Originally Posted by
Cygnus X
Bullet vs deans
a battery pack with wires coming out (direct wire) and deans offers the least internal risistance, lots of the onroad guys are changing to direct wire with deans, to get the max out of the battery
Caged bullets are crap and inconsistent connection, i ran really good caged bullets, and a couple of weeks i burnt my finger (it left a burn mark) as i pulled the caged bullet out of my battery so i changed out to solid bullets
4mm Solid bullets with a cross cut in them offers the best repeatable connection, i could see a huge difference in my scte 2.0 with 4000kv 550 motor, i got more punch, faster top end with solid bullets (team powers bullets), very noticeable, also before i changed bullets i would be putting in 5200-5500mah into my 7200mah 2S pack after a race...with the solid bullets that dropped to 4500-4800 mah...there must have been a lot of energy wasted in the caged bullet
i tried the same experiment in my TC6.1 in 17.5, and it made a noticeable difference for the better
bullets have higher internal resistance, than direct wire and deans connector
5mm bullets as offered in some pack also have higher resistance then the 4mm bullets
dont believe me ....go to SMC facebook page where Danny explains it all, backed up with actual measurements
Just went and checked it out, and I appreciate his testing. The difference between his Genuine Deans (0.11 mOhm) and caged bullet (0.39 mOhm) is 0.00028 Ohms. On a 30 amp pull, this will result in a
0.0084 VDC difference between the 2 connections. Or less than 0.1% of the battery voltage. I understand looking for every 10th on the track, but I don't think that difference is going to be felt. Even if you are talking unloaded RPM (rating you stated for your motor was 4000kV) you are talking 33RPM. Once loaded, this difference is even smaller.
This is assuming that they have similar resistance in all the solder joints. I find bullets much easy to solder to. Deans can melt slightly and lose contact area as the angle of the metal in the plastic changes, and getting a nice (non cold solder joint) is much easier with a bullet. Using larger gauge wire is also much easier with a bullet.
The average brushless RC car is going to have over a foot of wire in it. In Danny's post he points out that 1 foot of 12AWG has 1.46 mOhm's of resistance, and 10AWG only has 0.76 mOhm. With this information, you would be much better off increasing your wire size by a couple of gauges, rather than trying to save a couple 10th's or 20th's of a milliohms in the connector.
I take a little issue with his test rig too. One side of his test leads is 4mm bullets of unknown origin and resistance. Then the clamp has a flat mouth, favoring any flat connector. When clamped to a round connector like a bullet, there is going to be vastly reduced contact patch between the clip and connector. Finally, when you are dealing with fractions of a milliohm, a thin layer of oil from your skin can make a difference. Were these connectors cleaned before testing? How old/how much oxidation has happened to metal?