Battery Mod Info
- Thread starter damoncooper
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Thank you everyone for the fantasic read, very interesting thread! But left my head spinning 
.
What is the current recommended/optimal additional battery pack for Inspire Pro (upgraded motors) and TB48?
2 x 2700mah 6S 25C?
Thanks!
. What is the current recommended/optimal additional battery pack for Inspire Pro (upgraded motors) and TB48?
2 x 2700mah 6S 25C?
Thanks!
Thank you everyone for the fantasic read, very interesting thread! But left my head spinning
What is the current recommended/optimal additional battery pack for Inspire Pro (upgraded motors) and TB48?
2 x 2700mah 6S 25C?
Thanks!
Yes. Preferably Thunder Power RC 2700's at 25C.
Damon
How do I you find it with your x5 and The dual extra TP battery? How many more mins can you get
How do I you find it with your x5 and The dual extra TP battery? How many more mins can you get
Ok, here is the long awaited story of the crazy idea I had to try to be able to fly beyond the burn of a TB48:
I had an inkling to try to get the FET in the DJI batts to *accept* charge for part of a flight while the aircraft drew its power exclusively from external batteries. The FET is essentially a switch in the DJI batt that accepts or releases charge based on connected voltage. Above some V value, the battery accepts charge. Below, it releases charge.
The problem I was trying to solve is that when connected to external batts, although the main battery depletes slower, it still depletes in about 25-30min, regardless of how much extra power you have left in the external batteries. You could have an external 100,000mah battery that weighs 0grams and your flight will still end at around 25-30min.
So I did some experimentation and found the FET switched to accept charge around 26.1V or so. Up to about 27+V, the battery charges and the Inspire is still happy. Keep in mind that the DJI batteries are High Voltage meaning full they put out over 26V, so the Inspire is built to handle 26.1+V.
So I realized that to try to charge a DJI battery i needed to start with > 26.5V. 6S HV batteries for aux won't get you there though. Full you get only 26.1V.
So I had the crazy idea to try a 7S battery pair in parallel. Their nominal (read partially depleted) voltage is 25.9V, but of course full a HV 7S is 30.45V. I found out by testing this induces an unhappy red over voltage shutoff of the DJI battery.
So using partially depleted 7S batteries to lower voltage to around 28V, I was able to charge to the main DJI battery AND power the aircraft.
But. The 7S batteries I had on hand were only rated for 10C and they got screaming hot, obviously at the high voltage draw. The 7S route just seemed impractical, but the theory was still sound.
So I went back to the drawing board and thought: perhaps I can bump voltage from regular 6S lipos to the charge voltage needed by the DJI battery FET using a voltage regulator.
Problem was finding one that could handle >10amps (30A preferred) and that was light enough to be practical to put in the air.
That proved tough and sent me to a plethora of Chinese manufacturing sites soliciting bids for a custom made voltage regulator to meet my specs as one didn't exist.
I hit a wall here and couldn't seem to convince a manufacturer despite several conversations to create a regulator that matched my specs, the main one being light and small. They all though I was crazy and the smallest off the shelf 30A was something like 3lbs.
So in one last gasp, I searched far and wide to find a 10A regulator that at least could fit in the palm of your hand. A few in fact. But when they arrived, they had heat sinks the size of a TB48 battery and were very heavy (800g+), and only 10A in the end.
Thus, my journey to break the 35min barrier with the Inspire has come to an end.
I'll enjoy my 30+ min flight times for now and perhaps with this info others might be able to step in and come up with other ideas.
I would still LOVE to get to 45min+. I think it's entirely possible but being a software guy, I'll confess I'm a bit in over my head although it was fun learning and I never destroyed anything or burnt the house down.
Damon
I had an inkling to try to get the FET in the DJI batts to *accept* charge for part of a flight while the aircraft drew its power exclusively from external batteries. The FET is essentially a switch in the DJI batt that accepts or releases charge based on connected voltage. Above some V value, the battery accepts charge. Below, it releases charge.
The problem I was trying to solve is that when connected to external batts, although the main battery depletes slower, it still depletes in about 25-30min, regardless of how much extra power you have left in the external batteries. You could have an external 100,000mah battery that weighs 0grams and your flight will still end at around 25-30min.
So I did some experimentation and found the FET switched to accept charge around 26.1V or so. Up to about 27+V, the battery charges and the Inspire is still happy. Keep in mind that the DJI batteries are High Voltage meaning full they put out over 26V, so the Inspire is built to handle 26.1+V.
So I realized that to try to charge a DJI battery i needed to start with > 26.5V. 6S HV batteries for aux won't get you there though. Full you get only 26.1V.
So I had the crazy idea to try a 7S battery pair in parallel. Their nominal (read partially depleted) voltage is 25.9V, but of course full a HV 7S is 30.45V. I found out by testing this induces an unhappy red over voltage shutoff of the DJI battery.
So using partially depleted 7S batteries to lower voltage to around 28V, I was able to charge to the main DJI battery AND power the aircraft.
But. The 7S batteries I had on hand were only rated for 10C and they got screaming hot, obviously at the high voltage draw. The 7S route just seemed impractical, but the theory was still sound.
So I went back to the drawing board and thought: perhaps I can bump voltage from regular 6S lipos to the charge voltage needed by the DJI battery FET using a voltage regulator.
Problem was finding one that could handle >10amps (30A preferred) and that was light enough to be practical to put in the air.
That proved tough and sent me to a plethora of Chinese manufacturing sites soliciting bids for a custom made voltage regulator to meet my specs as one didn't exist.
I hit a wall here and couldn't seem to convince a manufacturer despite several conversations to create a regulator that matched my specs, the main one being light and small. They all though I was crazy and the smallest off the shelf 30A was something like 3lbs.
So in one last gasp, I searched far and wide to find a 10A regulator that at least could fit in the palm of your hand. A few in fact. But when they arrived, they had heat sinks the size of a TB48 battery and were very heavy (800g+), and only 10A in the end.
Thus, my journey to break the 35min barrier with the Inspire has come to an end.
I'll enjoy my 30+ min flight times for now and perhaps with this info others might be able to step in and come up with other ideas.
I would still LOVE to get to 45min+. I think it's entirely possible but being a software guy, I'll confess I'm a bit in over my head although it was fun learning and I never destroyed anything or burnt the house down.
Damon
Damon, I must take my hat down for your efforts and your extraordinary journey to find out the bat's sicret, I'm not a software guy, but I still believe that there is an hardwear solutions for that issue as I described in this post earlier.
Anyway thanks for your extremely effort to find for all of us in this treads the best flight time for our bird.
I will stick with the 2700 +25
as you recommend in the past.
Damon, Do you know what the highest voltage is, that would not cause an over voltage condition? You say 30.45v triggers an error and partially depleted battery pack at 28v works, would 29.4v work. After reading, I was thinking of trying a non high voltage 7S pack with a high C rating, each cell charges around 4.2v which would be 29.4v max. I think I could get a 7S3P 5550mah 29.4v fully charged battery with high C rating, possibly around 825 grams.
Last edited:
About 3.7-3.8V/cell was fine if I recall. More than that triggered over voltage shutdown. I recall 3.9 or 4.0 triggering. I didn't charge the LiHV 7S TP to HV level, to clarify, just to regular LiPo level (4.2). That was too much obviously as well.
Your mileage may vary. My memory is good, but short
31.33 mins flight time with Inspire Pro Black. Simply add a 6,600 mah LiHv battery. No need for 500$ mods. Landed with 10 %. Weather was cold,
only 10C degrees. Flight time pictures are: 50%, 40%, 30%, 20%, 10%, 10% landed.
only 10C degrees. Flight time pictures are: 50%, 40%, 30%, 20%, 10%, 10% landed.
Awesome!! Haven't yet tested flight times with my Pro Black but this is encouraging.
X5 camera attached or no camera?
Wow awesome time! Just a hover or did you do some flying around also? Also brand of battery is that? Thanks for sharing your test.
Can you post picture of battery mounting location and confirm weight of the battery?
Very nice! I have 2 X ThunderPower LiHV 3500mah 6S's I'll try today with the Pro Black and X5R.
Will report back.
I have 2x of the TP 3500 LiHV also that I have to yet try with my inspire v1 with upgraded motors to V2 and X5. Once I test I will let you guys know as well. It will be interesting to see what times you get Damon.
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