BK 18120, Wiring

I have an 18120 and instead of frying something I'd like to ensure that my wiring configuration is correct.


I run two battery packs (total of 14 cells-until I record enough data and figure out which LiPo is right for me). They need to supply serialized voltage (16.8v) to the speed control (18120). The 18120 has four power leads (two red, two black).

The four power leads come soldered red to red and black to black, from the factory. I can assume (I really hate assuming when it comes to electricity) that I just need to serialize the battery pack wiring and that all leads inside the controller terminate properly to support that config.

I sent the folks at BK an image from Run Runners (also found elsewhere) to indicate which battery wiring config I believe should be used. They responded w/ yes, that's the proper wiring.

Here's the pic -> http://www.rumrunnerhobbies.com/imag...packconfig.jpg



I'm basically going to leave the battery packs alone, no wiring changes necessary. I'll hook up male Deans to each soldered pair of power leads to the speed control, and finally serialize my batteries by using a heavy guage wire to connect the negative lead from one battery to the positive lead on the other battery (using the spare lead on each of the aforementioned mail Deans connector).

Before I blow a battery or fuse stuff together, would somebody mind giving me a sanity check? I'd like to wire my battery packs like the serial connection shown in the aforementiond link. Any clarification is appreciated. BK basically gave me a nod, but I'd prefer a diagram.

thx!

[Serum]

don't use deans, they are not suited for these high currents. better use 4 mm gold bullet plugs.

that way you can keep the cables shorter too.

[RC-Monster Mike]

The Dean's work fine. The diagrams are correct as well. I also wrote up a written explanation in the "how to program your BK controller" thread, which is at the top of the brushless forum.

Thx for the input, fellas.

As most folks use the 9918 (two power leads) I wasn't sure that your sticky contained the proper information regarding the 18120 (4 power leads). Still would like something official from BK...but I've been in communication w/ them for the last few days and haven't received anything definitive. Could be the language barrier.


W/ regards to the bullet style connectors I'm not sure I feel comfortable w/ a connector that doesn't force you to make a proper connection. Even I make simple mistakes every now and then... and I don't want it to cost me too much. ;)

[RC-Monster Mike]

The 18/120 controller works the same way. Treat the two leads that are soldered together as one lead. The bigger controllers like this have two boards wired in parallel(hence the double wires). I am 100% sure on this (I run the 18/120 in one of my emaxxes).
I use deans for the same reasons you stated-they don't allow the simple mistake of miswiring to be made. they also can handle quite a bit of current.

Originally posted by RC-Monster Mike
The 18/120 controller works the same way. Treat the two leads that are soldered together as one lead. The bigger controllers like this have two boards wired in parallel(hence the double wires). I am 100% sure on this (I run the 18/120 in one of my emaxxes).
I use deans for the same reasons you stated-they don't allow the simple mistake of miswiring to be made. they also can handle quite a bit of current.

Excellent.

I made a drawing addressing my concern. But I believe you just alleviated it (my concern, that is) :D

See if this makes sense and why I wanted cold hard facts from BK (hopefully I don't foobar the attachment process).

Depending on the internal wiring of the 18120 you can really mess up stuff if you get it wrong. And I realize the leads going to the motor have three wires...just wanted to keep it simple.

[RC-Monster Mike]

The drawing on the left is incorrect (one of the batteries has two red wires and the other has two black wires). Basically, for a series connection, wire as follows:

Connect the two RED battery leads from the controller to the POSITIVE side of a male dean's connector.

Connect the two BLACK battery leads from the controller to the NEGATIVE side of ANOTHER male dean's connector.

Then, connect the two attcahed dean's connectors to each other with another wire(positive to negative).

When you plug in the batteries, they will be wired in series.

[Dafni]

Originally posted by C.H.U.D.
Still would like something official from BK...but I've been in communication w/ them for the last few days and haven't received anything definitive. Could be the language barrier.

Even without a language barrier it's very hard to get some usefull information out of these guys, believe me.
Plus, if you write/speak english, there should be no barrier, IMHO.

[Serum]

@chud, the orange wirebridge that is on the right one of the two images is also wrong, and the mistake is also the reason why you have got doubts.

The wire bridge you drawed is not there in the controller.. There is only a wire bridge between the red/red and the black/black.. they basicly could have used one thicker wire to make it work. Imo, the reason for them using 2 wires for + and - is because the customer is able to connect packs parralel now with greater ease.

(high amp setups)

Thanks again for the replies.

I should have been more clear w/ the drawings I posted above.

I wired my speed control just as the other drawings I've seen indicated, which are identical to Mike's description above.

Here's how its wired;

I plugged in one battery then began to plug in the other, it arced. Fortunately I caught it quickly, it wasn't plugged in...but close.

I proceeded to leave one battery plugged in and hookup my voltmeter to the second set of leads. Low and behold there's voltage going across those two leads, forming a complete circuit. Here's the voltage test I performed, in pictoral form;

[Serum]

Go on.. Plug it in.. You are the first person i know who takes two days to plug in the controller.. (Kidding mate, better be carefull with these expensive stuff)

arcing is cool, it are the capacitors who have got a near 0 ohm resistance when they are not charged. One reason why you need to replace connectors now and then, because this arcing damages them.

I understand your precaution.

The reason why you measure the voltage is the same, it IS a circuit you are measuring. the 18120 is part of the circuit.

[maxxdude1234]

looks good....I've got to wire my set-up, hopefully gonna do it at the weekend :W: What motor are you running in your truck, must be quite a beast to verify using the micro controller....:eek:

Originally posted by Serum
Go on.. Plug it in.. You are the first person i know who takes two days to plug in the controller.. (Kidding mate, better be carefull with these expensive stuff)

arcing is cool, it are the capacitors who have got a near 0 ohm resistance when they are not charged. One reason why you need to replace connectors now and then, because this arcing damages them.

I understand your precaution.

Yeah, they're too expensive to not be cautious. And I don't have a lot of time during the week to mess around w/ my truck...so :p

Originally posted by Serum
The reason why you measure the voltage is the same, it IS a circuit you are measuring. the 18120 is part of the circuit.

My confusion regarding the voltage is that I don't expect to see a complete circuit until the speed control switch is complete when the throttle is opened...which btw, I don't have the ESC hooked up to the receiver yet...I wonder if that's part of the issue.

If my wiring looks correct (see pic above) why would it arc?

thx!

[Serum]

i allready explained why it sparked.

that is the reason why you measure a voltage too

it IS a circuit you are measuring. it simple is a circuit, nothing els.

the internal resistance of the capacitors and all the other electroncs that make part of the speedo is much, much lower then the internal resistance of the voltmeter that is why you measure something on the place you are measuring.. but like i stated for the reason why you see the sparcs (allmost 0 Ohm for the capacitors when they are not charged)

Your statement '0 ohm only at full throttle' is wrong too. it is not loaded the way you measure it. It needs to be fed with the full set of batteries and giving a WOT, loaded with a motor, before you can measure the difference in internal resistance of the controller. (only then the fetts/transistors can make a difference in internal resistance.

You need some electronical background to understand what i am saying, but i can't explain it in another way.

Looking at your drawings, you don't know what you are doing (no wrong intention here!! Don't get me wrong) but the measurement you are doing makes no sence at all.