Balancing Harness Conversion TB47/48

[Inspired119]

This is a TB47/48 Balancing Harness we made for external charger balancing batteries that have gone far out of balance.
Such batteries would not operate correctly.
The battery was discharged down to Battery Management System (BMS) Shutdown.
The residual individual cell voltages were then balanced using the external charger.
Using the external charger, we balance charged the batteries to Full.
The discharge was performed again to BMS Shutdown.
The discharge/balance/balance-charge cycle was performed about 3 time and the batteries now perform like new.
The external charger-balancer used was the T240-Duo.



The Balancing Harness is permanently installed into the battery.
Pos & Neg battery posts are brought out to the head to enable battery cluster maintenance without disassembling/removing the battery head.



BTW....we tried the HSABAT battery blocks available through Alibaba and found them to be inferior.
The HSABAT TB48 version is nowhere near the 'mAH' rating of the original batteries.
I would not buy those again.

 

[CoreySnipes]

Very clever fix!

 

[Donnie Frank]

BTW....we tried the HSABAT battery blocks available through Alibaba and found them to be inferior.
The HSABAT TB48 version is nowhere near the 'mAH' rating of the original batteries.
I would not buy those again.

Thanx for the warning. The irony of an inferior Chinese imitation of a Chinese product.....

FWIW, brand new TB48's became available again through DJI. Don't look for it anywhere on the DJI website. I was able to purchase it via chat support only. I purchased this March of 2022.



D

 

[Inspired119]

We will likely convert all of our inspire batteries to have this harness.
The additional benefit is that, with the conversion, the bird can easily be outfitted with dual saddle pack batteries which can be mounted & plugged in when needed for increased duration and safety backup.

 

[Donnie Frank]

We will likely convert all of our inspire batteries to have this harness.
The additional benefit is that, with the conversion, the bird can easily be outfitted with dual saddle pack batteries which can be mounted & plugged in when needed for increased duration and safety backup.

Have you explored the diminished returns of doubling the battery weight?

Back in my Phantom 1 days, I had modified a P1 to take any battery I wished. I immediately upgraded from a 3 cell (11.1V) to a 4 cell (14.8V) battery. This netted a real seat-of-the-pants performance improvement. As time went on I kept increasing the size (capacity) of the battery. 5200mAh was the sweet spot. Any more capacity and I started to see diminished returns. But that alone didn't discourage me. Naturally, as battery weight increases, so does the drone's handling characteristics - especially as I moved passed the 6Ah mark (6000mAh). The P1 became a real barge.

My experience with the Inspire 1 is pretty profound. I can say with a lot of confidence that even the increase of a mere 300 grams from the X3 to the X5 netted a real difference in how the bird handled. I can only imagine how profound the difference adding another 650ish grams for another TB48. I have seen these double TB48 rigs on YouTube. And, of course, you get more flight time. But do you get double the flight time for double the capacity?? I would guess not. In fact, I would venture to say probably not even close. Maybe 50% more flight time? Have you tracked this?

I would also be curious to know your thoughts on the handling characteristics. An Inspire 1 with a double battery set-up (with no other payload), probably handles similarly to a single battery with an X5 cameras. But add the X5 - or an X5S - and I bet that thing handles like a pig.

What was your experience in that regard?

D

 

[Inspired119]

What you say about handling is right on mark.
It becomes a trade off of handling vs a little time gained aloft. Making saddle batteries a "mission configurable option" chosen depending on the flight-mission and weather/wind conditions is the way we will go.
Higher winds with heavy loading and/or changed weight & balance reduce performance responsiveness and will affect the camera shot stability. Extra payload in such conditions, especially carrying X5R, are best avoided. We're using X5 & X5R but don't have an X3. There is the safety benefit of having extra batteries as they offer some redundancy in case of main battery sudden fault issues. Having parallel batts also reduces the strain and discharge temperature rise on the main battery extending longevity. Most missions can be adequately performed with stock battery times if properly planned/managed and especially if using an efficient flight waypoint management tool like Litchi to avoid fiddling and loitering.

We've not flight tested parallel battery options but only done time-discharge bench tests using 200 watt resistive loading. One single parallel TB48 does indeed near double discharge time. That of course is a bit misleading as the discharge into resistive load doesn't accurately reproduce what a real in flight load would look like.

We are now putting together a configurable setup of 2x 6S 22.8 1300Mah 120C (190g/ea) saddle batts with another heavy load option to saddle pack two 'top-stripped TB48's'.

 

[Donnie Frank]

What you say about handling is right on mark.
It becomes a trade off of handling vs a little time gained aloft. Making saddle batteries a "mission configurable option" chosen depending on the flight-mission and weather/wind conditions is the way we will go.
Higher winds with heavy loading and/or changed weight & balance reduce performance responsiveness and will affect the camera shot stability. Extra payload in such conditions, especially carrying X5R, are best avoided. We're using X5 & X5R but don't have an X3. There is the safety benefit of having extra batteries as they offer some redundancy in case of main battery sudden fault issues. Having parallel batts also reduces the strain and discharge temperature rise on the main battery extending longevity. Most missions can be adequately performed with stock battery times if properly planned/managed and especially if using an efficient flight waypoint management tool like Litchi to avoid fiddling and loitering.

We've not flight tested parallel battery options but only done time-discharge bench tests using 200 watt resistive loading. One single parallel TB48 does indeed near double discharge time. That of course is a bit misleading as the discharge into resistive load doesn't accurately reproduce what a real in flight load would look like.

We are now putting together a configurable setup of 2x 6S 22.8 1300Mah 120C (190g/ea) saddle batts with another heavy load option to saddle pack two 'top-stripped TB48's'.

Awesome. Sounds like you know what you're doing. I look forward to hearing future feedback regarding this system. Best of luck!

D

 

[Inspired119]

We ran a static test of two parallel saddle batteries, 2x1700mAh (3400mAh), on a TB48.
Total weight of the two saddle batteries is 418grams. The TB48 weighs 667grams.
An extended battery run duration by an increase of approx. 66% was observed.
The test was performed on the bench with a constant static resistive load of 200 watts having a current draw of 8.6 amps at full voltage and dropping to 7.8 amps at the lowest voltage before the Battery Management System (BMS) shutdown.
The measurements were performed with 'BQStudio' through an EV2400 interface.
The plot shows the "voltage-drop-roll-off" just before BMS shut down and the resulting voltage increase at the end of each run. The blue plot is the stock TB48 alone and the red plot is with the two saddle batteries running through individual Schottky isolation circuits.
In addition to the extended run duration, the collected data showed a marked decrease in the TB48 discharge temperature during the parallel configuration.

This experiment showed that the use of parallel saddle batteries, in addition to providing battery safety redundancy and extended run duration, also would reduce main battery stress by dropping operating/discharge temperatures, thereby likely extending battery longevity.

 

[Inspired119]

While the experiment yielded interesting results, it is clear that increased static run time does not yield directly corresponding flight duration. This is because increased battery capacity also increases weight. However, though not proportional, some increased flight time can be expected. The added battery redundancy security and operating/discharge temperature reduction are quite interesting for us.
More can be found here:
How Does Drone Payload Affect Flight Time

 

[Donnie Frank]

We ran a static test of two parallel saddle batteries, 2x1700mAh (3400mAh), on a TB48.
Total weight of the two saddle batteries is 418grams. The TB48 weighs 667grams.
An extended battery run duration by an increase of approx. 66% was observed.
The test was performed on the bench with a constant static resistive load of 200 watts having a current draw of 8.6 amps at full voltage and dropping to 7.8 amps at the lowest voltage before the Battery Management System (BMS) shutdown.
The measurements were performed with 'BQStudio' through an EV2400 interface.
The plot shows the "voltage-drop-roll-off" just before BMS shut down and the resulting voltage increase at the end of each run. The blue plot is the stock TB48 alone and the red plot is with the two saddle batteries running through individual Schottky isolation circuits.
In addition to the extended run duration, the collected data showed a marked decrease in the TB48 discharge temperature during the parallel configuration.

This experiment showed that the use of parallel saddle batteries, in addition to providing battery safety redundancy and extended run duration, also would reduce main battery stress by dropping operating/discharge temperatures, thereby likely extending battery longevity.

View attachment 33784

Nice test. Great information. But....

It would be interesting to see the test results during real-world test flights with an X5 or X5S payload. I would bet that the diminishing returns curve would sharpen appreciably.

Looking at your chart, we're looking at roughly 60% increase in flight time with roughly the same increase weight-wise. But once you add *dead* weight to the mix, I predict that those numbers will go South quickly. I could be wrong. It would be interesting to see.

D

 

[Inspired119]

You may indeed well be right. However, for our purposes, the added redundancy/safety and reduced main battery heating/longevity will be well worth it. There are many experiences of expensive machines falling out of the sky to destruction due to having only one battery.
We'll see.

 

[Donnie Frank]

You may indeed well be right. However, for our purposes, the added redundancy/safety and reduced main battery heating/longevity will be well worth it. There are many experiences of expensive machines falling out of the sky to destruction due to having only one battery.
We'll see.

Copy that. I hear you. But I think you're forgetting one very important variable here; handling. I fly an Inspire 1 pretty much every week. In fact, I'll be flying one again today. I speak from great experience when I say that these birds get very "barge-like" when you add weight to them. Dare I say that a TB48 with an X5 payload is already bordering on "barge-like" status. I can't imagine adding *another* 400+ grams to that payload....let alone with an X5 or X5S, which, in my humble opinion, would make that bird borderline dangerous in the sky....especially in the hands of a novice pilot.

My experience with Phantom 1 custom battery packages and payload packages showed me that diminished returns sneaks up on you VERY quickly. So there's that experience, too.

Now I concede that this is all speculation, but it IS based on my vast experience with the Inspire 1 v2 and Phantom 1. Which I why I'm so curious to know your real-world flying experience. I could be totally wrong. But only you can flush that out.

D