Battery discharger

[pious_greek]

it looks like the guys at 3DR went with 14 awg stranded for the battery terminal

 

[RichWest]

Thanks, and what do I use to plug into the battery?

Now that is the $64,000 question. I'm not going to get exotic right off the bat and buy a specific plug. I figure a couple of flat copper plates could be fashion, a little solder and heat shrink. Good old hardware stores still carry this type of stuff or re-purpose some junk electrical stuff. I'd use the stock charger's terminals as a guide for fit and finish, i.e. thickness, length and width of blades. Don't want to jack up the battery's receptical with improperly sized terminals May cut up a piece of HDPE plastic to create a spacer between the terminal spades. Polarity doesn't matter, but shorting out would....

The main thing is insure the setup doesn't over heat at any one point. Mainly at the battery.

 

[RichWest]

it looks like the guys at 3DR went with 14 awg stranded for the battery terminal

The leads are fairly short and the massive circuit boards dissipate heat quite well, 14 awg is fine in that application. Besides you use what you have on hand, plenty of SO cord laying around here...10 & 12awg on hand. go big or go home....

 

[Ed Beck]

Thanks everyone!

 

[twitchyzero]

Go try that. and let me know how far you get

? I do it all the time

I thought about running without props, then thought about the bearings and running unloaded motors. Putting unneeded wear on the bearings made less sense... .

who said anything about arming the motors? turn it on and walk away....or what might help it drain just a tad faster is manipulate controller loss with the red LEDs flashing

 

[RichWest]

who said anything about arming the motors? turn it on and walk away....or what might help it drain just a tad faster is manipulate controller loss with the red LEDs flashing

I think the current draw is minimal at best when the bird is sitting idle. Just a little better than being turned off and self depleting. Besides why load the bird when an alternative means could be done faster and without stressing the gimbal and other electronics.

The whole idea for me is to apply an actual working load to deplete the batteries. No facts that this benefits the life of lipos, but from my thinking the batteries were designed to discharge at a reasonable high rate. Doing otherwise, lower amp draw, could effect the battery capacity or battery life...time will tell.

Not sure about the bird, but the controller shuts down when left without input for a short duration of say 5 minutes.

 

[twitchyzero]

if your gimbal is balanced, the stress on the motors in negligible when it's at neutral position

I used and still baby the Solo but I'm not as crazy about it when the battery is $50 and gimbal $80 and have quite a few of each.


Self-depleting to 50% takes weeks. If anything that's more detrimental to longevity than idle draw that takes maybe 2 hours.

Phil Rowse also suggested featherlight throttles when battery is new for breaking in so I doubt trickle draw does more damage than working load.


You want to go Macgyver on something I dont feel is necessary then please go for it...I'm just saying let it idle is much easier.

The bird doesn't have an auto-off mode.

 

[healthyfatboy]

The higher the draw of the current, the more heat is generated in the battery and heat is what kills the batteries. The higher draw you're seeking probably won't heat the battery up so it's kind of a moot point but higher draw vs a lower draw won't degrade your battery any better/worse at the loads you're considering. Proper storage voltage is more important than how you get it there unless it's a really high load.

 

[RichWest]

The higher the draw of the current, the more heat is generated in the battery and heat is what kills the batteries.

That's actually the inverse for my reasoning for loaded amps from a discharger. I think there is an advantage in generating "working load" heat, rather than minimal discharge rate. I tend to get better battery performance in the heat of the summer and less when the weather is colder...ymmv. Lipos are designed for the amp draw and the associated heat. Solo is drawing anywhere from 15 to 22 Amps while flying.

Having read some where else, crystals are formed within the lipos that break down either the cathode or anode. This is the results of the failure, why it's caused or to extend the time to failure is why I'm going through this effort. No harm in experimenting. Besides, what am I to do when it's wet and cold outside...from this hobby.

 

[PdxSteve]

Besides, what am I to do when it's wet and cold outside...from this hobby.

Get lidar/optical flow man

 

[RichWest]

Get lidar/optical flow man

That's what she said....

 

[healthyfatboy]

That's actually the inverse for my reasoning for loaded amps from a discharger. I think there is an advantage in generating "working load" heat, rather than minimal discharge rate. I tend to get better battery performance in the heat of the summer and less when the weather is colder...ymmv. Lipos are designed for the amp draw and the associated heat. Solo is drawing anywhere from 15 to 22 Amps while flying.

Having read some where else, crystals are formed within the lipos that break down either the cathode or anode. This is the results of the failure, why it's caused or to extend the time to failure is why I'm going through this effort. No harm in experimenting. Besides, what am I to do when it's wet and cold outside...from this hobby.

You get better battery performance when it's warm because LiPo battery performance, just like any other battery, degrades when it's cold outside. There's no difference there. That's why car batteries tend to die in winter, not during summer.
If you're doing a slow discharge in your freezer, yeah, maybe you might damage the battery some way over time but at room temperature, whether it's a slow drain or a higher drain but not 15-22 A drain, it doesn't matter for longevity unless you're starting to heat up the battery. When you have a lot of internal heat, usually from running the battery hard, it starts to break down. LiPo batteries are designed to have higher energy density and can also discharge at higher currents than NiMH and NiCd but heat is heat for any battery and will damage it.
The loads you're proposing to put on the battery shouldn't really make much of a difference but whether you discharge it through a small load or a higher load won't matter much other than one taking longer than the other. Just don't heat the battery during the process because you're putting a high load on it and you should be fine.

 

[quick_dry]

my understanding was that the slowest processes (be it charge or discharge) are kindest to the battery. A high discharge or charge current might be more easily logged by the BMS than an incredibly tiny drain or supply.
The advantage of a faster discharger is only going to be time management, since you can drain one pack then move on to the next pack sooner.

 

[Stealth]

I have past experience in ordinary LiPo (no BMS) that I would like to share with you.
Generally LiPo Batteries have a Charge C-rating (usually less than 1C, meaning that a 5200 mAh LiPo, like the one Solo uses, could be charged with a max current of 5.2 A) and a Discharge C-rating (that varies a lot between 15C and 65C, meaning that a 5200 mAh with a 20C rating could be safely discharged at 104A continuous current). In addition LiPos have a burst (10 sec) discahrge C-rating that is higher than the continous discharge C-rating. But enough theory.
Solo's charge C-rating is 0.63 (3.3A / 5.2 Ah), if I am not mistaken. I have not read anywhere on the net what Solo's battery discharge C-rating is. Having some experience in flying Solo (around 50 flights already), it consumes 16-22A @ 16.80V (4S) = 369.80 W max. That leads me to the fact that if you wire 3 x 50 12DCV bulbs in parallel that will be 150 W @ 16.80V = 8.93A so after 20 min. Solo's battery would be aournd 50% of its capacity.
Talked to Mike (3DR CS) several weeks ago and asked him how do I discharge my batteries to storage levels (50%) and he gave me an advice that I turn on Solo and leave it as it is. Tried it this week as whether is going bad. Solo consumes around 1A when idle. It took me around 2,5 hours to discharge Solo's battery to around 50% of its capacity.
Another way (a more professional one) is to discharge Solo's battery is by using a Balance Charger. I use Imax B6AC v.2 for my ordinary LiPos. Unfortunately to be able to use this method you need to have a powerful Balance charger. Mine is rated 50W when charging and only 5W when discharging, meaning that when it discharges a LiPo to storage levels it uses 0.3A @ 16.80V (4S) = 5W and it takes forever -- 2.6A (50% of Solo's battery capacity) @ 0.3A = 8.6 hours. Tried once with a 5000 mAh hard case battery for my RC Truck and was stuck for hours.

Found this in another thread:
https://www.amazon.co.uk/gp/product/B01IV6QSMS/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
If this is a close to a OEM (same production factory, different labeling) battery, that means that Solo batteries are rated with 5C discharge rate = 5200 mAh x 5C = 26A constant discharge current. I have some other Zippy Compact batteries 2700 mAh, 25C that are rated with a higher constant discharge current (67.5A). I fly them on my fixed wing UAV and during take-off the OSD shows 25-30A constant discharge current. Just FYI.

I hope this helps.

 

[Jubalr]

Or you could kill 2 birds with 1 stone; Put it in a hover for 6-8min in manual mode (indoors if needed). I have done this frequently the last couple years. Not to discharge batteries (still not sure what the point is with Solo batts), but just to fly or test when the weather is too bad to fly outside. There is a 6-8' circle of space with no furniture at my office that makes a good place to fly. It's also great practice for manual mode, because after just a few seconds flying in a small space there is quite a bit of shifting wind.

Just my opinion. YMMV..

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[wsalopek]

That's a good question. Two purposes, I'd prefer to discharge at a rate higher than a trickle. My thinking is the slow rate could shorten the battery life, as they were designed to be depleted at relitive high amps. Don't know why, but this is what I think...based on other battery experiences.

Second would be to occasionally deplete the battery to a lower level than I fly to, I'm a 25% person. Reading here and else where, running the battery down allows the "smarts" to re-calibrate total capacity. I'd assume there is some benefit to draining the tank every now and then, get rid of some the low octane electrons...

I know lipo life is based on cycle counts for charges, I've read numbers from 100 to 300. I know damage is done when depleted to below 3.0V (correct me if I'm wrong) per cell and I assume this is the stable voltage rather than loaded voltage...

Besides I learn from doing. My #1 battery is still working well, but then #'s 2 & 4 died a mysterious premature death. From my recollection, I babied #1 to 50% the first odd number of flights. Everything after was full tilt out of the box. I'm conditioning new battery's 5-8 these last few weeks down to 50%. My hope is that I experience a longer life with these batteries. Penny saved, is a penny earned....

Rich,

I know batteries are a bit of a mystery, no matter how much we read about them, but I think trickle discharging is BETTER than at a higher rate, and I'm pretty sure I read to store batteries at about 40% charge for longest life (40-60%).

I know when I get new batteries in the mail (made for all kinds of devices, and including for the Phantom and Solo), they frequently arrive at 40%.

I'd just let the internal battery circuitry take care of the discharging.

--

Bill

 

[RichWest]

I have past experience in ordinary LiPo (no BMS) that I would like to share with you.

Thank you, very informative.

Put it in a hover for 6-8min in manual mode (indoors if needed).

No doubt you and vegasrobbi are the pilots of record that have manual flying skills...you're just bragging now....

I know batteries are a bit of a mystery,

They sure are, well at least LiPos are. By the way everyone tells the story, Lithium tech has resolved all shortcomings that are experienced from the older tech. If that is the case, why do some battery's die in under a year and others continue to perform.... I'm sure manufacturing defects is the main reason for these failures. But the other variables are user habits and/or their mis-use.

Again no harm or no foul from what I'm doing, we're just having a conversation and sharing opinions and/or facts about LiPo tech. I know you guys have a long term experience and have accepted how Li-Pos perform over their life. I respect your knowledge and experience.

 

[Jubalr]

No doubt you and vegasrobbi are the pilots of record that have manual flying skills...you're just bragging now....

I would certainly hope that a video of a 30sec hover would not be bragging for anybody on a 'pilot' forum, whether inside or out. And I would like to think that most on here could do the same. The point of the video was more of a humorous suggestion to show an alternative to light bulbs for getting current out of the batteries.

 

[RichWest]

I would certainly hope that a video of a 30sec hover would not be bragging for anybody on a 'pilot' forum,

Wink-wink....your video is the first that I've seen. Well beyond my skills in those tight confines. Learned quick with Parrot and others the ground/wall effect does not play fair. Nor do I have the skills to under-react to such effects.

Back to off topic:
It's funny how this simple question and now discussion became convoluted. I enjoy the exchange of ideas and even the statements to why care. Seems I've crossed a line of Soloism. In general this question applies to all Li-Pos and platforms.

Stepping back for a moment, you now have 10 birds and 100 batteries to support in a commercial application flying full time. FAA (or insurance accreditation review) comes in and says what is your failure rate, how do you determine end of life for the batteries or what is your maintenance program for batteries?

Just one of the areas of my interest. Solo as a platform is a discovery tool for me. I'm just a mechanic...

 

[Jubalr]

Wink-wink....your video is the first that I've seen. Well beyond my skills in those tight confines. Learned quick with Parrot and others the ground/wall effect does not play fair. Nor do I have the skills to under-react to such effects.

Back to off topic:
It's funny how this simple question and now discussion became convoluted. I enjoy the exchange of ideas and even the statements to why care. Seems I've crossed a line of Soloism. In general this question applies to all Li-Pos and platforms.

Stepping back for a moment, you now have 10 birds and 100 batteries to support in a commercial application flying full time. FAA (or insurance accreditation review) comes in and says what is your failure rate, how do you determine end of life for the batteries or what is your maintenance program for batteries?

Just one of the areas of my interest. Solo as a platform is a discovery tool for me. I'm just a mechanic...

Just my opinion, but it's not that an exact science. I fly LiPos as long as they perform according to my needs. I still use the very first Solo batteries I got with the bird in the pre-order in the summer of 2015. I have simply numbered them numerically as I acquire them. The older ones may not give me the flight time they once did, but are still fine for short testing flights or when I know I'm just going to go up and 'fool around' and bang the sticks a bit. If I charge batteries for a flight day and it doesn't happen, no big deal. If it's just a week later I will use them as is. If it's longer and they are down 1-3 lights, I will charge them up again. I have even used again the battery that went to '0' in flight after that 21min mission earlier this year.

When I started flying LiPo from nitro birds, I was doing all the research and picking everyone's brain that I could. I remember talking to someone that flew 3D helis in competition that put it perspective for me, and he was spending $400-$600 per battery. Like most hobbies, sports, etc. that we do there are consumables involved. For us, that is mostly LiPos and motors. Certainly you want to care for them and get what you can out of them. But to what expense? Do you want to try and set a record for most flights from a battery? Or use it for the enjoyment or mission at hand? There is a give and take of course and you can land at 25% after a 12 min flight. Or you can stretch the legs a bit and maybe be able to accomplish a task you couldn't normally. So if using a battery to it's fullest may mean a 6 month life instead of 12 month, what's the harm other than a few extra dollars a year for your hobby/profession? Even more so now that batteries are $49 instead of $149.

Again, just my opinion and how I look at it personally. YMMV.