Battery Calibration questions

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Hi guys, I have 2 battery packs with the well-known issue of rapid discharge. I tested both with the Solex "run motors" function and the result is that both have still a lot of power but obviously the battery chip is getting wrong information. When starting the motors with Solex the battery indicator drops quickly but stops between 10 and 8 percent and stays there felt like forever while motors are running and running. In the end, the batteries running as long as the ones that behave normally. So I assume the batteries are not dead they are so-called unbalanced, isn't it?

I now want to proceed with this official 3DR Battery Calibration procedure but since I am not an English native speaker I am not sure what every step exactly means:

Gently discharge the battery pack until it cuts off the first time (this is around 12V).
So this means I should run the motors until solo will stop motors by itself due to 0% battery, is that correct?

Charge the pack completely and leave it on the charger for 48 hours. The pack will relax, then do a balance cycle, then top off.

What does "do a balance cycle, then top off" means exactly? I don't get it.

Any help would be appreciated.

Cheers from Germany
 
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You'll want to use a light bulb or other resistive load connected to the battery terminals while monitoring the voltage.

As to your other question, please do a little reading on batteries and battery chemistry. It will be quite enlightening, I think.
 
The pack will relax, then do a balance cycle, then top off.

What does "do a balance cycle, then top off" means exactly? I don't get it.

Any help would be appreciated.

Cheers from Germany

The battery pack will do these things automatically. You only have to wait.
 
Is the purpose of the battery calibration just to get the percentage reading to be accurate or are there other reasons? My Solo seems to start beeping when the gets down to ~30% charge but the voltage is still quite high. It sounds like this is the way to fix that?

I am trying to drain the battery per this video but my battery is at 15v and 8% so I guess it will take a while.

Also looking at 3DR Solo - Smart Battery Calibration — Copter documentation and not sure what counts as "Gently". Any idea what the max recommended current draw is?
 
Is the purpose of the battery calibration just to get the percentage reading to be accurate or are there other reasons? My Solo seems to start beeping when the gets down to ~30% charge but the voltage is still quite high. It sounds like this is the way to fix that?

I am trying to drain the battery per this video but my battery is at 15v and 8% so I guess it will take a while.

Also looking at 3DR Solo - Smart Battery Calibration — Copter documentation and not sure what counts as "Gently". Any idea what the max recommended current draw is?
Don't bother calibrating an old Solo battery. It WILL NOT fix your battery. This is happening because you have a cell that has gone bad. If you keep flying on this pack it will eventually die without warning and fall from the sky. The Solo batteries were all made in 2015 and are well beyond their shelf life.

That being said, here's how to calibrate a Solo battery successfully. I do lots of these when replacing the cells. Use a hobby charger if you have one that discharges. It can be done by running the motors but that is far from optimal. To calibrate the BMS to the pack you need to drain it at 1A or less and stop when it is 3.5V per cell (14V). Then let it rest 30 minutes and immediately charge it to full. I usually charge at 1A also. If it doesn't report 5200 mAh capacity after calibration you'll have to repeat it until it does. Charging it with the Solo charger makes it less likely to read 5200 the first time because it charges at 3.3A. You can read the capacity in the parameter BATT_CAPACITY using Solex in the Vehicle Settings/Params.

If you want to replace the cells yourself follow this detailed tutorial. Solo Battery Mod for Dummies (Rev).pdf

If you want it done for you go here. 3DR Solo Battery Mod
 
Sorry, I should have clarified. I have a new battery Amazon.com

I don't have a hobby charger. I guess I could get one. How often will I want to be draining the battery? Maybe worth it so I can charge at a slower rate as well?

It seems like others say you should discharge down to 12V but 14V is enough? Is it a problem to go lower that?

Thanks for the quick response!
 
Sorry, I should have clarified. I have a new battery Amazon.com

I don't have a hobby charger. I guess I could get one. How often will I want to be draining the battery? Maybe worth it so I can charge at a slower rate as well?

It seems like others say you should discharge down to 12V but 14V is enough? Is it a problem to go lower that?

Thanks for the quick response!
Oh I see. You are doing a battery mod. When we first started calibrating using the "official" procedure it stated 12V so we used that number in the tutorial. Since then we have done many many of them and have found that draining it to 14V is enough if you drain and charge slowly. Draining a Lipo battery below 3.5V per cell will cause some damage to the cells and will affect some cells more than others due to slight inconsistencies between one cell and another. It might be minimal damage but damage nonetheless. 3.5V is safe for the cells and works fine even if it takes more than one attempt.

You shouldn't have to calibrate it again for years if the battery is not abused. Hard to justify the new charger for one time use, I know, but if you have more than one battery you will need to calibrate them all and you will thank me for suggesting a charger.

Also you will need the charger if you decide to go with the other battery option which is to get a BMSOne and connect any battery you want. There is no calibration involved with a BMSOne. If you haven't seen it, read about it here. BMSOne V2 Plug and Play
 
Ok, I went through the process without a new charger/discharger. I just used the props on high to drain it and the stock 3dr charger.
Drained to 13.95V or so. The battery now reads ~3800mah. I may break down and buy a charger. Someone recommended this on Amazon.com

Or I may just try again. Would draining the batteries a bit lower increase the odds of it working? Maybe 13.5v?
 
Yes that increases the chance of making the mAh go up but what would help more is discharging slower. 1A or less is best. The motors on high draw more than that. Just the Solo and gimbal/GoPro sitting powered on is closer to 1A. Drawing and charging slow helps the most. Draining it lower will reduce the life of the battery. It’s better to calibrate 2 or 3 times than it is to drain below 3.5v per cell. Each attempt will get it closer to 5200.
 

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