User manual

Irrtümer und Änderungen vorbehalten

II. Nickel Cadmium / Nickel metal hydride batteries

The charging procedure for Nickel batteries follows an

I-U characteristics with automatic stop when the battery

is fully charged. Also see gure below.

The rst charging phase is a precharge phase with

reduced output current I

. The precharge is very ef-

fective for heavily discharged batteries, providing the

possibility to prepare them gently for the charging.

After the charging voltage has risen to U

PC,END

or time

PC,END

is exceeded

the device changes to boost

charge with current I

CHARGE

. During the boost charge

the battery voltage will continuously rise. The highest

measured value serves as as reference for the determi-

nation of voltage difference ∆Ua. This difference results

when the battery voltage sinks again at the point where

the battery is fully charged. If the dened value ∆Ua is

exceeded, the battery is considered as fully charged

and the charging stops automatically.

Functional description

When charging Nickel batteries, the battery tempe-

rature is very important and has to be supervised.

Changes of the battery surface temperature may not

exceed a certain level. Thus is imperative to use and

install a temperature sensor. At the start of the charging,

the start temperature is measured. If the temperature

difference exceeds the value ∆T a,max or if it rises

within a minute so that value ∆T/∆t a is exceeded, the

charging is aborted. The battery capacity is additionally

supervised. A premature abort will happen if 1.3 Q is

reached for any reason, i.e. 130% of the battery capa-

city. Given, that the battery capacity was correctly set

in the battery prole, this will prevent the battery from

overheating.

Attention! In case the charging is started without

temperature sensor, there can‘t be a temperature-

depending fast charge with high C value.

Figure 2. Charging characteristics for Nickel batteries