Dual Battery Mod

Phantom751874 · Feb 25, 2016

phantom13flyer said:
It's kind of a shame all this extra work is going to be a waste in a couple weeks when the p4 comes out with 35 mins flight time stock.

All those sensors take power.

Phantom751874 · Feb 25, 2016

Ok, so my HK Nano-Tech's came in today. I bought a couple 4S 1,800's and a couple 4S 2,200's. My battery mounts and modified P3 battery from FPV Customs comes this Saturday.

I have a question about usage that I have not been able to find a post about. How are people starting their P3's up with this configuration? The P3 battery will have two leads one for each battery. Are people powering on the P3 with its battery first then plugging in each of the externals? Or can everything be plugged in and the P3 battery turned on to begin?

dirtybum · Feb 25, 2016

If you plug the lipos into the battery they will start charging it. So push smart battery in ,turn p3 on, then let bird go thru warmup/app checks. Then right before take off plug in lipos. Do reverse when it lands, unplug lipos then shut off smart bat

Phantom751874 · Feb 25, 2016

dirtybum said:
If you plug the lipos into the battery they will start charging it. So push smart battery in ,turn p3 on, then let bird go thru warmup/app checks. Then right before take off plug in lipos. Do reverse when it lands, unplug lipos then shut off smart bat

Cool. That way the external batteries won't charge the P3 battery during use right? The P3 will just draw from all three while in use?

GadgetGuy · Feb 26, 2016

dirtybum said:
If you plug the lipos into the battery they will start charging it. So push smart battery in ,turn p3 on, then let bird go thru warmup/app checks. Then right before take off plug in lipos. Do reverse when it lands, unplug lipos then shut off smart bat

Any harm in plugging the lipos in as soon as the smart battery is fully turned on, rather than waiting until after the warmup/app checks?

Cuong44 · Feb 26, 2016

Phantom751874 said:
Ok, so my HK Nano-Tech's came in today. I bought a couple 4S 1,800's and a couple 4S 2,200's.

are they normal lipo. as i known, Turnigy nano-tech is not LIHV.
does it work with stock batt. i am looking forward to see your flight time

phantom13flyer · Feb 26, 2016

GadgetGuy said:
Any harm in plugging the lipos in as soon as the smart battery is fully turned on, rather than waiting until after the warmup/app checks?

I was wondering the same thing . That's the way I have always done it .

Ed209 · Feb 26, 2016

I turn on the DJI battery first and then plug in the packs. You dont have to wait for full warmup...I just wait for the loud noise coming from the speaker when powering up the P3. If you're using LiHV then the voltages are the same so nothing is charging another battery. I did find that if I plugged the packs in BEFORE turning on the DJI battery, sometimes healthydrones could not identify the battery (serial number blank). So from that point on I have been turning on the DJI battery first and have not had any issues.

dirtybum · Feb 26, 2016

You don't have to wait until after the warm-up to plug the lipo's in ,you can plug them in as soon as you turn on the smart battery. I wait because I don't want to waste precious lipo battery life. I do all my warmups and app check routine, then start the lipo juice. I see no reason for the unit to be drawing from all three just to check on things sitting on the ground. It may or may not use up that much but we are all on this post because every little bit counts right

UnknownCaller · Feb 26, 2016

dirtybum said:
You don't have to wait until after the warm-up to plug the lipo's in ,you can plug them in as soon as you turn on the smart battery. I wait because I don't want to waste precious lipo battery life. I do all my warmups and app check routine, then start the lipo juice. I see no reason for the unit to be drawing from all three just to check on things sitting on the ground. It may or may not use up that much but we are all on this post because every little bit counts right

I actually do the samething I boot the drone up with an old battery so it can warm up and acquire satellites then I power down and put them on a battery in and turn on it's ready to rock.

solsystem · Feb 26, 2016

GadgetGuy said:
Without a birdside mod, using just the FPVLR v2 mod with both 2.5A Sunhans boosters, I have tried Auto Channel and Custom 22 and 21 and 20 with far worse results than I had with Channel 30 which shows no interference at all, while all the others under 23 are saturated with heavy interference. Amplifying interference won't improve the video. I'm replacing the 2.5A video booster tonight with a 3.0A one, with lots of hope. Also, under Autochannel, the video bitrate selection disappeared, so I could not select 4 anymore, and when I went back to Custom, the previous bitrate of 4 was changed back to 6. Don't try changing from AutoChannel to Custom video channels in the air. I lost all video for several minutes including the RC connection! Also Autochannel can't use the 32 channel hack, if you have it installed. It limits you to the limited approved DJI channels only. Only way to use the 32 channel hack is to use Custom and select from one of the channels above 20.

Tony at FPVLR said increasing the boosters power will not help from 2.5 to 3 Amps, because there is not enough power to initially drive the booster to its max output. He said normally the booster only supplies about 650 MWatts of increased power to the antenna. He also stated the same thing goes for the birdside amp. This is from memory, but I think you get the idea.

GadgetGuy · Feb 26, 2016

UnknownCaller said:
I actually do the samething I boot the drone up with an old battery so it can warm up and acquire satellites then I power down and put them on a battery in and turn on it's ready to rock.

Great idea! After an air conditioned icy cold IMU calibration, my boot up time is under 30 seconds, with full satellite acquisition shortly thereafter, but every second counts. It's either an extra margin of safety or more flight time. Bladestrike has also said that is the best way to get an accurate barometer reading. Let it warm up and then reboot. Swapping batteries during the reboot is an advanced move!

However, if the internal battery isn't swapped out, I can't see how waiting to connect the lipos/LiHV's until after warmup saves any battery capacity. The warmup time will still reduce the total remaining battery time of the three batteries combined, as the main battery just starts out that much lower than if the warmup was spead out across all three attached together.

GadgetGuy · Feb 26, 2016

solsystem said:
Tony at FPVLR said increasing the boosters power will not help from 2.5 to 3 Amps, because there is not enough power to initially drive the booster to its max output. He said normally the booster only supplies about 650 MWatts of increased power to the antenna. He also stated the same thing goes for the birdside amp. This is from memory, but I think you get the idea.

Thanks for that input. I'll be testing that today! I have them strapped together so I can instantly swap the connectors and power supply for comparison testing on the video receiving antenna on the FPVLR v2. As long as it won't hurt, it's worth a try!

Assuming that it works as Tony describes, is there any way to increase the power to drive the booster to its maximum power, or is the power that is being referred to the incoming video signal? I recall Tony suggesting you could further increase the birdside power output by adding power to it. On the bird, that would add weight, but on the transmitter, who cares!

shr00m · Feb 26, 2016

is it possible to use just the 2 external batteries and no stock batteries? im looking to eliminate the need for stock batteries not really longer flight times. i realize i will need a board from a stock battery installed inside the drone. is it possible to use the 2 packs outside the bird without stock battery also is it possible to just run a 5000-6000 mah battery inside stock compartment if so what battery???

KyleMaxxUAV · Feb 26, 2016

GadgetGuy said:
Thanks for that input. I'll be testing that today! I have them strapped together so I can instantly swap the connectors and power supply for comparison testing on the video receiving antenna on the FPVLR v2. As long as it won't hurt, it's worth a try!

Assuming that it works as Tony describes, is there any way to increase the power to drive the booster to its maximum power, or is the power that is being referred to the incoming video signal? I recall Tony suggesting you could further increase the birdside power output by adding power to it. On the bird, that would add weight, but on the transmitter, who cares!

I believe the way the boosters work is a sliding scale, the stronger the incoming signal the stronger it can effectively boost it.
When you boost a signal you start adding interference in and degrading the signal quality.
Imagine a photo, a small photo can only be enlarged so much before it gets pixelated. Where as a large photo has higher pixel count and can be enlarged further before pixelation occurs (if that makes sense)

I agree with the bird side mod being almost redundant, the issue seems to be 1) transmitter signal power 2) battery capacity 3) bird side transmitter signal power.

I think once 1 & 2 are boosted to the limits you will still be inside the effective range of # 3. The balance will start to get messy when adding more weight to the AC because it will degrade flight time.

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KyleMaxxUAV · Feb 26, 2016

Slightly off topic but when using DBS or FPVLR, the antenna sides 1 & 2 are interchangeable correct ? Since they are both in and out ?

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shr00m · Feb 27, 2016

is it possible to use just the 2 external batteries and no stock batteries? im looking to eliminate the need for stock batteries not really longer flight times. i realize i will need a board from a stock battery installed inside the drone. is it possible to use the 2 packs outside the bird without stock battery also is it possible to just run a 5000-6000 mah battery inside stock compartment if so what battery???

KyleMaxxUAV · Feb 27, 2016

Should Be fine! 2 x 2s is series or 2 x4s in parallel. Problem you will have trying to find batteries that keep up with DJI's weight to mah rating. They are actually not bad ratios.

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KyleMaxxUAV · Feb 27, 2016

Ok, brain was thinkin again.

If you were to connect the slave battery to the switched power side instead of the always hot contacts. Would this not build in some redundancy so if the smart battery shut itself down you would still have the slave battery power instead of falling out of the sky ??

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Ed209 · Feb 27, 2016

This is how the FPV Customs battery mod is wired... That is why if I plug the 2 ext batteries in, it powers up the P3. I thought it would be connected to unswitched but I could be wrong. I haven't opened up the battery to verify.