Canon BP-511 & BP-511A not holding charge very long

[Mazmania]

I have five Canon BP-511 and BP-511A batteries for my Canon D50 camera and they are not holding a charge for any significant length of time.  Is there a way to determine how many cycles a battery has already used and whether or not they can be trusted on a paying gig?  Or, is there a separate power source I could carry that can connect to the camera and power it without depending on the batteries that are presently failing for me?

[aoresteen]

I always use a battery grip that hold two batteries.  And I carry two spares.  If one fails, the other one will keep going.  I number all my batteries so if I suspect trouble I note it's number and deal with it later.  When a battery starts to swell it's time to dispose of it. The OP stated that his camera is a "D50" I think he means a "50D".  The Canon grip for the 50D is BP-E2N. I keep 6 batteries per my digital camera bodies in rotation.  Two in the camera, two for spares, and two back in the room charging.  I find 3rd party dual battery chargers work well.

A side note,  My first digital camera was an Olympus C-5060 that I bought in 2003.  I am still using it & the two original Olympus batteries for it.  They still hold a charge.  A number of other Olympus & 3rd party batteries for the C-5060/C7070 bit the dust, these two are still going strong.

[Mazmania]

Thanks.  I wound up getting two Wasabi batteries and a charger and I will use those as my primary batteries and my Canon batteries as backups just in case.