I have a Panasonic BQ-CC17 smart charger, and when I put some cheap non-LSD Ni-MH batteries, the LEDs start flashing and the batteries won’t be charged. These batteries came with my Panasonic cordless telephone that I bought in April last year. This means they’re dead, it is, the internal resistance has raised too much? My Sony BCG-34HH dumb charger and the cordless telephone base are able to charge them.
Is it dangerous to keep using these batteries, should I throw them away, or is it safe to use them in my cordless phone? Thanks in advance.
Yup, it means that the internal resistance has gotten too high. The Sony and the phone charger either don’t measure internal resistance or has a higher tolerance so they’re not complaining.
The cells might be getting a bit too old, but they’re still safe to use. Go ahead and replace them if you feel like the battery life’s too short.
Thanks for the reply. I’ll just keep using them with my cordless phone them. Most likely, the phone charger continuously overcharged them and lowered their lifespan. I also have some non-LSD Rayovac Ni-MH batteries, and they used to be charged by the dumb Sony charger mentioned in my original post. However, as this charger was a dumb one and thus couldn’t detect batteries state of charge, I always charged them respecting the charging times specified in the user manual, so it might have helped to extend the batteries longevity.
I’ll keep using using the cheap Ni-MH batteries with the cordless phone, and avoid using the phone base charger to charge the healthy batteries. Once more, thank you for the very useful reply. :+1:
I gave my BQ-CC17’s away but it could also be that the batteries are at such a low voltage that it’s not able to charge them. The next time this happens check to see what their voltage is. You can also put them on the dumb charger for a bit and then try them on the BQ-CC17. I once bought some Ikea AA’s that were at 0 volts when I opened them and none of my smart chargers would charge them until I raised their voltage on a dumb charger.
That’s actually a very smart ideia. Unfortunately, I don’t have any equipment to check the batteries voltage. I sold my dumb Sony charger, so I’ll charge the non-LSD batteries a bit with the phone charger, and then charge them with the Panasonic charger to check. Thanks for the reply, that was a very helpful tip.
You can also raise the voltage by connecting the discharged battery in parallel with a charged one for a minute or so.
this will result in a very high charge current probably damaging the charged cell
I’m not so sure that’s the case. I probably should have mentioned that this is done briefly just to raise the voltage some. IIRC HKJ has mentioned doing this in order to get a charger to recognize a dead battery. If I have time this weekend I’ll try to measure the current from a fully charged enloop to a totally discharged battery.
if you got one cell with 1.35V and 30mOhms
the other at 0.8V with 30mOhms
do the math to get the flowing current
I=U/R=.55V/0,06Ohm=9,16A
if the battery is hot from charger it will be more
That’s a lot of amps :sunglasses:
But from brief googling this appears to be a somewhat common thing to do with NiMh batteries (and only for a very short amount of time). Some go as far to say that it can also destroy dendrite crystal in the dead battery. So this is something that works but is potentially unsafe when done too long?
Just curious for my own edification.
for the few seconds this takes it wont hurt anything.
and the panasonic phone system at the shop can work ok with cells reading up to 4 ohms esr.
they are beyond worn out at that point and go down overnight if left off the charger.
good ones can last a week.
Sorry for replying to such an old thread, but I still use my CC17 and Google led me to this. - Generally I found out that it’s pretty sensitive to crappy cells. Not old, just crappy. Usually the CC17 has been (and still is) my go-to charger for old and somewhat questionable quality rechargeable batteries, but recently it started blinking when I tried to charge my “Tronic Eco” batteries. I do wonder why, because my old Nitecore D2 can charge the “defective” battery in question without a hitch. No heat, and no explosion/leaking.
However as others have replied, and I believe it to be so, it has to do with the internal resistance of the battery AND that the CC17 is set to be a tad too sensitive for my liking. Of course this charger is designed to only charge Eneloop/Fujitsu batteries and they perform very well over the years in my experience, with pretty low internal resistance even after after 5 years of use.
Also I’d like to point out that the official CC17 manual has no clue about blinking led’s. Not once did my charger blink before charging. It only blinks when there’s a problem.
I hope this helps some battery nuts in the future 
The charger is made in China and not does instruction has proper grammar, it also does not mention LEDs blinking.
I have bought Sanyo XX Eneloops AA 2450mAh in early 2010 and they have been sitting 95% of the time in drawer unused.
Yesterday after putting in 3 batteries I noticed LED turns on for several seconds and then starts blinking. Had to use Camelion charger to force battery to charge. Then I see LED blinking for another battery. And that considering it has been charging for hours. Did CC17 charger decided it is no good later?
I think these Panasonic chargers for eneloops were developed with planned obsolesce motive to get consumers to replace their rechargeables even when resistance readings are not bad enough to warrant the replacement. Maybe I should have bought general charger with advanced functions to cycle batteries.