Charging current, is my charger stupid, or just my ignorance?

[Aalsen]

Ok, so i´ve red somewhere that the charging current should not be more than half of the capasity of the battery.
Regarding eneloop AAA 750mah, my charger starts at 150ma, then 300ma. Towards the end of the charging it charges 600ma... Why? Will that ruin the battery?
The first batch of eneloop AAA i got a few months ago could not hold a charge. All eight of the triple a eneloops were trash. Could that be because of the charger?
The charger is MiBoxer C4

 

[sbj]

The slightly increased charging current towards the end of charging was chosen by the manufacturer on purpose in order to be able to reliably detect the end of charging using the -Deltapeak method.
As long as that works, that's not a problem. But you should remove the batteries when the charger shows "ready". Otherwise the charger will continue to charge with small currents, which is not good for the LSD batteries.

Here is the link to the test of "HKJ" on the charger:
https://lygte-info.dk/review/Review Charger Miboxer C4 UK.html

 

[Aalsen]

The slightly increased charging current towards the end of charging was chosen by the manufacturer on purpose in order to be able to reliably detect the end of charging using the -Deltapeak method.
As long as that works, that's not a problem. But you should remove the batteries when the charger shows "ready". Otherwise the charger will continue to charge with small currents, which is not good for the LSD batteries.

Here is the link to the test of "HKJ" on the charger:
https://lygte-info.dk/review/Review Charger Miboxer C4 UK.html

Thanks!

 

[Stress_Test]

Ok, so i´ve red somewhere that the charging current should not be more than half of the capasity of the battery......

Just fyi, the max charging current will depend on the battery (same applies to max discharge as well).

You may see this expressed as a "C" rating, where C is the capacity of the cell.

I haven't seen this spec before on NiMh, but it's common on lithium-ion.

So, if a Li-ion cell says max charge rate is 1C and its capacity is 2000 mAh, then it shouldn't be charged at more than 2000 mA. Some types can be charged at a much higher rate, like 3C. So that would be up to 6000 mAh for this 2000 mAh cell.

A quick look at Google seems like 0.5C to 1C is the range for Eneloops. So, a AAA with 750 mAh capacity should be okay up to a charge current of 750 mA.

If the charger is suspect at all, I'd try a different charger. Trashing that many Eneloops at once is going to get expensive quick!

Also, there are some really really knowledgeable people here on CPF, so do some searching for guys who have done extensive battery testing.

The second result I saw on Google was this CPF thread

https://www.candlepowerforums.com/vb/showthread.php?190625-Eneloop-Charging-Rate

 

[Stress_Test]

One more thing... it is possible to get a bad cell right out of the pack. I haven't heard of the entire pack being bad, but I guess it's possible if they had a manufacturing problem with one batch.

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edit:

Okay, I did some reading of my own in an old thread. Whew. I'm now reminded of the same charge rate arguments from back when I dabbled in some RC (radio control) stuff. People have been arguing about battery charging for decades.

"Best" or "optimum" battery charge rate is one of those Techno Holy Wars that will be argued about forever so long as batteries exist. It's PC vs Mac. Ford vs. Chevy. Democrat vs Republican (ok, maybe not that bad).

It's not my area of expertise, but if I were the OP in this situation, I would:

1. Buy a fresh pack of Eneloops from a known good source (to help ensure you don't get counterfeit)

2. Buy the "Panasonic BQ-CC17SBA" charger direct from Amazon for $17.

3. From the new set of batteries, separate them into two groups and mark them to tell them apart. (red and blue Sharpie)

4. Use the one group in the previous charger that (maybe) trashed the batteries. Use the other group in the Panasonic charger.

5. Proceed as normal and see if one group of batteries craps out vs. the other. That should indicate whether the charger doesn't play nice with these batteries, or if the others just happened to be a bad batch.

Again, that's just what I would do.

I feel your pain though; I tend to have bad luck with Li-Ion cells cratering unexpectedly and prematurely