psybernoid Posted July 18, 2015 Author Report Posted July 18, 2015 Hi. I built my first DNA200 mod earlier today. When I initially connected it to escribe all 3 cells where showing identical voltage values.After a few tests, one of which involved a shorted atomizer, the cells are now out of balance, and don't seem to be correcting themselves.Cell 1 has just been gradually decreasing to the point where it's now under 1 volt.The battery I'm using is a Turningy 2200mah Any suggestions ?
psybernoid Posted July 18, 2015 Author Report Posted July 18, 2015 I should also add, that when connected to a USB power source, or PC - the screen does not show the charging indicator
psybernoid Posted July 18, 2015 Author Report Posted July 18, 2015 No matter. Issue resolved. Had a dry solder join on the TAP connector
protovapor Posted July 19, 2015 Report Posted July 19, 2015 Good one to check, in our experience a bad solder at the tap socket can produce weird results like this.
combatwombat Posted July 21, 2015 Report Posted July 21, 2015 How close should all three batteries be, voltage wise, when fully charged? Mine read cell 1-3.36, cell 2-3.6, cell 3-3.35. Seems cell 2 charges more than the others. Lifepo4 battery.
John Posted July 21, 2015 Report Posted July 21, 2015 LiFePo4 has very, very little capacity difference between 3.36 and 3.6. Are they closer to each other when running?
combatwombat Posted July 21, 2015 Report Posted July 21, 2015 Yes, they are pretty close within .12-.15 when running. The voltages I gave are idle, fully charged.
John Posted July 21, 2015 Report Posted July 21, 2015 That's still a pretty significant mismatch. If you let it sit on charge for a few hours, does it get fully balanced?
combatwombat Posted July 22, 2015 Report Posted July 22, 2015 After 1 1/2 hours, cell 1 -3.5, cell 2 -3.5 cell 3 -3.36. Strange that cell 3 never goes above 3.36. I think my solder is good on balance charger, not sure what could be going on other than cell 3 is bad? I did accidentally let it charge without changing it to lifepo4 in escribe for a short time.
John Posted July 22, 2015 Report Posted July 22, 2015 Can you set up a graph of all three cell voltages in device monitor, then take a couple puffs and post the screenshot? We'll be able to see if it is a bad cell and if so, which cell.
John Posted July 22, 2015 Report Posted July 22, 2015 That all looks pretty reasonable. There's basically zero capacity difference in a LiFePO4 pack between 3.6 and 3.35 volts, so if it stays nicely balanced throughout the rest of the range (3.30-3.30-3.29 is fine) then I wouldn't worry about it.
KFCsocrispy Posted July 23, 2015 Report Posted July 23, 2015 so im having an issue with something causing the battery to not be balanced. Ive checked the tap connector and everything is solder nice and solid and tried two different lipos by two different companies and Escribe always shows cell 1 at 0 volts, cell 2 at 4.84 and cell 3 at 3.88 im so confused by this
John Posted July 23, 2015 Report Posted July 23, 2015 We've seen that if the resistor in the corner of board got knocked off. can you post a picture of the front of your board?
John Posted July 23, 2015 Report Posted July 23, 2015 Ah, this is an easy one. You have way too much solder on the top-most tap connector pin (GND), it is shorting out the cell one sense line. Remove the extra solder and you should be good.
KFCsocrispy Posted July 23, 2015 Report Posted July 23, 2015 so i did what you said to and its still doing it any other ideas im all ears just really want this to start working
KTMRider Posted July 23, 2015 Report Posted July 23, 2015 John, I pm'd you about my issue too. From the previous pic, it looks like one of my resistors got knocked off but not completely. I'm not sure if I can solder something that small back on.
John Posted July 23, 2015 Report Posted July 23, 2015 Ktmrider, take a stab at it, and if you can't sent it in and we'll fix it. Or just send it in, but soldering 0402s isn't too bad.
John Posted July 23, 2015 Report Posted July 23, 2015 KFC can you post a higher resolution picture of the area around the USB ports and the balancer? It has to be one of the outside two resistors in that set of four, or the balancer lead.
KFCsocrispy Posted July 23, 2015 Report Posted July 23, 2015 ill see if i can get my phone to focus on it but just looking at it they all look like their seat properly
combatwombat Posted July 23, 2015 Report Posted July 23, 2015 I contacted the company and they said to cycle it a few times. The strange readings only happen when fully charged, so gonna cycle it 3 times to see if it changes.
KFCsocrispy Posted July 23, 2015 Report Posted July 23, 2015 i dont know if this matters but when hooked up to the usb the screen stays lit like any normal dna but off the usb i have to hold the fire button for the screen to stay on or it will just turn off i was thinking its part of the battery being misread but idk just thought i should add as much info as possible about whats going on
John Posted July 23, 2015 Report Posted July 23, 2015 If you have a voltmeter, what voltage do you get when reading between the solder joints of the 1 and Gnd tap connections? Then what voltage do you get between the far side of the resistors closest to the side? Everything looks pretty textbook except the GND tap solder joint, but that doesn't look so egregious as to be making no contact. What's your serial number? I can see if the production data for your board shows anything unusual, but the board looks right to me.
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