Where do I find the battery level indicator

You can use a circuit in which led levels indicate the charge.The ckt diagram is attached. LED dot display based Battery charge level indicator circuit diagram...

When charging, the battery indicator will cycle from the current battery level to full. Once the battery is fully charged, the indicator will stop cycling.

Typically it takes approx. 6 hours to charge the battery from empty to full. (MMP8565 2GB Digital Audio Player)

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please read and execute the commentaries. God bless you
Charging Conventions

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  The majority of laptops will display a solid green, blue or purple battery light to indicate that the battery is fully charged. Most manufacturers indicate that a laptop is in the process of charging by displaying a solid or blinking green, orange, blue or purple light. If your battery indicator light is green, blue or purple, the battery is probably functional, regardless of whether the light is blinking. If the light is solid orange, the laptop is probably in the process of charging.
  
  

Battery Error Coneventions

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  Many battery manufacturers use rapidly blinking lights to indicate that a battery's charge level is low. In general, a laptop will rapidly blink orange or red when its charge drops below a certain level until the computer is plugged into a power outlet and charged. If your laptop's battery indicator continues to blink rapidly in orange or red or if it remains red even when it is plugged into the charger, it indicates a problem with your battery or the charger.
  
  

Red, Yellow, Green are the battery level indicators, Red being the lowest like a fuel gauge. If the green comes on right away after plugging in the charger then it must not indicate the charge cycle. If its a 3Ah battery whats the charger output amperage? Then you could just do the math to figure out how long it would take to charge that battery to full with the output. Otherwise it shouldn't hurt it to leave it plugged in overnight or at least a few hours to charge it.

Hello
Every phone has their own way to show the charging, Normally the running dots/line in the battery will show charging and stop this action will be the indicator of full charging.
Some phones shows the level of battery with colors, like red for empty and green for full Hope this helps if so do rate the solution

Sounds like your alternator isn't charging your battery.

How do you know it's fully charged? Is there a battery level indicator?

I don't know how to solve your problem but, the three lights mean this:
Red LED light indicates the battery is being charged
Green LED light indicates that the battery is fully charged
Amber LED light incidates that the battery power level is low - the battery needs recharge.
Do not recharge you battery over 24 hours.

From the manual:

"Attach the barrel tip of the AC Charging Adapter to the AC Charging port of the POWER TO GO® and plug the standard two-prong plug into an appropriate, functioning 120 volt AC outlet. The red Battery Status LED indicator will flash, indicating a proper connection has been made and the unit is charging. The green Battery Status LED indicators will gradually light as the charge level rises. The POWER TO GO® must be charged for approximately 11-17 hours prior to first use. All Battery Status LED indicators will be lit solid (the red indicator will stop flashing) when the unit is fully charged.

When batteries are placed into the charge mode, the red light will come on.
When fully charged, on those units with a green light, the green light will be an indication that your batteries are charged and if your unit has no green light, the fully charged indication will be when the red light turns iff.