Hi,

I have an Iota DL-55 that provides the 12V required for the normal
operations of the vehicle.

Car is a 1994 Honda Civic. Dc conversion 48 Thundersky 100ah 154volt.
Running a 11" Netgain using a 1K Zilla. Controller. The charger is an Elcon.
There is a main contactor at the pack and the usual one to engage the motor

The dc-dc is OFF when the vehicle is off. When opening the fuel door a
switch operates a relay to engage the pack contactor to close the circuit to
the charger.

The house battery is an AGM Odyssey PC680. 

This vehicle has run faultlessly under this configuration for 3 years.

 

The problem: Discovered the 12volt house battery melting down after two
hours of the dc-dc being engaged (vehicle on charge) The battery was cooking
- spewing suplfuric acid which had condensed across the underside of the
bonnet. Luckily no fire.

 

My novice understanding is that this is known as a thermal runaway and a bit
scarey too.  In retrospect I recall the trip prior to this, that there were
are few unusual behaviours with the 12 volt system in that the electric
power steering pump didn't start up (which I assumed I'd blown a fuse or had
a bad connection). I also recall that there were signs that the 12volt
battery may have been in the early stages of wearing out, for example the
interior light in the car would go noticeably brighter when the dc-dc was
engaged.

 

Could it be that I have had an almost flat 12volt battery (not flat enough
to switch the main contactor relay) that was no longer holding charge
particularly well,  that I have then applied the full 13.5volt to which
somehow has started off the thermal runaway??. When I hastily disconnected
the melting battery I noticed the negative terminal was loose, but it's hard
to say if that was a result of the meltdown.though I expect not.

 

Perhaps someone can give some feedback as to the correct set up for the
dc-dc or what protection mechanism I should put in place. For fitment
purposes I have replaced the PC680 with the same kind, so if the answer is
to use a SLA battery then that is the less preferred solution. I am using
the vehicle but continually check the battery temperature when charging
until I can sort out a fail safe solution.  Any assistance would be greatly
appreciated thanks. 

 

Kind regards,

 

Bob 

 

Australian Credit Licence Number 386632

Free Time Finance

 

PH: 02 4341 8445

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R Elton Investments Pty Ltd T/A Free Time Finance ACN 126 038 462

 

 

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