Results using Battery Calibration Procedure

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Been able to do lots of tests with my Rigol Battery Analyzer while home from surgery.
After following the procedure and noting results after 48 hour charge I still find significant imbalance between cells.
I did find that applying a light load say 2 amps and drawing down to 15.5 volts followed by a normal charge helped get cells in better alignment with each other.
The discharge curve dramatically improved after this soft discharge followed by normal charge.
Additional testing ahead, about 8 batteries through cycle already.
Tim
 
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Found that testing can kill batteries! Several of mine had cells go bad running 10A load to 14.5 volts.
Better on bench than in air, these batteries only had less than 10 cycles and had preformed well for short flights.
I think the aging cells are the cause of unexpected voltage drops when flying.
 
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Are these you existing Solo batteries? If so, this is just what happens when the battery is shot. If they're a new battery you bought and modified for the Solo, then perhaps it's defective? A 10 amp load is nothing.
 
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Are these you existing Solo batteries? If so, this is just what happens when the battery is shot. If they're a new battery you bought and modified for the Solo, then perhaps it's defective? A 10 amp load is nothing.
Yes old Solo Batteries
Agree they are old and explains why suddenly a battery that may have looked OK at start of flight just suddenly fails. Lipos have gotten a lot better since these Solo batteries were manufactured. I seldom find bad cells in my RC plane batteries.
Tim
 
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Something many people don't understand about the battery's reporting abilities and design: The battery has a design capacity, which is 5200mah. But that is not actually referenced or considered when the Solo is determining the battery status.

The battery has a calculated full charge capacity, which varies over time, and is always something less than 5200mah. It could be 5000. It could 4629. Or it could be 600. This is what the battery considers to be fully charged. And this is what it will end up reporting to you as 100%. It's 100% of what it is presently capable of holding. That is the value reported to and stored in parameter BATT_CAPACITY.

So it's accurate, but it's not very informative. 100% of a 600mah full charge capacity is a completely destroyed battery. But will be reporting a "full charge" and ready for takeoff! It will take off, and probably crash in less than a minute. This is generally what happens when you see people about taking off and the battery tanking from full to 10% to nothing in a minute or two.

There is currently nothing in ArduPilot or in any of the apps that take this issue into account. The only way to know something is amiss before taking off is if you look at the BATT_CAPACITY parameter and notice it is something horribly low. And in flight, the only way you know is the sudden horrifying series of battery alarms, at which point it is often too late.

One of the things I've been working on for ArduCopter 3.7 is adding battery cell monitoring to the battery failsafes and arming checks. AP_BattMonitor: Add smart battery cell voltage minimum and diff monitoring by Pedals2Paddles · Pull Request #10025 · ArduPilot/ardupilot. The first sign of trouble with a crap battery is usually going to be 1 or more cells dropping way faster than the others. This would detect and report that well in advance of the battery's traditional total voltage and capacity failsafes.
 

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