More than likely, the old battery developed a shorted cell, so it was a 10V battery (5 cells) instead of 12V. That would explain some things no longer working or being much dimmer. The high current from the Iota will then over-charge the 10V battery, causing all the good cells to heat up and cook away after a couple hours. if you want to protect from it, it might be good to install a temp monitor on a battery terminal so it detects unusual heating and stops the DC/DC.
Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: [email protected] Private: http://www.cvandewater.info Skype: cor_van_de_water Tel: +1 408 383 7626 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Robert Elton Sent: Monday, November 25, 2013 2:27 PM To: [email protected] Subject: [EVDL] DC-DC to house battery question 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 FX: 02 4341 1578 MB: 0409 834 837 VOICE message (saved to file) 02 4341 1578 <http://www.freetimefinance.com.au/> www.freetimefinance.com.au R Elton Investments Pty Ltd T/A Free Time Finance ACN 126 038 462 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20131126/a02d 23be/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
