The Cessna 120-140 Association Forum

Hi all,
I am looking to buy a Cessna 140 and the seller replaced the initial battery with an Odyssey battery in 2020 with a simple battery installation entry in the log. It changed the weight of the battery by 10 lbs and there is no 337 documentation.
I am wondering whether this should be considered as a major modification and if a new weight and balance calculation should have been performed.
The seller claims this is authorized by AC 43.13-2B. Does someone have experienced this type of battery modification?
I saw a 337 form in the ressources section which is what I was expecting to see for this aircraft as well, but maybe am I missing a step here?
Thanks in advance for your help/advice,
Best,
Mathilde

My IA did the same thing. You use the PMA version of the Odyssey battery and make reference to a previous version of the AC, AC43.13-2A Chapter 10 Paragraph 186, which specifically describes using wooden spacers in the battery box.

Make sure your spacers prohibit the battery terminals from contacting the cover of the battery box should you hit an "air pocket".

Yes, you must calculate a new empty weight and CG. A 337 is not required. Some folks confuse changing the actual weight and/or CG with changing the certificated allowable gross weight and/or CG, which would be a major modification.

Just for entertainment....

I looked in our operating manual to find that the original batteries were a "R24L", which I think translates to the Reading R24L battery.

Is the Reading a 24amp/hr battery? If so, then with the Odyssey SBS J-16 Dry Cell Aviation battery being a Reserve Capacity: 25 minutes @25amps, seems it's an equivilant to the original battery.

FWIW my IA just did a logbook entry and was done with it...