I wanted to try Dual deploy to learn some basic electronics, but I feel like I need a masters degree in LiPo batteries

[dhurstell]

I suppose the world has been spoiled the the plug-n-play of the modern USB and similar charging of our daily devices, but this LiPo battery stuff has me REALLY feel like I'm in waaaay over my head. Especially without an experienced person to work with and learn from.

How did YOU get comfortable with LiPo and charging?

Is there a repository here that has some solutions that "just work", that can act as a starting location?

I COULD just use JLCR, but part of what I love about the hobby is dabbling and learning. I'd REALLY like to move forward in the electronics area, but cant start w/o power

 

[WillMarchant]

Start off with a https://www.missileworks.com/rrc3 and a quality 9V battery then you can mess with rechargeable later.

 

[David Schwantz]

Egg timer Quark. Most user friendly ever. Just pull the pin to turn it on, wait for the Wroble and go fly. Takes a 2 cell LiPo. Cheap simple chargers from Motion RC.

https://www.motionrc.com/collections/battery-chargers

https://www.motionrc.com/collection...m_fields.Number_of_Cells][0]=2 Cell (2s) 7.4v

 

[bad_idea]

How did YOU get comfortable with LiPo and charging?

I read a bit about it - starting with Cris Erving's recommendations in his Eggtimer instructions - until it just clicked. There are still a lot of pain points around connectors, etc.

 

[Bruiser]

It's the minutia of it all that has kept me from electronic staging. I have decided to try out dual deploy because it seems to be a step to electronic staging. I'm going simple with a RRC2 and a 9 volt.

-Bob

 

[David Schwantz]

Batteries this size work well with JST connectors. They also do not come apart in flight.

 

[Azamiryou]

How did YOU get comfortable with LiPo and charging?

It does feel like more of a learning curve than it ought to be, doesn't it? They're just batteries!

But they aren't standardized like 9V and AA and all those we've been using forever.

Short version of what to know:

1S, 2S, etc: how many cells are in series. This multiplies voltage. Also, if 2S or more, you need a balancing charger.

Plugs: there are a zillion of 'em. Get comfortable changing them out, or making or buying adapters. Always always always protect against shorting the leads when working with the plug! Expose only one lead at a time, and cover the other with tape while you work.

Polarity: generally, it's vitally important to get the polarity right when hooking them up to your electronics. Unfortunately, there's no standard, so unless you buy it from the altimeter vendor, it's as likely to be wrong as right. As above, get comfortable changing the plug.

Charging: a good charger isn't all that expensive. I got a Tenergy TB6B and it works great.

Fire risk: there's a fire risk with LiPo batteries, but don't panic. Be in the room during charging and use a fire retardant bag for charging and storage. And don't use damaged batteries.

 

[FredA]

It does feel like more of a learning curve than it ought to be, doesn't it? They're just batteries!

But they aren't standardized like 9V and AA and all those we've been using forever.

JUST USE A QUALITY 9V and SKIP all the BS.

 

[KenECoyote]

Try one of these two... both charge from USB:

https://a.co/d/4H5w9R5

https://a.co/d/7My4k4W

The first one I personally like a lot (used in my L3 attempt rocket). The second one came highly recommended by an extremely experienced rocketeer. Both fit into 9v battery holders too.

Edit add: YMMV, ground test, ground test, ground test.

 

[Kane]

LiPos do take a little getting used to and I'll second what @Azamiryou says above. Besides getting a good balance charger like the Tenergy TB6B (I also use this charger), be sure to use the "Balance" feature when charging 2S LiPos. The idea is that both cells are balanced with the same voltage. I.e., each cell will be charged to 4.2V (8.4V total). Similarly, when you're finished flying, it's important to use the "storage" setting on the charger. This discharges both cells to 3.7V each (7.4V total). These practices will extend the life of your LiPos.

 

[cerving]

It's the minutia of it all that has kept me from electronic staging. I have decided to try out dual deploy because it seems to be a step to electronic staging. I'm going simple with a RRC2 and a 9 volt.

-Bob

Good plan, I would NOT recommend trying electronic airstarts until you are confortable with dual-deployment.

Regarding Lipo charging, it's no different than charging your phone really... except that the battery is out of the device (usually), and you may have to adjust the charging current for the size of your battery. And of course there are different connectors, but once you get around that hurdle it's pretty easy.

 

[Pilotx1]

most of the R/C world is centered around lipos, many of the various smaller models(cars especially) use 2s batteries and often come with chargers, you can get used to their handling with them and the smaller 2s lipos can be easily transferred into the AV bay

As cautionary note, many of the smaller 2s packs are simply shrink wrapped together without any outer hard shell to protect them, these cells can be vulnerable to being stabbed or smashed and they can react very negatively to such transgressions potentially resulting in a fire

 

[manixFan]

The 1S charger Featherweight sells is dead simple to use via a regular 5V charging block like one used for a phone. His small altimeter batteries are $10 so even if you only use it for a few flights it’s still fairly inexpensive. I bought a pack of power leads off EBay that allow me to have leads attached to different altimeters and just move the battery. Over the years I’ve bought a bunch more batteries and a 1S charger that will discharge to storage levels. At first I just left the altimeter turned on and checked the voltage every half hour or so until it got down below 3.85 volts. I still have batteries from 2016 that I use.

The only issue I’ve run into was not recovering a rocket until the battery dropped low enough to kill it. That’s only happened a couple of times in all the years I’ve been using LiPos.

Once you figure them out you’ll forget what you were worried about.


Tony

 

[lr64]

Try one of these two... both charge from USB:

https://a.co/d/4H5w9R5

https://a.co/d/7My4k4W

The first one I personally like a lot (used in my L3 attempt rocket). The second one came highly recommended by an extremely experienced rocketeer. Both fit into 9v battery holders too.

Edit add: YMMV, ground test, ground test, ground test.

I'm very skeptical of the 1300 mAh rating for the batteries in the second link. A 9V is MUCH smaller than the 1300 mAh 3S pack I have lying around. OTOH, I seem to recall one of the altimeter manufacturers writing that 250 mAh is more than enough. I suppose that's assuming the battery doesn't have too much internal resistance, like the one in my dying cell phone. Has there been another big advance?

 

[Buckeye]

I have decided to try out dual deploy because it seems to be a step to electronic staging.

I am working on my first 2-stage project, having done dual deploy for 25 years. DD is just a tiny step forward, in my mind. Staging requires many new concepts in design, construction, simulations, ignition, event logic, wiring, safety, etc.

...and yeah, LiPos are annoying!

 

[Pilotx1]

I'm very skeptical of the 1300 mAh rating for the batteries in the second link. A 9V is MUCH smaller than the 1300 mAh 3S pack I have lying around. OTOH, I seem to recall one of the altimeter manufacturers writing that 250 mAh is more than enough. I suppose that's assuming the battery doesn't have too much internal resistance, like the one in my dying cell phone. Has there been another big advance?

yea not a chance that theres 1300mah in there, especially considering the space loss of the USB connection and charging board

 

[rfjustin]

Start off with a https://www.missileworks.com/rrc3 and a quality 9V battery then you can mess with rechargeable later.

Yep, this, exactly.

 

[cerving]

JUST USE A QUALITY 9V and SKIP all the BS.

"Quality" 9V's are getting harder to find. Duracell, who used to be the go-to, recently changed the construction of their 9V batteries to six pressed cells, instead of six welded AAAA cells. Not only did that make them vulnerable to coming apart in flight, it also reduced the current sourcing capability. If you HAVE to use 9V batteries, get some that are marked "6LR61"... that endures that they are made from six welded AAAA cells.

And sometimes 9V batteries just don't have have the current capability for a given device, particularly if they have some kind of wireless connection. 9V batteries are designed to source trickle currents. If you look at the spec sheets for an Energizer Industrial alkaline battery (p/n EN522, their Type 6LR61 product) they are rated at 500 mAH at a 100 mA constant current draw. That's not bad, but for the same size with less weight you could put almost double the capacity in your rocket with a LiPo.

 

[FredA]

AMAZON's basic 9V is listed on the outside as 6LR61.
A fresh one can source 6A of short-circuit current.

Buy these and be done.

9V's were designed to drive transistor radios - far from a trickle.
They have morphed to smoke-detector batteries due to market changes.

 

[KenECoyote]

I'm very skeptical of the 1300 mAh rating for the batteries in the second link. A 9V is MUCH smaller than the 1300 mAh 3S pack I have lying around. OTOH, I seem to recall one of the altimeter manufacturers writing that 250 mAh is more than enough. I suppose that's assuming the battery doesn't have too much internal resistance, like the one in my dying cell phone. Has there been another big advance?

yea not a chance that theres 1300mah in there, especially considering the space loss of the USB connection and charging board

That's actually a good thing to discuss here. Please keep in mind that the 1300mah second battery recommendation was not mine, but from an extremely experienced rocketeer (I think one of his recent projects is a hypersonic rocket) and I haven't used it nor tested it enough to make a personal reco for it.

Personally, I feel that these cheap MIC (Made In China) lipo batteries have all gotten into a pissing contest where some/many/all are inflating the capacity listed since "everyone is doing it and if I don't, I lose", so I normally expect maybe 25% less than advertised in actual usage. However, if you're doubtful, you should read through the reviews (or Google) for any actual tests by electronics experts (with some level of skepticism if they got the product for free). If I get a chance to test them, I'll update, but it's low on my list.

Still, it's so cheap & easy and comes with a recommendation from a person with 10x+ my experience, so I passed it along as a good, cheap & easy first one to try.

Even then, you must do your own tests and YMMV. I say this because as Cris noted above, batteries change (I was actually going to post this link). We'll, with MIC lipos, it's moreso the case!

Back in 2014 I found some "9v lipos" on Amazon that worked great and I had been using for years without any problems nor failures. Last year, I was concerned about their age, so I ordered 4 more of the same. My next dd launch using two of the new versions (redundant dd) had both fail. and the rocket lawn darted!


After that unpleasant episode, I marked all the new ones with an "X" and went back to the old ones (used for my main altimeter in my L3 cert) and started looking for a new battery...

(10 year old reliable battery next to new battery.)

And that new 7.4v lipo became the first one I recommended above.

At our club one day, I was talking to the rocketeer next to me about the double battery failure (note: he owns an electronics company and is developing his own rocketry gps tracking system). I showed him the "X"'d battery and he said that those were complete garbage. I then showed him the new 7.4v lipo batteries and he got excited and then grabbed a tester and said that they were great and that he was going to order the same.

My best advice that everyone would likely agree with?...

YMMV, ground test, ground test, ground test.

 

[cerving]

AMAZON's basic 9V is listed on the outside as 6LR61.
A fresh one can source 6A of short-circuit current.

Buy these and be done.

9V's were designed to drive transistor radios - far from a trickle.
They have morphed to smoke-detector batteries due to market changes.

If you HAVE to use a 9V battery then the Amazon ones are a good deal. We designed our EZ-DD Rocket/Altimeter for them... the current draw from the altimeter is very low, only a couple of mA. With a Telemetry Module transmitter the average current draw is still only about 20 mA... if your "9V" battery is above 8.0V it's OK to fly, but you need to be careful because their current sourcing capacity drops off quickly as they run down.

9V batteries work fine with altimeters that don't have any wireless capability, but once you add that feature you greatly increase the current draw. Like everything else in rocketry, it's a tradeoff... and a pretty easy one to resolve. Just use a LiPo battery instead. I recommend getting them from an R/C hobby shop... I personally don't trust most of the stuff on eBay/Amazon. R/C hobby shops have some skin in the game, so they're not going to sell junk because they do not want to deal with returns.

 

[KenECoyote]

That's actually a good thing to discuss here. Please keep in mind that the 1300mah second battery recommendation was not mine, but from an extremely experienced rocketeer (I think one of his recent projects is a hypersonic rocket) and I haven't used it nor tested it enough to make a personal reco for it.

Personally, I feel that these cheap MIC (Made In China) lipo batteries have all gotten into a pissing contest where some/many/all are inflating the capacity listed since "everyone is doing it and if I don't, I lose", so I normally expect maybe 25% less than advertised in actual usage. However, if you're doubtful, you should read through the reviews (or Google) for any actual tests by electronics experts (with some level of skepticism if they got the product for free). If I get a chance to test them, I'll update, but it's low on my list.

Still, it's so cheap & easy and comes with a recommendation from a person with 10x+ my experience, so I passed it along as a good, cheap & easy first one to try.

Even then, you must do your own tests and YMMV. I say this because as Cris noted above, batteries change (I was actually going to post this link). We'll, with MIC lipos, it's moreso the case!

Back in 2014 I found some "9v lipos" on Amazon that worked great and I had been using for years without any problems nor failures. Last year, I was concerned about their age, so I ordered 4 more of the same. My next dd launch using two of the new versions (redundant dd) had both fail. and the rocket lawn darted!
View attachment 679950

After that unpleasant episode, I marked all the new ones with an "X" and went back to the old ones (used for my main altimeter in my L3 cert) and started looking for a new battery...
View attachment 679951
(10 year old reliable battery next to new battery.)

And that new 7.4v lipo became the first one I recommended above.

At our club one day, I was talking to the rocketeer next to me about the double battery failure (note: he owns an electronics company and is developing his own rocketry gps tracking system). I showed him the "X"'d battery and he said that those were complete garbage. I then showed him the new 7.4v lipo batteries and he got excited and then grabbed a tester and said that they were great and that he was going to order the same.

My best advice that everyone would likely agree with?...

YMMV, ground test, ground test, ground test.

Update: I did a bit more research on that 9v 1300mah battery (and similar) and it may be trickery because it may be a 3.7v 1300mah battery with a converter (to 9v... at least the voltage remains consistent before it drops like a brick), so it may really be ~500mah.

 

[FredA]

Almost all multi-cell (>3.7V) Lithium-based batteries sold these days incorporate a BMC [Battery Management Circuit.]
These are "mystery" devices.
Battery vendors barely acknowledge that they exist and rarely give any spec's.
Along with that comes the question comes "which BMC did they use today" unknown as vendors chase nano-pennies.

So what is in your circuit and what's it's effect is basically an unknown and adds risks.

A half dozen LR61's spot-welded in series is very robust and there are few surprises/unknowns.

Of course, if you need more power, you need more power and must look elsewhere.
But for regular DD altimeter operation, why do otherwise?

 

[Titan II]

Almost all multi-cell (>3.7V) Lithium-based batteries sold these days incorporate a BMC [Battery Management Circuit.]

Almost all multi-cell (>3.7V) Lithium-based batteries sold these days for RC use do not incorporate a BMC [Battery Management Circuit.]

 

[kramer714]

or... Missile Works RRC / perfectflight both work with OG 9V batteries...

 

[FredA]

Almost all multi-cell (>3.7V) Lithium-based batteries sold these days for RC

RC & Drones are the area where battery manufacturers assume the market is sufficiently educated to use a balancing charger and take proper precautions because they know they are dealing with high current capability devices.

Joe/Jane consumer is a different class.
So are the magnitude of the current capability of the product.
To reduce potential liability, batteries NOT targeting the above markets usually DO have a BMC in order to make them more idiot-proof.

Really just saying YOU NEED TO CHECK and UNDERSTAND what you actually purchased.
Just like it's hard to tell if your 9V is 6LR61 or a stack of crap.
Unless you look under the hood and comprehend you could be making a big mistake.
And looking under the hood of a conventional 9V is far easier and safer than some lithium contraption.

 

[Ronz Rocketz]

Polarity: generally, it's vitally important to get the polarity right when hooking them up to your electronics. Unfortunately, there's no standard, so unless you buy it from the altimeter vendor, it's as likely to be wrong as right. As above, get comfortable changing the plug.

This has been my challenge. It's not easy to check the polarity until you strip the wires and test with a volt meter.

 

[lr64]

This has been my challenge. It's not easy to check the polarity until you strip the wires and test with a volt meter.

Seems like the wires ought to be color coded or something. I've seen speaker wire that had a rib on one side. Or maybe I should say I've felt it. With some stranded wire, you can stick a pin in the end to measure voltage. Just don't let the two pins touch.

 

[Azamiryou]

Seems like the wires ought to be color coded or something. I've seen speaker wire that had a rib on one side. Or maybe I should say I've felt it. With some stranded wire, you can stick a pin in the end to measure voltage. Just don't let the two pins touch.

Usually they are black and red, with red positive. In fact, this has been true of every lipo battery I've bought. I still don't trust it though until I've checked, and then I use a Sharpie to mark the + and - on the battery. (Some batteries have + and - already marked on them. I don't trust these either.)

This has been my challenge. It's not easy to check the polarity until you strip the wires and test with a volt meter.

I've always been able to read the voltage by carefully poking the volt meter leads into the plug. You could make a mating plug with stripped wires for testing, and even make the wires different lengths to help prevent them from touching.

 

[Ronz Rocketz]

Seems like the wires ought to be color coded or something. I've seen speaker wire that had a rib on one side. Or maybe I should say I've felt it. With some stranded wire, you can stick a pin in the end to measure voltage. Just don't let the two pins touch.

That's the problem. Turns out there isn't consistency with polarity. As Az said, get comfortable with changing the plug.

I've always been able to read the voltage by carefully poking the volt meter leads into the plug. You could make a mating plug with stripped wires for testing, and even make the wires different lengths to help prevent them from touching.

Exactly...

Overall, DD is a pain compared to using a JLCR and motor eject. With DD, gotta futz with the altimeter in the payload, prep the charges, make sure the batteries are fresh, install the hard pins and the shear pins, and of course ground test. They're are several things that can go wrong.

OTOH, the JLCR is expensive and the string of components coming down is an awesome sight.