on manufacturer. Some donít last 100 cycles, while others are about 80% capacity at 300 cycles. The bottom line is that the cycle life is virtually guaranteed with a top tier manufacturer and itís a crapshoot when you buy a cheap cell.
__________________
I used to be a spitter, now I'm a swallower. I graduated.
linger is offline   Reply With Quote
Old 03-05-2007, 04:27 PM   #787
Tech Master
 
linger's Avatar
 
Join Date: Aug 2001
Location: Retired
Posts: 1,132
Trader Rating: 1 (100%+)
Default

SAFETY:

The first step in safety is a top quality cell construction (see quality control). The elimination of contaminants and internal shorts is good prevention. Iíve tested enough cells to know that there is not a single Lipo cell on the market that can take an extreme overcharge condition without going up in flames. The distributors that show a little video about how the cells ďcanítĒ be ignited through overcharging are sending the wrong message. Give the cell to me, I guarantee you that I can ignite it (except for the A123 Li-Ion cell). The next step in safety is the cell design itself. Most of the China cells use pure LiCo2 coating on the cathode which is the most volatile and also the most powerful molecule. That way, they have a great looking discharge curve for the first few cycles. Most of the top tier cells will have other additives that greatly reduce the volatility and also suppresses voltage slightly. This means that the cell can take a higher temperature before it reaches thermal runaway, and even if it does reach thermal runaway, the resultant flame is much less. Iíve purposely overcharged and ignited China Lipoís and all of them turn into immense flamethrowers that burn for about 30 seconds. When I purposely ignited a Kokam cell, itís chemistry self extinguished in about 2 seconds Ė the flame was an order of magnitude less than itís China counterpart. Furthermore, the Kokam cells use the negative tab as a built in overcurrent fuse. If you short out the cell, the negative tab vaporizes and creates an open circuit.
__________________
I used to be a spitter, now I'm a swallower. I graduated.
linger is offline   Reply With Quote
Old 03-05-2007, 04:27 PM   #788
Tech Master
 
linger's Avatar
 
Join Date: Aug 2001
Location: Retired
Posts: 1,132
Trader Rating: 1 (100%+)
Default

I have yet to visit a ďtop tierĒ manufacturer in China, though I admit, I havenít visited all of them, but Iíve visited enough to understand their pardigm. However, these Chinese factories are evolving at an accelerated pace. These low quality factories may equal the quality of top tier manufacturers in just a few years, but they definitely arenít there yet. Just about every China factory I visited was in the process of building another newer, better factory. Iíve referenced Kokam as a top tier lipo manufacturer. There definitely are more top tier lipo manufacturers and some even have superior manufacturing quality vs Kokam, but their pricing is the same as Kokam Ė which is nearly 4x more than their equivalent China counterpart. The top tier manufacturers admit that the RC market rates price over quality and itís obvious that the low price lipos are now dominating the RC marketplace. The good news is that some of these top tier lipo manufacturers are currently teaming up with top tier RC manufacturers to come out with high quality and high performance packs though I guarantee you that they wonít be able to touch MaxAmps pricing.

So there you have it. Other than the hard case Ė this is why the Peak/Team Orion Lipo is so much more expensive than their competitors.
__________________
I used to be a spitter, now I'm a swallower. I graduated.
linger is offline   Reply With Quote
Old 03-05-2007, 04:39 PM   #789
Tech Master
 
sportpak's Avatar
 
Join Date: Oct 2006
Location: Ft Wayne, IN
Posts: 1,314
Trader Rating: 26 (100%+)
Default

GULP ...That's the most LiPo information I've ever read in one sitting. It's good to hear someone lay it down like that. Thanks man.
__________________
-Tamiya TA05-R - Tamiya M05 - Summit Raceway Ft. Wayne, IN

www.summitrcraceway.com
sportpak is offline   Reply With Quote
Old 03-05-2007, 04:43 PM   #790
Tech Apprentice
 
Join Date: Dec 2005
Location: San Jose, Cali
Posts: 61
Default

Nice report.

On a side note I know you have tried the 4800 in your car but did you ever try the 3200 in your 415?
alang is offline   Reply With Quote
Old 03-05-2007, 05:37 PM   #791
Tech Lord
 
syndr0me's Avatar
 
Join Date: Dec 2004
Location: 5280 Raceway
Posts: 13,143
Trader Rating: 32 (100%+)
Default

Wow, thank you for that, it was very enlightening.
syndr0me is offline   Reply With Quote
Old 03-05-2007, 05:43 PM   #792
Tech Lord
 
Hebiki's Avatar
 
Join Date: Aug 2003
Location: Chino, CA
Posts: 12,919
Trader Rating: 26 (100%+)
Default

Quote:
Originally Posted by linger
I have yet to visit a ďtop tierĒ manufacturer in China, though I admit, I havenít visited all of them, but Iíve visited enough to understand their pardigm. However, these Chinese factories are evolving at an accelerated pace. These low quality factories may equal the quality of top tier manufacturers in just a few years, but they definitely arenít there yet. Just about every China factory I visited was in the process of building another newer, better factory. Iíve referenced Kokam as a top tier lipo manufacturer. There definitely are more top tier lipo manufacturers and some even have superior manufacturing quality vs Kokam, but their pricing is the same as Kokam Ė which is nearly 4x more than their equivalent China counterpart. The top tier manufacturers admit that the RC market rates price over quality and itís obvious that the low price lipos are now dominating the RC marketplace. The good news is that some of these top tier lipo manufacturers are currently teaming up with top tier RC manufacturers to come out with high quality and high performance packs though I guarantee you that they wonít be able to touch MaxAmps pricing.

So there you have it. Other than the hard case Ė this is why the Peak/Team Orion Lipo is so much more expensive than their competitors.
im jealous ling. you get to blow stuff up and light things on fire ON PURPOSE.
__________________
Hebiki Design Works
Custom R/C Vinyl Graphics & Apparel: Your gear, your way!
Web Design - Web Development - Logo Design - Graphic Design
www.facebook.com/HebikiDesignWorks
Hebiki is offline   Reply With Quote
Old 03-05-2007, 06:01 PM   #793
Tech Fanatic
 
kuzo's Avatar
 
Join Date: Jul 2005
Location: Connecticut
Posts: 948
Trader Rating: 11 (100%+)
Send a message via MSN to kuzo
Default

linger - I suppose you must get sick of repeating the same info over and over but I thank you for it. A rational easy to follow explanation of lipo chemistry will eventually win over more users than the usual anti-lipo diatribes will keep people from trying. That was the best overview on lipo differences I've read to date.
kuzo is offline   Reply With Quote
Old 03-05-2007, 08:48 PM   #794
Tech Addict
 
c1 racin's Avatar
 
Join Date: Nov 2002
Location: Gulfport, MS
Posts: 608
Trader Rating: 8 (100%+)
Send a message via ICQ to c1 racin Send a message via AIM to c1 racin Send a message via Yahoo to c1 racin
Default

Quote:
Originally Posted by kuzo
linger - I suppose you must get sick of repeating the same info over and over but I thank you for it. A rational easy to follow explanation of lipo chemistry will eventually win over more users than the usual anti-lipo diatribes will keep people from trying. That was the best overview on lipo differences I've read to date.
This will win more users over also! $70.49

__________________
NeXusRacing.com
MurnanModified.com
MobileRCRacing.com
c1 racin is offline   Reply With Quote
Old 03-05-2007, 09:01 PM   #795
Tech Champion
 
Join Date: Jun 2004
Location: St Louis
Posts: 7,868
Trader Rating: 198 (100%+)
Default

Very good info to say the least. China is a very big problem with manufacturing in general right now. The price is usually low and the quality is low also. Just go to Walmart. You will see.
__________________
Please become an organ donor.
www.donatelife.net
Custom decals and Sno-Tee'z, T-Shirts by Sno Camel
dodgeguy is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
NIP Team Orion 3200Mah Lipo Race Pack limbohz R/C Items: For Sale/Trade 0 05-30-2008 10:36 AM
Peak 3200mah carbon spec lipo aus jd 2703 Australia For Sale/Trade 8 04-23-2008 09:12 PM
Team Orion Carbon Edition 3200mAh LiPo squearl R/C Items: For Sale/Trade 7 03-11-2008 06:35 AM
Team Orion Carbon Edition 3200mAh lipo batteries dido41 R/C Items: Wanted to Buy 3 07-26-2007 04:10 PM
2 Team Orion Carbon Edition 3200mAh LiPo Batteries CCristo R/C Items: For Sale/Trade 1 05-04-2007 11:48 AM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 12:39 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net