5.4. Current and Power Limitations
Load Limit: 3A and 45W
The UBA can discharge at up to 3A per channel, with a maximum dissipation of 45W. During discharge, the UBA
converts the battery current into heat which it dissipates with its chassis. The power is limited to 45W per channel to
prevent over heating the chassis and load transistors. The UBA's internal fan turns on at a power dissipation of 10W
on either channel.
Thus for batteries 15V and lower you'll be able to use the full discharge current of 3A. For batteries higher then 15V the
UBA will reduced the current to keep within it's 45W maximum.
If you want a higher load current, then combine both channels (see the section UBA Accessories - Channel
Combiner) or use a series power resistor (contact us for more details). Don't worry about damaging the UBA from
over-current or over-power as UBA Console automatically limits the current to safe values.
Charger Limits: 2A (and 28W internal dissipation)
The UBA can charge at up to 2A per channel (power supply permitting). It uses a low noise linear constant current
charger that drops the voltage from the power supply to your battery. The difference between the power supply
voltage and the battery voltage is absorbed by the UBA's charger. The power is limited to 28W per channel to prevent
overheating the UBA.
Thus, when charging a single cell, the UBA might limit the charge current. For example if you have a UBA5GP with a
19V power supply and you want to charge a single 1.2V cell at 2A, the UBA would have to dissipate about 35W ((19 –
1.5V) x 2A). This is worst case, it's actually less than this as any wiring would drop the power supply voltage. So in
this case the UBA would reduce the charge current to about 1.7A. If you want to charge single cells or low voltage
battery packs at high currents then either combine two or more channels, use a lower voltage power supply (but not
less than 15V), charge the cell in series with other cells or add a resistor in series with the cell (contact us for more
details).
The UBA Let's Get Started Guide
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