PPRuNe Forums - View Single Post - 787 Batteries and Chargers - Part 1
View Single Post
Old 27th Jan 2013, 15:47
  #192 (permalink)  
syseng68k
 
Join Date: Jun 2009
Location: Oxford, England
Posts: 297
RR_NDB

Question: How many amps the thin white wires could carry without being transformed in fuses? 1 amp? By pass?
From the image, it looks like those cables are 2-5A rated, but difficult to say
for sure.

There's no sign of power semiconductors and heatsinks on the pcb's though, which
mitigates against the idea of cell balancing electronically. Power dissapation is related
to voltage and current. Consider the following:

Fast charge rate: 65Ah / 1.5hours = 43 Amps + say 10% for losses = 47 Amps,
Say 50Amps absolute max.

Balance current 5% of charge current worst case (from saptzae) = 2.5Amps

Cell voltage = 4.2V max

So, worst case power dissapation in the bypass circuitry would be: 4.2 x 2.5 = 10.5W, per cell.

You would need 8 power semiconductors for the whole battery, together with associated heat sinks and there's no evidence of this on the pcb's...

Just to complete the loop on voltage sensing, you would need 2 sensing wires
per cell, or 16 wires total for 8 cells...

Regards,

Chris
syseng68k is offline