NiCad - NiMh Setup on Turnigy Accucel 6

[Joe Trinidad]

Hi All,

My friend recently updated the firmware of the Accucel 6 to the latest version from this site: https://github.com/stawel/cheali-charger

The problem I'm getting is, it will charge NiCad and NiMh but to only 63 percent, and it Ab-ends with an error that says "Error Cap Coff".

Does someone have a setup recommendation for NiCad and NiMh batteries.  Also is there a manual somewhere that let's me know what the parameters mean?

Thank you in advance.

[Paweł Si]

"Error Cap Coff" - this message means that then charger delivered more 

then "charge" * 120% to the battery and the charge process was interrupted,

where:

1. "charge" - "...->edit battery->Ch:" (in mAh)

2. "120%" - "options->settings->cap Coff:" (default 120%)

please check these settings.

Best Regards,

Paweł

[Joe Trinidad]

HI There,

Thank you in advance for your help.

From the main menu -> Options-> Settings

Extern T: no

Extrn TCO: 60

dT/dt:  1.1c/m

NiMh –dV: 8mV

NiCd –dV: 12mV

D/C Cycles: 5 (I understand this is not enabled yet in this firmware)

Waste T.: 30

Beep: yes

Cap Coff: 105% (I brought this down from 120 and it still failed)

Input Low: 7V

Disch +:2 mV

Bal. err: 8mV

UART: Disabled

Speed: 9600

 

This is from the Battery Selection menu: I’m using a 2000Mah NiMh 5 Cell pack

Saved Battery -> NiMh 2000/5->Edit Battery

Bat: NiMH

V: 6.00/5C

CH: 2000

Ic: 400mA

Id: 625mA

Tlim: 600Min.

Thanks you for your assistance.  I hope it's something in the configuration.

Thanks again

[Paweł Si]

You should go up with the "Cap Coff:" value.

if you battery is a 2000mAh and "Cap Coff:" is set to 120%

then the charger will  deliver 2400mAh (max)

But this is a safety parameter it should be set to: 120%

Are you sure you battery is a 2000mAh?

if you are charging it with Ic=400mA then after ~5h the battery should be fully charged.

You can also check with a multimeter if the output current is 400mA.

"D/C Cycles: 5 (I understand this is not enabled yet in this firmware)" - 

yes, this is currently not implemented.

But Jozsef implemented this in his version: https://github.com/njozsef/cheali-charger-test1

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[Joe Trinidad]

Ok,  here's an update.

It looks like the "Peak Detection" is not working properly or the parameters are off.  The charger puts out the required MaH that is displayed on the unit and I can get it to turn off due to the "Time Limit" or by setting the Cap Coff to a different percentage.  Example, at 120% it charges to 2400 man, at 110% it charges to 2200 Mah, and the discharge circuit works fine, but goes beyond 1.1V / Cell.

Is there a manual somewhere that I can read to see what each of the parameters mean?  Example, what symbol on the charger is the "Peak Detection" value or Delta V with Time out to measure the Delta V?

Thanks again for your help.

On Thursday, March 13, 2014 9:21:52 AM UTC-4, Joe Trinidad wrote:

[Hans Schmitd]

Here is a manual translated from Hungarian into English using Google. I had promised to improve the English, but so far I haven't got very far due to chronic lack of time. In places it is pretty difficult to understand what the meaning of the text is, but in other places it can be helpful. Many things I don't understand myself, because my charger is not working. If you want to help with the improvement of the English, feel free.

[Joe Trinidad]

Thank you, this manual helps greatly.

On Thursday, March 13, 2014 9:21:52 AM UTC-4, Joe Trinidad wrote:

[Joe Trinidad]

Ok, further tests.. 

The Delta V circuits seem to be working fine, and I can see the Delta V cycle around on the display.  But the software seems to ignore the setting, regardless what the Delta V setting is put on, it's completely ignored.

The only difference between NiCad and NiMh is the Delta V setting, and both are ignored.  Hummmmmm

So bottom line is, the charger charges and consistently overcharges if not monitored for NiCad and NiMh.

Now if I can only read source code. ugh.

On Thursday, March 13, 2014 9:21:52 AM UTC-4, Joe Trinidad wrote:

[Paweł Si]

2014-03-16 22:04 GMT+01:00 Joe Trinidad <joe...@gmail.com>:

Ok, further tests.. 

The Delta V circuits seem to be working fine, and I can see the Delta V cycle around on the display.  But the software seems to ignore the setting, regardless what the Delta V setting is put on, it's completely ignored.

The only difference between NiCad and NiMh is the Delta V setting, and both are ignored.  Hummmmmm

So bottom line is, the charger charges and consistently overcharges if not monitored for NiCad and NiMh.

Now if I can only read source code. ugh.

Are You sure that the delta setting are ignored?

I haven'd tested them recently but I'm pretty sure they worked fine.

Here is the source code:

https://github.com/stawel/cheali-charger/blob/master/src/core/DeltaChargeStrategy.cpp line 79

and

https://github.com/stawel/cheali-charger/blob/master/src/core/ProgramData.cpp line 136

you have to take into account that these values are per cell.

In Your case: -8mV (-dV) * 5 (cells) = -40mV 

so the voltage should drop 40mV from maximum during charge.

[Joe Trinidad]

Thanks for the reply, I assumed that the code multiplied the -dV by the number of cells because when I tried to adjust it to -40, the software would only allow me to input a number of 20.

In other words: Options -> NiMh -> -dV = 20 Max.

BTW, I suck at reading any sort of code, I'm by no means a coder.. so from here on I'm stuck.

Thanks again for the help.

On Thursday, March 13, 2014 9:21:52 AM UTC-4, Joe Trinidad wrote:

[Paweł Si]

does it work?

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[Joe Trinidad]

I'll report back this evening when I get home.  I set the -dV to the max of 20, and put a new pack on it to test.  Fingers crossed.

On Thursday, March 13, 2014 9:21:52 AM UTC-4, Joe Trinidad wrote:

[Paweł Si]

we didn't understand each other:

when you set the "NiMh -dV" value to: 8mV (default) in "options->settings->NiMh –dV:"

and you are charging a 5 cell battery, the charger will stop 

charging when it sees a voltage drop of 40 mV (to be more precise the charger will stop when dV<=-40mV).

your charger didn't stop so there is probably a smaller voltage drop (or the charger doesn't work).

nevertheless you should DECREASE the "NiMh -dV" value to achieve Your goal, or increase the charge current.

please see also: "ΔV charging method"

http://en.wikipedia.org/wiki/Nickel%E2%80%93metal_hydride_battery

If however (during charging) you see a dV value equal or bigger to "-40mV" 

(actually I should say equal or smaller, note the "-" sign) 

and the charger didn't stop that means I made a mistake in the source code and You should report this.

Best Regards,

Paweł

[Joe Trinidad]

Ok, here's what I've tried so far with regards to -dV

12

8 (default)

5

4

Current:

I've tried: 400 mah, 300 Mah, 200 Mah, 199 mah.

These have all resulted in either Cap Coff or Time Limit (199).

Is there anything else you'd like me to try? 

On Thursday, March 13, 2014 9:21:52 AM UTC-4, Joe Trinidad wrote:

[Joe Trinidad]

Hi There,

Here's an update, even with all the -dV levels changed to the previous post, the charger completely ignores it, and goes to the time limit.  So at this point, this charger will not reliably charge NiCad's or NiMh's.  The discharge function seems to work fine, and consistently discharges the packs to 36%.

Thanks in advance for the assistance.

On Thursday, March 13, 2014 9:21:52 AM UTC-4, Joe Trinidad wrote:

[Hans Schmitd]

The Wiki article Pawel linked to points out that "However, the voltage drop is much less pronounced for NiMH and can be non-existent at low charge rates, which can make the approach unreliable". Why not increase the charge rate to 1C, then the dV will be much more easily detected.

[Joe Trinidad]

Ok, I originally had it at 400 ma, with -8 dv, I can increase the -dV to 15 to give it some margin of safety and increase the charge rate 1c.  This shouldn't take long to verify.

I'll discharge the battery first, then charge it at 1C.

On Thursday, March 13, 2014 9:21:52 AM UTC-4, Joe Trinidad wrote:

[Joe Trinidad]

Eureka!!!

I'm a happy camper.  Using the last suggestion, I kept the -dv at 8, but increased the charge rate to 1000 Ma (.5C), and guess what.

It charged and shut off when it hit the correct -dV... 

Thanks for your patience!!! 

On Thursday, March 13, 2014 9:21:52 AM UTC-4, Joe Trinidad wrote:

[Paweł Si]

That nice to hear.

Some remarks about about NiCad, NiMh charging:

1. the safest way is to use a external temperature sensor - it should be also calibrated (I'm assuming you don't have one)

    its called a "ΔT/dt method".

2. it is saver to go down with the "-dV" value, you can go even to "-dV"=0mV

  - the charge process may stop earlier, than you should increase "-dV" 

3. A battery gets very hot when it's fully charged and you are still pumping more current into it.

  The temperature can reach up to 60 Celsius, from that you can estimate if it's full charged.

4. when the battery heats up, the voltage across it drops - this is what the charger should detect.

5. the "ΔV (or dV) charging method" is mostly suitable for high current charging (up to 1C) - the voltage drop is bigger.

6. "Trickle charging" - You can charge a battery with a small current (up to 0.1C) and then the "-dV" can be ignored,

   for this method the "charge/capacity cut off" ("Error Cap Coff") safety feature will stop the charging process.

   ("Error Cap Coff" - maybe the message is not adequate)

7. the charge level indicator at the first screen is only an approximation - there 

   is no way to measure the charge level of a NiMH,NiCd battery (or at least I do not know any)

8. if you are charging 1 or 2 cells  it's better to use also the balance port for voltage measurement.

Best Regars,

Paweł

[Paulius Rutkauskas]

Hello all,

I want to correct a little bit ;-).

"3. A battery gets very hot when it's fully charged and you are still pumping more current into it.

  The temperature can reach up to 60 Celsius, from that you can estimate if it's full charged."

If temperature goes so high that mean that battery was overcharged or near it because when NiMh battery charged 100% then most of the charging energy is converted to heat. Both Panasonic and Duracell suggest a maximum rate of temperature increase of 1 °C per minute. Cutoff on 60 C should be used just for safety.

http://en.wikipedia.org/wiki/Nickel%E2%80%93metal_hydride_battery

[Paweł Si]

2014-04-04 11:41 GMT+02:00 Paulius Rutkauskas <paulius.r...@gmail.com>:

Hello all,

I want to correct a little bit ;-).

"3. A battery gets very hot when it's fully charged and you are still pumping more current into it.

  The temperature can reach up to 60 Celsius, from that you can estimate if it's full charged."

If temperature goes so high that mean that battery was overcharged or near it because when NiMh battery charged 100% then most of the charging energy is converted to heat. Both Panasonic and Duracell suggest a maximum rate of temperature increase of 1 °C per minute. Cutoff on 60 C should be used just for safety.

Yes that's right, thanks for the correction.

In fact a the "temperature increase of 1 °C per minute" is a indicator for cheali-charger that the battery is fully charged

(and there is also a 60°C cutoff implemented)

So the safest method is to use a temperature probe.

[Paulius Rutkauskas]

Hi,

maybe someone know how to disable -dV on 0.32m? Because I'm tried to cycle old NiMh batteries and just after it discharged to 1V/cell and started charging after few minutes stops because of -dV reached (-dV is max -20mV/cell).

Other question how voltage limit works on NiMh charging? Sometimes I see that voltage is more than 1.6V/cell it stops sometimes not.

[Paweł Si]

2014-04-09 17:46 GMT+02:00 Paulius Rutkauskas <paulius.r...@gmail.com>:

Hi,

maybe someone know how to disable -dV on 0.32m? Because I'm tried to cycle old NiMh batteries and just after it discharged to 1V/cell and started charging after few minutes stops because of -dV reached (-dV is max -20mV/cell).

Hm... strange request, but if you really need it I can implement it for You on weekend,

unfortunately my version dosen't have the cycling capability so You will have to

discharge/charge the battery manually. 

Jozsef cheali-charger version does have cycling.

 

Other question how voltage limit works on NiMh charging? Sometimes I see that voltage is more than 1.6V/cell it stops sometimes not.

The safety limit is set to 1.8V/cell for NiMH and NiCd.

[Paulius Rutkauskas]

Hi Pawel,

cycling (or exercise) is most useful to Nixx technology batteries could you implement it on your version? I don't know is -dV drop common on dead NiMh but as I read on batteryuniversity.com the cell resistance grow on age. On my test when I start charge such cells resistance goes down and voltage drops on the first stage. I used Jozsef version because of cycling.

There you can see that Cof happens just after 2 min of charging. -dV is not correct there because after charging stops is not fixed (I think just on Jozsef version) and continues calculating from stop point to present.

p.s.

You have done great job on this charger! Respect!

BR,

Paulius

[Paweł Si]

I've added "enab -dV: yes" (enable/disable deltaV) to the settings.

2014-04-10 10:54 GMT+02:00 Paulius Rutkauskas <paulius.r...@gmail.com>:

cycling (or exercise) is most useful to Nixx technology batteries could you implement it on your version?

I must admit that I'm not a very big fan of cycling.

I have some articles (unfortunately written in Polish) which say that

cycling doesn't work, at lease not for modern batteries.

According to them cycling makes sense only for old batteries produced in the 60-80's.

I did also some own tests with old NiCd batteries, after cycling 

the only thing I was able to measure was a capacity decrease. 

(but I did the experiment with cheali-charger which charges with constant current,

maybe it should be a pulsed current)

 

I don't know is -dV drop common on dead NiMh but as I read on batteryuniversity.com the cell resistance grow on age. On my test when I start charge such cells resistance goes down and voltage drops on the first stage. I used Jozsef version because of cycling.

There you can see that Cof happens just after 2 min of charging. -dV is not correct there because after charging stops is not fixed (I think just on Jozsef version) and continues calculating from stop point to present.

It would be great if you could record the charge process with LogView,

but You need a UART->USB dongle for that.

 

[Paulius Rutkauskas]

Hi Pawel,

Thanks for new function!
Maybe for modern NiMh cycling don't need like Sanyo Eneloop. I tested that batteries with chealy-charger and found more capacity than written on battery :-). But for one cell from Cobra radio cycling helps to restore capacity.
I will log this resistance change on charge after discharge when I get UART-USB dongle from ebay.

BR,
Paulius

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