Cons of using an infrequent use long range e-bike battery trailer using SLAs So I've recently purchased an ebike and started thinking about how I could go long distances without charging.

It occurred to me that whilst sealed lead acid batteries can't go through many cycles, for the odd long distance (~100 miles) some deep cycle ones could be perfect, especially if mounted within a trailer.

I have a 48v e-bike, so I'd need 4 SLAs in series. I'd probably only use this a few times a year so other than the discharge from using them they'ed always be topped off with charge.

Can anyone see any potential disadvantages of doing this? Perhaps SLA's are just too heavy and I wouldn't get the range I want?
Lead acid batteries are heavy. Too much extra mass, even in a trailer could to put strain on the motor and brakes. You'd have to figure out what the mass of  batteries you would need, and see if it would exceed the bike's maximum load specification.

Also, is it possible to run an eBike from an external DC power source?