What Lipo batteries are people using for the RRC3?

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Things are getting pretty complex now to protect those output transistors,,, No ???
It sounds overall like where we've come with this conversation is to
protect the altimeter in a rocket that's about to come in ballistic......

Doesn't make sense.........

Teddy
 
I just tuned in to this thread again. I took Teddy up on his advice for my RRC3. I got lipo, female jst connector to bare wire leads, and charger. The RRC3 works great hooked up to it on the table. I am bummed about not being able to fly it yet. I have the life thing getting in the way of flying (I hate when that happens). The jst connection is not going to come apart if taped over. I got mine to solve space issues in my Giant Leap Mariah 38. A 9V battery would be an issue for me with my av bay setup. The lipo is perfect. I had to cut a 1" wide G10 sled to fit the RRC3. The stock sled was 3/4" or something. I have the lipo, RRC3, Featherweight magnetic switch, in my Mariah 38 (still needs paint), and I am really psyched to launch. I am no expert on Lipos. The one thing that Jim Amos suggested was to get the battery voltage closure to 9V. I believe the 1 S lipo is a 3.7 volt, but the 2 S is 7.4. It has been awhile since I was up on this. Whereas the Raven 3 is made to work on a 1 S 3.7 volt lipo. The only thing that I regret is that I bought a recommended cheap lipo charger and then needed a 120v ac to dc adapter. Fortunately, I had one that will work. I wish that I had flight data, but I am happy before the flight that things look good. See above posts for lipo recommendation. I was also in another thread on same topic. If you need exact info. for what I got, let me know.

Chris
 
I found an extra cent to add to my previous 2 cents. I could be wrong, but I thought that I read in posts somewhere from Adrian of Featherweight, that the main source of shorts to alts. came in special shorting conditions mostly found in lighting second stage of two stage when hot motor gasses are near alt. and can cause shorts. I can't remember exactly, but the jist of it was that worrying about shorts isn't a big concern in most standard launches. Any thoughts?
 
The most important thing there is with lipo's is that they're charged properly......
They must be balanced charged by a balance charger made for that purpose.........
I paid $125 years ago for my computer charger......
It will do 2s thru 6s lipo and just about any other battery chemistry.......
I love it......
I had to buy a $60 12V power supply for my workbench to run it......
I have a problem now because it won't charge a 1s lipo,,,,,,,,
This is the charger I wish I had------------

https://hobbyking.com/hobbyking/sto...scharger_1_6_Cells_GENUINE_US_Warehouse_.html

Lipo's MUST be charged properly...........

Teddy
 
For my Tragic Little Aerospace GPS unit, I use the following setup:

I use this battery: https://www.amazon.com/gp/product/B001BFTPVI/?tag=skimlinks_replacement-20

With this charger: https://www.amazon.com/gp/product/B00466L0BW/?tag=skimlinks_replacement-20

With this power supply: https://www.amazon.com/gp/product/B0023Y9EQC/?tag=skimlinks_replacement-20

(the charger does not come with a power supply, so you need to buy it separately)

The GPS was transmitting for well over 3 hours as we were searching for the rocket. The charger appears to be working really well.
 
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4kids49 said:
I found an extra cent to add to my previous 2 cents. I could be wrong, but I thought that I read in posts somewhere from Adrian of Featherweight, that the main source of shorts to alts. came in special shorting conditions mostly found in lighting second stage of two stage when hot motor gasses are near alt. and can cause shorts. I can't remember exactly, but the jist of it was that worrying about shorts isn't a big concern in most standard launches. Any thoughts?
Click to expand...

In my experience, shorts across the deployment outputs during motor ignition happen quite frequently, pretty much whenever an igniter is in the motor when it comes up to pressure. The glowing-hot gasses in the motor provide a low-resistance path for the electricity to go from one deployment wire to another.

Shorts on a regular deployment charge are much more rare, but still happen occasionally.

[Deleted commentary not relevant to this RRC3 application.]
 
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Adrian A said:
In my experience, shorts across the deployment outputs during motor ignition happen quite frequently, pretty much whenever an igniter is in the motor when it comes up to pressure. The glowing-hot gasses in the motor provide a low-resistance path for the electricity to go from one deployment wire to another.

Shorts on a regular deployment charge are much more rare, but still happen occasionally.

A simple, fool-proof way to use Lipoly batteries for deployment charges is to simply use a lipo that's small enough (and high enough internal resistance) that it won't damage the altimeter if the output shorts. That's why all of the Featherweight products that have lipo batteries use a 1-series, 130mAhr cell. It can output just as much current into a typical 1-Ohm ematch load as a 9V battery, but not enough to damage Featherweight output switches. I haven't found any reason to use a larger battery than this for deployment charges.

On a large project with high-powered airstarts, there tends to be more of a temptation to use large batteries and high-powered igniters for the motor ignition (though there are plenty of ways to ignite a motor with just an ematch). For the Raven3 altimeter, the 3rd and 4th output channels, which are normally used for high-powered airstarts, have output FETs that can handle 30+ Amps so that even if someone over-does it on an airstart circuit, it won't hurt the altimeters.
Click to expand...
A 130 ma LiPo battery can source much more than 10 amps.

It is easy and cheap to put a 2-terminal current limiter in series with the battery and indeed many commercial battery packs (not used in RC planes) have such a protection device built into the battery pack.......

It's even easier to use an auto-setting thermistor switch in each pyrocircuit. For example https://www.batteryspace.com/Compon...p-limit-20-C----UL-Listed-TUV-CSA-Listed.aspx is a simple $1.09 semiconductor auto-resetting thermistor switch. It trips out at 9.5 amps. You can wire 1 in series with the pyrocircuit power supply wire (ground switched) or ground wire (power switched) and it will handle all pyro short circuits. For maximum redundancy and to put each pyro on a separate device, use 1 in series with each pyro device.

Bob
 
I appreciate all of the info. I am learning a lot. With all of the expert beta testers for the RRC3, someone must have used a lipo. The one recommendation that I read in a post somewhere for any lipo and alt. was to contact the manufacturer. I contacted Jim, and he suggested that a higher voltage might be better. The manual for the RRC3 says that it was designed for a 9V. The specs say it will handle 3.7 -10v. Maybe a 1S 3.7 v lipo would be fine. I am guessing that someone has done this. Anyway thanks for all of the expert input. This is what I love about TRF.
 
4kids49 said:
I appreciate all of the info. I am learning a lot. With all of the expert beta testers for the RRC3, someone must have used a lipo. The one recommendation that I read in a post somewhere for any lipo and alt. was to contact the manufacturer. I contacted Jim, and he suggested that a higher voltage might be better. The manual for the RRC3 says that it was designed for a 9V. The specs say it will handle 3.7 -10v. Maybe a 1S 3.7 v lipo would be fine. I am guessing that someone has done this. Anyway thanks for all of the expert input. This is what I love about TRF.
Click to expand...

I flew the RRC3 Beta multiple times with the battery that came with my Power Perch. 3.7V, 138mA. Worked perfectly each time with both Q2G2's and J-Tek electric matches.
 
patelldp said:
I flew the RRC3 Beta multiple times with the battery that came with my Power Perch. 3.7V, 138mA. Worked perfectly each time with both Q2G2's and J-Tek electric matches.
Click to expand...

Thanks Dan. That is really great to know.
 
bobkrech said:
It's even easier to use an auto-setting thermistor switch in each pyrocircuit. For example https://www.batteryspace.com/Compon...p-limit-20-C----UL-Listed-TUV-CSA-Listed.aspx is a simple $1.09 semiconductor auto-resetting thermistor switch. It trips out at 9.5 amps. You can wire 1 in series with the pyrocircuit power supply wire (ground switched) or ground wire (power switched) and it will handle all pyro short circuits. For maximum redundancy and to put each pyro on a separate device, use 1 in series with each pyro device.
Click to expand...

As the saying goes: "A transistor protected by a fast-acting fuse will protect the fuse by blowing first." What works nice for a (thermally relatively slow) battery can be insufficient for a semiconductor.

I wonder if it makes sense to modulate the pyro output. Lets say 90% to 95% duty cycle at a moderate frequency should give the arc discharge enough time to extinguish before the FET gets damaged, while the low voltage of our hobby altimeters makes reignition of the spark less likely. Rocket motors are different though, because they keep a plasma around, regardless of the arc discharge - but plasma discharges are sensitive to things like pressure. Ideal pressures are usually low, so there might be a chance that the arc discharge can be interrupted via PWM.

Reinhard
 
Take that Krech,,,,,,,
lol,,,,,lol,,,,,,,,lol,,,,,,,,,,,

Teddy
 
Reinhard said:
As the saying goes: "A transistor protected by a fast-acting fuse will protect the fuse by blowing first." What works nice for a (thermally relatively slow) battery can be insufficient for a semiconductor.

I wonder if it makes sense to modulate the pyro output. Lets say 90% to 95% duty cycle at a moderate frequency should give the arc discharge enough time to extinguish before the FET gets damaged, while the low voltage of our hobby altimeters makes reignition of the spark less likely. Rocket motors are different though, because they keep a plasma around, regardless of the arc discharge - but plasma discharges are sensitive to things like pressure. Ideal pressures are usually low, so there might be a chance that the arc discharge can be interrupted via PWM.

Reinhard
Click to expand...
The device is not a fuse, but after looking at the specs, it does not shut down fast enough for a short, high current pulse protection.

This $1.95 1S LiPo PCM unit is all solid-state and will do the job. It allows a 5 amp continuous current and limits maximum current draw to 7-9 amps. It will also protect the battery from over or under charging, and prevent reverse polarity damage, and weighs 0.3 grams. There's no reason that a circuit containing these components could not be built into an altimeter pyrocircuit as the cost is low and the size is tiny.

https://www.batteryspace.com/PCB-for-3.7V-Li-Ion-Battery-5.0A-limit.aspx

Bob
 
bobkrech said:
The device is not a fuse, but after looking at the specs, it does not shut down fast enough for a short, high current pulse protection.

This $1.95 1S LiPo PCM unit is all solid-state and will do the job. It allows a 5 amp continuous current and limits maximum current draw to 7-9 amps. It will also protect the battery from over or under charging, and prevent reverse polarity damage, and weighs 0.3 grams. There's no reason that a circuit containing these components could not be built into an altimeter pyrocircuit as the cost is low and the size is tiny.

https://www.batteryspace.com/PCB-for-3.7V-Li-Ion-Battery-5.0A-limit.aspx

Bob
Click to expand...

If you source batteries from Sparkfun, they have current limiting built in. It has the opposite of the intended effect with Altus Metrum altimeters, though, because they don't have hold-up capacitors and thus brownout when the chip lowers the effective output voltage.
 
OK guy's ,,,,,,

Very interesting,,,,,,

I'd like to post this here because this was a very well thought out,, in depth conversation about using lipo's for HP rocketry in general................

I moved away from 9V battery's because I believed a 9V's battery clip / holder
momentarily lost contact on a high G launch in my 3" Intimidator browning out the altimeter and ultimately costing me the rocket..........

I've been dealing with lipo's for many years because of RC aircraft and I like them......
You can't beat them for energy density with ANY battery chemistry and as long as you charge and care
for them properly I have found them safe and reliable.

Before the maiden flight of my Green Hornet at MDRA in Maryland,,,,, _LLS4104.jpg _LLS4105.jpg
I charged the 1s lipo that runs the chip on the Eggtimer
and it showed bout 4.2 volts or so........
I also charged the 2s lipo that is the deployment battery for both channels and it showed a little over 8 volts......

All good right.......

On the pad the Eggtimer went through it's normal cycle and gave me a warble tone meaning "Ready for Flight".........

Boost goes beautifully,,,, Aerotech J 340 Metalstorm,,,, very cool,,,,, at apogee there is an event and successful separation,,,, and the rocket comes down on a drogue.........

At the preset of 700 ft,,,,,,,,,,,,, no main,,,,,,,,, no event at all...........

After recovery I disassembled the rocket,,,, the B channel charge fired at apogee as it was supposed to,,,,,,,,,,
The Main or A channel charge was intact,,, it never fired........
On dis-assembly of the av bay,,, I tested the altimeter,,, It wouldn't set,,, gave me error codes that something was wrong with A and B channels.......
It was battery voltage,,,, I put a meter on the 2s lipo and it read 2.2 volts,,,,,,,,,, It lost a cell.......

So,,,,,,,,, that explains that...............
The moral of the story,,,,,,,,,,,,,,,,,,

Timing is everything...........

Teddy
 
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Onebadhawk, sorry to hear of the recovery woes. Been there and done that, brother...and recently. Last launch cost me two rockets all told!

Just bought this battery from Sparkfun after talking to Missile Works. I'll be using this in a 38mm airframe connected to the RRC2+ in one of those cool 3D printed sleds. At least there is only one cell, but the post above makes me think the battery might need to be semi-permanently mounted in the sled with hot glue for zero movement.
 
onebadhawk said:
OK guy's ,,,,,,

Very interesting,,,,,,

I'd like to post this here because this was a very well thought out,, in depth conversation about using lipo's for HP rocketry in general................

I moved away from 9V battery's because I believed a 9V's battery clip / holder
momentarily lost contact on a high G launch in my 3" Intimidator browning out the altimeter and ultimately costing me the rocket..........

I've been dealing with lipo's for many years because of RC aircraft and I like them......
You can't beat them for energy density with ANY battery chemistry and as long as you charge and care
for them properly I have found them safe and reliable.

Before the maiden flight of my Green Hornet at MDRA in Maryland,,,,, View attachment 166471 View attachment 166472
I charged the 1s lipo that runs the chip on the Eggtimer
and it showed bout 4.2 volts or so........
I also charged the 2s lipo that is the deployment battery for both channels and it showed a little over 8 volts......

All good right.......

On the pad the Eggtimer went through it's normal cycle and gave me a warble tone meaning "Ready for Flight".........

Boost goes beautifully,,,, Aerotech J 340 Metalstorm,,,, very cool,,,,, at apogee there is an event and successful separation,,,, and the rocket comes down on a drogue.........

At the preset of 700 ft,,,,,,,,,,,,, no main,,,,,,,,, no event at all...........

After recovery I disassembled the rocket,,,, the B channel charge fired at apogee as it was supposed to,,,,,,,,,,
The Main or A channel charge was intact,,, it never fired........
On dis-assembly of the av bay,,, I tested the altimeter,,, It wouldn't set,,, gave me error codes that something was wrong with A and B channels.......
It was battery voltage,,,, I put a meter on the 2s lipo and it read 2.2 volts,,,,,,,,,, It lost a cell.......

So,,,,,,,,, that explains that...............
The moral of the story,,,,,,,,,,,,,,,,,,

Timing is everything...........

Teddy
Click to expand...

That is interesting. A good point: there is no way to check the deployment battery easily without having test points on the outside of the rocket and a multimeter.
 
I did test it before the flight,,,
I ran a charge cycle on my computer charger,,,
If anything is wrong the charger will tell me....
The volts was bout 8.2 to 8.4 when the charger finished.....
When is an opportune time or moment for something to fail ????????????
I have found something in life,,,,,,,,,
Things don't fail when your not using them,,,,
It's when you need something that you find out about the failure,,,, usually........
Not when you don't need it..........
I'm still using lipos and JST connectors.........

You can't guarantee everything............

More interesting,,,,,,,,,,,
When I first got the ignitors from CJ,,,
The first thing I did was test them,,,,,
Open air,,,, on 1 single Nickle cadmium AA cell,,,,,,,,
Yes,,, 1.2 Volts,,,,,, the ignitor went off instantly,,,,,,,,,,
I believe,,, not proven,,, that the 2s lipo that lost a cell could no longer put out any current,,,,
and that's what fires an ignitor........

I'm considering myself extremely fortunate that the apogee event occurred,,,,,,,,,,,,,
I still have the rocket,,,,,,,

It's a good day........

Teddy
 
We've tested the single cell 3.7v lipos from sparkfun with the RRC2/3 and as long as they are charged, there is no issue.
 
I have 5 or 6 of the small 3.7 lipos that came with power perch and the featherweight av bays but am having trouble finding / ordering the small connectors cables for traditional sleds. LHS said mini jst but didnt have any.

Any info on how to lock down on a dozen of these ? Have two 38mm bays to build and would like to try one with rrc3 also.

Kenny
 
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KenRico said:
I have 5 or 6 of the small 3.7 lipos that came with power perch and the featherweight av bays but am having trouble finding / ordering the small connectors cables for traditional sleds. LHS said mini jst but didnt have any.

Any info on how to lock down on a dozen of these ? Have two 38mm bays to build and would like to try one with rrc3 also.

Kenny
Click to expand...

Kenny, I think you're looking for these. https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9727
 
KenRico said:
I have 5 or 6 of the small 3.7 lipos that came with power perch and the featherweight av bays but am having trouble finding / ordering the small connectors cables for traditional sleds. LHS said mini jst but didnt have any.

Any info on how to lock down on a dozen of these ? Have two 38mm bays to build and would like to try one with rrc3 also.

Kenny
Click to expand...

You said you wanted JST plugs.............

https://www.hobbyking.com/hobbyking...tail_10cm_length_10pcs_bag_US_Warehouse_.html

https://www.hobbyking.com/hobbyking...tail_12cm_length_10pcs_bag_US_Warehouse_.html

These are JST plugs.................

Teddy
 
Teddy - he's looking for the mini JST like I posted. I learned the hard way with these, too, when I bought my lipo charger. I ended up having to make another order, which is why I had the link. It's hard to tell the sizes from a web photo and I originally bought 2S balance plug extenders because I didn't know the difference at the time. The regular JST tails are quite handy and worth adding to the order. I also grabbed some of the crimp style so I can make custom lengths. :cheers:
 
matthew said:
Teddy - he's looking for the mini JST like I posted. I learned the hard way with these, too, when I bought my lipo charger. I ended up having to make another order, which is why I had the link. It's hard to tell the sizes from a web photo and I originally bought 2S balance plug extenders because I didn't know the difference at the time. The regular JST tails are quite handy and worth adding to the order. I also grabbed some of the crimp style so I can make custom lengths. :cheers:
Click to expand...

Wow Matthew,,,
I thought the same thing as you did....
That small white plug looks like a 2s balance plug........
But then I noticed there's only 2 conductors........
I'm not sure but I don't think I've ever used that little white plug before...........

In the pic's it's a dead ringer for the 2s balance plug........

Thanks Matthew............

Teddy
 
matthew said:
Teddy - he's looking for the mini JST like I posted. I learned the hard way with these, too, when I bought my lipo charger. I ended up having to make another order, which is why I had the link. It's hard to tell the sizes from a web photo and I originally bought 2S balance plug extenders because I didn't know the difference at the time. The regular JST tails are quite handy and worth adding to the order. I also grabbed some of the crimp style so I can make custom lengths. :cheers:
Click to expand...

Heh, even finding the battery style , Blade MCX LiPo 1s 3.7v 130 mah like the Tenergy 30128 didn't help shop the cable adapter.

Thanks Matthew, ordered 2 sets of 5 from your provided link to get me rolling.

Kenny
 
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