User's Guide

UC864-E-AUTO / AWS-AUTO Hardware User Guide

1vv0300795 Rev.11 – 2010/11/18

typically 10%. When this happens, the pulse charge stops and eventually the

maintenance starts.

The last phase is not properly a charging phase, since the battery at this point is fully

charged and the process may stop after the final charge. The maintenance charge

provides an additional charging process to compensate the charge leak typical of a

Li-Ion battery. It is done by issuing pulses with a fixed time length, again few

hundreds of ms, and a duty-cycle around 5% or less.

This last phase is not implemented in the UC864-E-AUTO / AWS-AUTO internal

charging algorithm so once-charged battery is left discharging down to a certain

threshold. It is cycled from full charge to slight discharge even if the battery charger

is inserted. This guarantees that the remaining charge in the battery is a good

percentage and that the battery is not damaged by keeping it always fully charged

(Li-Ion rechargeable batteries usually deteriorate when kept fully charged).

Last but not least, in some applications, it is highly desired that the charging process

restarts when the battery is discharged and its voltage drops below a certain

threshold. This is typical for the UC864-E-AUTO / AWS-AUTO internal charger.

As you can see, the charging process is not a trivial task to do; moreover all these

operations must start only if battery temperature is inside charging range, usually

5°C - 45°C.

The UC864-E-AUTO / AWS-AUTO measures the temperature of its internal

component in order to satisfy this last requirement. This not exactly the same as the

battery temperature but in common use, the two temperatures must not differ too

much and the charging temperature range must be guaranteed.