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Bullet plugs

#1
Will bullet plugs work for batteries if I'm careful about polarity? I don't want to have to spend the extra money to buy connectors when I have about 30 pair of bullets just laying around. Thanks!
 
#2
I've seen some specs for using bullet connectors on batteries. You have to be SUPER careful that the two leads can never contact each other. Gratuitous use of shrink tubing may work. I usually see a male end on one terminal and the female on the other. If you look at most of the popular plug systems they are a variation of bullet plugs in a protected housing. The XT60 uses 4mm bullets. With the amount of power in LiPo batteries, I caution against using separate bullet connectors.
 

Kendalf

Active member
#3
Main concern with batteries (besides polarity) is ensuring that + and - don't touch each other, creating a short circuit. The thing with bullet connectors is that it's not easy to completely cover them such that no metal is exposed. You can put heat shrink around all the way to the end of the female connector, but you can't quite extend it beyond the end without the heat shrink blocking the hole.

EDIT: A bag of 10 pairs of XT30U or XT60U (depending on battery size) costs less than $10. Seems to be a relatively small price to pay for safety when it comes to batteries. Imagine the cost of just a small mistake with the polarity or a short that fries your battery, or worse starts a fire.
 

Bricks

Well-known member
#5
Don`t forget your charger is going to need leads also. What are you going to do once your bullet connectors are used up buy more. and every battery ESC you buy will have to be changed to bullet connectors. I would pick one type of connector be it XT60`s or what ever you start with. Keep them all the same battery ESC connections it will save headaches down the road. Don`t ask my how I know.
 
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DamoRC

Well-known member
Mentor
#6
Don`t forget your charger is going to need leads also. What are you going to do once your bullet connectors are used up buy more. and every battery ESC you buy will have to be changed to bullet connectors. I would pick one type of connector be it XT60`s or what ever you start with. Keep them all the same battery ESC connections it will save headaches down the road. Don`t ask my how I know.
Agreed - you can use the bullet connectors for ESC motor wires and the motor wires themselves.
 

rockyboy

Skill Collector
Mentor
#7
I still use bullet connectors for battery connects to things around the shop - hot wire cutters and such - but agree with the comment to pick a standard and move all your equipment to it long term. I went with XT30 for indoor planes and XT60 for outdoor planes (and am starting to use some XT90 for bigger stuff). This way I only had a couple intermediate connectors to make for all the charging equipment and batteries to be interchangable.

When I first started out I did use bullet connectors on my two 2s800 batteries for my FT Tiny Trainer - I cut the wires to be different lengths so they wouldn't be able to accidentally touch and used shrink wrap like you would on a motor/ESC connection. It worked OK, but as I started to get more planes and batteries, it was easier (and safer) to go with a standard for the "fleet".
 
#8
Yep:
No matter what steps you take, it only takes one time connection backwards to smoke your esc or White Smoke of Death (WSOD) your battery. Use the XT connector for piece of mind!! Been there Done that Bought the T-Shirt!
 

rockyboy

Skill Collector
Mentor
#9
Yep:
No matter what steps you take, it only takes one time connection backwards to smoke your esc or White Smoke of Death (WSOD) your battery. Use the XT connector for piece of mind!! Been there Done that Bought the T-Shirt!
Strangely enough I never had a battery short out from that when I did bullet battery connectors. Must have been so paranoid knowing I could easily mess up. I did short a battery out when I stupidly cut both the power and ground leads at the same time with a pair of wire cutters (this is why you don't do RC work at 3am). I have also had two batteries flame out when the charger I was using had something go terribly wrong inside - immediate smoke/fire when the battery was plugged in (I suspect some relay inside shorted). Also put on an XT-60 connector backwards and smoked out an ESC. And burned up a flight controller due to a little solder trace on a connect.

So bottom line - yes, these things can be dangerous and burn stuff down. Be carefull. Build or buy a battery charging box or at least only charge on a concrete or metal or glass surface. Build and use a Smoke Stopper when you first plug in a battery to a new plane/quad. Be ready to run that battery outside VERY QUICKLY if something goes wrong - usually right when you plug it in. Only happens one in a thousand times, but it's really exciting when it does :eek:
 

FDS

Well-known member
#10
Buy XT60 connectors, they are cheap enough. Personally I would NOT EVER use a solution without complete inbuilt polarity protection and full insulation.
The problem with 3D printed insulation for the bullet plugs (aside from all the polarity concerns noted above) is that there are situations where the discharge leads or plugs can get hot. Those might not be good situations but they exist, in those circumstances the last thing you want is the separation material MELTING and the two connectors fusing together RIGHT BY THE BATTERY. That is bad for your house/plane/safety.
All those three things should come before saving $1 or a trip to the hobby store. Don’t be cheap where it counts, this is a place where it counts.