Makita dc24sa charging problems

Yes, the DC24SA will charge any Makita battery between 7.2 and 24 volts that will properly fit the battery slot.

I have a 12v an 18v Dewalt I can charge them both from the same charger

It should tell you on the bottom on the charger what that means. But this means the battery is not taking its charge. Sorry bad battery.

The DC24SA will charge 9.6V to 24V Ni-MH slide style batteries (1.7Ah to 3.3Ah)

Sounds like the battery is no longer good

on my charger (DC18SC) alternating red and green dual flashes mean a defective battery.
http://ubermanuals.com/product/makita-dc18sc-8866 also same for the DC24SA

Your charger is malfunctioning. Return it to the point of sale and request warrenty.

try cleaning contacts on the battery and the charger then push batter in to charge, if the battey is old that will cause it not to charge. How old is the battery?

Dust getting in the charger is a problem, Try blowing it out with a moisture-free dust remover, found at most any store. Green flashing means improper power, due to dust or power from the outlet, try a differant wall outlet. Red flashing means the charger or battery is to hot and must cool down before it will charge. The charger will not charge a battery if the lights are flashing. Solid Red light means it is charging and solid green light means it is charged. Plug the charger in first before putting the battery on the charger. If the charger has been droped or hit the floor the coil inside could have broke loose and dammaged the charger requiring it to be replaced.

• 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.