Another option is to make your own packs.
You will need a reasonable wattage soldering iron (100W) for the thick wires, heat shrink 6mm and 3mm i think, 12 AWG silicon wire and 20 AWG for flying charging lead.
Both my batteries went, one causing a bit of a crash due to high cell resistance.
So this is what i've done:
1) split open the drone battery pack.
2) remove old cells and the BMS board, recycle the board and cells. BMS board is only needed for the Yuneec charger which is a basic charger and I've replaced that as well.
3) Buy a 8000 mAh 15.2 4S lipo HV from amazon
Amazon.co.uk (£64.00)
4) strip the case off the new pack.
5) cut off balance plug with spare wire left on the plug for later use.
6) cut off main plug and bin it. **Important** I tend to cut then solder one wire at a time to reduce chances of wires touching and posible battery issues (fires) that may follow.
7) solder main wires and balance wires to the back of the connector in the drone battery housing. Ensure correct polarity. Heat shrink after soldering for insulation.
8) stick battery housing together, super glue or in my case insulation tape so i can get back in if needed!
9) strip down the Yuneec charger and desolder the battery connection.
10) throw the old Yuneec charger away
11) solder wires to the back of the charger plug to make flying leads with the 12 AWG wire for the main and 20 AWG for the balance. Heat shrink after soldering for insulation.
12) solder on the balance plug cut off the new pack to finish the balance flying lead. Heat shrink after soldering for insulation. shrink after soldering for insulation.
13) solder on XT60 plug to the main cables to finish these off. Heat shrink after soldering for insulation.
14) buy a good charger like one of these:
Amazon.co.uk (its up to you what charger you use, however I do a lot of lipo charging so I splashed out a bit on this one)
You really want cell balance, cell voltages and cell resistance display on the charger. Internal resistance is a really good indicator of failing cells. I would rather know when charging that the drone may fall out of the sky!
This charger has a USB port so I use this for charging the ST16.
A batt storage function is good and with the cells linked above you need a high voltage capability (normal 4S lipo's are 14.8v, the typhoon H Plus is 15.2V however it will run on 14.8v)
I'm lucky I do quite a bit of other remote control stuff, so had most of the bits.
However the big plus the charging / battery management / monitoring. Also you can change the cells when they die at reduced cost.
I'm slowly working on a 3D printed charging plug and battery case. I do have a 3rd battery with a 3D printed housing (14.8v pack) but the balance plug is on a flying lead and I want to incorporate that into the battery.
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