View Single Post
  #113  
Old 8th January 2008
Wreckdiver's Avatar
Wreckdiver Wreckdiver is offline
Senior Member
 
Join Date: Nov 2007
Location: From Liverpool, live in Chippenham, Wiltshire.
Posts: 1,765
Thanks: 94
Thanked 85 Times in 80 Posts
Likes: 119
Liked 130 Times in 72 Posts
Re: HLD-4 power grip

Quote:
Originally Posted by Ray Shotter View Post
PS - The state of charge of the batteries does not appear to be significant. I have just inserted into the HLD-4 a partially charged non-Olympus BLM-1 (which has been used in my E-510 over the Christmas period) with a fully charged Olympus BLM-1 and the E-3 is working perfectly.
Just some techy theory that may answer some questions.

The BLM-1 batteries, being Li-Ion, will maintain a constant voltage from fully charged right up to almost being discharged and then the voltage will drop off rapidly at the end of the charge. This is the nature of these batteries, so you get full performance of the camera right up to the last possible minute.

The reason why some fully charged batteries are showing a low level in the HLD-4 and yet fully charged in the camera lies in the HLD-4 itself. As there can be 2 batteries fitted they just cannot be wired internally together, if one battery had a higher charge than the other then the higher charged battery would discharge into the lower charged battery - which would cause heat build up and be potentially dangerous, even a fire or battery melt down. Therefore, diodes have to be inserted in series with each battery and these diodes could drop as much as 0.65volt. So the 7.2v output of the batteries could be as low as 6.6v. Therefore, because of my explanation above, the camera would see a voltage that would register as discharged. The difference between a fully charged battery and one that is at the "knee" of the discharge curve would be a fraction of a volt. I think this may be more applicable to 3xCR123A, but the theory remains the same.

This problem wouldn't have occured with the HLD-2 in the E-1 because it only had the one battery, hence no diode, no voltage drop and no loss of performance. Retaining the larger BLL-1 battery would, technically, be the better solution.

Right, lesson over - I hope you were taking notes

Steve
__________________
Old divers never die, they just go down on old wrecks
Take nothing but photographs, leave nothing but bubbles
My website
Reply With Quote