EricTyrrell

LiFe typically has a slightly less energy density than LiPo which translates into either a slightly heavier battery or less capacity. If extra capacity, less weight, or higher voltage is truly needed then I think the decision is obvious. However, in many cases the extra energy density only results in wasted power due to traction loss, or money due to broken parts. If the energy density of LiFe fits your needs then you also get all the inherent advantages of LiFe. Those advantages are: Higher charge rate, higher discharge rate, more charge-discharge cycles, lower or no low voltage cutoff, and a more stable chemistry. You have to choose which of the characteristics are right for your application.

nitrosportsandrunner

my 3s 30c 3000mah lipos are hardly warm after being fully discharged(about 20 minutes of runtime in my VXL)
so, maybe they get to 110 degrees. but no more than that. thats alot lower then my nimhs used to get. and its certainly a safe temp.
and my lipos are by no means "high grade" they only cost $25 each. i would assume that higher quality packs may run even cooler.

Brainanator

My Feedback: (1)

my lipos have never warmed up in my slash....always ambient temp.

Access

Actually LiPo is everywhere today, it's replaced the classical Li-Ion in a lot of the smaller devices. PSP, blackberry, many of the smaller devices are using LiPos now. LiPo will last as long as it does, until something better comes along. People who believe LiPo is unsafe are probably already using it and just haven't realised that.

cummins driver

My Feedback: (31)

Its everywhere right now. Give it a couple of years. LiPo has a lot of compomises as far as safety goes IMO. Its just that people are willing to deal with it because they provide good power.

As for them being used in cell phones and things. Why do they not have to be balanced, with low voltage cutoffs and all that stuff in phones? Or is that built into the phone somehow? They are also not as much of a performance battery as what we are running in our r/c's. "run time" and enough power to do the speakers and screen is about all they have to do. I still dont know a lot about the subject, but it seems they would not be near as dangerous if something did go wrong. I guess just call me anti-lipo, but I leave my r/c's and batteries in my truck a lot, and sometimes it takes me a while to get around to charging batteries back up after running. I just wouldnt feel nearly as safe using lipo. There is a reason people charge them in Ammo cans and lipo sacks, and its not for the looks

Eric

Slo-V Flyer

As for electronics such as phones etc, a lot of the batteries are not your simply r/c style setup ones. They have internal circuitry that helps protect low voltage and probably addresses the balancing issue if it is that sophisticated. Then again those cells probably don't see 50 amp bursts or even the kind of punishment r/c lipos do, so that may help the balancing part, Oh and they often use slower wall charger so it helps reduce the chance of becoming unbalanced further (not that it can't happen).

With that said, they opted NOT to use lipo for hybrid cars for now, due to the very dangers listed on this thread. Though it would theoretically double the MPG a car would get over Nimh batteries they use now (near double the energy density for a given volume). Funny though, Nimh have their own balancing and heating issues but they're still used in cars. Oh and their performance will degrade quite a bit I imagine over the hybrid car's lifetime. I hear some companies are looking at and working with A123 cells to get better performance out of hybrids.

Access

Well there are 'management' ICs in the battery that handle the charge, discharge, sometimes current limit and even coulomb count as the battery charges / discharges. And another IC in the charger probably. Also they are primarily single cells (3.7V) so no balancing is necessary. But beyond that IC it's basically the exact same battery that goes into our RCs, same discharge properties and all. You put a nail through it or put it into a fire and you get the exact same effect. Every once in a while you hear about a faulty batch of ICs (counterfeit, etc.) from China that causes a recall of the batteries in question.

And I would _not_ want LiPo in a hybrid car or any kind of personel vehicle I was riding / driving in. Those typically run 200-400V motors and a bunch of LiPo in your trunk or such would put not just you but anything you hit at risk when you have a 100-cell pack or better.

elpurete

Wow... reed some news... A123 is creating a big giant Assembly plant plant (old news) EDITED!!!
http://blog.mlive.com/svengustafson/...onia_will.html

Already launched news about a FIAT 500 A123 powered 2012
http://earth2tech.com/2010/03/22/chr...ium=navigation

A lot of invest on the battery field... even help from US goverment, so A123 here we go!!!

Tha chrysler already have selected A123 as the battery supplier for their vehicles... amazing!!!

OK... so more production, cheaper batts...

Access

elpurete that is old news and it is just an assembly plant. They don't actually build the cells, they get the cells shipped from China and put them into an assembly or something like that, if I remember correctly.

Another reason LiPo would be kept out of cars is the cycle life, A123 or LiFe in general is better for that type of application.

BigTb17

Someone mentioned that Li-Pos haven't changed over the years (and aren't inherently any safer), it's just that chargers have balancers now. However, cell construction and chemistry has constantly evolved. They are continuously being improved, allowing them to charge and discharge faster, as well as provide lower danger risk. The technology still has inherent risk, but they are safer than they were initially. Many Li-Po batteries now have 5C charge ability according to the manufacturer (I wouldn't personally charge them that fast, but they supposedly support it). Li-Po batteries have improved a lot over the years.

Not trying to talk anybody into Li-Po or anything. Just wanted to point out that they have improved over the years.

Slo-V Flyer

Yeah I didn't think about it at first, but lipo batteries are supposed to have a lesser life cycle than even Nimh if I remember. Of course I think the chances of me getting more than 50 cycles out of a Nimh pack with my luck are probably astronomically low.

And yes I was mentioning news that is probably 4 years old when I mentioned that some car companies are looking to A123 to source hybrid car batteries. So hopefully we will see this A123 cell usage coming to more and more main stream hybrids here in the US (Honda/Nissan/Toyota/GM). Last I read they're still mostly using Nimh.

Access

Mainly b'cos of cost I thought. It's the old problem of volume, you need volume product to drive down costs and you don't have any volume customers yet b'cos it costs too much. Someone needs to be first and many products go years or spend their whole lifetime waiting for that first volume customer to drive price down to make it a viable product. There's really no telling what will happen, execs are always looking to 'leapfrog' if possible so sometimes a whole generation of tech can end up skipped over when the next big/best thing comes along and someone bites right away.

Lilredmachine

Uh huh. Where on Earth did you get that idea? Nitro is easy. Put fuel in, twiddle some nobs and generally it runs for a while. Fill it back up and off it goes again, at least that is my experience of nitro. Even racing it's pretty similar, used the same Force .21 in a buggy for two seasons of races without opening it up or even changing a glow plug. By the time you get to 10 gallons the motor's probably knackered so you fit a new piston and liner and go again, that's about the limit of nitro maintenance. I'm not one of these 'OMG NitRoZ sO hArd tO TuNe N baLLer To ruN' types. For me electric has always been more complex, geeky if you will.

Compare that to my experience of electric racing back when I was running mod, changing brushes EVERY 3 5 MINUTE RACES and tearing the motor down to perform a comm cut on a motor lathe every 6 runs. Constantly cycling NICD and later on NIMH packs to avoid them dying from the massive draws placed on them, having cells vent or pop like miniature shrapnel grenades. Finicky gearing that will leave you slow on the straights one tooth down and burning hot one tooth up... The speeds were too much back then, for the tech at least. People forget how easy they have it nowadays with brushless and lipo, zero motor maintenance and trouble free batteries (apart from the apparently MASSIVE hassle of plugging in a balance charge plug every few runs and the apparently MASSIVE difficulty in allowing the brushless esc to judge when the battery is flat).

Bah. Man up. Nitro tuning is piss easy, electric is a whole different story. Would you have started 14 different threads to pick a nitro fuel? No.

cummins driver

My Feedback: (31)

Nitro has always been easy for me too. I guess thats why im so confused with this electric stuff

Access

Old electric was a mess and it was artificially made by ROAR to stay that way. Brushed motors, NIMH batteries, etc. any new tech was made illegal by ROAR. The goal of ROAR was basically to confine electric to a little space off to the side of nitro, more of a novelty and a pain in the %#! than any real racing. Bashers and club racers led the way, ROAR basically had to be dragged kicking and screaming into the new century, it wasn't until they were faced with irrelevency that they started to allow brushless motors, sintered (not bonded) rotors, LiPos, etc. Now with SCTs and such electric is becoming the growth of the racing side of the hobby, rather than old standbys like 1/8th scale nitro 4wd buggies and truggies.

Things irl are both incredibly complicated and incredibly simple. Modern electric is like that. It can be simple but once you get into the fine tuning, it gets quite complicated, very quickly. Doesn't mean it takes a lot of time though. Maintainance, etc. with modern electric can be reduced to almost nothing.

Jeremy Z

LiPos have been out for many years already. We had them in planes before cars. I would say they've been out for at least 6 years now. They keep getting better & cheaper.

I'm not sure what he means by zip charging from a car without a charger though.

LiFe may also get better, cheaper, and more popular. elpurete's post really made some good points.

However, with hardcase LiPos, there's really not much danger of damaging them from hard physical use. Originally, only foil case LiPos were available, because they were adapted from the plane world, where the extra weight of the case really matters. They are just foil & shrink wrap.

Preventing over charging is not hard. Just use a LiPo charger and balancer. It is just like saying you have to be careful to put the right fuel in your nitro car. It is assumed that you will do the right thing.

Preventing over-discharging is as simple as plugging a $3 low voltage alarm into the balance tap. Yes, it is one more connection to worry about, but it is not a big deal for the huge gain in performance.

If you've decided to go with LiFe, that is fine. There seem to be some definite advantages / compromises. But there's no need to over-state the inconvenience of LiPo just to make yourself feel better about accepting lower performance.

What I like to do is keep all my NiMh packs charged. When I'm just going out for a quick bash, I grab the NiMH packs. Just plug them in and go. When I'm going to be driving for longer or on a track where I'd need the extra performance, I bring them all and use the LiPos first. It takes maybe an extra 20 seconds to plug in the low voltage alarms.

on_your_six

My Feedback: (11)

We have done some battery destruction testing recently... it really is very hard to physically damage the batteries and keep them smoking.

Seems as if the only way to really make them spit fire is to way over capacity charge them.

I have found lipos safe and easy to use, with over three years of experience, I have not had a problem. There is a learning curve, but it is not that difficult.

wasp26jim

WOW this is sweeet, I never knew this was available. Does it show the voltage drop during a power surge?

stuffer

My Feedback: (11)

haven't read the entire thread, but what I like about LIFE batteries is their ability to retain a charge. I have a 6 cell pack for my glider. I haven't used it in over a year. I figured I would have to cycle it. when I discharged it, it still had the entire charge from a year ago. Plus I don't have to worry on how much juice I put to it for charge.

The Hedgehog

Yes I agree

The Hedgehog

Lipos do the same exact thing, and share the same retention properties.

stuffer

My Feedback: (11)

not in cold weather. LiPOs will lose charge when kept in cold areas. That I have seen. I don't know if they regain their charge when they warm up or not.

The Hedgehog

They do regaint their charge when they warm up. Just don't store them outside and you will be ok.

savagecommander

its my understanding life cells have les a voltage drop from full to dead- such so that you cant use a voltage tester to tell remaining capacity. 3.3v nominal, but only down to 2.8 or so with life. lipo is 3.7 and down to 3.0 LVC...... some ppl have stated life cells show a significant drop in voltage under high amp conditions but i have found an equal amount of discussions stating otherwise. the only drawback i see for life is cell capacity. rigth now its capped at about 2500mah.

cummins driver

My Feedback: (31)

Ill stick to Nitro's for cheap performance