Charge USB battery after each event?

[MannerTee]

I usually charge the USB batteries to full before I put them away between races. When there is a long time between races (6-8 weeks) I noticed some of the batteries loose charge and the LED lights yellow while others light green. Do I have some defective battery packs or are they not charging all the way to full even though the LED goes solid green?

[raceamerica]

I usually charge the USB batteries to full before I put them away between races. When there is a long time between races (6-8 weeks) I noticed some of the batteries loose charge and the LED lights yellow while others light green. Do I have some defective battery packs or are they not charging all the way to full even though the LED goes solid green?

First point, Lithium batteries should be stored in their lowest charge state and only charge the batteries before use. Lithium chemistry is always active so a charge loss when idle is normal and very different from SLA or alkaline chemistry which are only active when in use. This is one of the reasons Lithium is so efficient storing higher charges in a smaller package,

NOTE: charge loss decreases with charge level so a fully charged Lithium battery has a higher charge loss rate than say a 30% charged Lithium battery. The lower the charge rate when idle, the lower the charge loss rate when idle. Not to say the charge loss is massive, it is small but an idle Lithium battery left for 4-6 weeks will not be fully charged when put in service.

Second point is the LED indicator. This is not an exact science meter so some batteries will show yellow at 50% charge and others will show yellow as high as 75% charge. However, the flashing red is most consistent indication with 10%-15% charge remaining.

Also, a Lithium battery should not be left on the charger overnight since many chargers will continue to trickle charge the battery even though it indicated solid green. This can result in an overcharged battery which will damage the Lithium chemistry over time and slowly decrease the full capacity of the battery pack. This is something RaceAmerica was very aware of when designing the 5500 Desktop Battery Charging Station. Batteries can be left in the 5500 Desktop Charge Station overnight due to the charger stops charging when it senses low charge into each battery.

[Croston]

After how many hours of over-charging does the battery get permanently damaged?

[raceamerica]

After how many hours of over-charging does the battery get permanently damaged?

There is no easy measure of wear on Lithium battery cells. When a Lithium battery cell is fully charged, the really good charge circuits will disconnect the charger from the battery cell or limit charge rate very low, like 1,000 times smaller normal charge rate. When charging from a PC or multi-USB port unit, the charge does not fall off when fully charged and continues to trickle charge at a rate 1/10 of normal charge rate. This type of long term charging will slowly damage the Lithium over time. Best is to disconnect the charger when the battery's charge circuit indicates fully charged.