LiFe Batteries
 

So what do people think of these things? Where can you get them? How big of a difference is 6.6v they are rated at vs the 7.4v of a Lipo?

Maxamps is one place selling them. I've been using them, but the original, bigger 2300mah a123 cells. They are OK, but when mine wear out, I won't replace them, I'll just buy lipos. The voltage is a big deal as well as the weight and size diff.

http://www.maxamps.com/categories.php?cat=223

I'm interested in these as well. I want something safe & fool proof for my 'fun' runabout the house type rcs like the tamiya TLT-1 or equivalent. My questions :

1) Is there a difference betwwen LiFe & LiFePo4 (A123) cells specifically with regard to the chraging regime. I.e. can use charger for LiFe to charge A123 type of cells ?

2) LVC - How inherently safe is the A123 type of cells? They are similar to Lipo in a sense that they have a minimum cutoff voltage ? What happens if this voltage is breached ?

I know that a lot of questions have been answered when these were intoduced a while back but never bothered to study carefully.

I don't want lipo in my 'fun' rcs as my kids also get to drive them & the esc does not have any LVC built in. Getting an external LVC is kind of a hassle & I want the vehicles to be safer. Nimh will do but I want something that can hold charge a little better & not having to charge it up before fun time can start.

Regards,
Joe Ling

joeling, I too am intrested in the A123 batteries which are similar in every way othe than chemistry to the LiFe. I will answer your questions with information I gatherd from researching the net.


1-Charging LiFe and LiOn(A123) is the same as charging a LiPo and can be done on chargers with highly slectable parameters. A LiFe and LiOn peaks at 3.3V and a LiPo peaks at 4.3. So if you charge it on a LiPo charger it will overcharge the batteries but unlike LiPo they wont explode. The batteries how ever can be damaged and this will affetc their lifespan. There are specific LiFe and LiOn ballance chargers. Hyperion and Thunder Power make some which will also do LiPo.

2-The LV cut off for a LiFe and LiOn battery is 2.7V. You dont have to worry about over discharging them because Rc motors wont run when the voltage is under 6V. Thats just because there isnt any more power to make the motor go.

I found a place thet sells A123 batteries for 1/2 the price of other retailers but they are loose cells and i would need to build teh packs my self, which isnt a big deal. The weight of the A123 cells concerms me as well as I would like to run 5S, 2P in order to get 16.5V, 4600MAH to run in my 1/8 scale electric buggy and truggy. The up side would be that, by what I have read, these cells dont spike like some cheap LiPos do, safeguarding my expensive 1/8 scale electronics.


Hope that helps.

From what I understand, the power to weight ratio is not nearly as good as LiPo. If you arent racing this might not be a problem for you.

Thanks guys. These are good info.

Lower power, especially in classes that have become too fast for most (mod touring, mod offroad, etc.) is not necessarily a bad thing. The higher weight of the Life cells will also make it easier to balance the chassis too. I'm anxious to see how the new cells work out.

with the new genereation of LiPos, the big advantage of the A123 cells are gone. Fast charging at rates of 5C can now be done with the new hyperion cells.

The big advantage you have with the A123s are still life cycle(1000+ charge/discharge), A123's resistance to "flame and blow up", and ability to run without an LVC.

! run 2, 3, 4 cells configurations in my vendetta st and i find that the A123 do not hold the voltage under heavy load as well as lipos. However the A123 do not drop voltage like lipos as well. You get 6.2-6.4 volts under heavy load until the battery is drained. Then the cells just drop off, and you are ready to charge.

I use the A123 cells in 18650 size from Black&Decker VPX battery packs. I can get them fairly cheap if you want a few packs. Shipping would be up too you but the packs are about $15 USD for a 2 cell pack.

msg me if you want some or want me to build you a few packs.

here's my 2 cell pack in my detta...(pics in the link)

http://www.rctech.net/forum/micro-mi...ml#post5976918

WHAT? :weird:

cappy has a point....my LiFe's will drain right up to 2V on each cell...truck stops moving when pack voltage hit 3.7V :lol:

2-The LV cut off for a LiFe and LiOn battery is 2.7V. You dont have to worry about over discharging them because Rc motors wont run when the voltage is under 6V. Thats just because there isnt any more power to make the motor go.

Another WHAT:weird: Ever heard of 4-cell racing or single cell lipo racing:confused::confused:

this is relevant to my interests...any links on this racing please
http://www.rctech.net/forum/classic_...ies/kawaii.gif

I was quoting the other guy what are you intersted in?

ahhhh I took out your bolding and added my own...

sorry for the thread jacking...

A123 are great if you are a bit careless with you batts....they are robust, have a long life cycle, and are relatively cheap...

By the way if you are ghetto racing and you don't want a lipo charger that can do A123/LiFe specific charging grab your self a cheap multimeter from Harbour Freight, a light timer, and a regular wall charger that does NiMH charging. hook up your 2cell A123 pack to the charger, set the light timer to turn off after x minutes...x dependant of the charge rate of your particular charger... and when the voltage reads 8VDC on the battery unplug from the charger.

Not the best route but like I said the A123 chemistry make them fairly safe from blowing up and the light timer will shut off the charger at about the time it would take the charger to shove 1100mah into the battery...

like i said ghetto racing...