aaronski said:
I have a similar pack, 1 dead cell. I Think I'm going to solder a jumper across thecell, cut t he tabs off and just leave it in the middle and make it 5s. I did that with my Lifepo4 pack when a cell went bad. You'll get less speed, but save money. I guess that choice is up to you.
as for chemistries? each has it's user:
Poor and or reckless: Lipo, cuz your gonna break it anyway, and it's cheap and powerfull. Cycle life doesn't matter.
Rich and performance: a123- why not? it's got the power and it won't catch fire.
Commuter
ing pack. low c rate, cycles and distance are most important.
I'm lucky to get 100 cycles before I short/leave on over the weekend/screw up something else.
I've got to say this is a misconception.
I was a hard sell too when I first looked at LiPo, but just look at all the testing, experience and expert knowledge that someone like LFP, and many others here!
What you're saying
IS generally true of cheap LiPo, but if you buy quality packs, AND treat them well, not only will you get as much life as you want, you won't have the same voltage sag that is common of the cheap stuff. (1000's of charge cycles are very possible if you are kind to them)
IMHO, you get what you pay for, and buying cheap LiPo is like any cheap throw-away product, if you have the attitude "it's gonna break anyway" and expect to replace things often, then you're getting what you paid for.
I have heard many a story of HK LiPo packs that are DOA or have a weak cell, or don't perform well in the really cheap stuff, I have yet to hear the same thing about any of the higher quality packs to include the Turnigy Nano Techs (there are other high-end brands, but these are the latest advancement in technology).
LiPo can be dangerous, but only if you don't respect it, it's far less dangerous than gasoline any day! The worst that has ever happened with mine has been when I wasn't paying attention and let some contacts short, and I have had to replace connectors, but never have I seen a big problem.
I have noticed that if I am not using them hard enough, they tend to get out of balance easier, and when I wring them out a bit, not abuse them but take them beyond say, 70% DOD, they stay balanced much more. 8)
I have lots of time on my hands, and I tend to sweat the details a bit much, so I like to balance my packs down to 0.02 if I can, but if I wanted to just run them, I could easily balance charge once a week or even every two weeks, depending on how often I am riding.
All batteries will live a short life no matter what they are if you run them down to nothing too many times, and this is where LiPo has some danger involved, but it's really easy to have a controller & CA with a LVC, and even better a set of the LVC/HVC boards mentioned, they don't have any way to drain enough off the cells to ever hurt them, and will disable your throttle if you get close to a dangerous low or high voltage.
If LiPo is still sounding too much of a hassle, there is nothing at all wrong with LiFeP04, but to say they are just as powerful is just showing you haven't tried some yet. :wink:
Sure there are powerful LiFeP04 batteries out there, and IIRC there is now what, 30C Prismatic cells now from A123? I will never need much more than 20C for my commuter, but if you want to say who has the most power available, check out these 65 c -130C Nano Tech! (with a 5AH pack, that's 325 amps constant, 650 amps burst!
)
http://www.hobbyking.com/hobbyking/...y_nano_tech_5000mah_6S_65_130C_Lipo_Pack.html
for about $500 shipped you have a 12s 10Ah pack (about 46V) and add another $100 for a decent power supply & charger, and you have something WAY more powerful than anything LiFeP04 can even offer!
When was the last time you saw a LiFeP04 pack do this!
(and IIRC, this was last years "weaker" 45 - 90c Nano-Techs!
)
[youtube]WkKRqaNPIBE[/youtube]
And don't get me wrong, LiFeP04 is great, you can generally plug it in and go do something else, but if you short a high out-put battery, no matter the chemistry your fingers are no less Kentucky Fried!! :lol:
If you say "I just want to plug it in the wall" and don't want to build a pack?
Here is the SAME chemistry (I'm sure it's not the exact same formula, but it's the same family of the Lithium Cobalt as the Nano Tech LiPo) and it's plug and play! (36V 12 AH) It even has a *gasp!* BMS too!!
http://www.ampedbikes.com/tubebattery.html
I haven't had the opportunity to play with one of these packs yet, but I should soon in the next couple of months, and I would not be surprised at all if this battery puts out very similar performance to a typical 48V Ping or similarly priced LiFeP04 pack. Even at the lower voltage, it's going to have much higher C rate, and it's a plug it in and forget about it kind of slow charging system with the BMS built into the battery (not what I would use, but it requires none of the extra work building a pack from a HK LiPo packs).
I mean, if all LiPo is equal, why is a major manufacturer selling "dangerous LiPo" to "Joe Average" consumer who just wants a simple and easy to use E-Bike and not learn all about it?
Just my $0.02
