Quantcast

Beware Amazon/off brand JST

The Rocketry Forum

Help Support The Rocketry Forum:

jbrracer

Well-Known Member
Joined
Aug 11, 2020
Messages
355
Reaction score
148
Location
Indiana
Bought a bulk pack of JST connectors off Amazon.
Pulling moving wires creates a loss of power. Looks like I’ll be ordering a bulk pack of Genuine deans connectors.
see photos.

link to YouTube video of bad connection.
 

Attachments

cerving

Owner, Eggtimer Rocketry
TRF Sponsor
TRF Supporter
Joined
Feb 3, 2012
Messages
4,093
Reaction score
1,339
Not only are they often poorly molded, but I've seen a number of these with the wires installed backwards. Buyer beware...
 

NateB

Well-Known Member
Joined
Nov 6, 2012
Messages
1,528
Reaction score
1,346
Location
NE Indiana
I bought a small box of loose JST parts and some crimpers from Hobbyking a while back. If the wire isn't placed in the pins correctly, it won't crimp right or the pin won't lock into the plastic connector. This is easy to catch when you are assembling them and fix it yourself.
 

jbrracer

Well-Known Member
Joined
Aug 11, 2020
Messages
355
Reaction score
148
Location
Indiana
I bought a small box of loose JST parts and some crimpers from Hobbyking a while back. If the wire isn't placed in the pins correctly, it won't crimp right or the pin won't lock into the plastic connector. This is easy to catch when you are assembling them and fix it yourself.
Ive used the deans on everything RC and I think Im going back, just not that much more weight for a great connector, and it cannot be plugged in reversed.
 

KC3KNM

Well-Known Member
TRF Supporter
Joined
May 6, 2018
Messages
381
Reaction score
280
Location
South Burlington, VT
Ive used the deans on everything RC and I think Im going back, just not that much more weight for a great connector, and it cannot be plugged in reversed.
Not sure if you’ve seen them (or are referring to them now), but deans also has micro connectors. A bit lighter than a standard deans, I really like them.

 

jbrracer

Well-Known Member
Joined
Aug 11, 2020
Messages
355
Reaction score
148
Location
Indiana
Not sure if you’ve seen them (or are referring to them now), but deans also has micro connectors. A bit lighter than a standard deans, I really like them.

I have not. How positive is the retention? Is it just friction? These JSTs made me very nervous, hate to hurt someone or damage someone’s property
 

KC3KNM

Well-Known Member
TRF Supporter
Joined
May 6, 2018
Messages
381
Reaction score
280
Location
South Burlington, VT
I have not. How positive is the retention? Is it just friction? These JSTs made me very nervous, hate to hurt someone or damage someone’s property
I’ve landed small RC planes with the battery hanging by these a couple of times. If you ensure you’re getting the legitimate deans ones they hold very well, the poor quality copies have been too sloppy to trust in my experience. Just friction, but IIRC there were some clips available third party to lock them. I’d imagine it’d be pretty easy to 3D print something as well.
 

jbrracer

Well-Known Member
Joined
Aug 11, 2020
Messages
355
Reaction score
148
Location
Indiana
I’ve landed small RC planes with the battery hanging by these a couple of times. If you ensure you’re getting the legitimate deans ones they hold very well, the poor quality copies have been too sloppy to trust in my experience. Just friction, but IIRC there were some clips available third party to lock them. I’d imagine it’d be pretty easy to 3D print something as well.
thank you. Maybe I’ll get some for the smaller stuff
 

Mike Haberer

Well-Known Member
TRF Supporter
Joined
Jan 7, 2019
Messages
343
Reaction score
216
Not only are they often poorly molded, but I've seen a number of these with the wires installed backwards. Buyer beware...
What is/are the preferred option(s) for acquiring JST connectors (either build-your-own or pre-made). I've used Amazon stuff for simple bench testing but want the real deal when building my AV-Bays.
 

Banzai88

Lvl 1,Wallet....Destroyed
TRF Supporter
Joined
Jul 15, 2015
Messages
2,557
Reaction score
725
What is/are the preferred option(s) for acquiring JST connectors (either build-your-own or pre-made). I've used Amazon stuff for simple bench testing but want the real deal when building my AV-Bays.
The only sure fire way is to order things that have a traceable spec, like from DigiKey or one of the more reputable retailers like Amain Hobbies OR build your own from the provided terminals, plugs, and with the CORRECT crimper.

Hint....the crimper is the key element here, and realizing that ALL of this stuff is made in China.....just that some is to a 'good' spec and some to a 'cheapest' spec.

The first time that you take one apart and examine the retention and the pin interface tabs, you'll know how to tweak both of them to get a good connection that you have confidence in.

 
Last edited:

g.pitts

Well-Known Member
TRF Supporter
Joined
Aug 27, 2019
Messages
314
Reaction score
157
Location
Beaverton, OR
Bought a bulk pack of JST connectors off Amazon.
Pulling moving wires creates a loss of power. Looks like I’ll be ordering a bulk pack of Genuine deans connectors.
see photos.

link to YouTube video of bad connection.
I had the same experience on my L2 electronics bay design, and it took me a while to determine it was the connector and not my altimeters. For my next certification I'm moving away from the red "JST" (Chinese knockoff) connectors altogether in favor of a higher quality connector, and as @Banzai88 mentioned, a quality crimper.
 

OZRoc

Well-Known Member
TRF Supporter
Joined
Aug 13, 2016
Messages
81
Reaction score
42
Location
Orstraylya
Binder Design (Doghouse Rocketry) Locking connectors are the way to go.

Locking Connector

Positive retention and way easier to separate than JST.
I've completely redone my batteries & electronics with these. You can get just the connector parts and DIY.
Cheers
 

Reinhard

Well-Known Member
TRF Supporter
Joined
Jan 18, 2009
Messages
1,074
Reaction score
256
Location
Austria
What is/are the preferred option(s) for acquiring JST connectors (either build-your-own or pre-made). I've used Amazon stuff for simple bench testing but want the real deal when building my AV-Bays.
Digikey has already been mentioned. Mouser is another good source. You can use specialized search engines like Octopart to find more suppliers. The manufacturer data including ordering codes can be found here:
JST PH (e.g. Altus Metrum battery connector)

JST XH (e.g. LiPo Balancer connector)

JST RCY (see first post in this thread).

The official crimping tool is unfortunately expensive (~USD300) but a cheaper generic one like the Engineer PA-09 can be used.

Personally, I prefer locking connectors like the Molex SL (the above mentioned Binder Design / Doghouse Rocketry connectors), Molex MicroFit 3.0 or Molex Duraclik, but those have their limitations too.

Reinhard
 

Dave A

Lifetime Supporter
TRF Lifetime Supporter
Joined
Jan 22, 2013
Messages
1,149
Reaction score
116
I've been using the Chinese ones from Amazon for 2 years. I've only used them for my av igniter. I guess I've been lucky, all have fired and no issues.
 

jbrracer

Well-Known Member
Joined
Aug 11, 2020
Messages
355
Reaction score
148
Location
Indiana
I've been using the Chinese ones from Amazon for 2 years. I've only used them for my av igniter. I guess I've been lucky, all have fired and no issues.
maybe I only had one bad one, but that’s enough to toss them all for me.
 

manixFan

Not a rocket scientist
Joined
Feb 15, 2009
Messages
1,960
Reaction score
936
Location
TX
I also got come JST style connectors off of Ebay that had the wires reversed. Since then, I've had good luck with Hobby King:


They also have pretty good deals on batteries. For the best restuts you have to make sure you choose the US warehouse.


Tony
 
Last edited:

alexzogh

Lifetime Supporter
TRF Lifetime Supporter
Joined
Sep 30, 2010
Messages
759
Reaction score
219
I stopped using ANY connectors from Amazon. Just not worth the potential issues. Last one I used almost started a fire on my 3d printer.

IMG_20190514_201350.jpg


I stick with mouser, digi-key, or if its a replacement part, the original manufacturer.
 

Tech 68

Well-Known Member
TRF Supporter
Joined
Aug 22, 2019
Messages
69
Reaction score
129
After thoroughly testing the JST pigtails I bought, I am soldering them in parallel with a connector that mates with the battery's "balancing" connector. Though the "balance" leads on the battery are lighter gauge, I figure any "drop out" on the JST leads will hopefully not be on the "balance" leads at the same moment. This is for a two cell LiPo and I'm making sure I'm tying into the appropriate leads.
I figure it's like "free redundancy"...
 

jbrracer

Well-Known Member
Joined
Aug 11, 2020
Messages
355
Reaction score
148
Location
Indiana
After thoroughly testing the JST pigtails I bought, I am soldering them in parallel with a connector that mates with the battery's "balancing" connector. Though the "balance" leads on the battery are lighter gauge, I figure any "drop out" on the JST leads will hopefully not be on the "balance" leads at the same moment. This is for a two cell LiPo and I'm making sure I'm tying into the appropriate leads.
I figure it's like "free redundancy"...
that’s well devised great idea,I’m guessing you would have to have two switches per-battery/device although?
 

Tech 68

Well-Known Member
TRF Supporter
Joined
Aug 22, 2019
Messages
69
Reaction score
129
that’s well devised great idea,I’m guessing you would have to have two switches per-battery/device although?
No. The two connector's positives are "tied together" and in turn soldered to a single positive line going to the switch, then the altimeter, and likewise the two negatives "tied" to a single negative line going to the altimeter. Visualize two "Y"s coming from the battery.
 

wsume99

Well-Known Member
TRF Supporter
Joined
Feb 28, 2014
Messages
249
Reaction score
68
Can anyone share a photo of a micro deans connector next to a JST? I've never used a deans connector and I'm wondering how the two compare in size.
 

jbrracer

Well-Known Member
Joined
Aug 11, 2020
Messages
355
Reaction score
148
Location
Indiana
i dont have a deans micro on hand but volume wise id say they are close to the same. just the deans is more square while the just is more rectangular
 

Attachments

Rob702Martinez

Zip-Tie Oversight Committee
TRF Supporter
Joined
Dec 30, 2015
Messages
1,347
Reaction score
327
Location
Las Vegas
Are those wires the PVC or Silicone ones? I have had no issues with the silicon thicker gauge ones.
 

rocket_troy

Well-Known Member
Joined
Sep 9, 2013
Messages
134
Reaction score
43
Are those wires the PVC or Silicone ones? I have had no issues with the silicon thicker gauge ones.
Yup, me too. I've had a very nasty experience with the cheap PVC offerings which lead me to the silicone option.
If you want to be even more sure, crimp them yourself using Hobbyking's silicone wire (guaranteed maximum strand count per gauge nom. for max flexibility and less chances of work hardening the wire)

BTW: any ideas what the current rating is for the micro deans?
 

Banzai88

Lvl 1,Wallet....Destroyed
TRF Supporter
Joined
Jul 15, 2015
Messages
2,557
Reaction score
725
RC guys use them up to 10 amps continuous on airplanes and drones as per Deans recommendation, although I've never seen that in print other than the early days of their introduction on web boards. Well beyond anything rocketry requires.

JST's web site says that the JST RCY connector that's so ubiquitous and has served RC for decades is rated for 3 amps w/22 gauge wire.

 
Last edited:

rocket_troy

Well-Known Member
Joined
Sep 9, 2013
Messages
134
Reaction score
43
Cool, aren't the normal size flavours (of Dean's) rated to something like 10A though? I have a rocketry application that needs 20A+ at 15V for something like 2 minutes but drawing from 4 batteries - x2 2S parallel and x2 of those in series. Very tight space constraints for the coupling connectors. I can just fit in 4 coupled together JST sockets and plugs and was hoping for something even smaller.
 

Banzai88

Lvl 1,Wallet....Destroyed
TRF Supporter
Joined
Jul 15, 2015
Messages
2,557
Reaction score
725
Regular deans are rated for 60 amps continuous, 75 amp short cycle, and 100 amp spike.

If you are pulling 20+, you need something way more than the typical red JST and should give careful consideration to your main wiring AND the battery leads or you're courting an inflight electrical fire.
 
Last edited:

OverTheTop

Well-Known Member
TRF Supporter
Joined
Jul 10, 2007
Messages
4,662
Reaction score
1,930
Location
Melbourne Australia
As was alluded to earlier the current capacity rating of many connectors is dependent on the wire attached to them to provide heatsinking and limit temperature rise due to IR losses in the connection. This is important.

Having said that, you can usually push connector ratings beyond their paper specs if you reduce the time they are being used over specification. They typical situation is using a connector over the rated current for a short duration, and for most of the rest of its life it is under or not conducting at all. The specs usually quote maxmimum contact resistance, minimum number of insertions, maximum current, maximum ambient temperature. Remember when reading the data sheet that all factors must be within for the data to be valid, generally all concurrently. If, for example, you only do a few insertions, the resistance will likely be much lower, even when exposed to higher current, over the life of the product.
 
Top