How many charges are the battery for the Mavic good for?

Thanks,

200 according to what I've read here.

Although 200 is an approximate stated figure, it really comes down to how you treat the batteries. Excessive heat and/or cold may shorten their life as can a crash even if there is no external evidence of the crash. Continually flattening the batteries will also shorten their life.
If you use a battery just make sure that if it is left  between 40% to 60% which is the storage level. If it is a bit higher than that it won't matter for the short term but don't leave them sitting around with a low charge.

my experience with tb48 is that the full charge capacity drops about 40mah every recharge. If this trend continues I am sure you will a useful life of 200 charges. When the capacity drops to less than 60%, your battery is carrying dead weight and your flight time drops to probably half.

This is a good summary of Lithium batteries and their life.

http://batteryuniversity.com/lea ... ium_based_batteries

When I went to drone school our instructor said that Li batteries generally last ~300 cycles when used in quadcopters. Not sure if this applies to DJI ones too.