Most Samsung camcorders made since 2008 including the HMX10C, HMX20C and the HMX-H100 series do not work with 3rd party batteries. The original Samsung battery (IA-BP85ST) contains a patented Samsung chip which not only authenticates the battery to the camcorder but also prevents the use of 3rd party chargers.
While Samsung would needless say this is to protect us from potentially dangerous fakes rather than to protect their revenue, the big issue here is that there are literally thousands of IA-BP85ST "replacement" or "compatible" batteries for sale on eBay which claim full 100% compatibility with the original but which are absolutley no use in any of the above camcorders, and probably all future Samsung camcorders using this battery. Likewise there are hundreds of external chargers for this battery for sale on eBay which are useless - even with the original battery.
I bought several batteries and two chargers all on eBay, each from a different source and all guaranteed to be "100% compatible". It is little comfort when the guarantee just means that you get a refund less the cost of international return postage and packing when you find they do not work.
Specifically, there are two issues which are widely documented.
Firstly trying to power up from a non-original battery, the camcorder will display the message "Check the authenticity of the battery" then automatically power down. It is not possible to operate any controls or access the menu, or keep the camcorder switched on. There is no known workaround. Third party batteries cannot be used with these models.
Secondly, even if the original Samsung battery is charged with a 3rd party charger, the camcorder will not accept that it has been charged and power down with a "low battery" warning displayed. These chargers do actually charge the batteries (as can be measured by a voltmeter across the outer two contacts) but they do not communicate with the chip inside the battery to change its charge status. Third party chargers usually only have two pins, while the battery has three contacts.
There must be hundreds of these sold everyday on eBay to unsuspecting buyers. I have reported back to each of my sellers but they continue selling these as being 100% compatible. I suspect many buyers do not bother to return their incompatible batteries because of the cost and effort of doing so. Elsewhere on the web many 3rd-party battery sellers are starting to list the above camcorders as not been compatible with their own IA-BP85ST replacement batteries. I hope that eBay sellers will eventually follow suit.
I wrote a previous eBay guide documenting these issues but it was removed after two days probably due to pressure from these unscrupulous big eBay sellers.
I repeat that the sellers' guarantee of compatibility is only a refund of the purchase price less international postage. You will still waste time and lose money.
For now, owners of these Samsung camcorders will have to stick to original Samsung batteries and either in-camcorder charging or to using a genuine Samsung external charger.