backup power pack - 24v, 4ah+

[myzter]

Im using lead acid batteries in my kids 24volt scooter, would building a backup pack with M1's or other lithium cells
@ 21+ VOLTS and 2+ AH allow :

10-15 min charge time, w/ultra portable AC charger / 1 mile range (flat surface)

The motor :
24v, 22amp rated

controller :
24 volt

basically, when the leads go dry, flip a switch and my kid could get back home/with the scooter.

 

[fechter]

I think you could do that. Charge time is a function of the charger and cell type. 15 min. might be pushing it.

Get more lithium batteries and ditch the lead completely

 

[tomv]

You actually don't need to build anything. Milwaukee V28 batteries give exactly the same voltage as charged 24v lead batteries. They are 3Ah, 84Wh. That should give a range of 4-8 miles. Standard charger will charge in 1 hour (or you can charge for 15 mins and have range of 1-2 miles), battery weight is 3lbs, warranty is 2000 charges or 5 years (that's 10 times better than the best lead acid batts).