Battery Replacement

[8341]

Does below have some bearing on this discussion, i believe there are two ways to go, PMA'd installation and a TSO with a 337 installation, as the exact Battery that Cessna used is no longer made.
Gene Manley Cessna 140A

What is a TSO?
An FAA Technical Standard Order (TSO) means the part is qualified to a Minimum Operational Performance Standard (MOPS) for specified materials, parts and appliances utilized on civil aircraft. A TSO authorized part qualifies as an airworthy component.
What is TSO-C173?
This particular TSO is for manufacturers of permanently installed rechargeable lead acid aircraft batteries and nickel-cadmium aircraft batteries.
What type of aircraft batteries does TSO-C173 apply to?
TSO-C173 applies to permanently installed batteries providing power for aircraft equipment including emergency and standby systems and electrical power to start aircraft engines or auxiliary power units.
Can a TSO authorized battery be installed on any aircraft?
The TSO battery can be installed on an aircraft only after showing that the airworthiness requirements (certification basis) of a specific aircraft model are met by the TSO battery. A separate FAA approval may be required to install the battery on an aircraft.
What is the difference between TSO authorization and PMA approval?
TSO authorization means the battery is qualified as an airworthy component and can be installed in any aircraft by showing that the requirements (certification basis) of the specific aircraft model are met by the TSO battery.

[VIP645]

Is there an STC for installing a battery on the firewall. I have seen a sealed battery installation on the RV series aircraft. I would like to get rid of the battery location behind the baggage compartment. I think at one time I saw information for installing the Cessna 150 battery box on the firewall.