Life vs Lipo Batteries

[renewilson]

Hello, So this is second post. First post I wrote was in introduction and I included some suggestions, I am going to mirror them here seeing as this is correct forum spot for it:

I would like to know a lot more about LiFE batteries. Here are some questions you can answer for it.
Why are these not more popular if they are so much safer?
If there isn't to much of a difference and person isn't trying to win races, why not use those batteries more?
Are they lighter or heavier then battery with same (or about the same) rating?


You could also do a demonstration of LiPo and Life batteries in a plane to show a difference in flight characteristics of plane with the different batteries. How bout a quad copter, would the same out come as a plane. How much longer can they last as in run time/ charge time and limit. How durable are they. Just some questions that could be ask. I would love to see other people comment on this on some questions that I may not of even thought of.

I have seen some reviews of them on other channels but 1, they seem like they are trying to sell the batteries instead of the unbiased review of them and 2, I enjoy Josh/Josh commentary more. So how bout it fellas, Battery comparison show?

 

[bitogre]

Lets start with LiFe batteries are heavier and run at lower voltages (3.2V nominal vs 3.7V). Both contribute to less stored energy per unit of weight (oz or g) and the lower voltage also means that you will get lower motor speeds (and max thrust) for the same number of cells. All of which mean less performance of your aircraft.

Then there is the problem and most LiFes currently available have significantly lower C ratings. So, you cannot draw as much current out of LiFe batteries without problems.

BTW, I do use LiFe batteries. In my case, I use it in my TX. A 3S 1500mAhr works great in my Taranis. If just fits and lasts a good long time while being safe from fire if I forget and leave my TX on unattended.

 

[renewilson]

Thank you for your answer bitogre, Please don't take my questioning as argumentative but more for a thought provoking question. So aside from using in your TX, you don't see any other applications that you could use them for when it comes to RC powering? Maybe not a park flier but something a bit bigger, in that the slight difference in weight and a RC that wouldn't need to be as quick as a racer or something like that? I guess that's my question, I can see what 3.7 is better than 3.2 but if there was a 4.3V would the 3.7 be abandoned because it didn't have as much thrust? Would a LiFe battery be good enough for any of the same R/C planes and would you see a slight difference or MAJOR difference when flying it.

 

[Snarls]

Hey renewilson, welcome to the forum!

LiFe batteries are generally used in TXs and for the RXs of gas/nitro planes. As bitogre says, they have a lower nominal voltage compared to lipo batteries. They have a lower energy density, so they weight more per mAh. The discharge curve of a LiFe battery is much less dramatic than a lipo. The voltage stays around 3.2v until the very end, unlike a lipo which drops fast to around 3.7v where it plateaus, then drops fast again to 3v and the danger zone. This makes LiFe batteries good in situations where you do not want a large variation in voltage over time.

Life batteries are also a lot safer. You can fully discharge a LiFe battery without too much consequence, unlike a lipo which could swell and burst. That is why people like them in TXs where if they accidentally leave the TX on, or forget to charge, there is little threat of anything happening. If cut open LiFe batteries will also react less violently than lipos, perhaps only releasing some smoke.

LiFes supposedly have a pretty good power density (C rating), but as bitogre mentions, it is difficult to find a high C rating LiFe battery. They are generally less commonly sold and have less variations beyond the handful of transmitter packs out there.

To answer your first question, it is a complicated issue. If LiFes can supply the C rating they could make nice safe entry batteries for beginner fliers. One thing is that eventually people will want to move on to Lipos to get better performance, and learning to handle lipos after relying on the safety of Lifes may be a hard and potentially dangerous thing to do.

Here is a good resource I found if you want to read more.

 

[renewilson]

I see your point with the C rating, but I guess aside from the safety aspect, I was looking at the discharge curve life too. I am thinking that having something with a pretty constant discharge rate to me would be better than something that takes off like a rocket then just drops out of the sky when it gets low. Your answers make sense, so thank you *FOR BLOWING MY UP AND COMING AWESOME SHOW OUT OF THE WATER!!!* No, thanks for the answers.

 

[ViperTech]

I use LiFe for my Rx's cant beat the charge life! I have flow 1 plane with 3s LiFe pack and it worked ok but there was a significant difference in performance not good for a pattern ship which I was flying there was just no punch when you needed it. I could see them working well with a fpv craft that has lots of lift and performance is not an issue using a low kv low amp motor. That's my 2 cents.

 

[renewilson]

HA, so maybe there is a show here after all!

 

[ViperTech]

Here is the plane actually flying on the LiFe 3s pack and it's last flight also sadly!

 

[Snarls]

I think a show would be a great idea regardless. Not many people know about LiFe batteries and FT would be able to present the pros and cons.

 

[bitogre]

Thank you for your answer bitogre, Please don't take my questioning as argumentative but more for a thought provoking question. So aside from using in your TX, you don't see any other applications that you could use them for when it comes to RC powering? Maybe not a park flier but something a bit bigger, in that the slight difference in weight and a RC that wouldn't need to be as quick as a racer or something like that? I guess that's my question, I can see what 3.7 is better than 3.2 but if there was a 4.3V would the 3.7 be abandoned because it didn't have as much thrust? Would a LiFe battery be good enough for any of the same R/C planes and would you see a slight difference or MAJOR difference when flying it.

Your question about a 4.3V nominal vs a 3.7V nominal is not a bad question but is also too simplistic. There are many other variable. What is the C rating? What is the weight difference for the same capacity? In order for a new type of battery to be considered better, the C rating has to be at least 20 (I am unaware of a LiFe batteries that high) for non-acrobatic basic flight and lighter or similar weight for the same capacity. Then the voltage would be considered. A heavier battery might be acceptable if the voltage was higher than a LiPo.

Unfortunately, LiFe is worse in every aspect (it is heaver, lower C rating, and lower voltage) except safety.

 

[ViperTech]

I was wondering about the C rating on my LiFe batteries I flew the Formosa II with and checked them and they are rated 30 C.

 

[bitogre]

I was wondering about the C rating on my LiFe batteries I flew the Formosa II with and checked them and they are rated 30 C.

Ok, I could be wrong on the C rating on LiFe. :black_eyed: I just could not find any with a C rating above 5 before I made my previous post.