Will 12v 12ah batteries fit in a Schwinn S-1000 Stealth?

12Ah batteries will definitely NOT fit in the stock battery tray and allow the foot deck to fasten down. You would need to put some type of spacer between the frame and the deck to raise it.

When my stock 10Ah batteries failed, I replaced them with (3) 17Ah. These are physically much larger than the 10Ah. However, you can lay (2) of the 17Ah on their side in the battery tray and still close the deck. You may have to trim one plastic support on the bottom side of the ABS plastic deck. You will have to mount the third 17Ah somehwere else and just run wires to it from the other batteries. I fastened mine to the backside of the seat tube with a couple U bolts and a nylon plate. You can mount it anywhere that's convenient, you can lay SLA's on their sides without problem. Just make sure it is fastened securely so it does NOT get loose or shift while you are riding.

If you want to wake-up that stealth, you could also fit (4) 9Ah batts in the tray. It's a snug fit, but it works. Then you'd have a 48V scooter. Very noticeable improvement in your performance. The stock 36V controller may work on 48V, or it may not. Worst case is that you buy a good aftermarket 48V controller ($40-$50). The motor should run fine on 48V. The caution is that this overvolting will put more stress on the gearbox, and draw a lot of WattHours from your pack unless you are frugal with the throttle most of the time.

If you want more range, stay with 36V and buy the biggest batteries you can stuff on that thing. If you want more of a hotrod, overvolt to 48V and if you use the little 9Ah's, the scooter will still look stock.

Hope this helped.

Harlow

Fitting the bigger batteries will pay off! The 7 amp batteries will wear out very quickly, don't expect much range with them, probably only 3 to 5 miles with your size and a few hills, at 10 to 15 mph. 15 to 17 ampere-hour batteries will give MUCH better life and distance! (Much more than DOUBLE)