At what (max) rate LiPo batteries in consumer electronics are charged (for example in cell phones). I mean that LiPo-s are dangerous when overcharged, so what is the best charge rate to be absolutely sure that battery will not set on fire. I presume this will be much less than 1C, because my phone has 1750mAh battery and its wall wart is rated only 1000mA (though I doubt a cell phone draws max. current, this would be bad design I think).
It of course varies from chemistry to chemistry.
But also from manufacturing procedure to the next.
A good manufacturer of batteries knows what they are doing and can give you very detailed specifications for allowable maximum rating, advised rating and absolute peak rating. For LiPo there are many cheap manufacturers that get relabelled and resold and then, well, you can't be sure and you might be best off to stick to 0.5C, because a cheap manufacturing process in the Lithium trade can create unequal surfaces and high currents may then cause very annoying aberrations on the "plates" of the cell. Which is bad for its life span to the order of NO!
If it's a very doubtful cell I'd say don't even go over 0.25C.
But with increased experience and insights in how to make a good Lithium based cell, there are procedures that create cells that handle 5C charging with only a 10% decrease in usable life cycle, which in many products can be very desirable.
So, to TL;DR: If you know the battery's specification, because it comes from a reliable source and with a datasheet showing many charge and discharge graphs and such, you can go by whatever it says. If it doesn't, at least stick to below 1C, if possible to below 0.5C.
(Very good factories even include a graph that shows Charge and Discharge current effect on expected average cell life time in cycles)
for a standard lithium battery, i would say 80% of its mAh rating.
what is important is that they are not ever over charged. so a 3.7V cell must not be charged with a greater voltage of 4.15V/4.2V
some chargers pump higher than rated voltages into different batteries for short periods of time to decrease the charging time but i am against it. i'm also against charging batteries in series as each battery will not have the exact same level of charge and the the voltage across each battery will vary.