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Second hand batteries

CaptainRisky

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I've just bought another MPP fly more set, minus the drone which is apparently now living with the fishes.

Very nice old gentleman, just about gave it to me. 2 batteries, controller, car and mains chargers, everything but the drone. Also a foam insert case and the original bag.

The batteries showed 3 solid lights when we pushed the button, and he said they were always storage charged, but when I got home and put them in my drone one shut down and the other started giving a low battery alarm. Both then only showed one light after that.

It was getting dark so I've charged them both fully, which seemed to go normally, and have left them on a table outside for the night. I guess in the morning I'll put them in the drone and see how many charges, how well balanced the cells are etc. I guess I could do a time hover test like I did on my new batteries, which gave a pretty consistent 19 min from full to low batt/30% alarm and see if they give around that.

They look as good as mine and there's absolutely no sign of swelling or anything. Are they likely to be buggered?
 

CaptainRisky

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storage charged batteries can act a bit weird, I think I had to charge and drain mine for a few times before they started functioning. I wouldn't risk actually flying with questionable batteries since you may get voltage drops and that could cause many bad things.

Yes I will monitor these a bit before I trust them too much.

I charged them right up and out them in the drone. According to the app they have 9 and 14 charges. The cells were balanced within 0.01v of each other so it's looking good so far. I'll do a hover test down to 30% and see how they go, and if that's all good I'll fly them within my property boundaries for a few flights.

I think they might be OK, but I'll be careful how much I trust them for a while.
 

FLDave

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Upload your hover flight log to AirData so you analyze battery usage/discharge data during the flight. Do this for all your fights.
 
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Mavicmagique

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Yes I will monitor these a bit before I trust them too much.

I charged them right up and out them in the drone. According to the app they have 9 and 14 charges. The cells were balanced within 0.01v of each other so it's looking good so far. I'll do a hover test down to 30% and see how they go, and if that's all good I'll fly them within my property boundaries for a few flights.

I think they might be OK, but I'll be careful how much I trust them for a while.
I usually test batteries by hovering for a bit, applying a decent amount of throttle and regularly monitoring voltages for huge drops. I guess ascending with 100% throttle and sport mode will use the most amount of power but I'm not entirely sure. that's what I do after checking my batteries but can't recommend it to others.
 

G Saunders

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The Mavic Pro batteries will show all or fewer lights if you hold the power button down for more than five seconds. That gives some indication of the life left in the battery. Your GO4 menu will let you look at the batteries in some detail while they're in the drone.

Your question got lots of good battery advice, but I didn't see where anybody advised about these features, and they may help you figure out your batteries...
 
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CaptainRisky

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It's all good it seems.

I've got the GO4 battery specs on one of the C1 buttons, as I like to have a look at how they're going. There's no sign of unequal cells. They're sitting there fully charged for a day, and I'll try to get a moment off work to hover test them today/tomorrow.
 

LaserMark

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A newbie here, and maybe this question has been asked before, but is there a good way to "exercise" the batteries (run down and charge up) without having to run the drone? I have 3 batteries and wanting to keep them in good shape when they are just sitting in the case. Not sure how to do that without flying, etc.
 
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