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Battery charging problem

mamba1242

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Hi Guys,

Does anybody know, Why suddenly my charger charges battery 1.5 hour. Battery is 4s 1300mah. All cells have 4.20v after an hour of charging and capacity reaches above 1300 on charger. Last half hour it charges with 0.1A. On the end amps on charger shows aprox 1450 mah even that the battery is 1300 mah. That start happening now, battery is 5 days old and I used it about 10 times.

Thanks
 

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It is in the balancing phase of the charge and that is why the current is so low, it could be that there is a weak cell that will not finish getting to proper voltage. It is possible that the charger puts in more than the rated Mah if the battery is over-discharged, and the chargers are usually not super accurate anyway, but I would let the battery rest for a day and check to see if a cell is losing voltage on its own.
 
Thanks for answer. I dont have voltage indicator on my drone, so probably it would be better to fly on timer right? Because now I waited till the drone lost power on throttle and then stop flying. Also if cell is bad is it ok to charge with new batteries on parallel board?
 
You really want to get a voltmeter, you need one in this hobby for various things, like troubleshooting and checking batteries. There are really inexpensive ones that will do the job like this one if you have a Harbor Freight (or something similar).


Yes you should fly by timer and adjust it up or down until the quad lands with no less than 3.2 volts per cell (preferably 3.4 or higher after resting). As you get better you will fly faster and use the battery quicker, so you will want to reduce the timer as you get better.

I would not charge that battery with others until you have flown it a few times and it seems to be ok, a bad battery can cause good batteries to be damaged.
 
Thanks for advice. I have voltmeter at home, I meant that I don't have it on my plane so I could watch battery status trough goggles. I will leave to rest battery full battery for few days and then meassure the voltage. Thanks again
 
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@mamba1242,

After re-evaluating everything you've said I have new conclusions...

The reason it took so long to charge was simply because it was run until the quad dropped, so that will severely over deplete the battery and it will take a lot longer to charge at a 1C charge rate.

Having flown the battery to likely less than 3 volts per cell, some amount of damage was done to the battery since it is never a good thing to let a LiPo fall to less than 3 volts per cell.

I have many batteries that have been over discharged and I think you will find that it still works fine and is likely safe to charge with others in parallel.

Try not to leave a LiPo battery fully charged for more than a day or 2 before flying or discharging it down to less than 4.0 volts per cell (ideally down to 3.9 or so).

Make sure you charge your used packs back up to the storage level and let them balance (3.7-3.9 volts per cell), this will help keep the battery from over self discharging to an unhealthy level, and it will make charging them for your next flight much quicker than charging a completely drained battery (which should never be resting below about 3.2 volts which is considered over discharged).

I hope this all makes sense.
 
Thanks. It makes sense. I have figured out that if I will fly for 5 minutes exact, battery still have 3.7V per cell, so that should be fine. On storage charging I have only 1Amp maximum option, so it will take lot of time for 4 batteries in parallel to reach storage voltage. What is the point that the maxium amp option is so low on storage charging?
 
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If you rest at 3.7v per cell I would up my timer by 15 seconds at a time until they came in and rested at 3.4-3.5, you are leaving a bit of flight time on the table and most would want to get that extra flight time out of each battery.

It makes no sense at all that Storage mode only allows 1 amp max charge rate. What charger is this exactly? It should have the exact same current options for both balance charging and storage charging, unless it is actually discharging to get to storage level since all chargers are limited in how much current they can absorb during the discharge function. Once I know exactly the make and model of the charger I can look into that for you to see if I can see what might be going on.
 
It is Sigma EQ eco. I have attaced the picture. It is pretty old charger, I think I have it about 8 years now. I checked and discarge current is also 1amp max. But I connected the battery with 3.7v on cell and it was charged in storage mode up to 3.8v. You think that charger have options on storage mode to charge or discharge battery to 3.8V depending how full is it when I connect it? That would make sense that 1A is max then.
 

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Hmmm... the charger manual seems to show a Storage charge setting with 2 amps leading me to believe that during a Storage mode operation where the battery needs charged instead of discharged that it should go higher than 1 amp.

1588013284626.png
 
Thanks for answer. I dont have voltage indicator on my drone, so probably it would be better to fly on timer right? Because now I waited till the drone lost power on throttle and then stop flying. Also if cell is bad is it ok to charge with new batteries on parallel board?
I ruined one of my batteries recently from over-discharging it, so lately I've been stopping at the first sign of power reduction, which is around 3.8 volts. So I just stop there, with 5 total batteries to use in a session I can get around 25 minutes (or more) in flight time. I'm planning on getting a few more batteries, so I can use 8 in a session.

I just got a little voltage alarm, which I've set to 3.6 volts, which I'll use soon. It's this one:

Either method might help you to prevent over-discharging your batteries.
 

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