issues with AW's new RCR123s + Maha MH-C777 Plus II

dabiscake

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Hi, I posted a question in AW's original sales thread, but I don't think it's getting any read since most people will go to his consolidated sales thread...

So here it goes:

Does anybody have problems charging AW's new Hi-current protected RCR123s with a Maha MH-C777 Plus II?
I've tried with all 4 of the cells I have and they all behaved the same.
It probably has something to do with the overcharge protection circuitry, but whenever they get close to completing the charge, going for peak charge topping-off and reach about 4.1, 4.2V the charger just resets with beeping sound like the battery's being unplugged, maybe for 1 or 2 secs, then beeps again to indicate charging is being restarted, but then voltage reads 4.0V, even lower on 1 of the 4 cells, at 3.8V.
This cycle (takes about 3-4 secs total) loops indefinitely, it seems... and they never seem to complete a full charge. Maybe I haven't left them long enough, but I called it quits after an entire day and not seeing any improvement. The older AW protected 750mAh RCR123a charges fine in about 2-3 hours depending on the level of depletion (Maha is a good but sloooow charger!).

I've never had problems completing a charge with any battery before, I'm just wondering what would be the explanation, or the workaround here?

Thanks!
 

wptski

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You are probably right that it's the cells! What's your cells read off the charger? I get about 4.15V. Your overcharge circuit might be sensitive but if they are over 4.1V, it would be close enough!
 

SilverFox

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Hello Dabiscake,

The protection circuit adds a little extra resistance to the cell. I see roughly a 0.030 ohm impedance increase with the protection circuit in place.

If your charger limits the charge to 4.2 volts, the added resistance will make the cell finish up at a slightly lower voltage.

Your description indicates that the over voltage protection is being activated. This is why the charger resets.

Tom
 

dabiscake

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thanks for the replies guys. I know it's the cells, every other battery I have, protected or unprotected, charges just fine with this charger.
Just wondering if there's anything I can do to see the charge complete?

"Lumenhound" said:
Do your 4 cells charge up ok on a different li-ion charger?
I have a DSD charger and a Nano charger. Both will seem to complete the charge (green light), but that's also because they cut off at a lower voltage, IIRC around 4.05V and 4.12V last time I checked, can't remember exactly which voltage for which charger from the top of my head.
Although it's slow, I like to use my Maha because it's always worked perfectly for me, topping off right below 4.2V, and whenever I use other chargers, I can put the battery that just finished charging in the Maha and get an additional capacity top-off. At least that's my impression of it.

SilverFox, if the overcharge protection circuitry kicks in and the behavior keeps looping like that, is that a bad sign for the batteries (never get fully charged, charge being reset everytime lowering cycle life)? Do they actually get fully charged when the circuitry resets the charge cycle?

Lastly, I feel like that they're not fully charged in the chinese chargers because the voltage is low, but I read on some other threads about how end-charge voltage affects cycle life... my question would be how is the nominal capacity affected in turn, depending on the end-voltage?
Even if the voltage off the chinese chargers is lower, can I assume I will still get full capacity from the cells?? Up to now, I tended to think the opposite, therefore always topping off the cells on the Maha if needed be, they are "more full"!

Thanks for the help, guys.
 

SilverFox

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Hello Dabiscake,

In general, charging a Li-Ion cell to a lower ending voltage will increase cycle life, but it reduces capacity.

Tom
 

dabiscake

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Thanks for the replies guys... the voltage range issues have been covered, but I guess what still bugs me to find out is whether there's a significant difference in battery capacity between the first time the protection circuit kicks in, or after 10 of those cycles, or 20, 30 cycles? (see my first post to read about the behavioral "cycle"), since the charge never completes and charger never shows that the battery is "full", literally.
 

SilverFox

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Hello Dabiscake,

If you don't see an increase in cell voltage, you are not adding any additional capacity.

Tom
 

dabiscake

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SilverFox said:
Hello Dabiscake,

If you don't see an increase in cell voltage, you are not adding any additional capacity.

Tom
Thanks for the confirmation!
 
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