VCC gives 1.8v (was Battery doesn't appear to charge)

[SuperRoach]

I have a problem where the battery may be worn out or something - I'm not sure.

Took a sample video to try show what happens:
https://vimeo.com/72499637

It will blink green (indicating charging) briefly, before staying fully green, then not charging. Is the battery dead, or is there something else I should look at?

I took a measurement of it while it does work, and it was giving 4.1v which is the correct voltage.

Any ideas?

[tobias]

Very strange behavior... Does the battery seem to perform as normal? Can you measure the voltages VCC and VCCA when running from the battery. They should both be close to 2.8V. If you connect to the Crazyflie with the cfclient what is the voltage reported and is it the same as if you measure the battery voltage with a mulitmeter?

[SuperRoach]

You may be on to something there then.
Charges:
VCCA: 2.78v
VCC: 1.86v

I'll try connect it to the laptop and see what it reports.

Battery life wise I may get 30 seconds tops flight time.

[tobias]

This sounds like the voltage regulator U9 has broken. Can be fixed by replacing it. See this thread.

[SuperRoach]

Ohhh I remember that thread! Thank you. I'll order some parts and wait around for a bit

Btw, an idea for the future would be to offer a "hackers kit" on your website, with a bunch of things like the regulator, spare set of motors, blades etc. Give a bit less of a wait when breaking things.

[tobias]

A hackers kit is actually not a bad idea but the problem is there are so many good ideas which makes it less likely to happen...

[SuperRoach]

Trying to solder the six pins of this onto a board. http://i.imgur.com/Or7VYrb.jpg . Not fun.
It's just so tricky to hold it in place (the crazyflie), and the part with tweezers, while then needing two hands free to do solder and soldering iron :/

Calling it a night and returning to it tomorrow.

[SuperRoach]

*edit* images update
For anyone interested in soldering at this scale....

http://i.imgur.com/fsZ0kAn.jpg
A bobby pin was used to hold the u9 regulator in place

The end result of a day of soldering lol:
http://i.imgur.com/mUxZrne.jpg


May need to look into it further - I've soldered a new regulator as mentioned in the thread above by tobias on, and I think I have brighter lights... And I think it's taken a while to charge up (which is much better than the green light staying on after not too long).

but the VCC is still giving me a 1.8v readering (VCCA is 2.86v). I'll do some further diagnostics including checking a connection to it and seeing what battery charge rating it gives.

*edit* update:
Good to connect it to the PC again... I'm not sure if the FPV setup has a constant or idle drain, but cfclient gives me 3530mV. Link cuts out if the throttle goes up above almost the minimum throttle setting (35%), so sounds like I've still got the same problem. Doh. Motors are all ok which is a minor success.

May try to take out the part I have, and use the last spare next week.

[tobias]

Hmm, that is strange that the new regulator didn't work.
What sets the output voltage is the feedback programmed voltage since these are adjustable regulators. You can check that the feedback voltage is healthy by measuring it, which is pin 5. Be careful not to short against any of the other pins as you have to do this while the board is powered. The voltage on the feedback pin should be close to 1.22V.

[SuperRoach]

Oh neat I'll give it a go.

Reading the other fpv thread, You could possibly be on to something there - I have had a fair few flights without the regulator, but barely any with it on. The first few was when trying it on 4v (adjustable regulator) which was ok... but the 5v may be too much draw perhaps.

From the regulators website, it does mention about power on spikes.

LC Voltage Spikes

When connecting voltage to electronic circuits, the initial rush of current can cause voltage spikes that are much higher than the input voltage. If these spikes exceed the regulator’s maximum voltage, the regulator can be destroyed. If you are connecting more than about 9 V, using power leads more than a few inches long, or using a power supply with high inductance, we recommend soldering a 33 μF or larger electrolytic capacitor close to the regulator between VIN and GND. The capacitor should be rated for at least 16 V.

More information about LC spikes can be found in our application note, Understanding Destructive LC Voltage Spikes.

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