Jim is on the right path, but there is more: - DC/DC may see too little input voltage OR it may see so much high frequency noise, that its output voltage comparator gets offset by (rectified) noise and tells the DC/DC to lower the output voltage. - or your measurement of output voltage is somehow off, due to currents or noise when the Zilla is delivering power... Cor.
-----Original Message----- From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of jim--- via EV Sent: Thursday, April 26, 2018 7:51 PM To: Electric Vehicle Discussion List Cc: j...@k6ccc.org Subject: Re: [EVDL] Weird DC-DC problem Yes, part of that does sound like a REALLY trashed 12V battery. The other part is a guess that when the Zilla draws a lot of power, the HV battery pack is sagging enough that the power supply is at least partially shutting down. What is the power supply and what is the power that it's getting supplied with? Jim Walls -----Original Message----- From: "John Lussmyer via EV" <ev@lists.evdl.org> Sent: Thursday, April 26, 2018 19:44 To: "Electric Vehicle Discussion List" <ev@lists.evdl.org> Cc: "John Lussmyer" <cou...@casadelgato.com>, "SEVA" <seva_l...@googlegroups.com> Subject: [EVDL] Weird DC-DC problem I have my F-250 back on the road after some (long drawn out, time wasted) repairs to a motor terminal, and rebuilding the transmission. (and exploding a contactor...) I'm getting some really WEIRD results with my DC-DC. (ok, power supply) It's capable of 50A output, and is set for about 14v output. When I start the truck, it zooms up to around 50A for a few seconds (probably trying to top off the weak 12V battery), then gradually drops down to 25A or so for the trucks basic needs. All this time the voltage sits at around 13.9V. Then I start driving, as I have the Zilla start pulling significant power - the DC-DC output voltage drops, sometimes as low as 11v. The REALLY REALLY weird bit is that it's still only supplying 25-30A. If I take my foot off the pedal, the voltage shoots back up to 13.9v. Right now, I'm assuming the (nearly dead) 12V battery is the main issue - but shouldn't the DC-DC start pumping out more current when something is drawing down the battery like that? Also, since the Zilla doesn't actually use more 12V power, it makes no sense. The voltage drop does seem to be kind-of in proportion to how hard i'm pressing on the accelerator pedal. (I should also note that my Tach Sensor seems to be not working correctly, as it's readding way low - and not fully consistent. So probably having noise problems on the signal or power lines. Gonna try replacing the capacitors on those.) -- Worlds only All Electric F-250 truck! http://john.casadelgato.com/Electric-Vehicles/1995-Ford-F-250 _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at 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 Please discuss EV drag racing at 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 Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
