One of my lithium batteries wont charge and the fault sequence flashes on the charger,is it worth trying to fix it ? would rather not fork out for another battery

I took a similar battery apart and was surprised to discover a surprising amount of electronics inside. Clearly the modern lithium type of cordless tool battery is very different from the earlier ni-cad type.

The modern charger for lithium type batteries have electronics inside that qualify them as "intelligent". They can "see" inside the battery and will refuse to charge any battery it is not safe to charge, either because there is a danger to the charger or because there is a danger of fire or explosion of the battery.

Unless you are confident the charger has a fault it is best to believe it. It certainly isn't wise to attempt "jump starting" it due to the relatively large amount of current contained in such a battery.

There are dotted around the world, companies that will recondition cordless tool batteries much cheaper in many cases than the manufacturer's replacements.

battery. Time to decide if its worth fixing an 8 year old drill. Buy a new one with lithium ion battery

My 20V battery was stored completely discharged for over 8 months. After all that time I bet the battery was holding no charge whatsoever. When you plug a completely drained battery to a charger the charger will experience a big demand in current and will fault out, flashing red. So we need to put just a little bit of charge in the battery for the charger to start working. What I did is with the battery in charger unplug and plug the charger like 10 times. Every time you plug it in it will send voltage to the battery for a split of a second before the charger fails. Eventually the battery will get enough charge for the charger to start working.

This worked for me .. Put battery in charger , unplug and plug in charger repeatedly until it charges

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.

If the charge count on the batteries is under 300, Makita will replace them. Makita has a known defect in this battery that causes the battery to shut down before it is dead. So as of now they are exchanging ones with low use.

If they are truly defective and makita won't replace, you have to open them, find the dead cell or blown fuse, and replace. Search youtube makita battery for a video on repairing this battery. But once the red and green lights on the charger flash, the the battery can't be charged on a Makita charger -- it's been locked. So use a third party charger.

Lithium-Ion batteries require careful charging and temperature monitoring while in the charger. Ryobi's Charging station monitors many functions and shuts off when the battery has gone through a complete charge. This is indicated by a steady Green light. Once the Charge indicator is a steady green the charger stops charging. With any battery It will slowly discharge and I don’t think the Ryobi will maintain a battery that is never removed. For example, if after a complete charge cycle if the battery was left there for 2 years and then you went to use it, it would likely be completely discharged. However if the battery charger is unplugged then plugged back in a new charge sequence would start. I lose power at my house about every 6 months or so. Once power is restored a new cycle would start and the charging cycle begins again.
Hope this helps and have a great day.

If you are sure your charger is working properly then your one battery may be shot.. i even had a new battery quit charging and had to replace it. they do not come cheap.

Hi, Thanks for getting back to me. The yellow and blinking red indicate a defective cell. Since it has lithium cells and is that new any repair to it would be a waste of your time. Ryobi tools purchased in 2008 have a 2 year warranty. I am guessing you probably got it at a home depot and you should return it under the warranty. All new Ryobi tools have a three year warranty. Good Luck! and Thanks for using fixya!

For others with the same problem (flashing red light won't go off)...make sure you FIRMLY PUSH the battery down onto the charger and engage the latches. Simply resting the battery on the charger will not work.