E-scooter needs Help!!!

Well...if the new batteries are giving only a fraction of your former top speed, then I've got to wonder if you've actually got 48 volts going? Can you confirm this? For instance, do you have four 12 Volt batteries hooked up in series?

As far as the pros and cons of the different types of batteries goes I can only speak in generalities since I don't have much experience.

SLA's are probably the best bet for newbies. They are less expensive, if nothing else. Also you don't have to be an electrical engineer to charge them properly. Or to charge them 'well enough'. One downside to them is that they really don't last all that long. Deep discharging and recharging is not their strongpoint and they really should be viewed as an item that is 'consumed' as opposed to a component that might last the entire life of the vehicle.

The 'higher tech' batteries have some attractive pros. They'll pack more energy into a lighter package than lead/acid batts. There are a few, such as nickel/cadmium or nickel/manganese, that (I think) are not terribly pricey and that (I think) don't need to be treated as gingerly as some of the lithium types. But I do get the impression that they can be ruined quickly and easily if not charged just right.

And there are lithium-ion and lithium/phosphate type batteries. These clearly have the advantage of packing a lot of 'get-up-and-go' into a surprisingly light package. But the cells themselves plus the proper charging equipment quickly turns into a whole lot of money. And it seems that it's not hard at all to damage these batteries and that a flash fire is a common result of such damage.

I know of a guy who frequents another forum dedicated to electric vehicles. From his posts I can see that he puts a lot of effort into designing and building battery packs. He measures and reports results and such. He put things in a nutshell once. "If you want to plug it in and go to bed, then these are not the batteries for you". He was talking about either lithium ion or lithium phosphate. Can't remember which, but they seem to be pretty similar.

I've seen a video of a battery pack on a bike erupting into a flash fire. It's something to be avoided at any cost.

I kept up an electric bike for a few years. Ran it on SLAs. When it was at it's best, it was pretty good. But I had to put a lot of effort into keeping it, or getting it back to, at it's best.

I considered going to lithium-ion or lithium phosphate. But it seemed pretty clear to me that I didn't have the knowledge to do it without risking my wallet, a burnt down home or burns to myself. I chose not to do it without a good deal more knowledge.

So I went back to the internal combustion engine.

But to get back to the real point; it's probably not a good idea to try the high tech batteries without the knowledge to use them safely. I'd be inclined to recommend sticking with the SLAs. While they'll give you some headaches, it's the alternative most likely to work best for you.

Motorcycle batteries are designed to start engines. Lotta amps for a short time. Electric vechicle batteries are designed to put out less amps for a long time.

I suspect you have some worn out batteries.

If you want to have fun get a 48 volt, 15 AH Ping battery. Should have about a 30 mile range. Should cost about $600.

MikeB told you right, M/C batteries are not what you want no matter how cheap. 12ah SLAs are all over ebay for $24.95 including free shipping. If you don't want to invest in a high$$ battery go for the SLAs.

The cheap sla's that come with these chinese scooters are the weak point. Buy new and replace often is the best advice I can give.
Upgrading to a real battery will easily cost several times what a new scooter would run.