[weieva]

 how to chose a RC batteries？

[TheOtherCliff]

https://librepilot.atlassian.net/wiki/spaces/LPDOC/pages/96110366/LIPO+battery+info

Here is what I am familiar with:

hobbyking.com sells good batteries at a good price, but their customer support is sometimes very bad.  Stay away from the high voltage, the carbon, the nano-tech, graphene, etc.; the fancy ones.  Buy the regular Turnigy, Zippy, Multi-Star, Rhino.  At least those are the ones I have used.  Buy at least twice as much current as you need.  If you need 22 amps, then buy batteries that claim 44 amps (for instance 2200mah at 20C equals 2.2 times 20 equals 44).

If you buy batteries from eBay, I think it is best to buy a name brand.  I have had good luck buying Venom batteries from eBay.  I have had consistent bad luck buying cheap LiPos (and NiMh cells too) from eBay.

I am going to make a guess that most "in country" hobby shops (mail order and walk in) will sell you good batteries, but that they will be more expensive than needed.

Buy and use these LiPo alarms during flight.  Set them to 3.7V or 3.6V per cell.  You will probably find that they read about 3.8 or 3.7 after landing.  They watch individual cell voltage which is the best way by far.  On last flight of the day, set alarm so that you land at 3.8 for storage.
https://www.ebay.com/itm/RC-Lipo-Battery-Low-Voltage-Alarm-1S-8S-Buzzer-Indicator-Checker-Tester-LED/172595705357
https://www.ebay.com/sch/i.html?_from=R40&_nkw=8s+lipo+alarm&_sacat=0

Charge or discharge all your packs at the end of each day so that each cell is 3.8V.  Do not leave LiPos fully charged unless you are flying the very next day.  A friend refused to do this and always charged his LiPos fully.  Every 6 months he would come out to fly and new batteries would be worthless so he bought new batteries every 6 months and they were ruined the next time he wanted to fly.

When storing LiPos for months, store them in a sealed baggie (plastic bag) in your refrigerator, at 3.8 per cell.  They can last for years that way.

If you accidentally drain a LiPo dead, like fly till it drops, immediately charge it back up and it will still be usable.  Don't wait till you get home.  Every minute counts.  Leave it charged to 4.0 per cell for a week because it will slowly drop voltage for a few days and just charging to 3.8 may let it drop too low.  The drop is worse if it was very low voltage (like 2.5 or less) for a long time (hours).

[jdl]

I'd like to add a comment. Just to share my own expirience...

TheOtherCliff explained in details how to take care of, use and store the LiPo batteries if you want to use them for years. I completely agree with that. In fact, I use an old small fridge, dedicated solely to store my LiPos.

What my expirience differs here is that I favour and I've got best value for money from Hobbyking Graphenes, Nano-Techs and LiHVs (for multirotor use). Almost all my batteries for the last 3 years are such ones and still perform very well, no one has puffed or degraded noticeably. There were two or three occasions when I've received a bad battery (I remember for one Multistar 5200/3S/15C and one Nano-Tech 2250/3S/65C). Contacted Hobbyking and they immediately sent me replacements without having to pay extra shipping costs or to return the defective ones.

Worths to mention that I do not stress the batteries too much. Usually, when I land, they are only slightly warm. I beware to land with no less than 20% power left in batteries (approx. 3.7V rest voltage). 

I do fly 220 size mini quads and use 3S & 4S batteries in the range 1300mAh-2200mAh. Also few Graphenes 5200/3S/15C for long range flights.
I generally use 65/130C ones while the quad can fly well with even weak 20C batteries. It uses 7-10A in normal flight (on 4S) and 60-70A on full throttle for a few seconds. Not a powerful one.

I do not fly race-style. Mostly mild freestyle. This definitely contributes for the longer battery life

As for LiHV ones, I've read a lot of negative comments how quickly they degrade and puff. But they are lighter than corresponding capacity/current rating Nano-Techs and I like this.
I do only have 30-40 flights on my LiHV 1800mAh/4S/65C packs till now and have no complaints so far. But again, I do not stress them much. 

I do also like normal Multistars 10/20C. The perform well but only use them on a plane, well below their rated currents.

On the other hand, all batteries I've bought from ebay, Banggood, etc (cheaper no-names) died after 10-20 flights and didn't perform very well even when brand new.

Zippy Compacts were a big disappointment for me, I've bought two of them and both puffed after few weeks.

I have some positive expirience with Infinity branded ones from Banggood. But some time ago Banggood stopped shipping batteries to my country so I switched to HobbyKing as a primary battery source.