I charge the barbie 12 volt jeep and get nothing. i also got two 6 volt batteries and wired them in series bypassing the original batteries but still nothing,are these fused?

if you want the same voltage but with increased capacity connect positive to positive and negative to negative on each successive battery ---connected in parallel
example 6 X 12 batteries each of 200 crank hours will be equal to 12 volts and 1200 crank hours ( good for mobile fridges , winches , battery hoists etc)
if you want to increase voltage in the bank then connect positive to negative for each successive battery ---connected in series
for example
with 6 X 12 batteries of 200 crank amps you will have 6 times the 12 volts which equals 72 volts and the current flow is increase from 200 crank amps to exceed the 1200 crank amps because of the electrical principles and formula I think it works out to be around 72 times the 200 crank amps ( I am sure that there are mathematicians out there that will adjust the sum to make it correct)
However I think that you get the idea
when charging batteries it is always positive to positive with the battery leads to the first battery in the bank and the difference is if in parallel the charger has to be big enough the charge at the accepted rate of the batteries ( 12 volts charge at 14.5 volts and around 20 amps an drop back as the batteries charge
when the batteries are in series it all changes and best talk with a good battery supplier as to how it is set up and if you need to change the charging circuit and equipment

nothing wrong with the ECM unless it has the voltage regulator as part of the system
indicates faulty wiring and faulty alternator
have a load test done on the battery
have an auto electrician do a full charging system check
charging voltage should be 14.5-14.8 volts DC
battery voltage should be 12-13.5 volts dropping to 11 volts when cranking the engine
make sure that the drive belt tension is correct and the belt is in good condition

i'm having the same problem. checked fuses and both are good. going through the wiring harness to look for shorts. have a bad feeling the micro controller died, that is the little plastic box with metal fins on it under the seat post behind the batteries ******* to the frame. i can bypass the micro-controller and connect one 12 volt battery directly to motor and runs full speed. somehow it is wired with 2 - 12 volt batteries in series to give 24 volts and them the processor cuts back down to 12 volts to run the motor. not sure why this is engineered this way? still working the problem. what sucks so far is that the micro controller is encased in resin so it is virtually non repairable.
* Update added.
Found these wiring harness for sale online scooter stores and on ebay. I replaced mine with some intermediate level adapting the harness to my model scooter and this includes some soldering and wire splicing changing power connector heads off old harnedd to new harness to fit bike. Works great.

the radio runs off of a seperate battery source, so that wouldn't have any effect on this, i would first of all check the battery and charger with a multimeter and make sure that they are showing the correct voltage, if its a 12v battery make sure that they are showing at least 12 volts, if its a 6v battery make sure that its showing at least 6v

One thing you need to check is all the grounds and the positive lead coming from the battery. Cut the insulation back at both ends and check for corrosion. If the wires green or dirty, i'd reccomend replacing the wire. Corrosion on battery wires on the terminals or on the alternator side, will keep the alternator from charging. Make sure the grounds aren't loose and aren't too corroded either. This may not be the problem, but its definitely a probable cause and wouldn't hurt to look. Just my two cents.

to increase amps your best bet is to get two deep cycle marine batteries with high cranking amps

You can get the replacement battery on link below.

http://www.walmart.com/ip/Fisher-Price-Power-Wheels-Long-Ride-12-Volt-Battery/882948

http://www.amazon.com/Fisher-Wheels-12-Volt-Rechargeable-Battery/dp/B00004TFT1

Good luck and please rate 4 thumbs for the free answer.

You shoulld expect more than 12.8 volts from the alternator up to nearly 14 volts when charging a low battery. The battery can only show the amount of voltage your alternator is sending to it after being used for a while. I would suggest that you have the battery tested & recharged completely, your voltage will be above 12 volts and if it returns to below that , you will know your alternator is not charging. Also, if you test the output of the alternator and see it is below 12 volts after the battery is fully charged at 12+ volts you will have confimed the problem also.

good luck.

It has a thermal fuse. Depress the gas pedal for 25 seconds and try it then

When you mean wired in series you mean you tied the positive from one battery to the negative of the other. That will put 12 volts into the system. Is it supposed to run on 12 volts or 6 volts? If it is only supposed to be 6 volts you should wire the batteries in series. Negative to negative to negative wire to load. Positive to positive to positive wire to Load. Hope this helps