dlwmacgregor
Newly Enlightened
According to SkyRC the change from v1.15 to v1.17 was as follows...
Optimized internal resistance detection. |
SkyRC — IFA 2014 — MC3000 charger-analyzer
- Thread starter kreisl
- Start date
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I do appreciate your doing something no one else has apparently done by submitting this question and getting an answer. Good on ya for that.
Unfortunately, it is a 'non-answer' which provides no specific or useful information.
According to HKJ, there were no issues with the IR measurement ~10 years ago, and it has remained unquestioned, to the best of my knowledge, until the manufacturer (apparently) changed it recently. Unfortunately that fact renders this answer of no value IMO. The very fact that their response is a non-answer is itself quite revealing to me, but I offer no further comments at this time, although I anticipate those will follow at a later time. Also IMO, HKJ's test would fail on V1.18.
dlwmacgregor
Newly Enlightened
dlwmacgregor
Newly Enlightened
I totally agree.
Does anyone do some advanced programming for mc3000? I want to create my own termination for nimh cells. I have some old nimh which terminate early on 0 dV/dt. I don't want to use - dV/dt not to harm cells furthermore. What I want is not to let charger terminate before reaching certain mAh and program the termination point of voltage curve at a certain slope I desire. Maybe I could read voltage data from dataexplorer and eveluate the data inside or outside of dataexplorer and then send charger termination command when desired conditions for termination are met. But I don't know how to do that, I even don't know with what protocol charger communicates with PC. Does anyone have an advice about this?
MidnightDistortions
Flashlight Enthusiast
I run into the same issue. I just add a high trickle charge rate and let the batteries sit for days.
It can be harmful
MidnightDistortions
Flashlight Enthusiast
Well If they're older cells that don't terminate properly they're junk anyways. If they quit working after 'overcharging' them from a trickle charge then it's time to retire them. I never had an issue other than overcharging symptoms where the battery has reduced power output but then return to normal from discharging them. Usually they terminate later from doing this. Nimh batteries are forgiving in overcharging provided the cell isn't cooked.
HKJ always mentioned LSD NiMH cannot tolerate over charging however I have no in depth knowledge about this.
MidnightDistortions
Flashlight Enthusiast
Well if they are LSD then you could lower the trickle charge rate and use this calculator http://www.csgnetwork.com/batterychgcalc.html
However since they are still NiMh cells a low enough charge/trickle charge rate might be fine for doing a recharge for up to 16 hours. However you would have to estimate how long it would take to recharge a battery with trickle mode which I had thought it usually will just keep the battery topped off, it's not actually charging, just maintaining the battery.
Another piece of information is if the battery is left sitting idle for at least several hours resting charge you could note the battery voltage which would indicate battery charge level however it might not be accurate due to it being worn out but still worth a shot.
picrthis
Enlightened
I can't believe this has been out for 5 years now and it still has connectivity issues.
Unfortunately, you cannot do this on the MC3000. You can set the -dV to something like 2-3 mV. This will not overcharge them much, and should solve the problem with premature termination.
Thanks. In fact increasing charge current for short term during charge gives clues about charge level. I would like to create such charging algorithm with variable current to evaluate charge level and stop charging before reaching 0dV/dt.
I don't think you can do that either. Terminating before peak voltage (0 dV/dt) is not necessary. It will undercharge your cells with little benefit. How often do you get false terminations BTW?
One strategy will be to increase charging current for the whole charge. What is your charge current in relation to the capacity of the cells?
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I don't get false termination but I have some bad old Varta cells (by the way I don't recommend varta NiMH to anyone unless varta decides to rebrand FDK cells one day) which have low voltage when charging and never reaching 1.50 even when charging with 1C. When charging voltage increases fast for some minutes and then voltage rises very very slowly for long time not having - delta V. These cells are actually 2400 mAh but measure 1900 mAh when discharging. They are bad since I bought them. They never terminate with xtar vc4 and charge forever since I bought them.
That's strange. Seems like these cells were never formed properly. What's the IR?
In this case, the only thing left is to discharge them fully and time charge them with 0.1C for 13-14 hours.
Varta is not the brand it used to be. I fully agree with you on that. Even their car batteries are no longer highly regarded. Their NiMH are just cheap Chinese cells, rebranded to bear the brand name of what once was a reputable German manufacturer.
In this case, the only thing left is to discharge them fully and time charge them with 0.1C for 13-14 hours.
Varta is not the brand it used to be. I fully agree with you on that. Even their car batteries are no longer highly regarded. Their NiMH are just cheap Chinese cells, rebranded to bear the brand name of what once was a reputable German manufacturer.
Certainly, Varta is never the quality brand it used to be. I discharged them to 0.8V for very long time and recharged but it didn't help. Internal resistance is high and measures 150mOhm. But they measure that high from very beginning. There's something wrong with these cells but I don't know what. They say NiMH doesn't really wear by sitting on shelf but these were worn since very beginning.
God knows what is in these cells and who made them. I'd suggest to charge them for 14 hours at 0.1 C snd use them in something like remote controls and wall clocks. Not worth much effort IMO.
Thanks, i also think so. These cells are not for high power applications. I use them in a door bell and they work fine unless i don't deplete them.
New firmware 1.21 is available. I noticed the following changes compared to v1.18:
- modified IR calculation (higher values than before; could be an interesting change as IR calculation was considered broken for firmwares released after v1.15)
- new battery type "Na-ion"
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