PPA Battery Board (Fast Charging)
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mwpmo

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I just finish PPA Battery Board (Fast Charging) with the following config. (Standard Config from tangent's page)

12 x 800mA AAA Battery
LM1086-ADJ
R1 1K
R2 4.7
R4 10K
R5 1.2K
R6 short
R7 short
R8 open


Install everything and check the voltage between R4/R5 and ground is about 1.3V.

Turn on the power supply (+24V) and the LED is not flashing !!!

Both LM1086 and R2 is warm and after half an hour, I turn off the power and recheck the voltage between R4/R5 and ground, it is about 1.7V.

Any idea why the LED is not flashing ?
 
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tangent

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What's the LED config?

Is the LED off, or on solid, or on dimly?

Are the TLEs installed?
 
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mwpmo

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Quote:

Originally posted by tangent

What's the LED config?


LED config:
RLED 1K
Q1 2N8454
LED (volatge across it 1.8V)

Quote:

Is the LED off, or on solid, or on dimly?


on solid

Quote:

Are the TLEs installed?


Yes both U2 & U4 are installed.
 
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tangent

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Lose the JFET for now. There's evidence that it causes problems. If this fixes it, let me know and I'll update the docs. You'd be the second person to see a problem from having the JFET.
 
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mwpmo

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BINGO!

After I remove Q1, It is flashing now !!!

But the flashing is not "On" "Off" "On" "Off",
it is "Strong" "Weak" "Strong" "Weak" in brightness.

When I use 1K as RLED, the difference in Brightness is small.

After I use 10K as RLED, the difference in Brightness become bigger. (the "weak" become weaker)

Is it possible to make the flashing as "On" "Off" "On" "Off".
 
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benjohnson

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Quote:

Originally posted by mwpmo
BINGO!

After I remove Q1, It is flashing now !!!

But the flashing is not "On" "Off" "On" "Off",
it is "Strong" "Weak" "Strong" "Weak" in brightness.

When I use 1K as RLED, the difference in Brightness is small.

After I use 10K as RLED, the difference in Brightness become bigger. (the "weak" become weaker)

Is it possible to make the flashing as "On" "Off" "On" "Off".


That's a normal behavior. The current across the LED never really drops to zero...it just gets really low. Just play with different RLED values (and try different LEDs too). I had a blue one and a white one. The white one's "dim" mode is more obvious than the blue one. I don't know if you'll be able to completely eliminate it, though.
 
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ITZBITZ

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Quote:

Originally posted by tangent
Lose the JFET for now. There's evidence that it causes problems. If this fixes it, let me know and I'll update the docs. You'd be the second person to see a problem from having the JFET.


I think I was the first. I removed the JFET and it started working properly (blinky, blinky).
 
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tangent

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Quote:

it is "Strong" "Weak" "Strong" "Weak" in brightness.


That's normal when you use the TLEs. There's a current path through them regardless of what the MC3334x is doing. The only way to avoid it is to drop the cell count down to the point where you can avoid using the TLEs.

Personally, I kind of like the strong/weak cycle, because it tells me more about what the circuit is doing. "Off" means the battery board has no power at all. "Weak" means it's in fast-charge mode. "Strong" means it's in trickle-charge mode or (if it's a momentary blink) that the charge controller is sampling the pack's voltage.

If I somehow managed to fix this (unlikely), you'd only have two states, and the "off" state could mean two entirely different things.
 
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