(thanks to Chopper)
If you are using 6 or 12volt SLA (sealed lead acid) batteries(such as from Gruber), many have found that the Schumacher Automatic battery Companion (that's the name of the charger)works very well. It will fully charge your batteries, then will switch to float mode to keep them "topped off", but will not overcharge them like the stock PW's chargers will.
Also another alternative I found from Schumacher was this. If you are one of those with stock batteries, this would be an excellent alternative to the charger that came with your power wheels car.
If you are looking to charge multiple batteries at the same time, you may want to look into something with higher amperage, but hopefully someone with a little more experience can chime in on this one.
The average you could expect to recieve from a brand new 12 volt sealed lead acid battery, with a 50 pound kid on pavement, should be a little over an hour. Here comes the it depends part. If the battery is older, then not as long. If the kid is lighter/heaver, then longer/shorter respectively. If it's ridden in grass/uphill/rough surface then shorter run times could be expected.
info thanks to GECKO
Lead Acid Scooter Battery Charging
How often should lead acid scooter batteries be charged?
To maximize battery life recharge batteries immediately after every use.
It is an old wives tale that you have to run your scooter batteries until fully discharged. the same goes for these types of batteries having a memory and can only be charged two hundred times.
FACT 12v lead acid batteries do not have memory so they are immune to memory effect ( this is a NiCd battery issue).
We will use your car battery as an example.
Scooter batteries are like miniature 12V car batteries.
For some reason your car will not start. You grind away at the starter until the battery will no longer operate the starter. You leave it for an hour and return to find the battery will now operate the starter.
Why will the battery turn the starter now? The battery has charged itself through chemical reaction .
What did we learn in science class?
Newton's Third Law
For every action, there is an equal and opposite reaction.
We did not introduce a charge to the car battery so it charged itself through chemical action. it is not fully charged, but it has regenerated it self enough to turn over the starter.
The reaction is deterioration of the battery's lead plates through oxidation.
When a charge is introduced to the battery using an alternator, generator or charger the degradation rate is much lower than allowing the battery to charge itself.
Speed, Distance, Torque... Pick any 2