bullet connectors

[rcaddict]

if using bullet connectors between lipo and esc what is the normal - ie should the positive wire on the esc be male bullet ??????

[Former Member]

[This posting has been removed]

[Bill Wood]

Why?

[Broken Prop]

Bill, it is to take away the chance of touching a live male connector on the battery lead to something and causing a short.

It is normal of course to add shrink wrap to the connectors to protect them but on the 4Max website there is a useful variation:

The heat shrink on the male connector is extended about 6mm beyond the end of the connector. Only the part in contact with the connector is shrunk leaving the protruding part free to slip over the female connector (which also has heat shrink on it).

Difficult to explain but there are photos on the website showing how it is done. It is in 'Useful Information', last item.

Pete

Edited By Broken Prop on 30/05/2018 20:19:03

[Bill Wood]

I appreciate the explanation but for the last 15 years or so I have had the positive battery lead (red) with a male connector and the negative (black) with a female. As long as care is taken to shield the positive connector when the battery is disconnected then it's safe. Of course modern connectors such as deans, XT, etc are probably safer, I find them not as easy to solder as the bullets.

[Geoff S]

I adopted the convention of male bullet on the battery positive way back when using NiCad packs and continue it now. There are no particular reasons to choose either as long as you remain consistent. In fact those connectors that combine positive and negative 4mm connectors in a single plastic shroud vary themselves. Turnigy/HK adopt the opposite from me but Flouron 4S 4aH LiPo packs I buy on eBay are the same.

I've gone over to XT60s for 3S 2.2Ah LiPos but fr anything bigger I've continued with the convention I adopted at random years ago when cutting off the old Tamiya connectors which can't handle the current..

Geoff

[Chris Bott - Moderator]

What Geoff said.

[Mike Blandford]

I use the same, male bullet on the battery positive. I also use short lengths of hardwood dowel (3/8 inch diameter) in which I drill a hole part way through that accepts the male bullet. I then put these over the battery positive connector to help protect from any accidental shorts. I only remove them for charging or when connecting in the 'plane. They are large enough that they don't get lost, I normally slip them into a pocket when a battery is in use so they are easy to find when disconnecting the battery.

Mike

[Geoff S]

Good idea, Mike. I use fuel tube but I might drill a few holes in some dowel

Geoff

[Former Member]

[This posting has been removed]

[Craig Carr]

I also use a female on the positive but that was just chance from when i soldered up my very first pack all those years ago now. However in my club quite a few had done them the other way

But, like what Geoff said, the overall conclusion was it makes no difference as long as your consistent

[Richard Ashworth]

I agree that it makes no difference as to which lead has a male bullet on as long as there is a female on the other lead. The more important issue is making sure that the shrinkwrap insulation on is preventing metal to metal contact, and adopting a safe routine when soldering on the connectors.

I don't use bullets but would think that whichever way around they are fastened the female bullet should always be done first and covered, as the male bullet will have exposed metal which could de touched when soldering the female.

Richard A

[Keith Berriman]

I use 3.5 mm bullets with female on positive etc. For safety I use female XT 60 to put two negatives of two batteries into these the wire end is covered in heat shrink. As mentioned routine is the best safety rule.

[Biggles' Elder Brother - Moderator]

I used to use bullets until about 3 years ago when I standardised on XTs. I put the male on the positive and cover with a piece of fuel tube when not in use. It seemed a perfectly safe arrangement to me and I never had a shorting incident in the whole time I did that.

BEB

[John Lee]

I did manage to plug the positive into the negative on the battery (instead of the intended ESC) when I misidentified the leads in the cramped confines of a model. The resultant bang was quite impressive.

To prevent a reoccurrence I used some heatshrink or tape near the connectors to hold the leads together so it was impossible to short, with 4mm ID 1mm wall thickness silicon tubing (from Ebay for a few pence, fits much better than fuel tubing. ) to shield the male plug.

However I have also now standardised on XT's.

[Geoff S]

Posted by Tom Sharp 2 on 31/05/2018 01:27:17:

A male bullet on the battery positive, it sends a chill down my spine.

Edited By Tom Sharp 2 on 31/05/2018 01:29:44

Why?

Geoff

[Chris Bott - Moderator]

I think the issue is that there are bare negative connections around. Unused receiver ports for one.
If an uninsulated male is inadvertently allowed to drop into the model, there is the potential of it touching the Rx pins.
I've not had the issue myself, but I see the potential.
I use a short length of the white outer insulation off some 3 core 5A flex for my protective covers.

[J D 8]

Posted by John Lee on 31/05/2018 11:37:34:

I did manage to plug the positive into the negative on the battery (instead of the intended ESC) when I misidentified the leads in the cramped confines of a model. The resultant bang was quite impressive.

I did the same as John with the same result and went over to Deans.

[eflightray]

I use 4mm female connectors on the battery covered with heatshrink. Always have right from the start of electrickery.

On the ESC, I use the male connector with only the lead attachment end sleeved.

On a charger lead, I use the male connector with full length heatshrink, but only the lead end shrunk. The connection end of the heatshrink is left large enough to act as a cover but still let the battery end slide inside.

On the positive ends, I use red heatshrink, but also paint a bright yellow ring around it so that it stands out. I once had the problem of getting the red and black leads wrong when connecting a battery in a deep dark fuselage with my hands blocking the view and light. Everything on the positive side now gets the 'yellow ring of confidence'.

Ray.

[Geoff S]

Posted by Chris Bott - Moderator on 31/05/2018 15:04:05:
I think the issue is that there are bare negative connections around. Unused receiver ports for one.
If an uninsulated male is inadvertently allowed to drop into the model, there is the potential of it touching the Rx pins.
I've not had the issue myself, but I see the potential.
I use a short length of the white outer insulation off some 3 core 5A flex for my protective covers.

By the same token there are bare positive connections around, too. Unused receiver ports have both positive and negative pins as well as signal pins. I really don't see a problem. It would be really difficult to get a battery 4mm male connector onto an unused receiver input on any of my models. You'd have to try very hard.

Geoff

[Gary Manuel]

A couple of years ago, I managed to get my wedding ring between the + and - 5.5mm bullet connectors of a 6 cell 5000mAh battery. Both were insulated with heatshrink as above. I didn't have chance to pull by finger away - the gold melted quicker than I could react.

The photograph of my finger does not make good family viewing, so I've not posted it. Needless to say, I do not wear my wedding ring when flying electric now.

The good news is that my ring has been repaired and you can't see the joint. Can't say the same for my finger.

P.S. The ring is 8mm wide.

[Geoff S]

That's one reason I never wear rings. I used to repair TVs when they had very high voltages hanging around.

Back in the 1960s I worked on ICT1301 computers at the manufacturers, GEC in Coventry. Low voltage high current power supplies were fed along uninsulated bus bars on the top of 19" racks about 5' tall. One guy was wearing an expanded metal arm band to keep his shirt sleeve at the right length and casually leant against a rack and shorted out the 6v 20 amp busbar. It was entertaining to see him frantically trying to pull his arm band off as it burnt both him and his shirt sleeve. Another guy, who wore a ring on each hand did a similar thing to you.

Rings and electricity don't mix well.

Geoff

[robert chamberlain]

While on the subject of connectors I have a quick question.---What about the Sermos or Anderson Power Pole type? I find the Sermos easy to solder up and safe to use however, I have no idea of the Amp rating. I have heard there are different Amp ratings available. I am getting into higher power applications and need to plan ahead.

Thanks in advance,---Bob C

[Martin Harris - Moderator]

Is this any use?

[Peter Jenkins]

I find these are by far the best bullet connectors I've come across. I usually separate the two parts to make it easier to allow parallel charging but series use. I need a 10S pack but buy 2 x 5S packs. Soldering is easy and I cover the exposed part and lead with shrink wrap. The plastic shrouds prevent the bullets contacting each other without any other precaution. The plastic is also polarised so that you cannot cross connect and as the metal part of the bullet is a good couple of mm below the end of the plastic shroud this provides excellent protection when all plugs are pulled out.

I find these 4 mm bullets, which are good for 100 amps, are much easier to connect and disconnect than any other connector type.