FreeLists / 18650 / [18650] Re: Questions of Current Design (6/28/04)

[1davide@xxxxxxx (Davide Andrea)]

> 
> 1) Temperature sensor on PCB? 
> Since the power resistors are also on the PCB, wouldn't this affect the 
> temperature of the PCB? I would think a remote temperature sensor embedded 
> in the module would be more accurate. 

Yes, I considered that. 
1) I assume that the resistors won't be On but in special cases, and then we'll 
know not to trust the temperature reading
2) If fit snugly against a cell, the sensor will sense that cell's temperature. 
Now, if that temperature increases because of the shunt resistors, then that 
still is that cell's temperature
3) The resistors dissipate only 2 W, which won't heat-up the cells that much (I 
assume)
4) The ease and reliability of having everything on one PCB was for me the 
overriding factor; everything else is just me rationalizing ;-)

> 2) ICSP ? which programmer? 
> I do not have a in-circuit programmer and plan to get one. Which one 
> are you using and which one you recommend? 

The EPIC. It's OK, cheap, decent software. I'm looking to get a USB ICSP, much 
better. It's what my German partners are using, made in the Check republic. But 
I have to import it. I'll send you a link later.


> 3) 2.048V ref might be better? 
> I think a 2.048V reference voltage would put us closer to the mid point 
> of the ADC range. 

I'll look into it. Not much difference. I'd decide based on accuracy. I'd think 
that 2.5 V is a bandgap volatge, and therefore inherently better. I'll let you 
know.

> 4) Why ground pin 10? 
> Why is pin 10 on U1 (PIC) grounded? 

PCB layout reasons. Otherwise I'd need a bridge. (It's a single sided PCB).

Davide