[Coco] OT: Battery chargers

[J.P. Samson]

On Oct. 15, 2011, at 11:56 AM, Tony Schountz wrote:

> ...So I thought I could put 1400 mAh NiMH cells in it and use my  
> PowerEX 9V "smart" charger (which puts out 11V at 200 mAh). When I  
> connect the battery to the charger it takes about 7 hours to fully  
> charge (charger light turns green), which is about what it should be  
> based upon its mAh output and the mAh of the batteries. However, if  
> I don't even use the camera, the cells deplete in about 2 weeks,  
> such that I need to recharge the pack.

My first guess is that you are not using 9V NiMH batteries with a low  
self-discharge rate, like these:

<http://www.mahaenergy.com/store/viewItem.asp?idProduct=433>

Standard (i.e. older) NiMH have a nasty habit of discharging over  
time.  I found that my older PowerEX 1.5V NiMH cells would be close to  
depleted after sitting around unused for one month after being fully  
charged.

Also, a 9V battery is a pretty small physical package for the given  
amount of voltage.  (Just think about the size taken up by six AA  
batteries which, in series, could also provide 9V.)  So I wouldn't  
expect 9V batteries to last very long before they are depleted of  
charge.

-- JP