new to DD.. 3 leads on a 2S LiPo battery

[Ron Soto]

So, i've built and can connect to my Eggtimer Quantum. Currently just using a 9v battery. Yes, i know i'm not supposed to use the 9v for flights.. but just using to test for connectivity.

this said, i did buy 2, 2s batteries (from amazon) and the ones i purchased have 3 leads. I've looked online.. and i'm stumped!.. One lead has 3 wires attached, red, black, purple. and the other 2 have just the red and black. I've never dealt with this type of configuration and was wondering if someone could explain what the 3 leads are for. (picture attached.)

currently, i have the Apogee DD kit, and am wanting to make the Zephyr DD and am going try and use these batteries.

thanks in advance,

ron-

 

[terryg]

The 3 wire connector is the balance plug and connects to the balance port on your charger. The 2s battery designation indicates that the battery had two cells. The balance plug allows the two cells to charged identically by the charger.

 

[Pinetree]

It's a balance lead, used to ensure that both cells receive the proper voltage.

Any LiPo battery with more than 1S will have one, and it gets plugged in the charger in addition to the power lead.

 

[David_Stack]

and to add to what terryg and Pinetree posted, I believe the other two leads are redundant. Both are output leads, just terminated differently to allow you flexibility...

 

[Ron Soto]

and to add to what terryg and Pinetree posted, I believe the other two leads are redundant. Both are output leads, just terminated differently to allow you flexibility...

ahhh... ok.. so when i buy the charger.. i'll be using the 3 wire plug. and i'll be able to use either of the 'other' red/black wired connections to power the quantum. Thanks!

ron

 

[Rob Campbell]

ahhh... ok.. so when i buy the charger.. i'll be using the 3 wire plug. and i'll be able to use either of the 'other' red/black wired connections to power the quantum. Thanks!

ron

You will need to use both the power output leads and the balance leads. The chargers charge through the output leads and siphon power off each cell to balance the charge to keep the cells equally charged.

 

[KenECoyote]

Not sure if it was clarified, but you use the red plug ("jst" type) to power your stuff. You can buy the jst plugs with leads cheap on Amazon. I use it on all my rocket electronics.

 

[Titan II]

Not sure if it was clarified, but you use the red plug ("jst" type) to power your stuff. You can buy the jst plugs with leads cheap on Amazon. I use it on all my rocket electronics.

True.

Now watch your polarity. You may want to review this thread.
https://www.rocketryforum.com/threads/lipo-batteries-and-connectors.185437/#post-2567890

 

[Ron Soto]

Ok.. so i did buy JST connectors from amazon. i just looked and checked the connection wiring. when connected, red to red/ black to black. Is this correct?

 

[Ron Soto]

Well and also I'll just say that i basically know absolutely nothing about electronics. i did purchase a pull pin switch kit and the relay is: closed (current flows) between C and NC. I'm in the process of research on how to wire this up to my Quantum.

So far I believe that i will wire the neg (black from battery) directly to the Quantum, and that i'll have a pos (red from battery) to the NC pole on the switch and another red from the C to the positive on the Quantum.

That's what i've got.. and so totally lost and probably wrong. pictured is the relay. positioning of the poles: C NO NC (as pictured).

I've been looking online this afternoon and have come across a few posts with descriptions and images, but nothing concrete. If someone has something where i can look or a schematic ... that would be great.

thanks,
ron

 

[KenECoyote]

Ok.. so i did buy JST connectors from amazon. i just looked and checked the connection wiring. when connected, red to red/ black to black. Is this correct?

Actually, the red plug is what I've known as "jst" for decades and is much more common.




Apparently that white one you're connecting is a new version 2.0 (which I wasn't aware of, sorry).

 

[Raythain]

Actually, the red plug is what I've known as "jst" for decades and is much more common.


View attachment 653209

Apparently that white one you're connecting is a new version 2.0 (which I wasn't aware of, sorry).

View attachment 653210

There are about 12 versions of the "JST" connector.

The red ones are more properly JST-RCY connectors, and the white ones are JST-PH connectors. Its a pain.

 

[KenECoyote]

There are about 12 versions of the "JST" connector.

The red ones are more properly JST-RCY connectors, and the white ones are JST-PH connectors. Its a pain.

This has learned me something new!

My exposure to the JST-RCY was back in the 70s with Japanese radio control receivers that used it for the battery connection plug. Maybe that's the origin of "J" and "RC" parts there?

 

[Raythain]

This has learned me something new!

My exposure to the JST-RCY was back in the 70s with Japanese radio control receivers that used it for the battery connection plug. Maybe that's the origin of "J" and "RC" parts there?

According to the infallible Wikipedia, JST connectors are made by JST Mfg Co. JST standing for “Japan Solderless Terminal”, and given that the RCY’s popularity in Radio Control applications, I’d put a wager on that being the source of the name.

 

[n3tjm]

Those pull pin switches make me a little nervous. If they are using spring loaded micro switches to detect when the pin is pulled, there are several conditions where you can get enough g--forces to disconnect the switch, resulting in bad things happening. I personally recommend key switches or screw switches.

 

[rharshberger]

There are about 12 versions of the "JST" connector.

The red ones are more properly JST-RCY connectors, and the white ones are JST-PH connectors. Its a pain.

Specifically the JST-PH is JST-PH 2.0mm. I prefer the JST-RCY myself due to the slightly larger wire gauge, but I am currently working on a project that uses 1S 300mah Lipos that are fitted with JST-PH connectors instead of JST-RCY.

 

[terryg]

I am a little puzzled on why you would want to use a pull pin switch on a quantum which is activated on the pad with a wifi connection.

 

[lr64]

You will need to use both the power output leads and the balance leads. The chargers charge through the output leads and siphon power off each cell to balance the charge to keep the cells equally charged.

Some chargers work with just the balance plug, which is more convenient and less annoying. On large packs, that may limit just how fast you can charge. I have one that charges fast enough with a 1300 mAh 3S lipo, though.

 

[Titan II]

I am a little puzzled on why you would want to use a pull pin switch on a quantum which is activated on the pad with a wifi connection.

It is drawing power just sitting there. For example, some of us go to the launch with our rockets ready to fly. They may have been assembled long before the launch. A hard break keeps the battery from going dead.

 

[wonderboy]

So far I believe that i will wire the neg (black from battery) directly to the Quantum, and that i'll have a pos (red from battery) to the NC pole on the switch and another red from the C to the positive on the Quantum.

I've been looking online this afternoon and have come across a few posts with descriptions and images, but nothing concrete. If someone has something where i can look or a schematic ... that would be great.

Your description of the connections is correct.

In case it wasn't obvious regarding the terminal labels, C refers to the "Common" terminal. NO is the "Normally Open" terminal, and NC is the "Normally Closed" terminal.

"Normally open" means that when the switch is in its non-activated state, this contact is open (disconnected) from the common terminal. Normally closed means that the contact is connected to the common terminal.

So the way you've (correctly) described your connections, with the pull-pin inserted the switch is in its activated state and the Normally Closed terminal connection to the common is broken. Once you remove the pull-pin, the switch goes back to its normal state and you now have a continuous connection for your positive battery lead to the altimeter.

Like was mentioned earlier, since the switch actuation is spring loaded, the situation could exist where if the switch is mounted in a certain orientation and the rocket experiences enough g's, it could theoretically cause the switch to temporarily turn off. Lots of people use these switches though, so there may be some recommended practice on how to orient the switch so that this doesn't happen.

 

[terryg]

For robustness its hard to beat these switches.


https://www.fingertechrobotics.com/proddetail.php?prod=ft-mini-switch