Yes, You can buy exide batteries. The regular UPS batteries you can ask for. It is available in the same form factor, either 7ah or 9ah. 9ah is 20% costlier, but will give you a bit more backup time, but 7ah will do well.
As mentioned before, carefull remove the sticker and keep it somewhere. It is just two cross connected batteries in serial. Take a photo before disconnecting batteries. Plug in the new batteries by referring the photo. Put back the side stickers and you are all done. Make sure that you keep the sticker in clean place when you remove.
In case you mess up with stickers, the only cheapest option is to wind the batteries with insulation tape. It does not look good.
All the best! You can do it and it is not rocket science.
Also, found out that some battery shops do it for free if you buy batteries from them, at least in Bangalore. You can give a try for one of those shops.
I asked locally around here but 9Ah almost no one has stock. The one outlet that said they can get 9Ah is quoting 5K for 2 batteries (still need to get more details about brand and other specs). Isn’t this a bit excessive? I was hoping I’d get them for under 3K or something .
I was told 7Ah Exide Chloride is available but amps are a bit different. Again, pending precise details.
Would love to get thoughts on this situation. If you or others here know about any good sites to order from, would love to know as well.
I got myself 7AH batteries two years back. Not much of a difference considering the price premium you will be required to pay for 9AH.
Price should be between 900 - 1300 and not more for 7AH Exide Sealed Lead Acid.
An update: I got my batteries replaced today from a battery vendor in town. They were seeing this arrangement for the first time but well were bit more brave than me to take it apart. Got Exide 2 × 7Ah 12V as the replacement since 9Ah wasn’t available/priced high. Cost me Rs. 2200 in total.
BTW, here’s a YT video I found that shows how it’s connected together. Just need to remove the stickers like @saidu said:
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