Using Pila charger for bare Li-ion

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LitFuse said:
I don't yet have any Pila cells, (soon to change with the arrival of the LionHeart) but below is a copy of another post a while back regarding a bare cell charger. I've been very pleased with it's performance. It will even run on 100-240V and 50/60Hz (with adaptor) and 12VDC. I plan on using it to charge the cells for my LionHeart too. I occasionally even use it to charge my camcorder batts! /ubbthreads/images/graemlins/smile.gif


I use a Lenmar MSC-1 for my bare Li-ions. I did have to "homebrew" the battery holder though. I just got an AA holder from RatShack, chopped it in half, stuck it down on one of the supplied charger plates with double sided tape, and soldered two wires. The whole thing took 10 minutes. This charger cuts out at 4.15V. It takes about 50 minutes to fully charge a 17670 cell. I use a one hour dial type mechanical timer as a safety.

I paid around $50 for mine about a year ago. You may find them cheaper now though. I have been extremely pleased with this charger. /ubbthreads/images/graemlins/smile.gif It even comes with a 12V plug for use in the car.

As I'm sure someone will say shortly, using bare Li-ion cells can be hazardous to your health. Be sure you are aware of the issues and take proper precautions. (or just use Pilas /ubbthreads/images/graemlins/smile.gif )


Peter

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I am assuming that you MUST use a timer here right? It seems as if I can't throw the bare cell on this charger and then go to bed and wake up the next morning (several hours later). There is no concept of trickly charge with bare cells?

Thanks.

Curtis

 

[Billson]

The charger is probably smart since Peter says it cuts out at 4.15v.

 

[KevinL]

The charger HAS to be smart, if not, things could get Very Interesting, Very Fast /ubbthreads/images/graemlins/grin.gif

 

[LitFuse]

Yes guys, it's a "smart" charger, I only use the timer as a redundant safety. I have on occasion left a cell in the charger for many hours without the safety, and have not had any problems. As far as I know, there is no such concept as trickle charging Li-ions. When the battery is charged, the charger cuts off, and stays off.

Peter

 

[Ray_of_Light]

The charge of Li-Ion batteries is a three phases process. First, a constant current to 4.2 Volt, limited to 0.5 - 1 C. The second phase is constant voltage 4.2 V, until current drops to C/20 or C/30, then the charging source is disconnected.
Unlike SLA, Ni-Cd or Ni-MH, in the Li-Ion batteries there is no Hydrogen-Oxygen recombination cycle; so the constant voltage phase must be terminated accurately, otherwise the cathode of the battery (cristalline lithium cobaltite) will self-destroy.
Using Li-Ion with the their own embedded microcontroller is the best solution; bare Li-Ion cells must be protected from overcharging with a specific charging circuit or, in the case of current limited bench power supply, with a timer. Not the best solution... I embedded a "protection board" removed from old Li-Ion batteries inside the charger, in order to charge bare cells, since I haven't find any suitable charger here in Italy...

Anthony