If the battery charger light is red, does it mean it's not charging?

Sounds like a bad charger my friend..test suposly charged battery with a multimeter and you will find your answer...can also test charging unit with it too...GL

Battery is weak. Those lights are really useless...more a marketing gimmick. It almost sounds like it developed a memory...this happens when certain types of batteries are not fully discharged before being placed on the charger. Replace the battery and make sure to follow charging directions for that particular type of battery

That means the battery is bad, replace it

the trimmers switch may be faulty.

CHARGING THE BATTERY PACK
Battery packs for this tool are shipped in a low charge condition
to prevent possible problems. Therefore, you should
charge them until the green LED on the front of the charger
comes on.
NOTE: Batteries will not reach full charge the first time they
are charged. Allow several cycles (operation followed by
recharging) for them to become fully charged.
CHARGING A COOL BATTERY PACK
See Figure 3.
If battery pack is within normal temperature range, the red
LED on charger will come on.
NOTE: If the charger does not charge the battery pack
under normal circumstances, return both the battery pack and
charger to your nearest Ryobi Authorized Service Center for
electrical check.
n Charge the battery pack only with the charger provided.
n Make sure the power supply is normal household
voltage, 120 volts, 60 Hz, AC only.
n Connect the charger to the power supply.
n Place the battery pack in the charger aligning raised rib
on the battery pack with the groove in the charger.
n Press down on the battery pack to be sure contacts on
the battery pack engage properly with contacts in the
charger.
n Normally the red LED on charger will come on. This
indicates the charger is in fast charging mode.
n Red LED should remain on for approximately 1 hour
then the green LED will come on. Green LED on
indicates battery pack is fully charged and charger is
in maintenance charge mode.
NOTE: The green LED will remain on until the
battery pack is removed from the charger or charger is
disconnected from the power supply.
n If both yellow and green LEDs come on, this indicates
a deeply discharged or defective battery pack.
Allow the battery pack to remain in the charger for 15
to 30 minutes. When the battery pack reaches normal
voltage range, the red LED should come on. If the
red LED does not come on after 30 minutes, this may
indicate a defective battery pack and should be
replaced.
n After normal usage, a minimum of 1 hour of charging time
is required to fully recharge battery pack.
n The battery pack will become slightly warm to the
touch while charging. This is normal and does not
indicate a problem.
n Do not place the charger and battery pack in an area of
extreme heat or cold. They will work best at normal room
temperature.
NOTE: The charger and battery pack should be placed
in a location where the temperature is more than 50°F
but less than 100°F.
n When batteries become fully charged, unplug the
charger from power supply and remove the battery
pack.
Source(s):http://toolboyworld.com/eBay/Ryobi_P110/...

Could be either one, but the odds are its the charger. You can check both with a multimeter or try someplace like Battery's Plus to check them.

it might be that your battery need changing even though the machine is lightly used the battery might have aged prematurely.

Ryobi Trimmers unscrew halfway down the shaft (so it fits in the box). If this gets loose, the trimmer will stop working. Simply tighten the connection between the upper and lower half.

most recommend taking the battery off the charger and you don't have to unplug the charger all the time.

i always thoiught that when you light is green it is fully charges yellow is weak and red is dead
maybe you have it reversed check it again also make sure that (altho hard to do) the battery is in right

Does it not hold a charge, or will the charge not indicate "fast charge"? I had to apply a initial jump charge on the battery to get it up to 20 volts, then I put it in the Ryobi Charger, and it started charging it.