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Okay, I sent Brandon a PM yesterday and he just replied.He sent me the wrong chargers.
Just stumbled on to this forum as I have been starting my own mods, BreakTru and CraigHB you both do fantastic work and the discussions here are an invaluable resource. I'm planning two mods, one based on the DNA and eventually a more complicated mod using something like a TI4050 with a control circuit and the needed safety monitoring. The DNA is attractive as a first project as it contains the safety monitoring and simple setup so I can get the sensing circuits and display dialed in before taking on a more complicated project. What have you found to be the best way to get an accurate current measurement? Hall effect sensors or are you measuring the voltage drop across a small resistor in series with the load and driving that to the ADC with an op-amp? Thanks!
Thanks! Do you mind if I ask what sensor you are using? I've been looking at this part (http://www.digikey.com/product-detail/en/ACS711ELCTR-12AB-T/620-1370-1-ND/2470594) since I'm using the 3.3 mini board and dont want to put a 5v reg in to keep it small and the component count down. Like that it has an overcurrent latch as well, could be useful later on. Wish it was through hole but that can be overcome.Love that OLED display you are using, has a lot of advantages for modding being small and clear.
batteries arrived today, got everything together and tested. Voltages are dead on, but current needs some work. Will take a bit to get the ratio correct. Almost there...
Hmmm...dont have a DC supply here, but I think this usb charge breakout board can be modified to 1 amp. I think BreakTru did this so I'll see if I can find where he found out how, that would be better at least. Got it all boxed up and (still) charging, vapes pretty nicely. Ranges between 6 and 12.5 watts which is plenty for me. My PTN4050C samples are calling my name now....did someone say digital pot?
Thanks sir! Not too bad I guess, I did not do great at modding the case - hence the electrical tape. I do have these two cases coming in a week or two that I'll plan a little better and do a nicer job:http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=380335740247&ssPageName=ADME:L:OU:US:3160http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=330357824336&ssPageName=ADME:L:OU:US:3160This is the charge board:https://www.sparkfun.com/products/10401
Hmmm...changed the resistor this weekend and it didn't seem to complain although I didnt watch it that close. Charge time was reduced although without any timing or calculations to back that up. The AC charger I use is .8A so maybe it just sneaks under from throwing it into thermal limit (or I just wasnt paying enough attention to notice) . Will look into that circuit, thanks for the tip Craig!
Looking at the datasheet for the 73831, its a CC/CV type charge circuit and I wonder if trying to boost the current will throw off the algorithm. It also says that charging at 500mA is "Not production tested. Ensured by design."Adafruit has the MCP73833 modules but they look to be a bit bigger as it has 2 jst connections. Default is 500mA but is adjustable to 1amp with a 1K thru-hole resistor and can also use a thermistor for temp monitoring during the charge. https://www.adafruit.com/products/259
The evolv charger is small, what IC does it use? I like the one from Spark as it uses the CC/CV charge cycle which is supposed to be better for preserving the longevity of the batteries (like a Pila charger for IMR's).
Taking the DNA out to put in a simpler mod this weekend, just the DNA and an LED voltage display with a 3 way switch so I can see either atty or battery voltage.
I'm thinking about doing the same thing. Im planning to use a 3way switch but im thinking i might damage the dna cause the negative for Vin and Vout are separated. Is it ok if we wire it altogether with the negative wire from the display?