Go Back   Steve's Digicams Forums > Digicam Help > Batteries or Power Packs

Reply
 
Thread Tools Search this Thread
Old Jun 19, 2005, 10:52 PM   #11
Senior Member
 
Alan T's Avatar
 
Join Date: Jun 2003
Location: Chester, UK
Posts: 2,980
Default

geriatric wrote:
Quote:
Batteries are all rated in ma/hr, that is it will pass this stated current for 1 hour...
No!

If you try to draw 2000mA from a 2000mAh battery it is unlikely that it'll last for an hour. The mAh rating will apply at a much lower discharge rate corresponding to typical use in consumer equipment. You'd need a pretty big &beefy digicam to contain wiring and contacts that would pass 2 Amps reliably.
Alan T is offline   Reply With Quote
Old Jun 20, 2005, 12:18 AM   #12
Senior Member
 
geriatric's Avatar
 
Join Date: May 2005
Posts: 326
Default

The ma/hr rating on all nicad and nimh batteries is stating what the battery is CAPABLE of delivering. 2000 ma for 1 hour, 1000 ma for 2 hours, 500 ma for 4 hours..Cameras draw a quite heavy current, that is why the batteries and camera warm up after prolonged use. Just as a little experiment , use a mains adaptor with the correct voltage but rated at 1000 ma`s. I bet most cameras will say "No way Jose" Or rig up a little test bed with a variable resistor, run it at different current flow.

PS I worked in Bridge St way back in 1949.


geriatric is offline   Reply With Quote
Old Jun 20, 2005, 12:32 AM   #13
Baz
Senior Member
 
Baz's Avatar
 
Join Date: Aug 2003
Posts: 219
Default

Thankyou Alan for the clarification. It is as I thought. I found it difficult
to accept geriatric's advice of ohms law assumptions, light bulbs etc for
one hour.

I have a collection of NiMh AA's + the Maha C204F & Lightning Pack 4000N
chargers. They have been satisfactory. Recently I got the Lacrosse BC-900.
It is excellent with features to charge/discharge/refresh or test for mah.

It sorts the good from the not so good cells. Results have been surprising.
A collection of 12 Powerex 2200mah cells, which I had considered good, gave
test results varing from 1750 to 2510mah !

The best cells are the 8 Sanyo 2500mah cells that I got from Ripvan100 with
the BC-900. These varied from 2570 to 2850mah on test !

I consider the results significant. I have kept my cells in sets of 4 as required
for my 602 camera. Each set is only as good as the weakest cell, and so
knowing the mah of each cell, one can sort the sets with similar capacities.

Did you get a BC-900 Alan? I recall you asking about it in the forum recently.
Or am I mistaken?

Regards,
Baz.
Baz is offline   Reply With Quote
Old Jun 20, 2005, 1:29 AM   #14
Senior Member
 
VTphotog's Avatar
 
Join Date: Mar 2005
Location: Extreme Northeastern Vermont, USA
Posts: 4,214
Default

Alan T wrote:
Quote:
geriatric wrote:
Quote:
Batteries are all rated in ma/hr, that is it will pass this stated current for 1 hour...
No!

If you try to draw 2000mA from a 2000mAh battery it is unlikely that it'll last for an hour. The mAh rating will apply at a much lower discharge rate corresponding to typical use in consumer equipment. You'd need a pretty big &beefy digicam to contain wiring and contacts that would pass 2 Amps reliably.
I ran a test with ammeter in series with one of my bench supplies. Camera is Minolta Dimage 7hi. With 6V external supply, current varied from about 600mA to over 1.6A. Didn't have a peak reading meter handy, so can only guess that peak startup current is in excess of 2A. The DC-DC converter in the camera will draw more current from battery, as it is only 4.8V. Digicams are rather heavy current users, though the newer models are improving in this respect.

brian
VTphotog is offline   Reply With Quote
Old Jun 20, 2005, 5:06 AM   #15
Senior Member
 
geriatric's Avatar
 
Join Date: May 2005
Posts: 326
Default

Hey Baz, I thought you understood ohms law. The worst case scenario is when you switch on the LCD look at it and zoom your lens. Thats when the current is heaviest. our new friend states that he estimates the peak current flow is in excess of 2000ma.I couldn`t agree more. The proof of the pudding is in the eating. Don`t theorize, check it out, set up your little test bed. Of course batteries will differ from maker too maker. I have just bought 4 1700 ma/h AA batteries costing £1.99, I don`t hold out much hope for them. But one never knows.
geriatric is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 6:22 AM.