Danny/SMC

iTrader: (2)

I wanted to do the comparison between inboard connectors with circuit board and 12 gauge wires with Deans connectors.

I've said it since day one that the inboard connectors will add resistance which will also decrease the voltage. Now that were releasing 2 new packs with inboard connectors I'm able to test the difference.

I took a pack with inboard connectors and soldered 12 gauge wires with a Deans connector where the tabs of the cells are soldered to the circuit board. I then took bullet connectors and soldered them to 12 gauge wires and made the wires the same length for the Deans and Bullet connectors.

When testing the Deans setup I attached the voltage sensing leads to the Male Deans connector. When testing the inboard connector setup I attached the leads on the end of the 12 gauge wires so both setups have the same length of wires and connections. The only difference is the circuit board where the female tubes are soldered.

Deans: 6.6 IR - 7.36 voltage

Inboard: 8.0 IR - 7.30 voltage


I also tested the pack with the voltage sensing leads attached right where the 12 gauge wires are soldered to the male Bullet connector. The results are pretty interesting as the IR dropped 0.4 and the voltage went up .02 which shows the effects of wire length.

KoE

iTrader: (6)

danny thanks for the info

even if the figures turn out the same, i'd still prefer deans for reverse-polarity protection

or8ital

iTrader: (38)

Any theories on why it adds resistance? Would the type of bullet connector matter? I know some have big differences in price. The Great Planes connectors are like $3 for a set and Tekin is $10 for a set. I know Tekin says theirs are higher quality but I don't know what is different.

syndr0me

iTrader: (32)

It's probably the circuit board. The tabs are soldered to the board, along with the bullet connectors. With connectors, I'm pretty sure they're soldered (welded?) right to the tabs.

or8ital

iTrader: (38)

Is a circuit board necessary for bullet connectors? Is it to get more distance between the connectors? Sorry, haven't really ever taken a lipo apart to see where the tabs are.

sillypuddy

I am a firm believer in SMC batteries (i only run SMC whenever possible)

but the new 28C and 40C does not fit well in my TA05 IFS cars.. the wires come out where the battery hold down comes out :-P

does that position work for other brand of cars? if not, can we get it moved to the right side?

-joe

Danny/SMC

iTrader: (2)

Our current cases fit in the majority of cars out on the market. It's really hard to have a case and wire position that will work for all cars.

Danny/SMC

iTrader: (2)

The reason why there is extra resistance is due to extra solder points plus the tracks on the circuit board will also add resistance. We use gold plated copper tubes to keep resistance as low as possible.

Stuart Pid

Will this be available for the single cell lipo?

syndr0me

iTrader: (32)

The carbon reinforced chassis has slots cut in it so you can tape batteries in. It's not the greatest solution, but it's workable.

Stealth_RT

iTrader: (5)

I've also seen too many packs where the solder joints break loose on that circuit board, either where the tube is soldered on or the tabs themselves. Basic Soldering 101: Solder is NOT a mechanical support. You have to have a solid mechanical connection/mounting FIRST, then solder for the best electrical connection. Even though we've all violated that rule plenty of times in RC. Danny's pics show that there's not a whole lot of solder period on those tubes. Add the weight of the wires/plugs bouncing around and stressing that solder, and I'm actually surprised that packs built that way EVER last a long time w/o failure. I personally would never use a pack with inboard connectors. 10-12 ga and Deans work the best!

JayL

is this for the EFRA spec? wonder why they chose this setup?

SpraydbySprague

iTrader: (64)

Another reason the inboard connectors lose performance is a lack of contact patch.

Look at the profile of the male connector on the end of the wire, there is a curve to the spring loaded spline around the connector, this is of course to place tension inside the female connector on the pack to keep it in place. When you insert the male connector into the pack the spring does not compress completely flat against the inside wall of the female connector on the pack. The only contact points between the male and female connectors are the high points around the spring loaded spline on the male connector touching the inside wall of the female connector.

Top this off with the fact that the spring loaded spline around the connector is a separate piece, it actually "floats" on the male connector. This can cause yet another drop in voltage and rise in internal resistance.

So for me it's Dean's plugs all the way!

ta_man

iTrader: (168)

That can be improved by [carefully] soldering the spring load spline to the bullet, but I still won't use packs with inboard bullets either.

adamge

iTrader: (1)

Also, for more proof that 3.5mm and 4mm bullets, with their stand-alone spring section, are a poor design is the extreme performance connectors. Beyond Deans in power handling, you have 5.5mm and 6mm bullets. Those super connectors (easy 100A+ continuous) have the spring built into the body of the bullet.
http://www.rctoys.com/rc-toys-and-pa...RS-WIRING.html
http://www.rctoys.com/rc-toys-and-pa...RS-WIRING.html