you might want to look at Carbon Foam (special lead acid). These can be deep cycled without loss of capacity. Cost is likely higher than pure flooded lead acid but less than lithium. Advantage is same charging system, longer life, and deep discharges without damage. I'm assuming your scooter does not have regenerative braking (this charges batteries while creating braking forces). If you do, it would make a conversion to lithium harder.

 

Yes, the 12V batteries are wired in series, for a combined voltage of 24V

Was looking at this...24V Battery

You can use that , if you like throwing money away .... you only need a small 7s lithium ... since your scooter is 24v , the voltage match perfectly with 7s lithium ... look on ebay you'll find them with chargers ... if the battery weighs more than 1.5kg it's too big ....

You may want to keep your old lead acid on the scooter , all that weight low down stops it from tipping over .

 

You need to be very careful putting several lithium batteries in series. Internal resistances should be match between batteries in series or you are over exercising the lowest resistance battery. We found even with matched battery pairs, one is getting exercised more than the other.
The batteries will last longer when they are charged more frequently. The battery life is related to the amount the batteries are discharged. You should be able to get the battery application guide to see the relationship for the particular batteries you are interested in using.

Another battery technology you might want to look at that is lore cost competitive and you can use the same chargers is pure lead batteries. They approach lithium performance but are less expensive. They are still as heavy as the lead-acid batteries, however.

So many errors in that post I don't have time to deal with them all !!!

 

Have you thought that the other parts of the system may be tired you don't say how old the scooter is but looking at the picture it is not that young,
If any of the wiring connections are dirty for instance,or even if the motor commutator is burned, sticking brushes all things I would check first for a cheap fix.
I say this because you mention poor performance on grass and hills,
Is the scooter rated for a top speed? looking at it I would guess 4/6 mph so this is geared low for curb climbing and low 10% inclines.

The scooter is approximately 10yrs old. The brushes were checked recently and were good.
Top speed is about 5mph on level surface. The poor performance is primarily due to the hills that I climb. They can approach 40 deg. but of short duration, 100ft. I am stuck with these inclines due to the location of my house.

 

You can use that , if you like throwing money away .... you only need a small 7s lithium ... since your scooter is 24v , the voltage match perfectly with 7s lithium ... look on ebay you'll find them with chargers ... if the battery weighs more than 1.5kg it's too big ....

You may want to keep your old lead acid on the scooter , all that weight low down stops it from tipping over .

Not sure what you mean by "7s Lithium." Can you provide an ebay link to what you suggest. Thanks

This might be a good test batt to verify that the scooter can be run on 24V Lithium.

 

Not sure what you mean by "7s Lithium." Can you provide an ebay link to what you suggest. Thanks

This might be a good test batt to verify that the scooter can be run on 24V Lithium.

7s just means the battery has 7 (multiple) cells in series to get 24V ..... this is the sort of battery that would be OK , perhaps a too big , but then you'll have plenty of range.. .....
https://www.ebay.co.uk/itm/24V-8ah-...006095?hash=item3d8a85710f:g:wZMAAOSwpUVc1UXJ

 

....The poor performance is primarily due to the hills that I climb. They can approach 40 deg. but of short duration, 100ft. I am stuck with these inclines due to the location of my house.

This maybe due to the size of the electric motor , in which case lithium battery may not help ... but then again it may.