john d hamilton wrote:

I have a few 9v Ni-MH batteries 200mAh.

I have two chargers one with output at 9v of 10ma and the other a very old
one that says output is 7.2v (even though its designed to take two 9v
batteries) and whose output says it is 15ma x2.

Which would be the best to use on the 9v Ni-MH and what would be roughly be
the minimum charge time to ensure batteries are fully charged please?
thanks for advice.

The one that is designed to recharged NiMH batteries. The charger needs
to cease charging NiMH batteries when they reach full charge and then
not charge thereafter (i.e., no trickle charge to top-off the battery).
If a thermistor is not used to detect a full charge then a timer should
be built into the recharger to ensure the charger turns off (to no
longer continually try charging the battery).

NiMH should be charged at a very low rate. It is unclear if 15mA x2
means 15mA is used for each of 2 battery slots or if it gets split and
7.5mA is used for each battery. You didn't indicate if the both
chargers were expressly designed to recharge NiMH batteries or if they
might be for rechaging NiCad batteries.

http://www.powerstream.com/NiMH.htm
http://www.greenbatteries.com/bachfa.html
http://en.wikipedia.org/wiki/Nickel_...ydride_battery