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Mikado V-BAR Control Mikado V-Stabi/V-BAR Control Flybarless System Software and Hardware Support


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Old 12-31-2020, 10:42 PM   #1 (permalink)
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Default Poor calibration of battery monitor on V control touch

The battery on my Vct is getting weak so I decided to buy a new one. No one has them in stock and they seem to be overpriced for what you get. I have a new 4S 6600 mah 10C pack that was a extra for an fpv airplane so I measured and found that 1 cell would fit into the vct case. I disassembled it and soldered on a lead and heat shrinked the pack. I'm now doing a discharge on it to find its true capacity. While I'm waiting on that I decided to connect the Vct to my Kepco power supply to see how much current it pulls. During normal transmit my Vct pulls 380ma. I then put a carefully measured 4.20 volts on the vct and to my suprise the on screen battery monitor said the level was at 78%. It took 4.36 volt to get the display to show 100% I left it at 4.36V just long enough to see what the display said and backed it down. Following is the remainder of the test.

4.36V=100%
4.20V=78%
4.00V=50%
3.90V=34%
3.85V=27%
3.80V=20%
At 3.8V the display is unstable, going less and the tx shuts off.
For what this transmitter costs I would expect the on screen battery meter would be better calibrated. I can't tell if the calibration is done in software or with fixed resistors but it doesn't matter the calibration should be better. Maybe my tx is an outlier and most of the other Vct's are better calibrated, I don't know. Just thought I'd share this with you guys.
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Old 01-01-2021, 03:15 AM   #2 (permalink)
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4.35 volts is what the HV lipos charge to.
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Old 01-01-2021, 08:02 AM   #3 (permalink)
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ive seen it stated here that my old school vcontrol can safely be flown to 0%, but theres a lot of other things going on with the touch.. like the big screen and other programming that takes a lot of battery.
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Old 01-01-2021, 01:21 PM   #4 (permalink)
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A little more info.
Nowhere on the Gens ace lipo does it state that it's the hv version. The ending (terminal) charge voltage as supplied by the wall wart included with the transmitter is 4.193, taken with a calibrated Fluke 289 meter. The charge current is .55 A
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Old 01-02-2021, 06:48 AM   #5 (permalink)
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Perhaps it supports HV lipos though? So the meter only goes to 100% with the presence of an HV lipo? Mine is not 100% after charging either. I've seen it say like 97% when i first turn it on after a charge but within seconds it drops to 90% or less.
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Old 01-02-2021, 07:42 AM   #6 (permalink)
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Mine does the same.

Quote:
Originally Posted by fiddle View Post
Perhaps it supports HV lipos though? So the meter only goes to 100% with the presence of an HV lipo? Mine is not 100% after charging either. I've seen it say like 97% when i first turn it on after a charge but within seconds it drops to 90% or less.
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Old 01-02-2021, 10:11 AM   #7 (permalink)
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Quote:
Originally Posted by fiddle View Post
Perhaps it supports HV lipos though? So the meter only goes to 100% with the presence of an HV lipo? Mine is not 100% after charging either. I've seen it say like 97% when i first turn it on after a charge but within seconds it drops to 90% or less.
Point taken, however with the ending charge voltage being around 4.2V it doesn't make sense to calibrate the charge to one standard and the reporting of that charge to another standard.
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Old 01-02-2021, 04:41 PM   #8 (permalink)
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well - it also has a second plug inside where you could plug a second battery but it doesn't come with such ...
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Old 03-23-2021, 08:57 AM   #9 (permalink)
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What kind of wiring (wire gauge and length) did you use to connect the power supply to your radio? At 380 mA there's quite probably some voltage drop through the cables.


If you measure the voltage directly at the battery plug inside the radio using your Fluke, what does it read?
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Old 03-23-2021, 11:20 AM   #10 (permalink)
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In this link, he goes through connector types to charge the tx..

https://www.helifreak.com/showthread.php?t=856329

But if you turn off the Wi-Fi the battery should last quite a while
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Old 03-24-2021, 06:16 AM   #11 (permalink)
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My VBCT charges to a max of 96% to 97% reading. With the WiFi on, the battery comes down to a low to mid 50's % reading after 14 flights. That includes time spent making adjustments on the radio between flights.
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