So I bought these batteries a while ago:

12V DC Rechargeable Li-ion Battery for CCTV Cam 9800mAh
Capacity of battery: 9800mAh
Input voltage: 12.6V
Output voltage: 12.6-10.8V



12V DC USB 5V Rechargeable Li-ion Battery
DC input: 12.6V
DC output: DC12.5V~10.8V
Rated current: 1000ma
Capacity：3800mah
Gross weight: 355g


Now the thing is I get quite a bit of use out of the smaller 5V/12V batteries (3800mah), and running from the 12 volt it can power a HDV-Z96 LED light (96 LEDs/800Lx/7W/5.8-16.8V Input) for just under 2 hours at full power... not bad! I Velcro them to the back of the Z96... works like a charm!

The larger 12V (9800mAh) will run the same light for between 7 1/2-8 hours straight through on full power! (but it's heavy to carry around and I have to run a longer cord to where the battery is supported)

All in all for the price they work great and I'm happy with them... EXCEPT: They take FOREVER to charge with the supplied charger! The green light goes out on the 3800mah indicating a full capacity charge after about 8 hours charging (for 2 hours runtime) while the green light has NEVER gone out on the 9800mAh battery, not after 24 hours charging, nor 36 hours charging... so I don't really know when it hits its full charge... 24 hours seems to do it though. (for 8 hours runtime)

I'm thinking the charger it comes with is inadequate, and I would like to know if I could increase the output of the charger from 12.6V DC 350mAh t something higher to cut the charge times by at least half? What can be done?