Lee, very strange circuit topology for the implementation of the DC/DC in the USElectricar with the Datel DC/DC. The DC/DC input has a fuse added, that looks good. The output, however, is very strange. the common output pin of the DC/DC goes directly to the Emeter negative lead. The positive DC/DC output pin is routed through a diode, and then two 5.1ohm resistors in parallel (2.55ohms) and finally to the positive input of the emeter. There is also a 1000uf 16vdc electrolytic cap on the output. No wonder I see such odd input voltage to the emeter when it is drawing current. The diode drop alone is at least 0.6v.
Paul Wallace > 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)
