[ausev] Iota converter

[Brian Lasseter]

On Tue, Dec 29, 2009 at 7:32 PM, Joseph Kroesche <joe at kroesche.org> wrote:
> Anyway this question about the DC-DC converter raised some questions in my mind about the best way to deal with the 12V system.  The "Safety First" page says you need a 12V aux battery regardless so I was thinking I would just use a 12V car battery for that and not need a DC-DC converter.  My thinking was that the aux battery would last as long as the traction battery and I would just recharge both at the same time.  Is this arrangement common or feasible?  Do you tend to discharge the aux battery too fast if there is no DC-DC?


The answer to this question depends on what you are powering at 12V.

George Mullins who is planing on buying the DLS-30 to power his
headlights and radio might could get away with it.  Headlights are
usually 100W, and a car stereo is 50W at full volume.  So, George
could probably get away with a regular 170Ah 12V car battery... that
would last him only an hour... and then the 12V battery would die.
There are trade-offs here though.  A 170Ah 12V car battery would
likely weigh over 60lbs... the DLS-30 would be much lighter.  Also...
once the 12V battery dies, it would turn off any contactors, and your
car would just shut off... no matter how much power you had left in
the big battery pack.  (Having to jump start your Electric Car is just
embarassing...)

In my case... I have a 12V power steering pump that will pull above
480W when my steering wheel is fully to one side or the other.
Therefore my power needs were above any reasonably sized 12V battery,
so I have a 45A Iota DC-DC converter with a small 15Ah 12V motorcycle
battery.  (In reality, I probably need a larger DC-DC converter since
my headlights noticibly dim when I turn my steering wheel fully to one
side or the other.)  Also, my DC-DC converter is "always on", thereby
charging the tiny 12V battery once I get home and shut my electric car
off.


-- 
TTFN,
Brian "Lasso" Lasseter

"No Sane man will dance."   -Cicero (106-43 B.C.)