First I would replace the fuse so the circuit is working again, per benchtop mode.  Oh, you *did* put a fuse in there right?  On both sides?

I believe it was suggest about putting a current limit, or maybe even a soft start feeding it from the solar panel.  Linear Tech makes a nice 48V hotswap controller that acts like a soft start, and will shut off the FET when the voltage drops below a set threshold.  

It wasn't clear about what wire you attached where, so assumption is you are taking the input from the solar panel to boost for the battery, so was it connected to the solar panels and then it went sparkly when connecting to the batteries?  I think Olin or someone mentioned about monitoring the current, you will want to do that so you don't cook the batteries, and also monitor the voltage on them as well.  Your first attempt is a rather brut force method, but there is alot more to doing a charging circuit than just giving the batteries 52V for a period of time.


--- On Thu, 8/14/08, Matthew Miller <namiller2@naxs.net> wrote:

> From: Matthew Miller <namiller2@naxs.net>
> Subject: [EE] Need advice on a boost converter for charging batteries.
> To: "Microcontroller discussion list - Public." <piclist@mit.edu>
> Date: Thursday, August 14, 2008, 9:28 AM
> Hello,
> 
> I posted about this a while back and this is a bit of an
> update. I have an
> electric golf cart that has solar panels mounted on top the
> canopy. The
> solar panels produce about 15V under load and the lead acid
> battery pack has
> a voltage of 48V. My problem is to raise the panel voltage
> in order to
> charge the batteries.
> 
> My first attempt was to build a boost converter using the
> LT1680
> controller. I built the typical application circuit that is
> in the device's
> datasheet and under workbench tests it operated fine, with
> the exception of
> a bit of audible noise. The web page for the LT1680 is
> here:
> http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1042,C1031,C1115,P1597
> 
> My trouble is that I connected the converter ground to the
> battery pack and
> then when I touched the positive wire to the battery
> terminal there was a
> big blue spark and now the converter is no longer working.
> :( I haven't
> repaired the converter yet, but I'm wondering if the
> converter design I used
> is appropriate for this application?
> 
> I would appreciate any suggestions, insight, or questions.
> 
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