Hello all. I had a unusual event today. I have two 6s batteries connected in parallel on my quad. They are both 16000 mah batteries rated at 15c. After the flight I let them rest and then put them on my charger. When the charge was complete i was astounded with the results. The batteries were disporportunately discharged during the flight. One battery took 8000 mah and the other took 15000 mah to charge them back up. I have not experienced this before. Can anyone explain this and give me an idea how to correct this problem?Thanks in advanceWill
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probably your charger had a bad day counting the amps... i would try again. If this occurs regularly it can only be explained by
1. A difference in capacity of one battery -> the 8000mah one has lost 8000mah in capacity
2. A difference in resistance within the battery -> The battery with higer resistance drains more slowly
3. A difference in resistance in the power lines connecting the batterys... probably one of your plugs is almost burnt away from the connection sparks and has therefore much higher resistance ?
Best regards
Seb
William Cox > Sebastian UngerlandMarch 26, 2015 at 12:57am
Thanks for the reply Sebastian,
I hope the charger had a bad day. I use anti spark plugs for the very reason of reducing spark when connecting the batteries. I am trying to come up with a reliable way of logging power consumption of the batteries and I do not trust mission planner. The connections between both batteries are consistanT in size and length. upon inspection the plugs look to be in good condition. This is the first time that I have had this problem and I am concerned with damaging one of the batteries. Do you have a reliable solution to measure mah usage? I have considered getting balance port meters but was not sure if they would be reliable enough.
I always use these little lipo warners. They dont give me the drawn mah´s, but much more important the prevent me from discharging single cells too low and warn me when cell voltage drops because of full throttle accelerations. Why dont you try each battery seperately ? If one gives you a significantly shorter flying time and then takes only 8000mahs on recharging.. it´s done. You should ALWAYS monitor the cell voltages in flight, because from my experiences some cells sometimes discharge faster and you will destroy them if you dont stop using the battery at the point where one cell gets below 3.0 volts.
Happy testing
Seb
William Cox > Sebastian UngerlandApril 3, 2015 at 3:17pm
Well I found the problem to be that the charger stopped mid charge. I restarted the charger and it finished within a couple mah of the other one. It doesn't give me warm and fuzzies for it to do this.
some chargers hav a mAh limit....which annoyingly in the case of my multiplex charger can't be changed.....it assumes a limit based on the current set, and assumes you are charging at 1c.
Check for a capacity limit maybe.
I also use batteries in parallel and try to keep the batteries in pairs always using the same batteries together. There is normally some difference though, particularly on my older batteries.
William Cox > Stuart BrookesApril 4, 2015 at 7:16am
In my case (I don't have a clue, lol) I have a four station battery charger. I plug one battery in to one port. I guess everything is entitled to an error or two.
At this point with these batteries it is a moot point. if you follow one of my other discussions this heavy quad crashed. I'm going through each piece to see which is salvageable and what I need to start over with. The batteries are definitely toast. Each of them have a nice arc to them. And a puncture or two.
Replies
Hi Will,
probably your charger had a bad day counting the amps... i would try again. If this occurs regularly it can only be explained by
1. A difference in capacity of one battery -> the 8000mah one has lost 8000mah in capacity
2. A difference in resistance within the battery -> The battery with higer resistance drains more slowly
3. A difference in resistance in the power lines connecting the batterys... probably one of your plugs is almost burnt away from the connection sparks and has therefore much higher resistance ?
Best regards
Seb
I hope the charger had a bad day. I use anti spark plugs for the very reason of reducing spark when connecting the batteries. I am trying to come up with a reliable way of logging power consumption of the batteries and I do not trust mission planner. The connections between both batteries are consistanT in size and length. upon inspection the plugs look to be in good condition. This is the first time that I have had this problem and I am concerned with damaging one of the batteries. Do you have a reliable solution to measure mah usage? I have considered getting balance port meters but was not sure if they would be reliable enough.
Will
Hi,
I always use these little lipo warners. They dont give me the drawn mah´s, but much more important the prevent me from discharging single cells too low and warn me when cell voltage drops because of full throttle accelerations. Why dont you try each battery seperately ? If one gives you a significantly shorter flying time and then takes only 8000mahs on recharging.. it´s done. You should ALWAYS monitor the cell voltages in flight, because from my experiences some cells sometimes discharge faster and you will destroy them if you dont stop using the battery at the point where one cell gets below 3.0 volts.
Happy testing
Seb
Thanks for the hell anyway.
Will
some chargers hav a mAh limit....which annoyingly in the case of my multiplex charger can't be changed.....it assumes a limit based on the current set, and assumes you are charging at 1c.
Check for a capacity limit maybe.
I also use batteries in parallel and try to keep the batteries in pairs always using the same batteries together. There is normally some difference though, particularly on my older batteries.
At this point with these batteries it is a moot point. if you follow one of my other discussions this heavy quad crashed. I'm going through each piece to see which is salvageable and what I need to start over with. The batteries are definitely toast. Each of them have a nice arc to them. And a puncture or two.
Will
ah sorry to hear that