Something strange.

[Explorocam]

Hey all,

I'm trying to set up my low voltage on my Tarot 960. DJI Naza V2.
I'm running two 5300mAh batteries in parallel on a pretty much stock system except for my homemade power distribution board and 50V 220uf capacitors before each ESC.
After 7~8 minutes I seem to loose 2 volts but my mAh expenditure is only 2.7%.

I started with approximately 25.2V in each 5300mAh battery running in parallel, after 7~8 min I was down to 23.2V but when I balance charged the batteries in parallel I only needed to put 3868mAh to bring them back to full charge.

This is really strange to me and I don't know what's going on. Is this a battery problem or is this some kind of inefficiency in my system? But I think it's something to do with the way I'm setting things up. Anyways this my Power Distributer that I made of brass, I know this not as conductive as coper but I can't see this being my issue. Here are some photos:
View attachment 14918View attachment 14919View attachment 14920View attachment 14921View attachment 14922View attachment 14923View attachment 14924
I hope this makes sense. If not please feel free to ask questions. I really want to get to the bottom of this.

 

[PeteDee]

Personally I have given up on the LVC on my Naza's far better to fly to time or use telemetry to check voltage or mH's used.

Pete

Sent from my GT-I9300 using Tapatalk

 

[Explorocam]

Personally I have given up on the LVC on my Naza's far better to fly to time or use telemetry to check voltage or mH's used.

Pete

Sent from my GT-I9300 using Tapatalk

So does that mean you think I'm not having issue with my wiring and more so with my Naza low voltage setup?

 

[bensid54]

Are those resisters you installed and if so why? They can explain your power drop.

 

[Explorocam]

Are those resisters you installed and if so why? They can explain your power drop.

No those are 50V 220uf capacitors, one before each ESC. This is prevent inductance. Inductance can damage the ESCs over time. I'm using this because I have long power wires to each ESC.

 

[bensid54]

Please explain inductance? Is there any way you can make your contact ring wider to reduce your wire length there's a lot less resistance with that ring than there would be with the wire and as you and others know resistance equals heat equals power loss.

 

[Explorocam]

Please explain inductance? Is there any way you can make your contact ring wider to reduce your wire length there's a lot less resistance with that ring than there would be with the wire and as you and others know resistance equals heat equals power loss.

This should explain inductance and where I first became concerned about power wire length.
http://www.rcgroups.com/forums/showthread.php?t=952523
I could have used long phase wires but the ESCs take up too much room in the frame, plus you don't really want long phase wires either. I cold have put the ESCs half way along the arms but this would have made it look messy. So I opted to keep the phase wires short, ESCs under the motors and use one capacitor/per ESC to smooth out the voltage spikes coming in from the power wires to the ESCs.
Hope this helps.

 

[bensid54]

From what I see by the vise picture you have the capacitor wired in series (positive to negative) where they should be wired in parallel (both wires inline). Think of it this way, on the pressure side of some plumbing you will see a short pipe going straight up and capped. Like a capacitor this little pipe will absorb the pressure spikes, difference is one is water one is electrical spikes. I would get rid of those capacitors buy new and place them inline this time. Let us know how it works out for you.

 

[PeteDee]

So does that mean you think I'm not having issue with my wiring and more so with my Naza low voltage setup?

Yes don't use it as it does not work properly, time your flight or use telemetry to see how much power you have used.

And you numbers in your OP don't add up, where do you get 2.7 percent from, looks more like about 30 percent to me if you are putting back 3868mH.

 

[bensid54]

Pete is right about the usage and with my Naza low voltage warning it goes on far before half the battery mha capacity is used up.

 

[Explorocam]

From what I see by the vise picture you have the capacitor wired in series (positive to negative) where they should be wired in parallel (both wires inline). Think of it this way, on the pressure side of some plumbing you will see a short pipe going straight up and capped. Like a capacitor this little pipe will absorb the pressure spikes, difference is one is water one is electrical spikes. I would get rid of those capacitors buy new and place them inline this time. Let us know how it works out for you.

I was going by the pictures in the link I added and by advice from Motion RC.
Here are two pictures that show the caps wired in the same way I have.
View attachment 14975View attachment 14976

 

[bensid54]

I see where I got it wrong. I am always inclined to keep things simple even the capacitors can be faulty from new that's why warranty on electronics is so dicey. In the article it says you can remove the problem by extending the motor wires and twisting them to prevent electronic interference why didn't you choose that route? I looked at the article again and see where you are coming from to me it appears what they are talking about are magnetic fields that can cause impedance as opposed to resistance. Excuse me with my logic most of my electrical experience is on repairing heavy equipment and I am finding some of my knowledge needs to be upgraded, which is cool because this old dog wants to learn new tricks.

 

[Explorocam]

I see where I got it wrong. I am always inclined to keep things simple even the capacitors can be faulty from new that's why warranty on electronics is so dicey. In the article it says you can remove the problem by extending the motor wires and twisting them to prevent electronic interference why didn't you choose that route? I looked at the article again and see where you are coming from to me it appears what they are talking about are magnetic fields that can cause impedance as opposed to resistance. Excuse me with my logic most of my electrical experience is on repairing heavy equipment and I am finding some of my knowledge needs to be upgraded, which is cool because this old dog wants to learn new tricks.

I like all advice and comments. I think everyone can teach me something.
I went with the short motor wires because I wanted the ESCs under the motors to give the centre frame more room. In addition it's lighter to have 2 long wires per arm than to have 3 long wires per arm, that's 6 less long wires. Plus the prop-wash acts like a natural cooler.
So you are ok with the way my capacitors are wired now?

 

[Explorocam]

I think it's the Naza Low Voltage thing to.
I posted the same issue on DIY drones and one of the replies said that his T960 takes a bunch of voltage at first but then levels off and he gets like 22 some minutes. So I think this is the issue.
I might try and implement this idea to:

 

[bensid54]

I like all advice and comments. I think everyone can teach me something.
I went with the short motor wires because I wanted the ESCs under the motors to give the centre frame more room. In addition it's lighter to have 2 long wires per arm than to have 3 long wires per arm, that's 6 less long wires. Plus the prop-wash acts like a natural cooler.
So you are ok with the way my capacitors are wired now?

I was going to come back with something witty but I forgot what it was when I started typing so you have my blessings on the wiring. Thanks for the video I think I'll adjust my warning too, right now I ignore it and go by time.

 

[Explorocam]

I was going to come back with something witty but I forgot what it was when I started typing so you have my blessings on the wiring. Thanks for the video I think I'll adjust my warning too, right now I ignore it and go by time.

THanks dude.

I'll try playing with the voltage a bit more and make sure I can get like 20 min or so. I tested all leads through everything with to my multimeter before the build and found virtually no resistance. But I'll keep searching and testing.