rhondas
How do I check the voltage on this charger Turnigy 420 as to calibrate it to the 4.2 volts out per cell, it has individual adjusting pots , yet I do not know how to see the voltage with a digital meter . any one ever perform this function please let me know thank you Rhonda
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squishy
it should already be calibrated to 4.2 volts per cell, but if not you can always place a multimeter on the output leads of the balance plug, just check one cell. Use the balance plug output jack to test with a meter, the black wire is ground and then test any of the other wires which connect to a single cell in the battery. If you do not know if you are adjusting the correct one, place the multimeter on a output and adjust each knob till it changes, in this way you can map the knobs to the output pins.
"Education is not about filling buckets; it is lighting fires." W.B. Yeats

http://www.youtube.com/user/squishy654
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rhondas
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it should already be calibrated to 4.2 volts per cell, but if not you can always place a multimeter on the output leads of the balance plug, just check one cell. Use the balance plug output jack to test with a meter, the black wire is ground and then test any of the other wires which connect to a single cell in the battery. If you do not know if you are adjusting the correct one, place the multimeter on a output and adjust each knob till it changes, in this way you can map the knobs to the output pins.

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the problem each cell is different after a full charge, for example a 3S battery 4.25- 4.13- 3.98 v
should I have a load on the charger ,a 3 cell lipo hoked up ready to charge?
and just use my digital test leads and go from blk ground to pin 2 then 3 and 4 with everything on ,will I still get the full out put reading of the charger for each balanced cell or does the battery have to be fully charged,this is where I get confused. Thank you so much for the help
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rhondas
Quote:
it should already be calibrated to 4.2 volts per cell, but if not you can always place a multimeter on the output leads of the balance plug, just check one cell. Use the balance plug output jack to test with a meter, the black wire is ground and then test any of the other wires which connect to a single cell in the battery. If you do not know if you are adjusting the correct one, place the multimeter on a output and adjust each knob till it changes, in this way you can map the knobs to the output pins.
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dtribby
Seems you're not alone in getting an uncalibrated unit. Unfortunately, you'll just need to play with those calibration pots until you get the proper end voltages. The cell voltages you listed are certainly outside the tolerance I would accept. You'll need to crack the case and do like squishy said above to get your unit into spec.

Now, since it doesn't look like this charger has a discharge circuit like more expensive chargers, if you adjust the wrong pot and allow more than 4.2V on a cell, you'll need to discharge your battery a bit and go again until you get it sorted out. Be patient. You'll get there, but it may take a few charging cycles to get it right.
Yes, I've known that I'm "different" for some time now...
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rhondas
Quote:
Seems you're not alone in getting an uncalibrated unit. Unfortunately, you'll just need to play with those calibration pots until you get the proper end voltages. The cell voltages you listed are certainly outside the tolerance I would accept. You'll need to crack the case and do like squishy said above to get your unit into spec.

Now, since it doesn't look like this charger has a discharge circuit like more expensive chargers, if you adjust the wrong pot and allow more than 4.2V on a cell, you'll need to discharge your battery a bit and go again until you get it sorted out. Be patient. You'll get there, but it may take a few charging cycles to get it right.

I cant adjust nothing with those pots either with or without a battery hooked up"
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dtribby
Post pics - maybe we can help you figure it out. Apparently you have to open up the case to get to them.
Yes, I've known that I'm "different" for some time now...
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dtribby
Changing the pot settings won't have any affect over the real-time voltage applied to the cells as it's charging. The only way to know what is changing is to measure the end voltage of each cell AFTER the charge is completed.

To think of it like a toilet: You have a 3-tank (cell) unit. When you fly your plane, you flush all three at once. When your done and you put in on your charger, you've got three separate water lines going to each of three tanks. All the pots are doing for you is adjusting the float bowl to determine when (at what voltage) the tank stops refilling. If you try to measure how fast the water (current) is filling each tank, it will always be the same. What is important is to get all three tanks to fill to the exact same level (end voltage). They may even fill at different rates for a lot of reasons, but that's okay, as long as they get to the same level (voltage).

Back to your battery: You won't know what changing a pot did for you until AFTER the charge cycle is completed. Here are the steps to repeat: 1) Measure your cell voltages after charging and write them down. 2) Go use your battery (great excuse to fly!). 3) Make a small change to one of the pots, and record which one and how many degrees in which direction. 4) Charge the battery. 5) Measure and record the cell voltages again. 6) Note which cell voltage changed from last time, and make a note of the change on your pot "map". Repeat steps 2-6 until you know which cell each pot adjusts and which direction turning each pot affects the end voltage. From there you should be able to dial 4.2V in for each cell. Typically a 0.05V variance is acceptable, but my $40 Thunder AC6 keeps things within 0.01V. Money well spent in my opinion.

Good luck!
Yes, I've known that I'm "different" for some time now...
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squishy
woop there it is..
"Education is not about filling buckets; it is lighting fires." W.B. Yeats

http://www.youtube.com/user/squishy654
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