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John

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Reply with quote  #16 
Ah ha. Here's the confusion. 

The load you're measuring isn't resistive.

Burden voltage doesn't enter into it to measure the current accuracy of our charge sensor/display. Microamps or not. 

So I think we're on the same page now. Test away. 


SSV

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Reply with quote  #17 
Quote:
Originally Posted by John
Ah ha. Here's the confusion. 

The load you're measuring isn't resistive.

Burden voltage doesn't enter into it to measure the current accuracy of our charge sensor/display. Microamps or not. 

So I think we're on the same page now. Test away. 




ahhhh.....is the load purely capacitive (no ballast resistors on the input stage)? that def quenches my concerns....(I mean obviously any load is resistive, but if it's = to free air I see your point)
protovapor

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Reply with quote  #18 
Quote:
Originally Posted by SSV
Quote:
Originally Posted by John

There isn't a way to force charge display, but you can put charge parameters on the main display if you're interested. 



John seems to be confirming what my test board is doing....@protovapor



There is no command to immediately make it switch to that mode, however it will switch normally based on your time parameters. To my understanding, it switches after "active time" and "idle time" settings both elapse. If you set both of those to a very short time you can sort of get it to switch on demand.
SSV

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Reply with quote  #19 
Quote:
Originally Posted by protovapor
Quote:
Originally Posted by SSV
Quote:
Originally Posted by John

There isn't a way to force charge display, but you can put charge parameters on the main display if you're interested. 



John seems to be confirming what my test board is doing....@protovapor



There is no command to immediately make it switch to that mode, however it will switch normally based on your time parameters. To my understanding, it switches after "active time" and "idle time" settings both elapse. If you set both of those to a very short time you can sort of get it to switch on demand.


mine is not doing that.....can you test/verify that on one of your units?  If my test unit is connected to eScribe, it doesn't switch over to charge display at any point....I did play with times and nothing....*scratches head* 
protovapor

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Reply with quote  #20 
Yes verified on a bare board as well as on test mods. Do you have the screen set to be on (brightness >0) during charge?
John

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Reply with quote  #21 
I think he is using device monitor, so it sees the device as active. 


protovapor

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Reply with quote  #22 
It will switch even if being monitored... until it is fired of course
SSV

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Reply with quote  #23 
Quote:
Originally Posted by protovapor
Yes verified on a bare board as well as on test mods. Do you have the screen set to be on (brightness >0) during charge?


No, brightness was set on 50% for that scenario.....

I am going to try and reload the entire eScribe suite and FW......I am very puzzled why my unit won't go into charge display while connected, and another will.....
SSV

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Reply with quote  #24 
ok this might be a potential bug.....I just set the idle time to 10 seconds and it's catching now....I see charge stats onscreen AND via device monitor, and via my eternal test jig correlates those numbers....let me start ramping up idle times again and see where it stops behaving correctly....I did reload eScribe etc....will report back if the issue crops up again....

Thanks for the feedback @protovapor I can scratch this issue off the list for now....[smile]
SSV

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Reply with quote  #25 
idle time up to 30 seconds and still working fine....switching over to charge display after 30 seconds (timed it) and still showing stats correctly in device monitor, dna200 display and my external test gear....current draw is accurate (minus cabling losses)
SSV

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Reply with quote  #26 
idle time up to 60 seconds and active time bumped back up to 10 seconds, and still working fine.....it was failing to switch over, with these exact settings before *scratches head* 

*shrugs* I'll knock this one off the list and put it to bed....all is well ATM. 

I am experiencing some VERY strange behavior when using a dedicated PSU as charge input though....at 5v everything is just fine, but as soon as I dip below 4.8v things go haywire.....I will start a new thread on that subject, and include a video demo of the activity....PSU is not switching over to any kind of CC operation, BUT the current draw is very erratic....I'll get some data up as soon as I confirm there is no issue in the test loop.....to confirm the data lines are not active....I am assuming data lines in USB are 3.3v logic signals?  I will hook up another external PSU and try to simulate some logic inits, and throw it up on the scope and see what I can see....I knew that eye diagram would be useful one day or another
John

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Reply with quote  #27 
USB chargers don't leave the data lines floating, there is very specific signalling. 

DCD is the mode prevalent standard for USB chargers. 
SSV

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Reply with quote  #28 
I traced the non linear current reduction problems in the test to a fault in the PSU.  I terminated the data lines coming from the dna200 into the front end of the scope (through a FET probe) and the logic level seems to be correct, even under a fault condition.....I don't need to see packets, just want to see if any logic level faults can drive the dna200 to pull some oddball current spike.....so far everything is looking very good.....on screen vs device monitor vs my test loop only show a 2mA sDEV....data lines 24mV.....I can't seem to break it with a fault yet.....so I am moving it over to a sacrificial laptop....I built the interrupted USB cable we had talked about.....so I can take some metrics at any point in the USB line, and from both ends of the host/slave.....

I have to say i am very impressed with the overall accuracy and safety in the dna200 charging....I have a few minor software gripes, but the hardware is looking very solid....I am gaining a lot of confidence in using USB as the primary charge method, with a fixed pack in the mod....I am seeing all the benefits that come with this approach, with none of the problems that other controllers have had (such as not living up to industry ratings or safety standards).  You really don't want to play dice with a 30c 2200maH li-Po....the BMS on this early board is pretty good
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