Lee, the DC/DC is connected to an always hot 12vdc source in the power distribution block in the truck.
The main DC/DC that down converts from the traction pack 320vdc to the 12v aux system is a Ford/Lambda unit from the old Ford Ranger EV program, good for 100amps from 180v to 385v input and backed up with four 10ah headway cells in series so I don' think I have fading problems with the 12v input to the emeter DC/DC. The emeter DC/DC is a Datel UWR-12/250-D12 isolated 12v (9v to 18v input range) to 12v converter good for 250ma max and with an output regulation of 0.5%. The emeter seems to have the internal EV filter. There is a very large electrolytic cap stuck to the top of the controller IC with foam tape that looks like the 1000uf 35vdc part you describe. I think that the problem may be the DC/DC converter itself. When I measure its output voltage with the Emeter display sleeping, only the bar graph lit, and with a flashlight on the light sensor, I read an input voltage to the emeter of 11.1vdc. If I wake up the display, the digits showing 333 (traction voltage), the input to the emeter falls to 10.2vdc. Looks to me as if the emeter DC/DC can't supply enough current to drive the emeter, or it is failing. This part is from the early '90s when the truck was first built by USElectricar. It may be that noise on the voltage sense lines coming back from the traction pack is propagating to the output of the DC/DC, shutting it down momentarily. It uses a fold back output protection scheme with auto restart. thanks for the insight. Paul Wallace > Date: Thu, 24 Oct 2013 22:53:15 -0500 > From: Lee Hart <[email protected]> > To: Electric Vehicle Discussion List <[email protected]> > Subject: Re: [EVDL] Anyone have issues with Emeter resetting with > noise from controller > Message-ID: <[email protected]> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Paul Wallace wrote: >> My Link-10 is going through a reset at random times when the inverter >> is switched to drive. I've looked down to see the display switched >> to blinking volts more than once. > > This is usually caused by the Link-10 momentarily losing its 12v power. > If the power dips below about 10.5v, the display blanks. When the power > goes back up above this, the display will be blinking and it will have > lost certain values (like amphours). > >> The Emeter is powered by an isolated DC/DC converter. > > Where does this DC/DC converter get its power? From the car's 12v > system, or from your DC pack voltage? The pack voltage probably dips > under load. This dip either directly makes the Link-10's DC/DC drop out, > or it causes the car's main 12v DC/DC converter to momentarily sag, so > the 12v falls, and this makes the Link-10's DC/DC sag. > >> I wasn't anticipating too much noise would make it through at a >> magnitude great enough to cause this sort of problem. The current >> shunt wires are twisted together from the shunt until they reach the >> Deutch connector, along with the voltage sense wires. > > The shunt, and the prescaler wiring won't cause this sort of reset > problem. They can make the display blank; but they won't cause the meter > to reset and forget the amphour reading etc. > >> Since the front panel says Link-10, I'm thinking that it should have >> the EV filter already installed. Has anyone added extra filtering to >> mitigate noise getting into the E-meter? > > It may, or may not have the EV filter inside. Physically, the filter is > a 1000uF 35vdc electrolytic capacitor across the Link-10's power input, > plus a 1N4001 diode and 3.3 ohm resistor in series. Bad ASCII schematic > (view with fixed width font like Courier). > > +12v power____|\|____/\/\________+12v power to Link-10 > from DC/DC |/| 3.3ohm | > 1N4001 resistor _|_+ > diode ___ 1000uF 35vdc capacitor > common________________________|__common (NOT ground!) > > Without the filter, it only takes a few millisecond power dip to reset > the meter. With the filter, it takes more like a half-second power dip. > > You can add this filter externally yourself. It won't hurt to add it > again, even if it's already inside. A schottky diode (1N5818 etc.) is a > slightly better choice than the 1N4001. There is no upper limit for the > capacitance; bigger is in general better. > -- > Any intelligent fool can make things bigger, more complex, and more > violent. It takes a touch of genius, and a lot of courage, to move > in the opposite direction. -- Albert Einstein > -- > Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.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)
