High current melting solder on PDB

Flydigital

Flydigital

Member
I have an octo diy build which crashed after deans plug melted mid flight. A few months on now and I have rebuilt and done a bench test to repeat the issue.
I put an in-line amp meter in to see the current at full power: 85A. This time the deans plugs were ok but the connection popped on the PDB. The main live terminal jumped off due to overheating of the solder joint.
Now I would not plan to actually fly like that but it still seems like an issue to fix.
How can I avoid overheating? Do I add a heat sink at the main connection or should I go for thicker AWG wire?
Thanks for any suggestions.
 

maxwelltub

maxwelltub

Member
If your PDB is getting to 180 C then we got to step back and look at whats going on here. Maybe its not completely unheard of to others here but I personally have never heard of these temps or come close to them myself. Can you list your set up?
 

stevemaller

stevemaller

Heavy Lifter
My guess is that something in your install (wires? solder? connectors?) is introducing too much resistance, which is being manifested as heat. Lots of folks fly systems with current draws in excess of 100A. My heavy lifter routinely did this, and the temperature of its ESCs (MikroKopter BL 3.0) never exceeded 50°C.

It'd be helpful to post details of your build, and maybe even photos.
 

Flydigital

Flydigital

Member
The set up is as follows:
6s power using 2 x 3s 5000mah 25c lipos.
8 x 320kv motors
8 x 45A ESCs
Flight controller is pixhawk.
Power all runs into component that steps down power to 5v for the FC then flows through to a board to distribute to the escs. The connection broke where the power first connects.

I can get a photo later but will be difficult to make sense of it i think.
I was testing it indoors and it felt pretty intense to have it full throttle. It probably took about 4-5 minutes for the circuit to break.
 

stevemaller

stevemaller

Heavy Lifter
So you're running the batteries in series, right?
I would strongly suspect whatever power distribution board you have. Can it handle that amount of power? Whose is it?
 

Flydigital

Flydigital

Member
Thanks Steve, here's the details:

All eBay stuff from China...
Board spec is as follows:
      • KK Power Distribution Board (x1)
Product Details
This quadcopter PDB can be used with any frame. It distributes power from the flight battery to ESCs to power the Quad's motors.
​
      • 100% brand new and high quality
      • Material:glass fiber
      • Color:Blue
      • General purpose power distribution board for APM/MegaPirate/CC3D/MWC multiwii/KK MultiCopter controllers
      • Compatible with MK KK Flight control bolt Center
      • Max voltage: 6s LiPo / 22V
      • Max current: 100A
      • Size:5cm*5cm*0.2cm
      • Net Weight:20g
58f03e4be24a4ff9d2d3ba639f11fd6a.jpg


Also the point where the solder actually popped off was on this part:
Power module which separates of a 5v supply for the flight controller.

sku_104870_3.jpg



APM2.5.2 APM2.6 Pixhawk Power Module V1.0 Output BEC 3A Deans Plug
Power Module is a simple way of providing your APM/Arduflyer with clean power from a LiPo battery as well as current consumption and battery voltage measurements, all through a 6P cable. The on-board switching regulator outputs 5.3V and a maximum of 3A from up to a 7S LiPo battery.Special for APM2.5.2 APM2.6 Pixhawk flight controller

Note: The Power Module is only designed to power APM/Arduflyer, a RC receiver and accessories (GPS, Radio telemetry). It is not designed to power servos. Use your aircraft's own ESC/BEC for that.

Features:- Deans Plug
- Max input voltage: 30V
- Max current sensing: 90A
- Voltage and current measurement configured for 5V ADC
- Switching regulator outputs 5.3V and 3A max
- 6P molex cable plugs directly to APM/Arduflyer 2.5's 'PM' connector
- Max input voltage: 30V
- Max current sensing: 90A
- Voltage and current measurement configured for 5V ADC
- Switching regulator outputs 5.3V and 3A max
- 6P molex cable plugs directly to APM/Arduflyer 2.5's 'PM' connector
- Max input voltage: 30V
- Max current sensing: 90A
- Voltage and current measurement configured for 5V ADC​
- Switching regulator outputs 5.3V and 3A max
- 6P molex cable plugs directly to APM/Arduflyer 2.5's 'PM' connector
Specifications:- Dimension(mm): 25 x 21 x 9
- Weight(g): 17(include all wire)
​
The point where the solder popped was on the 'power module v1.0' on the live input

 


crayfellow

crayfellow

Member
Mactadpole said:
Its the power module is my guess. I have had the exact same thing happen when I decided to try one of these cheap ebay power modules. I think it failed at like 60A max, resulted in about $1k of damage. I highly recommend you build your own: http://copter.ardupilot.com/wiki/co...age/common-using-a-pixhawk-with-6s-batteries/
Click to expand...
Do you/they advocate modifying the 90A vs. simply getting the 180A simply because the 90A-modded-for-150A-range should be more accurate? I recall somewhere on diydrones the designer of the attopilot questioning this practice but I don't recall his reasoning.
 

Mactadpole

Mactadpole

Member
I didn't modify the 90A for my use so can't really comment. But I can tell you that have pushed ~100A through the 90A for very brief moments during testing with no issues. It is a very rare occasion (if ever) that I would peak 90A. I think the same for your build too.
 



Flydigital

Flydigital

Member
I think it is sorted now thanks. I have put the 6s power direct into the PDB for the ESCs and upped the connector in to a EC5 with 10AWG wire. The power module to the Pixhawk no comes out of the PDB rather than flowing into it. I have also added an ATTO 180A to give me current readings. I have bench tested at full throttle and no brown outs so it seems to be working!
 

Bartman

Bartman

Welcome to MultiRotorForums.com!!
are you stepping down the power only to the FC or are you running 5V power to the ESC's?
 


Mactadpole

Mactadpole

Member
I assume the ATTO is between the battery(ies) and the PDB? Just verifying, since you won't get accurate readings if not.
 



Flydigital

Flydigital

Member
I've done quite a bit but often quite sloppy. Having an underpowered iron in some situations doesn't help. With the big wires the heat gets sucked out and the solder doesn't always look that great.
 

Bartman

Bartman

Welcome to MultiRotorForums.com!!
Flydigital said:
I've done quite a bit but often quite sloppy. Having an underpowered iron in some situations doesn't help. With the big wires the heat gets sucked out and the solder doesn't always look that great.
Click to expand...
that could be your problem. if the solder doesn't get hot enough and really form a strong, well distributed bond then you'll get what are called cold solder joints and they'll be weak and there will be high resistance at the joint. I think @stevemaller mentioned it earlier in the thread. as the current goes up so does the heat and that might be causing the solder to melt on you.

a good soldering iron is a must, it would be worth it to invest in one now that will last at least as long as you'll be active in the hobby. Weller is a good brand to look into.
 
Last edited by a moderator:

econfly

econfly

Member
The key to a great soldering iron/station is temperature control. Weller is great (e.g., WESD51). Hakko is also very good (check out their FX888D model).
 

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