EG4 Life Power4 Li Ion batteries start up , more batteries for bigger loads ?

[WiredSmart]

Does the quantity of batteries connected up in parallel affect the start up of a load (say a compressor )

I watched a video    on someone connecting multiple batteries in parallel and testing what happens when you add  too few batteries the load wouldnt even start up

I assumed that a large load (compressor) would run on a single 5.2 kwh li ion battery at least for a short time . However in the video link here shows that the load simply would even turn on without connecting enough batteries in parallel.  Since the battery voltage is the same why would a compressor not run for even a short time?   

 . My limited knowledge of batteries are as follows:

1)Batteries connected in parallel increases "the time" or the amp hour capacity
2) Battery voltage stays the same

link of test can be found here

 








fast forward to 6min approximately to skip time.

[Kean]

The key term is "inrush current" which he mentioned at around 6:45.
Paralleling the batteries as shown doesn't just increase total run time (amp hour capacity) but also instantaneous current capacity.

This kind of question would be better posted in the Renewable Energy section of the forum.

[WiredSmart]

Thank you for your valuable feedback, I'm still new to the site , i have a lot to learn on how the site functions as well as inrush current haha .

Since inrush current is something I've overlooked, could you provide me with some pointers/ formula of how i can go about calculating the minimum amount of batteries needed to cope with the  inrush current . Youve just added a new dimension i need to further develop  my understanding around this topic .

I'm looking forward to hearing from you again.

[Kean]

The need for the pre-charge circuit in the batteries that he discusses is because of the inrush current of the inverter.  I believe he even demonstrated this in the video when talking about proper power on procedure.

Further, even when the proper procedure is followed and the compressor load is turned on, there is effectively another inrush current event which trips the fault detection - thus the alarm condition.  With more batteries in parallel the inrush load is shared between the batteries and thus doesn't trigger the fault detection or alarm.

You should be able to find plenty of info about inrush current via a search here and on the internet in general, but the best advice will be from the suppliers of the batteries and inverters you are working with.

Another related term for batteries that you might want to research is "internal resistance".  There are many other installation and usage related factors that come into play as well, but these are probably the main ones.