iCharger 106B+ 2x18650 series sudden current climb

[VegasF6]

Not too terribly long ago I purchased the Junsi iCharger 106B+ and I am still playing with it trying to figure it out, along with the logging functions and LogView software.

Today I was series charging 2 unprotected 18650 cells I recycled from a laptop some time ago. I discussed them in this thread: http://www.candlepowerforums.com/vb/showthread.php?t=223884
If I have the correct cells, here is the data sheet:
http://battery.sanyo.com/en/spec/ion/UR18650F.pdf

I have been using them in a 2x18650 P7 light, and they were pretty well balanced, better than .1V. So, despite the fact that I was charging them without a balance cable, I believe it should have been fine.

I set the charger for LiPo charge, 1.5A 7.4V (2S) and connected with my self made magnetic charging cables. 12ga wire approx 10 inches long, so next to no resistance. Approx 8-10 minutes in I heard the fan controller kick on and my lab power supply current limit kicked in, so I turned up the current knob until it FINALLY went back to voltage limit (13.4V). At that point it was drawing ~8 amps from power supply! According to the graph I am posting charge currents were also that high (minus I guess whatever the chargers electronics were using, negligible.)

Well, of course I terminated immediately, but, any idea what may have caused it? Luckily I was right there monitoring the situation.

Bad cells? Bad charger? User error?

 

[VegasF6]

I restarted this test, 33 minutes ago, and it seems everything is working fine, this time. From looking at the new graph, not the one posted above, the charger is in the CV stage and current has been dropping from the beginning of the charge cycle from 1.5A to currently 1.10A.

To look at the LAST graph, (the one above) it looks like about 8-9 minutes in it switched from CC to CV and just went crazy, both voltage and current soaring!

Could have been dangerous. I think I will need to by a temperature probe to use with this too as a last ditch defense against *POOF*

 

[zer0ne]

Latest firmware? 3.13f?

 

[VegasF6]

Correct, V3.13F and on the right side is AAA

 

[zer0ne]

Weird. Maybe you can try to post in rcgroups whereby Junsi support is there to help.

 

[Th232]

Lol, 24 hours after I buy that exact charger I see your thread. Will be interested to see the cause and solution.

 

[Selectron]

I don't know anything at all about that charger, but looking at the green current trace, it doesn't just increase at the eight or nine minute mark, but rather it appears to fall suddenly first, and then it rises dramatically a moment later. Is the mains power stable in your part of the country, or do you suffer from power disturbances? It almost looks like the charger lost power for an instant, and then recovered but with a glitch.

 

[VegasF6]

Yes, power is quite stable.

Remember, I was powering this from a lab power supply, the glitch you see is almost certainly when the current suddenly climbed, the current control kicked in, hence dropping the voltage. Since I was sitting literaly right next to it, it only took me seconds to reach over and crank up the current control knob, which also allowed the voltage to climb.

At least, that is my theory.

 

[zer0ne]

Maybe you try to charge them together with balancing cable plug into the built in balancer and see the result. For me, anything more than 1 piece, I will use the balancing cable unless we are talking about parallel charging.

Edit: Another thing is to do a discharge test for the 2 cells and check whether how well the capacity holds as they are not new cells.

 

[Justin Case]

I thought that the iCharger was supposed to be able to detect both short circuit and open circuit conditions at the output, which would help to protect you against trying to charge a bad cell. In addition, if you set the charge current to 1.5A in normal charge mode, then I would have thought that this becomes the max charge current that the iCharger will use for that charging cycle. The iCharger also has a input current limit that you can specify in the program select settings. Check that and use it as a redundancy. Is it set to something greater than 8A? The default is 22A. I'd set it to something lower.

It would seem that the max charge current setting of 1.5A didn't work right -- it didn't limit the max charge current to 1.5A, instead allowing over 8A sent to the cells. It would also seem that the LiPo charge voltage setting also didn't work right -- it didn't limit the output voltage to 4.2V * 2 = 8.4V. That sounds like a firmware problem to me. Assuming you set the 106B+ correctly, the charging excursions shouldn't have exceeded your settings.

 

[VegasF6]

http://www.rcgroups.com/forums/showthread.php?t=839657&page=560#post16169649

The short version is don't quickly adjust the Vin.

 

[Justin Case]

Junsi's answer makes no sense:

"Would you please check if you have set a very low value for the current limit protection? If so, the phenomenon you met is normal. When you adjust the input voltage of power supply, the charger doesn't react so quickly and the current will climb."

What is the point of having an input current limit setting if it doesn't work properly and allows the charger to send dangerously high charge current to the cells, far exceeding the limit that was set?

In fact, Junsi's answer doesn't say that rapid changes in the input voltage from the power supply is the culprit. He simply says that the charger can't react quickly enough "when you adjust the input voltage of power supply". So we don't even know how fast of an adjustment is too fast for the iCharger to keep up. That's simply unsat.

Based on his answer, it looks like a very serious firmware bug to me that needs to be fixed immediately. IMO, it is not acceptable function and should not be considered "normal".

I also note that Junsi never addressed why the float voltage also increased beyond what the max should have been (8.4V).

 

[HKJ]

For me the answer from Junsi makes sense and probably explains the reason for the problem.

The iCharger always adjust the output current slowly and if the input voltage has been limited due to the current limit in the power supply, then adjusting that limit up will increase the input voltage and give to high a charge current, until the charger can get it adjusted down.

 

[Justin Case]

For me the answer from Junsi makes sense and probably explains the reason for the problem.

The iCharger always adjust the output current slowly and if the input voltage has been limited due to the current limit in the power supply, then adjusting that limit up will increase the input voltage and give to high a charge current, until the charger can get it adjusted down.

Let me clarify. Sure Junsi's answer makes sense in terms of what may have happened. But it doesn't make any sense (to me anyway) in terms of his apparent view of the seriousness of the event. He seems to believe that this should be considered normal behavior. IMO, it is manifestly unsafe behavior. As far as I can tell so far from Junsi's response, he views this as a non-issue. Even though the charger's behavior completely ignored the charge current setting of 1.5A and perhaps the input current limit setting. Those ought to be inviolable safety settings. That's the part that doesn't make sense.

Do you think it makes sense for a charger design to allow the charge current to vastly exceed the maximum charge current setting, in this case going from 1.5A up past 8A? Same with the float voltage. That was also vastly exceeded.

 

[cheech]

jp, there is nothing wrong with icharger.
because it use DC/DC in input, and if there is voltgae leeking DC/DC increase the current to provide enought power for charging.

in you're graf did not monitoring output current which don't increase.

read manual, and set input limit (voltage and current) high enught that if we say that charger has 90% efficiency or less that within input limit can provide enought output power.

set power supplay to 18V which is charger upper input limit, and set up the curent limit in you're power supplay to max, than set up only current limit in the charger to you're max power supplay.

regards, Simon

 

[HKJ]

Do you think it makes sense for a charger design to allow the charge current to vastly exceed the maximum charge current setting, in this case going from 1.5A up past 8A? Same with the float voltage. That was also vastly exceeded.

Generally no and it would have been nice if it had stopped charging and shown an error message. But the rising input voltage is not a normal condition and obvious a problem with the hardware design of the charger.
I do not believe the problem would occurred if the input current limit on the charger had been set below the current limit on the power supply.

 

[Justin Case]

I do not believe the problem would occurred if the input current limit on the charger had been set below the current limit on the power supply.

Well, Junsi's reply was this:

"Would you please check if you have set a very low value for the current limit protection? If so, the phenomenon you met is normal."

So it appears that it does not help if you set a low value for the input current limit. Tell me, does that make sense? What is the point of an input current limit if it is ignored in such a way that introduces an extremely dangerous overcurrent and overvoltage condition?

VegasF6 was series charging some Sanyo 18650 cells, which have a nominal capacity of 2500mAh. Thus, a max 1C charge would be 2.5A. According to the datasheet that VegasF6 linked, the standard charge current is 1.75A. When the iCharger glitched out, the charge current apparently was over 8A (looks like about 8.5A). That is over a 3C charge rate. Instead of a float voltage of 8.4V, the voltage also increased to what appears to be about 9.4V (4.7V per cell).

Normal? Hardly!!!!

 

[Justin Case]

in you're graf did not monitoring output current which don't increase.

Maybe I'm misinterpreting VegasF6's original post, but this is what he wrote about the graph he posted:

"According to the graph I am posting charge currents were also that high ...."

So it seems to me that the graph is showing the charger output to the Li-ion cells, not the power supply input to the charger.

I would be very happy to be proven wrong since I also have an iCharger (a 208B) and would prefer not taking a face shot from some Li-ions that I'm charging.

 

[cheech]

I have missed that.
so you claim that output current to the battery is also 8A ?
that's definitely not ok.
my suggestion is that you use Pb as the source and measure input and output with current clamp meter.
power supplay with current and voltage limits could cause variation (when current limit is kicking in voltage could drop for a moment) in input voltage and thats why dc/dc of the charger could do some correction and increase current from the source to provide enaught power to the output
mybe you have for a moment voltage drop to zero, and that's why input current suddenly increase.
as I say, use Pb for comparision.
waiting for new report...
reagrds, Simon

 

[HKJ]

Well, Junsi's reply was this:

"Would you please check if you have set a very low value for the current limit protection? If so, the phenomenon you met is normal."

Junsi does not specify if it is the current limit on the charger or on the power supply, I read it as the power supply limit. I.e. a power supply with a current limit below the chargers current limit can trigger this problem.