LiFe question

[Drewmugx5t]

I'm curious if any of you have run LiFe packs for sport running. I was thinking about it purely due to the fact that they are capable of charging so much faster. I use one as a receiver pack in my MBX6 and love it however I have heard they are not great in 1/10 scale offroad. I just wanted to gather some thoughts about them in boating.
Thanks in advance for your replies.

[Chris Harris]

My experience is with A123 Li-fe. The problem is that the voltage per cell is lower than L-ipo. A 2s A123 is only 6.6 nominal whereas a 2s Li-po is 7.4. When cell counts are specified in class structures whether it be boats or 1/10 car racing it puts Li-fe at a disadvantage. Also Li-fe do not have the capacity or the amp load capabilities of Li-po. However, for sport running you can run whatever you want so you can overcome the lower voltage issue by adding more cells and to a degree amp handling by paralleling. These cells are only about 2300 mah each so 2p is a must even with mild setups. They will work, as long as your setup isn't too crazy.

Chris

[Drewmugx5t]

Thanks, that is what I thought, but figured I would ask anyway.

[Brushless55]

also you need a high amp charger to support fast charging..

[norbique]

A123's won't catch fire, and will outlast any of your lipos. (1000+ cycles) They can be fast charged. Manufacturer says 10A max. Some people charge them at 20A without any issues. I'm charging them at 3-5 amps normally. But when we are at the pond/river I charge them as high as my charger is able to, 15-16A. No issues. Slightly warm after such a charge. I balance charge them every time, though they tend not to go out of balance, like Lipos do, especially the cheaper lipos.

[knpc]

If any of you guys are interested
I have a bunch of extra A123 packs still new in their package. They are 2s2p 6.6v 4600mah packs 30-60c

Send me a PM if you're interested.

[Brushless55]

A123's won't catch fire, and will outlast any of your lipos. (1000+ cycles) They can be fast charged. Manufacturer says 10A max. Some people charge them at 20A without any issues. I'm charging them at 3-5 amps normally. But when we are at the pond/river I charge them as high as my charger is able to, 15-16A. No issues. Slightly warm after such a charge. I balance charge them every time, though they tend not to go out of balance, like Lipos do, especially the cheaper lipos.

15amps on a 5000mah pack is only 3c
most any lipo will charge to 5c with no issues at all
some of my smaller lipos I charge at 2.5-3c every time when I'm at the flying fields
and all my (cheap priced) lipos balance out great every time
oh and I've never ever had a lipo catch fire..
to much hype on that one

[norbique]

I never said I was charging 2P configs at 15-16 amps. I charge 1P packs with that current! That translates to 6-7C charging. Those charging at 20A charge them at almost 9C! Wouldn't try that with a lipo! I see lipos ballooning here and there, some at the local club as well. It's not hype, it's something to be aware of. Something to take into consideration. And if all your cheap lipos balance out great every time, you must be a very lucky person. Not everyone has the same experiences.

[Brushless55]

I never said I was charging 2P configs at 15-16 amps. I charge 1P packs with that current! That translates to 6-7C charging. Those charging at 20A charge them at almost 9C! Wouldn't try that with a lipo! I see lipos ballooning here and there, some at the local club as well. It's not hype, it's something to be aware of. Something to take into consideration. And if all your cheap lipos balance out great every time, you must be a very lucky person. Not everyone has the same experiences.

1p 5000mah at 15-16amps is 3C
3C into a 5000mah pack is 15amps
you have not said how big your packs are but that is a typical size pack
your packs would have to be around 2500mah to run 6C at those amps (15-16amps)
the only reason I don't charge higher than 3c is I need a bigger charger to do so, and I would not hesitate to charge at 4c or even 5c, but I don't need to charge that fast as I have 10 small packs for my planes

Cheap price does not mean a cheap pack
I have 30lipos all from Hobbycity and all of them balance out nice, its not luck bro!

[SwampNut]

to much hype on that one

Unless you've had it happen to you, like I did. Nearly-new name-brand battery, caught fire while inside my RC plane in the air. It was in a plane that could pull only about half of its discharge rating.

I just picked up two Life batteries to try out. I'm shocked at how huge they are, for being rather small in capacity. We'll see how they do. Disappointed so far. I don't even know if they will fit in the boat, and definitely won't fit in my planes or helis.

[Brushless55]

Unless you've had it happen to you, like I did. Nearly-new name-brand battery, caught fire while inside my RC plane in the air. It was in a plane that could pull only about half of its discharge rating.

I just picked up two Life batteries to try out. I'm shocked at how huge they are, for being rather small in capacity. We'll see how they do. Disappointed so far. I don't even know if they will fit in the boat, and definitely won't fit in my planes or helis.

I do like the chemistry or whatever its called in these batteries
but yeah, they are bigger and don't have the volts like lipo
but I have had several Nimh batteries vent on me

[norbique]

Hey Brushless55, don't be upset bro!

I wasn't clear enough. When people are talking about A123 cells, (not LIFE in general) they usually mean the ANR26650 Cylindrical cell which has a nominal capacity of 2300mAh. OR the smaller APR18650 Cylindrical cell which has 1100mAh nominal capacity. There are newer cells they make, but not yet available to the general public. For example they have the AMP20 Prismatic Pouch (lipo like flat) cells which have 20000mAh capacity. etc. Take a look at http://a123systems.com/products-overview.htm if you want to know more about those.

Sooner or later we'll have those as well, and I'm sure they'll outperform any lipo in safety, reliability and cycle life as well. Although they can only be used in huge boats weighing 480g /cell. Here you can see most of the cells A123 Systmes is producing: http://www.a8power.com/ProductList.asp?id=2

The A123 cells I was talking about have 2300mAh nominal capacity. So 5000mAh is NOT a typical battery size when talking about A123s. Charging 2300mAh cells at 15-16 Amp is a lot better rate than most Lipos can take without being abused.

I respect your feelings towards the various lipos, yes they are good, (very high energy packed in very small size/weight, also form factor is much better then the cylindrical cells) they just aren't safe enough for my liking. As SwampNut said you might not accept this until one catches fire in one of your models. Hope that doesn't happen nor to you or anyone else! But we've seen such events in the past, and probably and unfortunately we'll see them in the future as well. I also know many times such a event is not directly the battery's fault, but more likely it was over-discharged or overcharged before and so on and so on but the fact that they can be very volatile scares me much. I know lipo chemistry is also being developed and I wish some day they come up with a safe lipo. Then I'll switch over to using those. Until that time comes, I'll stay with A123's which are simply put MUCH safer.

[norbique]

For those saying Lipo fires aren't real, please take a look at this thread:

http://www.rcgroups.com/forums/showthread.php?t=719116

I know the chargers (and users of those chargers :) ) have developed a lot since, but if you scroll to the end of the thread you can see quite recent mishaps.

[graill]

Flat cell "prismatic" A123's have been sold for the last year. I did a piece on them over on RRR before they came out, not to many folks were interested. I received two of the first made and asked a few folks if they wanted to test them, no takers.

Most likely because of the weight as one will need to add 2 cells or more to match lipo output.

I currently use a couple for my radios, slightly modded. camera died or i would post a pic.

They dont sell well at all as i see several sites having sales on them.

The biggest market for these are the powered bike crowd in which they are quite popular. a 36 v "pack" is a huge beast.

[graill]

Cameras work if the battery is installed, meh. Anyway here is the pic of the one from last year.