Battery Maintenance

So I along with many others have been spending time working on the battery failures in the Makita 18v LXT range.  If you check out my other posts including;

http://makita18vmod.blogspot.com.au/   - Which is the repair and modification of the failed batteries

http://makitaradiomod.blogspot.com.au/ - Creating a Bluetooth Makita Radio

The Causes of Battery Failure (lithium Ion Type)

Every person you speak to has a different method or view on battery life and how to manage your batteries. Unfortunately most of these methods are for the older types of batteries (NiCd, NiHh or the standard lead acid car battery).  Some of these methods include flattening the battery before recharging and leaving them flat if you are not using them..

 These methods are FALSE!

Q: Am I giving the battery a memory by not fully discharging them?

A: Lithium batteries do not have memories and by fully discharging the batteries actually damages the cell packs. The packs consist of 5 x 18650 type 3.7 volt cells and they should preferably be discharged no lower than 15v (3 volts per cell) at worst case scenario. 

Q: Should I store my batteries flat or charged?

Lithium batteries have much lower self discharge capabilities than the older style batteries.  Self discharge is the loss of energy over time whilst now being used.  To keep the Lithium cells happy always if possible store them fully charged to avoid the cells dropping too low.

Q: Can I put a Battery that is only half flat onto a charger?

Yes! any chance you get to keep these batteries fully charged the better!  One cycle of a battery is defined as one complete discharge cycle so if you only half discharge a battery and charge it again it is not counted as one cycle but as a half.  so the next time you discharge it by a half its classed as one cycle.

 Other Factors

Temperature is another factor that affect Lithium Ion cell packs and by temperature i mean rapid discharge and charge causing internal heat not ambient temperature.  Most of the tools and the the chargers have methods to avoid this but avoid short circuiting the battery when using it in other non standard equipment.