Raven power down during flight?

[MountainRocketeer]

{Edit} To be more precise, it's powering down during the last part of the recovery sequence, not while under thrust.

View attachment 2013-04-13_Icarus's Revenge_H170-14,F6,C13.FIPa

This is the second time that my Raven was powered off when I recovered it shortly after touchdown (25 mins the first time, 5 mins this time).

I had it programmed for drogue at apogee, with backup 2 seconds later (and also motor backup 4 seconds after predicted apogee). Main was programmed for 416 ft, with backup at 352 feet. However, I did not connect a charge to the main backup, so that circuit was empty.

Looking at the FIPa file, it appears that the Raven powered off when it hit 350 above the pad, or the same instant when the empty main backup channel was supposed to fire.

Any ideas?

 

[mikec]

Any ideas?

Your battery lead is coming loose under thrust?

I find the small screw terminals on the Raven a little tricky to get wires into correctly. Always try to pull the wires out after tightening them down.

 

[CarVac]

Your battery lead is coming loose under thrust?

I find the small screw terminals on the Raven a little tricky to get wires into correctly. Always try to pull the wires out after tightening them down.

A better option is to solder the wires to header pins which are securely gripped by the screw terminals.

 

[warnerr]

guessing as to your setup: battery holder? Prefer cheap leads to snap top direct. Mass of battery can momentarily disconnect while thrusting on most battery holders. Sample of basic leads: https://www.summitsource.com/eagle-...ent-applications-single-pi-11866.html?image=0

 

[mikec]

Mass of battery can momentarily disconnect while thrusting on most battery holders.

A momentary loss of power shouldn't bother the Raven, it has a large capacitor.

The OP never described what kind of battery he was using. Obviously defective batteries could be a problem. I assume you've just tested your system on the ground and it runs fine?

 

[MountainRocketeer]

To be more precise, it is powering down during the last part of the recovery sequence, not under thrust. Both times, channels 1,2, and 3 fired on time, but it appeared that the Raven powered off when channel #4 fired. Last time there was a charge on channel #4 that did not go off, and this time there was no charge on that channel.

I am using the Raven Power Perch, so I know the battery and battery leads did not come loose.

I had already downloaded the log and put the altimeter away before I reviewed the FIPa file, and I have not yet gotten it back out to run a diagnostic. All previous tests worked fine.

 

[Fdog]

If you open your .fip file, and hit the <Ctrl> key as you click Volts Battery (V) in the Parameter Selection window, you will see:

Main Battery volts go to zero as the Main deployment charge fires. The system carries on for a few seconds on capacitor storage. I would examine your other flights to see if there was a similar drop-to-zero during other high-G events.

There are a couple of things that could cause this, I'd think:

• Battery not secured
• Loose battery connector on battery side
• Loose battery connector on PowerPerch side
• Defective battery
• Raven terminals not fully tightened

All the best, James

 

[bobkrech]

What are you using for your e-matches? If they are homemade, what is the gauge and material in the bridgewire?

Is pyro 4 shorted?

Bob

 

[MountainRocketeer]

What are you using for your e-matches? If they are homemade, what is the gauge and material in the bridgewire?

Is pyro 4 shorted?

Bob

I'm using Quest Q2G2 igniters.

Channel 4 was empty on this last flight.

 

[billspad]

I'm using Quest Q2G2 igniters.

Channel 4 was empty on this last flight.

Could channel 4 be shorted on the board?

 

[Adrian A]

{Edit} To be more precise, it's powering down during the last part of the recovery sequence, not while under thrust.

View attachment 125664

This is the second time that my Raven was powered off when I recovered it shortly after touchdown (25 mins the first time, 5 mins this time).

I had it programmed for drogue at apogee, with backup 2 seconds later (and also motor backup 4 seconds after predicted apogee). Main was programmed for 416 ft, with backup at 352 feet. However, I did not connect a charge to the main backup, so that circuit was empty.

Looking at the FIPa file, it appears that the Raven powered off when it hit 350 above the pad, or the same instant when the empty main backup channel was supposed to fire.

Any ideas?

The data shows that the measured battery voltage went to zero when the main charge fired, and stayed there until the hold-up capacitor ran down and the altimeter shut down a few seconds later. If it were just a short on the main output, the unit would have recovered because it stayed up longer than the normal 1-second firing time. There was a pretty large G shock recorded when the main fired, so perhaps that knocked loose a connection to the battery?

Update: I read now that you were using a Power Perch. In that setup, whether the battery can move will depend on the mounting of the battery restraint. See if you can move the battery enough to disconnect it while it's installed. Could you describe more about your rocket?

 

[bobkrech]

Could channel 4 be shorted on the board?

I was wondering the same thing. The Quest Q2G2 igniters don't pull enough current to kill the battery. https://www.rocketshoppe.com/info/Igniter_Continuity_Tests.pdf

The 130 ma LiPo battery shouldn't get flattened by these igniters that draw not more than 1.25 amps, or less than 10 C. The all-fire current rating is 350 ma. and the cold resistance is between 3 to 4 ohms so 3.7/3 ~ 1.25 amps. As the igniter heats, the resistance increases so the current will actually drop.

I suspect a short, maybe from carbon deposits, a bad connection, or a defective battery or charger. Channel 3 also showed some unexpected behavior.

Bob

 

[Adrian A]

It's not a shorted output because the battery was down for more than the 1-second on-time. After 1 second is up, the output switch would open to cut off the short. Also, the battery dropped out at the time of the main firing, and the continuity reading shows that nothing was connected to channel 4.

 

[WoShuGui]

Sure does look like a battery disconnect from g-shock at main deploy. Battery voltage sampling rate is too low to be sure, but it is down to 0.12 V on first sample after g-shock and was 3.9 V on last sample just before g-shock.

 

[G_T]

I've been flying a Telemetrum with a recently manufactured LiPO cell that seems to have a built-in current limiter. When it detects something resembling a short, it shuts the battery connection down until the short is removed. Thankfully I was flying fully redundant circuitry - separate type of backup altimeter, second type of battery, etc. I had two flights with anomalies right at/after firing charges. It was most perplexing... Perhaps you've encountered a similar situation?

Gerald

 

[billspad]

I've been flying a Telemetrum with a recently manufactured LiPO cell that seems to have a built-in current limiter. When it detects something resembling a short, it shuts the battery connection down until the short is removed. Thankfully I was flying fully redundant circuitry - separate type of backup altimeter, second type of battery, etc. I had two flights with anomalies right at/after firing charges. It was most perplexing... Perhaps you've encountered a similar situation?

Gerald

You should contact Altus Metrum. Keith Packard was fixing them at the USLI/SLI launch.

 

[keithp]

I've been flying a Telemetrum with a recently manufactured LiPO cell that seems to have a built-in current limiter.

I'm fixing these for free (you'll have to get the battery to me though) if you don't want to try your hand at soldering the lipo terminals.

 

[CarVac]

I'm fixing these for free (you'll have to get the battery to me though) if you don't want to try your hand at soldering the lipo terminals.

Do I just short it out if I want to do that?

 

[cvanc]

I'm fixing these for free (you'll have to get the battery to me though) if you don't want to try your hand at soldering the lipo terminals.

Keith, are you comfortable starting a thread here with info on how to check/modify batteries for those of us who are handy with a soldering iron? Even knowing how to tell what kind of battery you've got would be most helpful. Thanks.

 

[troj]

Do I just short it out if I want to do that?

Never short a LiPo. The results are not good.

-Kevin

 

[bobkrech]

Refer to https://pe.usps.com/text/pub52/pub52apxc_044.htm for detailed instructions.

Summary:

0. USPS Ground Parcel Post is the cheapest way to ship lithium-ion batteries and equipment containing lithium-ion batteries.

1. Make sure battery can not short. Put masking or electrical table over bare ends of wires or contact pads or end of socket or plug.

2. Tape any wires so they will not move.

3. Put battery in ziplock bag. Fold over so battery can not move in bag and use tape or rubber band to keep bag folded.

4. Pack in box. Used crushed newspaper to prevent battery from moving in box.

5. The shipment is a secondary lithium-ion battery not packed with or installed in equipment (individual battery).

6. It is mailable domestic via surface transportation only in a small corregated box.

7. The outside of the packge must be marked on the address side with the label "Package Contains Lithium-ion Batteries (no lithium metal).&#8221;

8. Labeling is not required if the battery is installed in elecctronics.

Bob

 

[CarVac]

Never short a LiPo. The results are not good.

-Kevin

Of course. I meant "short out the control circuitry".

 

[bobkrech]

Of course. I meant "short out the control circuitry".

To prevent possible damage to a FET, I'd recommend using a 10 ohm resistor as a short.

Bob

 

[Adrian A]

To prevent possible damage to a FET, I'd recommend using a 10 ohm resistor as a short.

Bob

Just for test purposes? That's much too high to use in a firing circuit with the small single-cell Lipo batteries under discussion. In a Featherweight av-bay setup, the battery has about 500 mOhms resistance (quasi steady-state), the current-measuring shunt on the Raven is 25 mOhms, and the FET has around 5 or 20 mOhms, depending on the channel. Terminal blocks and wire make the total around 600 mOhms. When connected to a 2.8 Ohm Q2G2, the circuit puts out about 1-1.5 Amps, vs. the all-fire current of about 0.3 Amps. With a 1-Ohm Estes ignitor or a Jtek, it puts out about 2.5 Amps. If the output has a hard short, it will put out around 7-10 Amps for the 1 second that the firing FET is on, and the little battery doesn't even warm up noticeably when that happens.

If you put a 10 Ohm resistor in series, those numbers go down under 0.3 Amps, which is marginal even for a Q2G2, and almost certainly would prevent the other loads from firing.

 

[keithp]

I just posted a link to the tutorial Bdale wrote up a couple of weeks ago.

 

[cvanc]

I just posted a link to the tutorial Bdale wrote up a couple of weeks ago.

Excellent, I had not seen that before. Thank you!

Is there a similar worry when the LiPos have a molded on connector (example: like what a Raven Power Perch uses)?

 

[keithp]

Is there a similar worry when the LiPos have a molded on connector (example: like what a Raven Power Perch uses)?

I don't know for sure, but from what I understand, these batteries are designed for use in RC aircraft and support significantly higher current draws for long periods of time. Adrian would know for sure.

 

[Adrian A]

Excellent, I had not seen that before. Thank you!

Is there a similar worry when the LiPos have a molded on connector (example: like what a Raven Power Perch uses)?

The 130mAhr batteries I sell on my site and include with the Featherweight av-bays don't have any cell protection circuitry, so unintended cutoff under high currents is not an issue.

 

[GRIFFIN]

The 130mAhr batteries I sell on my site and include with the Featherweight av-bays don't have any cell protection circuitry, so unintended cutoff under high currents is not an issue.

On this same topic, will the batteries go dead in a power perch after a flight (if the altimeter is not turned off). For example, the rocket was stuck in a tree and could not be recovered for a few days. I ask because this happened to me and now, that battery will not take a charge. I know LiPo's are not supposed to drop below a certain voltage. Does the Perch have a voltage cut off/shut down/battery protection?

The cost of a 9V is higher than the small LiPo, so If they are damaged in a flight, i still don't mind. I was just wondering if that what happened to that battery.

-Jason

 

[bobkrech]

Just for test purposes? That's much too high to use in a firing circuit with the small single-cell Lipo batteries under discussion. In a Featherweight av-bay setup, the battery has about 500 mOhms resistance (quasi steady-state), the current-measuring shunt on the Raven is 25 mOhms, and the FET has around 5 or 20 mOhms, depending on the channel. Terminal blocks and wire make the total around 600 mOhms. When connected to a 2.8 Ohm Q2G2, the circuit puts out about 1-1.5 Amps, vs. the all-fire current of about 0.3 Amps. With a 1-Ohm Estes ignitor or a Jtek, it puts out about 2.5 Amps. If the output has a hard short, it will put out around 7-10 Amps for the 1 second that the firing FET is on, and the little battery doesn't even warm up noticeably when that happens.

If you put a 10 Ohm resistor in series, those numbers go down under 0.3 Amps, which is marginal even for a Q2G2, and almost certainly would prevent the other loads from firing.

I thought he was discussing the shorting of the outputs of an altimeter for shipping a misbehaving altimeter back to the manufacturer.

Instead of shorting the output and accidently destroying the FET, I was suggesting using a 10 ohm resistor which would effectively short the outputs but not damage the FET if accidently fired, nor would it excessively heat up.

Bob