Charging A123 cells with a PSU

[IMSabbel]

A123 cells can be charged at 5C, with a termination voltage of 3.6-3.8V, and are mentioned to be "robust".

I dont want to spend lots of money for a charger of the single pack i have, especialy considering my psu should be able to do everything a real charger can do (via computer connection)

Well, i just want to know if the following is advisable:

Connecting pack to PSU.
Set voltage limit to 3.6V
Set current limit to 2C.
Let it run for 40 minutes.
(alternatively: Abort charge if current drops below xxxC)

 

[Black Rose]

You might want to put the cells etc inside some type of non flammable container....that sounds like an explosion waiting to happen....

 

[Fallingwater]

A123s are not explosive or flammable.

 

[Black Rose]

A123s are not explosive or flammable.

They're not Li-Ion?

 

[BVH]

A123's DO "vent" (not sure I'd call it "explode") very rapidly with a loud pop (slight "bang"), however I did not see nor feel the "flame" part. I have been told that a PSU can be used to charge batteries but that a diode should be placed in-line so as not to back-feed the PSU?

 

[Fallingwater]

They're not Li-Ion?

They are LiFePO4, or lithium iron phosphate.

They can vent, but they don't damage their surroundings while doing so.

 

[IMSabbel]

You might want to put the cells etc inside some type of non flammable container....that sounds like an explosion waiting to happen....

I am not stupid, no matter what you might think.
And if you dont have a clue about whats going on, stay away from a thread instead of spreading FUD.

 

[Fallingwater]

I am not stupid, no matter what you might think.
And if you dont have a clue about whats going on, stay away from a thread instead of spreading FUD.

He may not have known about the difference inbetween the cell types, but he was just trying to help you. I see no reason to be aggressive.

 

[SilverFox]

Hello IMSabbel,

I don't see any problems with that method of charging.

Tom

 

[Black Rose]

I am not stupid, no matter what you might think.
And if you dont have a clue about whats going on, stay away from a thread instead of spreading FUD.

I never said you were stupid.

As Fallingwater said, I was not aware that A123 cells were LiFePO4, and I hadn't heard of someone trying to use a power supply (in my line of work PSU is a computer power supply) to charge batteries before. It simply sounded like a really bad idea to me.

 

[BVH]

No harm, no foul. Life's good! On with life.

 

[jzmtl]

I am not stupid, no matter what you might think.
And if you dont have a clue about whats going on, stay away from a thread instead of spreading FUD.

Geez, way to treat people trying to help you and have your well being in mind.

 

[Flintstone]

In my world a PSU seems like overkill. It's easy to get a suited charger off DX for $10-12 that does it's job OK (you might not get 100% capacity).

My concern is mostly that if you do something wrong and the cell vents - the gass isn't exactly healthy (from what I've heard). I don't want to subject my family to that... Pila chargers seem to be what's recommended but I atleast still use my DX one for now...

 

[eprom]

Using a CV and CC PSU wil work as Orjinal, because the way of chargers working is: First uses Constant Current (CC), than turn to Constant Voltage (CV) until the needed voltage reach (4,2 for Li-Ion) and Cut-Off.

So only one thing you don't have is Cut-Off. So set an alarm clock, charge them and stop charging when the alarm begin. My 2 cent

 

[wasBlinded]

One thing to be careful about when using a CV/CC power supply unit to charge cells. Be sure to set your voltage and current before attaching the cells, not afterwards. If your voltage is set lower than your cells when you hook them up, there is a good chance you will fry some diodes in your PSU from the backfeed, and it won't take very long - especially with the high current capability of A123 cells.

I managed to do that to my BK1743 using Nimh cells. I thought I was in for an expensive repair or a new power supply, but I found the fried diodes (commonly available, even at Radio Shack) and was able to replace them.

 

[Fallingwater]

Huh, I wasn't aware of this. I always start my bench PSU at 0 volts and crank it up to what's needed, but I haven't blown any diodes even when doing that with various batteries connected.
Perhaps my PSU is protected against that?