add in the charger.
Looking at numerous options. Was looking to go with
Limh batteries but locating a charger to charge a 4.8v 800mah battery and using same charger, not at same time, a 9v 1200ah battery pack.
Now looking at using LiFePO4 Batteries. Both packs are 9.6 volt but different mah ratings.
LOTS to consider and getting frustrated.
using
https://www.batteryspace.com/howtochooseanimhbatterypack.aspx
battery packs # 3021 and #3925. Charger # 3287. Thought about DIY??
Do you mean NiMH or a lithium chemistry? Since the voltage you mention is 4.8, I assume you mean NiMH.
One question that needs to be answered is what voltage and current do you need? What are your size limitations?
In terms of general advice, lithium polymer batteries (i.e., the ones most susceptible to fire) should probably be reserved for those applications where their light weight, high capacity, and high discharge rates are
all needed. I have the feeling that is not the situation here. So, I would not even consider them.
Of the safer lithium chemistries, LiFePO4 is common as are some other lithium ion versions. They are relatively safe, but but still subject to less spectacular loss.
NiMH are great batteries in my opinion. Their main disadvantage is limited discharge current compared to the lithium batteries. In exchange, you get safety. Some versions, such as Sanyo eneloop, give a very low self-discharge rate, which means good shelf life and less frequent charge cycles. That leads to longer life. For my model airplanes, I uses NiMH for everything (ignition and radios) except for propulsion. For propulsion, I use lithium polymer or the old NiCd's. LiFePO4 's are also being used by other modelers for propulsion.
Without full knowledge of your project, I would still recommend that you consider NiMH at 4.8V. If you need the higher voltage and current of lithium chemistry, then the LiFePO4 is a good choice.
John