Re: gEDA-user: design problem question

[Bob Paddock <bob.paddock@xxxxxxxxx>]

On Thursday 19 July 2007 12:59, Jonathan Starr wrote:

> Each "battery box" is going to consist of four 12V packs wired in
> parallel. One complication is that there needs to be a microcontroller
> and circuitry to perform battery monitoring and protection.

Take a look at the AVRMega406.

http://www.atmel.com/dyn/products/product_card.asp?part_id=3587

Absolutely stay away from Application Note *AVR450* that you may
run across for use with anything but Lithium batteries.  The 406 examples
had a few problems of its own as well.

> Additionally, another complication is that the packs need to be charged
> in series at 48V. 

I've had the miss fortune of having to do something similar.
It can be done with a few diodes and a few FETs to switch between
parallel and series.  Look up the TI UC3906, and UC3909, and  related application
notes at http://www.ti.com for background on charging lead acid batteries.

> Basically, the problem is that I lack a background in power electronics.

Be careful, there is far more energy in batteries that most people realize,
treat them with a lot of respect.

Stating clearly your requirements always makes a project go smother.

> I apologize if this is an inappropriate place to ask this question, but
> finding help is part of my difficulty. :) Thank you in advance for your
> help!

We are all happy to help, we are however reluctant to do a students
homework assignment.


-- 
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 http://www.softwaresafety.net/ http://www.designer-iii.com/
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