I didn't realize that my post had gotten replies. Thank you and sorry for the delay in responding.
I think the batteries for the G2 are larger, at least is seems that way from the images and prices on the Recharge site. the Recharge site price is also $799 for the G2 and $399 for the G1.
The battery for the G1 is listed 2 different ways. In the manual is it listed as a 12V 55ah and on line in the parts sections it is pictured with 12V 38ah on the battery. Unfortunately it doesn't list the dimensions so I would need to take it all apart to measure the batteries. I have been researching online today again for possible replacements. From your reply I take it that one can replace the batteries with higher amp hours. I didn't realize that. That changes the possibilities for the better. I don't know what is actually in the mower (38ah or 55ah) since I haven't dismantled it yet and am waiting for the mowing season to be over. This year and last, I managed by using it 15 minutes at a time and recharging. When the mowing season is over I will take it apart so that I can measure the batteries. I've attached images supporting the battery information that I have from the Recharge site and the G1 manual (first time doing this, so hope I did it correctly). The thumbnails are showing the images as being the same in the preview, but they are actually 2 different images when you click on them.
I also just learned today what the terminals on my batteries are called, i.e., insert terminals, which according the images on the site are the same on both models.
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View attachment 27327
I'd also like to find a source for replacing the blades. But again there are no specifics about the blades except for the photo. The G1 blades cost less, and I know that the G2 is a bigger mower so most likely the blades are not the same size.
So onward with the problem solving.
Thanks for your input.