Charger doesn't charge anymore

My Ryobi 18V One+ charger blinks green while it's charging. When the battery is fully charged, the LED goes to a solid green. However, one battery recently had a faulty cell. After several hours on the charger, the green and red LEDs both were blinking. That indicated that the battery failed late in the charging sequence. It didn't fail the initial testing by the charger. The other battery I charged that day charged fine.

The extended capacity batteries can take 12 hours to charge in my experience. The regular batteries take less time. The charge time will depend on the battery chemistry(The older NiCd batteries take longer to charge then the Lithium batteries.)

I hope this helps. Assuming you aren't dealing with a cold or hot battery or charging environment, if you have any suspicion about a faulty battery, replace it.

Cindy Wells
(Note: I have a 12V drill as well. Those batteries takes longer to charge for the same relative capacity than the 18V NiCd batteries.)

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.
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If both lights on the charger are flashing it is indicating you have a bad battery and the charger will not charge the battery. The charger has circuitry that tests the battery and if it 'thinks' the battery is defective it will not attempt to charge it. The only way to verify whether it's the battery or charger is to try charging your battery on another charger or try charging another battery on your charger. Most of the time it's a bad battery.

The pcb inside the battery has a microcontroller that monitor the charges and charge cycle. When the cell falls below a certain voltage, it will instruct the charger not to charge and will show with a red-green flashing light. If the battery has been tried 3 times in succession then the pcb will brick itself from the makita charger. So first replace the bad cells. There are 2 solutions at this moment: charge with a 3rd party lithium charger like the imax b6 or replace the pcb with a working one. check out my blog on http://mkbl1830.blogspot.com/

Battery is shot. Replacements are $75 - $100. If its new you have a 1 yr warranty.

If you put a battery on your charger and both red and green lights flash it is indicating that battery is defective. There may be a short in the battery or they just may be too old and worn out to charge anymore. If the charger is reading the battery as defective it will not charge the battery. The only fix is to buy new batteries.

• When the battery cartridge is inserted, the charging light color will change from green to red and charging will begin.
The charging light will remain lit steadily during charging.
• One red charging light indicates charged condition in 0 – 80% and two red ones indicates 80 – 100%.
• With finish of charge, the charging lights will change from two red ones to two green ones.
• The charging time is as follows:
Battery B9017A, BH1220, BH1420, BH9020A: approx. 20 minutes.
Battery B2417, BH1233, BH1433, BH2420, BH9033A: approx. 30 minutes.
Battery B2430, BH2433: approx. 60 minutes.

Hello,
Here's a copy from the owners manual:
■ Charging LED 
Red LED is on = Being charged 
Red LED is blinking = Charging error 
Green LED is on = Carging is complete


● If the charge indicator blinks as red, it indicates a battery charging error.
- The battery is not properly inserted
- The terminals of battery are dirty or damaged
If the battery is inserted properly and the charge indicator continues to blink, contact the
nearest Samsung Camera Service Center.


Another charging error is when the batteries are so depleted, they won't charge up to 100% anymore = red light doesn't go out and remains on for too long, means get a new battery.