Connection between Battery Pack, System Load and Charger

[cube007]

Hello,

I'm designing a little battery application which will be powered with 2 Li-Ion cells. The charger for the battery pack should be on board. I found a lot of information about chargers from www.linear.com, www.national.com, www.ti.com and www.maxim.com. But I didn't understand one point. What is the general connection between battery pack, system load and charger?

These are my questions:
1. Could I connect the charger and the load parallel to the battery pack?
2. -> is it possible to drive the load when charging?
3. Does the charger have to be between the battery pack and the system load?

Best regards,
Cube007

 

[beuch]

Hi,

The load can be supply when charging if the battery voltage is enough.

The charger is directly connected to the battery.

bye.

 

[jzo777n]

Yes, You could do that, but you must consider two things

1) If the charger doesn’t compensate for the load current, the charge time is increased.

2) If the battery is very depleted i.e. < 3.0V/cell , many of the chargers use a trickle current at the beginning of charging. The trickle current is not usually sufficed to drive the load, so it must be disconnected under this phase.

Another solution is to have a power mux that connects the load to the battery or to the external charger supply.
TI, Siliconix and others makes this type of IC.
One of the drawbacks is that the voltage regulators may not be able to withstand the external voltage if for example somebody plugs in a power supply with higher voltage.