Re-chargeable 1.5 volt lithium ion AAA batteries

[MRMILSTAR]

I have been trying some of those re-chargeable 1.5 volt AAA lithium ion batteries. I am using the "EBL" brand. I have had mixed results. Initially they seem to work well. I have now had two that failed to take a charge after the initial charge and discharge. Does anyone know of a brand for these batteries that is reliable? Normally I just use NiMH batteries but I have a calculator that needs that 1.5 volts instead of 1.3 volts that the NiMH batteries provide.

[davekni]

I've tried EBL AA and AAA and Hixon AA.  I've been quite happy with EBL "9V" LiIon batteries (8.4V fully charged).  EBL 9V batteries I've tested meet their claimed 600mAH, which is quite good for 9V battereis.  The EBL 1.5V cells do not meet their claimed energy rating, and their charger is not very friendly to the internal LiPoly cell.  No failures yet, but I feed the charger 4.2V instead of 5V to make charge current taper towards full charge as it should.  The Hixon AAs are close to their rated energy spec, and their spec energy is a little higher than EBL's.  The Hixon charger properly tapers current too.  Had a hard time finding Hixon AAA cells, however.
Above were versions using separate charger, not ones with built-in USB charging port.

[MRMILSTAR]

Thanks. I'll give that brand and charger a try if I can find them.

[davekni]

Are the dead EBL AAA cells completely dead or just won't run the calculator reliably?  In case it is a printing calculator or for some other reason draws step load current, that can be an issue with these cells.  At light load internal regulator is in a low power mode.  Response to step load isn't instantaneous.  Haven't scoped step response yet.  But I do know that AA cell powering a wall clock with second hand stepping once per second is not reliable.  Works most of the time, but occasionally the step response causes clock to miss a second.  The EBL AA cells are a bit worse for this, but the Hixon ones still cause the clock to occasionally miss a step.

[MRMILSTAR]

I may have found the problem. I tried a different more advanced charger for lithium ion batteries and this time the dead battery took a charge and output 1.5 volts. Apparently the cheap charger that came with the batteries is not reliable. I'll try a few more.

[davekni]

I may have found the problem. I tried a different more advanced charger for lithium ion batteries and this time the dead battery took a charge and output 1.5 volts. Apparently the cheap charger that came with the batteries is not reliable. I'll try a few more.

Glad to hear that your cells are working again.

BTW, it is also easy to measure charge state of internal LiIon cell.  Works for both brands.  Charge battery with a ~2-3mA trickle current.  Voltage across terminals will be very close to internal cell voltage.