Murata VTC6, how to terminate charging?

[JayEmm]

Hello everyone, and @Mooch specially,

Now my friend managed to locally procure a couple of Murata VTC6 batteries that were imported by soneone else from NKON.NL and I'm now trying to help him test them. And I have questions about these batteries too... will be be posting them on the VTC6 thread.

Tried posting at the "Bench retest" thread but it shows as "closed for further replies", so I opened this new thread instead.

Here are the pics:

Given they were in a shrink-wrapped package and the seller even had a receipt from NKON showing them being purchased a couple of weeks ago, I'm not too worried about them being fakes -- but I want to test their capacities all the same.

First thing that I found strange was their off-the-package voltage, which was exactly 3.49V for all of them... a bit too low in my experience with other batteries, which are usually shipped at ~3.7-3.8V, but them some googling brought this up this, which (at the bottom of p.4) states: "Cell condition at the shipment About 75% discharged". 75% discharged is the same as a SoC of 25%, which sounds about right for a resting voltage of 3.49V.

My MC3000 confirmed those voltages, and addionally indicated IR values of 13-15mOhms, which doesn't sound too absurd for these batteries at 25% SoC:

So now I'm trying to test them, and that's where the problems start: I can't find any official info on what the end-of-charge current is!

• The current official datasheet straight from the Murata website states two contradictory things: "Charge: CCCV, 3.0 A, 4.2 V, 2.5 h, at 23deg.C" right at the top (so no end-of-charge current termination, just leave the battery charging for 2.5h -- total? since the start of the CV phase? it doesn't say...), and then, at the bottom of each graph, it states "Charge: 4.2V/3.0A/150mAcut" which I interpret as meaning 150mA end-of-charge current termination... but 150mA looks more than a bit too high.
  
  
• Some googling also brought up this, which on p.4 states "Charge: 23deg.C, 4.2V, 4A (CC/CV), 100mA cut" which is an altogether different number.

So I gotta ask y'all who know more than me: which is the correct/official/up-to-date information on how to terminate charging of these Murata VTC6s? Is it end-of-charge current? If so, how much? Is it total charging time? Or time spent just at the CV phase? Can someone please tell me?

TIA!

EDIT: fixed "end-of-discharge current" as there's no such thing... correct is obviously "end-of-charge current"... duh...

 

[JayEmm]

Some googling also brought up this, which on p.4 states "Charge: 23deg.C, 4.2V, 4A (CC/CV), 100mA cut" which is an altogether different number.

This has been further corroborated by this other PDF I found on the Wayback Machine: p.8 is virtually identical to the p.4 on the other PDF above, with the same graph embedding the same phrase.

 

[JayEmm]

So I gotta ask y'all who know more than me: which is the correct/official/up-to-date information on how to terminate charging of these Murata VTC6s? Is it end-of-charge current? If so, how much? Is it total charging time? Or time spent just at the CV phase? Can someone please tell me?

Answering my own question: after weighting all available (and conflicting!) information, we've decided to go ahead and use a residual charge current of 150mA as the charging termination condition, since the most up-to-date, official infomation from Murata (in the datasheet linked above) consistently mentions "150mAcut" as part of the charge conditions under all graphs.

We just did a couple of C>D cycles on four of them and the charger consistently indicated between 2993mAh/10.91Wh minimum and 3030mAh/11.00Wh capacities (at 1A discharge current), and given the consistency among these results themselves and with the Murata datasheet, we've decide to call the 150mA charge current termination a good one in order to fully charge these batteries.

I hope this eventually can be useful to someone else.