Feedback/impressions on the PhD-M6 custom battery pack
- Thread starter wquiles
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Thanks for your suggestion, but I always double check that.
The thing with the resistor is that even if it works to turn the pack ON, unless the voltmeter has an AC+DC RMS function, the voltage read will be wrong. You have to use something like a Fluke 189, or 289 (the two that I have), manually set it to the AC+DC RMS mode, put something like a car bulb (12-13 volt rated) across the pack, and then measure the RMS voltage under load. That will tell you if the pack is regulating at the desired dip switch voltage setting.
In this thread, post #11, Willie Hunt explains the problem with measuring RMS voltage with a standard voltmeter - the problem is the duty cycle. If the duty cycle is not 50%, the measurement will not be accurate:
http://www.candlepowerforums.com/vb/showthread.php?125451-M6-R-LVR3i-change-from-6-8-to-7-5-volts-also-explaining-DC-RMS&highlight=Fluke
Willie does talk about some ways to come up with an approximate value, but I just use the Fluke 289 to read the value directly.
Will
JimmyM
Flashlight Enthusiast
Absolutely. I was just hoping to see something OTHER than pack voltage to see if the FET wasn't failed-ON.
I've got the 189. You have the 289!? Nice. I'd be thrilled with the 287.
Interesting reading, Will. Wouldn't it be better to use a higher resistance load, rather than a car bulb, so that the batts dont sag and I could use the guidelines from the above mention post to calculate the true RMS voltage from the time averaged V measured by my volt meter? I think that anything larger than, say, 100 ohm would be good for that purpose, right? The question is whether 100 ohms or larger resistor would trigger the pack into operation?
JimmyM
Flashlight Enthusiast
A car bulb (1157/3157) only draws 2.6-ish amps. They just don't like more than 15V. So you should be OK.
Ahh, yes. I see that you mean. I am pulling my hair over here trying to figure out what might be wrong 🙁
The 189 I got brand new (great deal on Ebay), and the 289 was used, but it was nearly brand new - it was a fantastic buy.
The one that I use draws (if memory serves) 5+amps with a full pack. The beauty of using a 12 volt car bulb is that it is nearly impossible to blow/flash with 3x LiIon cells in series, since they are designed to work comfortably above 12 volts (since the alternator is charging the battery at over 12 volts).
In fact, it is quite the opposite. In the PhD-M6, the pack is expecting the very low resistance of a cold filament, and that is what wakes up the regulator, start looking at the input voltage, looking at the dip switch settings, doing the soft start, etc..
All of the voltages are tested/adjusted under load using a real bulb, so using a resistor (which does not have inductance like a real bulb does) might not work to wake up the pack. I don't think you can hurt the pack itself, but I don't know how it will behave since that is not how I test them.
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I just found an fm1909, installed it in an fm socket and put into the m6.
it is identically bright and very white at the switch positions that are supposed to be 6.8V and 11.1V. While I'd need some extra wires and clips to measure actual voltage, I am pretty sure that in both cases the bulb was powered direct drive.
it is identically bright and very white at the switch positions that are supposed to be 6.8V and 11.1V. While I'd need some extra wires and clips to measure actual voltage, I am pretty sure that in both cases the bulb was powered direct drive.
Interesting. Direct drive (near 100% duty cycle) happens when the voltage is lower than what can be regulated, but with the voltage right at approx. 12volts, I can't explain what is happening. I have never seen a pack behave that way
JimmyM
Flashlight Enthusiast
If the FET has failed, it will do this. Just locked ON.
Gotcha. I have not had a FET fail yet in any of the packs, but if/when I get the pack back, I will check that out. Thanks 🙂
JimmyM
Flashlight Enthusiast
I agree with you though. Damned peculiar.
Jimmy, you are a genius :bow:
Got the pack yesterday, check it this morning on my setup.
- Visual inspection: normal. everything looks OK
- Load test: nothing. Dead.
- Microprocessor test: everything looks perfect. Can read all status information normally.
- Solder joints/dirt/corrosion: nothing. everything looks OK.
So everything looks OK, micro is happy, but no worky. So I figure I try your idea of swapping the FET. So I remove the FET and solder a new one:
Now everything works perfectly again:
I have now been re-testing the pack, and all 4x set points work again as designed:
I have will have the pack ready to ship back in the next few days 🙂
Will
JimmyM
Flashlight Enthusiast
Hey, Will, Glad you got it all worked out!
Thank you so much for the tips/advice :bow:
JimmyM
Flashlight Enthusiast
C'mon, Will. Any time for you. Plus I love this stuff.
Just got the restored pack from Will, so my dream M6 is young and strong again. No more unproved, unsupported untested "new generation" cells..
Will, thanks a lot for standing behind your product, I very much appreciate your help!!
Will, thanks a lot for standing behind your product, I very much appreciate your help!!
You are welcome 🙂
